I love how you can get inside this thing, in like 2 seconds. It's not a bunch of janky clips or tabs, just a couple screws and you're good to go. Simple and straightforward.
I've got a dual output version of this, talk about bulletproof power supplies. They might be from the 60's but I think the things can outlive me 2 times over still! Say that for the electronics these days.
This is a beautifully made unit with much care given to design and construction. A friend at work built a miniature version of this supply and it had meters for V and I and two smooth vernier dials. Nice to use.
It's lovely to see that old wiring style when so much care went into it. Don't see those bifurcated terminals very often now, just occasionally on really high-reliability kit.
In my hammond M3 (and pretty much every Instrumentation Amp made prior 1970) it´s the same, not all the way but on some points they used to solder 2 components on the upper and 1-2 on the back(lower side)...and with all these little cables it´s by far more complicated to do some replacements...As all wires had to come off prior to flip the component board, to gain access to the lower side...
I just bought one month ago a Fluke differential voltmeter. When I started to do repair and calibrate back to origin specs, I realized how something with this precision can simple like this. The engineers in this days use the brain. All the parts are not more than 60 pieces. So I learn this and now I start to design some audio analog processor with same method. I suggest to everybody buy some old gear even if is not working and do a tear down. All of this old gears made by hand and hand selected parts. Also the mechanic solutions like somebody build for make sure will work until the Sun will eat the Earth. Lot of fun inside this gears. Nice video Dave. Thx!
Classic test gear really pushes my buttons!! The build quality and construction is a joy to behold. Proper metal chassis, purposeful controls, superb attention to detail, it all makes me warm and fuzzy! New stuff may be feature laden etc but it won't be here after the same time that this has survived. More of this please Dave!
I have one of these units as part of my workshop...still working spot on. Thanks for the video on this. I wish I had a schematic for mine, I suppose I need to search for one.
2:42 - As soon as he started turning the current limit knob, I knew by the sound it made that it was absolutely top quality. That's not just any old potentiometer; it's wire-wound, which is probably the best there is.
That is correct. While turret board have a few styles, this style was common in amplification circuits. The other common style of turret boards have "posts" that look a bit like wire wraps with a cap on top. These are VERY common in military applications and still in use/manufactured today for the repair of military grade vintage hardware (that does not have a cost effective replacement). I cannot give any examples due to NDA stuff, but suffice it to say that they are for amplification/power delivery setups. I worked on this stuff in the military and loved it when I got the chance to see them.
Do they actually drift up or down? Can't find a straight answer anywhere, I have a circ. 1960's record player with a resistor that smokes, cant find anything wrong with it apart from maybe a resistor has drifted massively
dannysanchez7924 They drift up. Very rarely do they drift down. Only time I have seen it is if there is arc-over in the resistor itself and it can cause a lower resistance. But for that to happen you would have to be grossly overvolted. I have worked on tons of tube and early solid state gear, smoking resistors indicate a short somewhere. either at the electrolytic capacitors, or the tube is drawing too much current.
thanks for the info :) gonna look for shorts next time I have a go at mending it, don't think the tube is causing the issue as the smoking resistor isn't part of the heater circuit, too bad the resistor is too old and charred to see what value it is (was) haha
dannysanchez7924 Go to jestineyong.com. Click on e-book store. Scroll down to the book, "How to find the value of burnt Resistors". Then you can find the value of it. I have the book, and I've tried it and know it works.
Robert Calk Jr. Do you think they're going to interfere with the voltage regulation? Though low-quality caps are a thing of the last decade. 90s and earlier had good quality caps, lots of stuff from the 70s and 80s still running stock all over the world
I've got a very similar model (PD2010, same front panel and specs but 1A output) which is RIGHT on spec, even after all these decades. Bought off ebay and no adjustment needed, though it could probably use some new caps eventually. Maybe whoever owned it last took good care of it.
Probably the quickest fix would be adding resistor in series/parallel on that potentiometer and changing its max/min value so that you get ~150mV down in range, and you can fine trim it later with back pot. Strange Dave didn't do that, takes about a minute, maybe it will be in another video. But otherwise great video as always!
EEVblog You have my vote for a calibrating video. Thanks Dave for a peek into the past. The point to point with eyelets kind of reminds me of the island pad pcb construction boards. Interesting.
awesome bit of kit! You should throw some new caps and resistors in for giggles and see if it comes back to life. Equipment of this quality deserve to live on :)
Beauty that Dave. Please do bring it back into cal. Something that nice needs to either be on display somewhere or in use by someone who appreciates it.
I have an hp6111a from the late'60s with thumbweel adjustments . It has 100uV resolution an is still spot on .Good enough to check the accuracy of most of my DMMs! Btw. Modern voltage refs are still temperature controlled ,for example the LM 119 family has an on chip heater! The hp6111a has the reference and diff amps all ovenized!
I was only 4 years old when the power supply was manufactured. I would love to see more, because it looks like the same as the first transistor electronics I designed as a teenager in the late 1970s, and improved later when I got to know the 741 ic. after that, my cheap analog multimeter no longer sufficient to measure the improvements. Try to zero trim using the R39
I fondled one of those at the Orlando Hamfest. Build quality was instantly apparent. I vaguely recall the guy asking a small fortune for it. (otherwise it would be sitting on my bench right now. lol)
The remote sensing in this case refers to a 4 wire method to ensure that there is no loss of precision due to copper losses in the wiring between the power supply and the load!!
I would love to see you get this beautiful old supply back into calibration, Dave. Vintage electronics are awesome, and this old supply deserves to be put right. Perhaps a shiny new set of caps? By the way, the company that made those old caps, Sprague, is not pronounced like "sprog", it's more like the word "spray" (long A) with a g at the end, all one syllable. In case you're curious how I know, I live 30 miles from their old plant, and I spent 3 years working side by side with a guy who used to be their plant engineer. If I had ever pronounced it as "sprog", he probably would have smacked me with a wrench.
Power Designs made some very good supplies. About a decade ago I picked up a 0-20v dual supply (2a each) and it was made like a brick shit house, a lot better then anything made today. I got it dirt cheap and all it needed was a new DPDT toggle switch, once that was replaced it worked just fine. They are definitely old school but they are solid power supplies.
It's called an "eyelet board". It''s kind of weird though because on the other side it looks like a "turret board". Usually you have one or the other but here it looks like they've made the turrets hollow. This is like 50's style circuit board design before solid state components ushered in printed circuit boards which could be more compact because of smaller components and more complex circuits in a given space. These old school electronic devices are like the muscle cars of electrical design.
Dave you have to bring this classic back to spec. It would most likely be one of your most reliable power supplies on your bench. I be curious what the ripple voltage is once you recap the pws
It looked like you were adusting the trim pot on the underside while the granular pot on the front was in the 12 oclock position. It seems like the front pot should have been turned to the left to zero when you made the adjustment on the bottom.
Wouldnt it be easy to bring it into spec by just adding a resistor in series or in parallel with the adjustment pot? I personally am certainly interested in a follow up video!
I love old circuitry, like when I see thoughs brown resistors. Most electronic design concepts haven't changed a bit. But they did do a few things differently back then, design wise. Quite interesting.
Dave, the Voltage offset might be that the Oven/Thermostat/Heater circuit is wonky/ stuck always on or off. The neon bulb is across the heater resister that is series with the thermostat and that goes right across the mains/line/120 VAC. The thermostat might be stuck. You might try driving the heater circuits 120 VAC input with a variac and drop the mains voltage to see how this moves the Supplies DC output voltage around. The thought is the thermostat is stuck on and the heater thus always on and thus the reference Zener is too darn hot.
11:12 That's not a bodge; that's how you soldered a bypass or snubber cap back in the day. We call this "flying lead wiring"; you can still see it in modern valve guitar amps, especially in the booteek market.
R80 is just screaming to be replaced with a nice ~200ohm pot (adjusted via a talented and angled tongue of course). I'd love to see this thing back in spec with all the dried up caps and all intact :D
The 'upside-down' schematic could be an indication that it is is primarily a germanium-transistor circuit. Very common to see these drawn with earth at the top and a negative rail underneath. The whole thing looks upside-down if you're used to looking at Si-based circuits because you have PNP where you would expect NPN and vice versa.
yep i'd love to see a video of you trying to bring it back to spec. I figure you could bodge on a resistor in series with one or both of those trimmer pots you were fiddling with. I'm assuming you were *adding* more resistance as you turned the pots since you were trying to lower the voltage down, so that's why I'm assuming you should bodge a resistor in series.
One way of troubleshooting this PS is to assume that someone either plugged it into a 220 volt socket, or they overloaded the current. I think EEVBlog has to tools to check the main transistor, and the input protection circuits.
AT 15:20 those tiny little diodes. Why is the right hand one's leads bent to make it slightly lower than the left hand one? Can't get them to close to one another for some reason? As Dave would say, "Hmmmmmm". Love those pastel colored transistors!
I have noticed the "regulate the ground side" on a lot on 1960s broadcast video gear (my vintage interests). They had good NPN power transistors then, like the famous 2N3055 so I don't know why they used this odd configuration in commercial designs? Was there some subtle benefit? Also note the rotary switch wafers are made from FR4 or G10. Not the typical pressed Bakelite junk found in consumer gear of the era.
The Darlington pair is actually a Sziklai pair.Well, they are sometimes called a complementary Darlington pair. The Sziklai pair uses NPN and PNP transistors.
I was actually going to say eyelet board (Fender used them a lot in their Tweed amps) but you're right, the turrets on the other side make it a turret board. (Eyelets and turrets are both old-school approaches to what eventually became plated-through holes and vias.) Strange that they just soldered everything on the turret side rather than filling the whole turret with solder.
The PNP pass transistor with all the regulation on the low side is a huge clue to me. It tells me that it's probably a Germanium transistor instead of Silicon. Ge was apparently easier to make in PNP and as such, all the Ge circuits are arse backwards compared to their Si counterparts. You should have seen the look on my face when I found my first Ge transistor based amp after messing with countless Si based circuits. Test the Vbe drop...If it's around 0.3V, you will know it's Germanium. The loss of cal is likely caused by carbon composition resistor drift. If ripple is high as well, the old electrolytic caps are almost certainly the cause.
long time since this video was published....but just seen it now and read your comment: nope, these are silicon transistors. The Vbe is written on the schematic as 0.7volt. But since it was cheaper to do pnp wafers in those days, all transistors are pnp, and the schematic is upside down (with our modern npn eyes)...
Hey Dave! How it goes?! Well, just wanted to voice my opinion once again. I enjoyed your video's but it's just too advanced for the everyday beginner like me. I commend you for being the first TH-camr to introduce me to Electronic Engineering/Design as a hobby but to be honest I need to stick with TH-camrs that are more about electronic design/tutorials for beginners. The Ben Heck Show, Afrotechmods, and other TH-camrs. So it's been enjoyable and I'll still watch some of ur video's but as I've said before, I have a very strict sub list. lol Because I pay attention to my subs watching their video's frequently rather than having 100 and not watch their video's often, making it difficult having a large sub list. Once again appreciate the introduction and I'll still be around! Thanks!
Hobo Maximus No worries. It's simply impossible for me to cater for everyone at every level, and that's the biggest problem of running a relatively broad interest channel like mine. The EEVblog was never envisioned to be a beginner/tutorial channel.
Totally understand and see how this is more useful to the advanced crowd, maybe once i learn more I'll understand you lol. I'll still be to your channel often. Just hard to pay attention to so many TH-camrs!
Any place or person specifically that you learned all of your skills and knowledge in electrical engineering? My current major is EE and I get pretty overwhelmed with all that you talk about in your videos. Thanks.
MrMac5150 I have not actually got into the meat of the program, I am only going into my second semester this fall and my first mostly consisted of mandatory but unrelated classes. I only say this because I began reading through my Intro to electronics textbook during this summer and I got a little confused just reading and practicing the concepts and formulas. Not having a lab does make understanding the practical parts a bit more challenging. Hopefully actually attending the class that the textbook is related to will increase my understanding and confidence with the field. To answer your question, a community college in New Jersey.
Your DC will be easy, but the AC will twist your head till you get the hang of it, they will teach how to break circuits down to two or three components to look at, makes it a little easier, but I can not do complex circuits my self even with the training I find that hard and not having a schematic with voltage points, I get lost too.
CaptmagiKono I may get some hate for saying this, but that's part of the major. EE is geared towards R&D, not practical designs per se. EET (Electrical Engineering Technology) is the major geared towards practical designs. It actually goes back to Sputnik and the need for such R&D... (disclosure: I'm a senior in EET @ Purdue University's New Albany campus)
This thing is incredibly beautiful. The view at 11:17 almost makes me cry because of the sheer beauty there ... This piece of equipment is 10 years older than I am myself, and I can say that it has aged WAY better than me.
Add a series resistor to the potentiometer (the wire wound one), and adjust it to bring the unit back into spec! It's a 2 minute job considering it's not surface mount. Peace
Have you checked the jumpers on the terminals on the back? That's one potential source of it being out that I would look at. Another obvious source of issues that comes to mind is any Ge components, some of them have this tendency to grow whiskers that cause them to go off-spec.
I spent a whole month of my electronics apprenticeship at GEC learning to loom properly - 1977 :) So I can appreciate the skill and dedication the assembler put in on this
I saw a screw on the bottom of the oven that looks like it will let you rotate and pull off the outside casing. Maybe there's something worth looking at in there?
It would have been really cool to see inside of that oven can, it does come off I saw a locking mechanism with a screw on the side of it. Cool stuff, would love to see it put back into specifications though.
@@AtAGlimpse_UB Whatever purpose you can imagine using an oven can for. You can oven it, you can can it, you can oven can it. The possibilities are endless.
I think a lot of people would love to see a repair vid on this :)
I love how you can get inside this thing, in like 2 seconds. It's not a bunch of janky clips or tabs, just a couple screws and you're good to go. Simple and straightforward.
I've got a dual output version of this, talk about bulletproof power supplies. They might be from the 60's but I think the things can outlive me 2 times over still! Say that for the electronics these days.
We had a bunch of those in our instrumentation lab. It was one of the few pieces of equipment we didn't calibrate ourselves.
What a beautiful looking power supply ...
Definitely want to see what it takes to bring this back into spec!
This is a beautifully made unit with much care given to design and construction. A friend at work built a miniature version of this supply and it had meters for V and I and two smooth vernier dials. Nice to use.
It's lovely to see that old wiring style when so much care went into it. Don't see those bifurcated terminals very often now, just occasionally on really high-reliability kit.
In my hammond M3 (and pretty much every Instrumentation Amp made prior 1970) it´s the same, not all the way but on some points they used to solder 2 components on the upper and 1-2 on the back(lower side)...and with all these little cables it´s by far more complicated to do some replacements...As all wires had to come off prior to flip the component board, to gain access to the lower side...
This is so beautiful... It's something else.....
I just bought one month ago a Fluke differential voltmeter. When I started to do repair and calibrate back to origin specs, I realized how something with this precision can simple like this. The engineers in this days use the brain. All the parts are not more than 60 pieces. So I learn this and now I start to design some audio analog processor with same method. I suggest to everybody buy some old gear even if is not working and do a tear down. All of this old gears made by hand and hand selected parts. Also the mechanic solutions like somebody build for make sure will work until the Sun will eat the Earth. Lot of fun inside this gears. Nice video Dave. Thx!
I vote yes for a follow up, vintage is always interesting.
Classic test gear really pushes my buttons!! The build quality and construction is a joy to behold. Proper metal chassis, purposeful controls, superb attention to detail, it all makes me warm and fuzzy! New stuff may be feature laden etc but it won't be here after the same time that this has survived. More of this please Dave!
I have one of these units as part of my workshop...still working spot on. Thanks for the video on this. I wish I had a schematic for mine, I suppose I need to search for one.
Very nice, I want one now. "You can never have too many power supplies!"
2:42 - As soon as he started turning the current limit knob, I knew by the sound it made that it was absolutely top quality. That's not just any old potentiometer; it's wire-wound, which is probably the best there is.
I believe that the circuit board is a turret board.
That is correct. While turret board have a few styles, this style was common in amplification circuits. The other common style of turret boards have "posts" that look a bit like wire wraps with a cap on top. These are VERY common in military applications and still in use/manufactured today for the repair of military grade vintage hardware (that does not have a cost effective replacement). I cannot give any examples due to NDA stuff, but suffice it to say that they are for amplification/power delivery setups. I worked on this stuff in the military and loved it when I got the chance to see them.
Also used in many classic guitar amplifier designs. Think Fender and very early Marshall.
Would definitely be interested in seeing a follow up video of bringing it back into spec :)
That is such a beautiful piece of kit. Love the controls, just sexy. Worth a recall, could probably last another 50 years!
the carbon composition resistors drift way up with time, thats likely or issue. That and the electrolytic capacitors drying out.
Would love to see an R&R on a unit like this to restore it.
Do they actually drift up or down? Can't find a straight answer anywhere, I have a circ. 1960's record player with a resistor that smokes, cant find anything wrong with it apart from maybe a resistor has drifted massively
dannysanchez7924
They drift up. Very rarely do they drift down. Only time I have seen it is if there is arc-over in the resistor itself and it can cause a lower resistance. But for that to happen you would have to be grossly overvolted. I have worked on tons of tube and early solid state gear, smoking resistors indicate a short somewhere. either at the electrolytic capacitors, or the tube is drawing too much current.
thanks for the info :) gonna look for shorts next time I have a go at mending it, don't think the tube is causing the issue as the smoking resistor isn't part of the heater circuit, too bad the resistor is too old and charred to see what value it is (was) haha
dannysanchez7924
Go to jestineyong.com. Click on e-book store. Scroll down to the book, "How to find the value of burnt Resistors". Then you can find the value of it.
I have the book, and I've tried it and know it works.
I was actually surprised that it was that close to the spec after all these years!
There's not much in it that can really drift, is there ;)
*****
E-caps...
Robert Calk Jr. Do you think they're going to interfere with the voltage regulation?
Though low-quality caps are a thing of the last decade. 90s and earlier had good quality caps, lots of stuff from the 70s and 80s still running stock all over the world
I've got a very similar model (PD2010, same front panel and specs but 1A output) which is RIGHT on spec, even after all these decades. Bought off ebay and no adjustment needed, though it could probably use some new caps eventually. Maybe whoever owned it last took good care of it.
n17ikh Either that, or the previous owner has already put new components inside!
Restore it! it would make for a cool video.
Probably the quickest fix would be adding resistor in series/parallel on that potentiometer and changing its max/min value so that you get ~150mV down in range, and you can fine trim it later with back pot. Strange Dave didn't do that, takes about a minute, maybe it will be in another video. But otherwise great video as always!
Awesome, thanks Dave. Given the lack of comments so far I guess we won't be seeing it, but *I'd* like to see a repair video on this one at least.
EEVblog You have my vote for a calibrating video. Thanks Dave for a peek into the past. The point to point with eyelets kind of reminds me of the island pad pcb construction boards. Interesting.
Please put a series resistor in with the calibration pot to force it back into spec (or, you know, troubleshoot it and find out what's really wrong)
awesome bit of kit! You should throw some new caps and resistors in for giggles and see if it comes back to life. Equipment of this quality deserve to live on :)
Yes please! I am VERY interested in seeing this being brought back to spec!
Beauty that Dave. Please do bring it back into cal. Something that nice needs to either be on display somewhere or in use by someone who appreciates it.
I was -21 in 1965! This video was just awesome!
Would love to see a follow up video putting it back into spec!
Would love to see a repair video to bring the thing back into spec. Its probably a resistor or something that has just changed value over time.
Dave, I have one of these and it works like a champ. Great bit of kit. Bob's my uncle? Fair Dinkum, and Bobby Dresler? Cheers, Mate, Confused Yank...
I have an hp6111a from the late'60s with thumbweel adjustments .
It has 100uV resolution an is still spot on .Good enough to check the accuracy of most of my DMMs!
Btw. Modern voltage refs are still temperature controlled ,for example the LM 119 family has an on chip heater!
The hp6111a has the reference and diff amps all ovenized!
I was only 4 years old when the power supply was manufactured. I would love to see more, because it looks like the same as the first transistor electronics I designed as a teenager in the late 1970s, and improved later when I got to know the 741 ic. after that, my cheap analog multimeter no longer sufficient to measure the improvements. Try to zero trim using the R39
I fondled one of those at the Orlando Hamfest. Build quality was instantly apparent. I vaguely recall the guy asking a small fortune for it. (otherwise it would be sitting on my bench right now. lol)
I love how it says "remote sensing" on the back (I'm coming from an earth remote sensing environment). :)
The remote sensing in this case refers to a 4 wire method to ensure that there is no loss of precision due to copper losses in the wiring between the power supply and the load!!
I would love to see you get this beautiful old supply back into calibration, Dave. Vintage electronics are awesome, and this old supply deserves to be put right. Perhaps a shiny new set of caps?
By the way, the company that made those old caps, Sprague, is not pronounced like "sprog", it's more like the word "spray" (long A) with a g at the end, all one syllable. In case you're curious how I know, I live 30 miles from their old plant, and I spent 3 years working side by side with a guy who used to be their plant engineer. If I had ever pronounced it as "sprog", he probably would have smacked me with a wrench.
Power Designs made some very good supplies. About a decade ago I picked up a 0-20v dual supply (2a each) and it was made like a brick shit house, a lot better then anything made today. I got it dirt cheap and all it needed was a new DPDT toggle switch, once that was replaced it worked just fine. They are definitely old school but they are solid power supplies.
it really is awesome to see how they did old electronics
Would love to see you get this beauty into specs again.
Follow-up video a must! Try and get it back in spec
This is quickly becoming my new favourite youtube channel.
Though I don't really follow what he says, there's something really interesting about his videos that makes me watch them.
It's called an "eyelet board". It''s kind of weird though because on the other side it looks like a "turret board". Usually you have one or the other but here it looks like they've made the turrets hollow. This is like 50's style circuit board design before solid state components ushered in printed circuit boards which could be more compact because of smaller components and more complex circuits in a given space. These old school electronic devices are like the muscle cars of electrical design.
Definitely gotta get that bobby dazzler in spec!
Dave you have to bring this classic back to spec. It would most likely be one of your most reliable power supplies on your bench. I be curious what the ripple voltage is once you recap the pws
It looked like you were adusting the trim pot on the underside while the granular pot on the front was in the 12 oclock position. It seems like the front pot should have been turned to the left to zero when you made the adjustment on the bottom.
Wouldnt it be easy to bring it into spec by just adding a resistor in series or in parallel with the adjustment pot?
I personally am certainly interested in a follow up video!
Yup, would love to see you attempt getting this back into spec :)
I love old circuitry, like when I see thoughs brown resistors. Most electronic design concepts haven't changed a bit. But they did do a few things differently back then, design wise. Quite interesting.
wow, you could drop that off a table top and it would still work! LOVE the turret post construction!
but, DONT drop it!
Thumbs up for the Canon HF G30, I absolutely love mine !
The board the components are installed on is referred to as a 'turret board'. The metal standoffs/through-holes are the 'turrets'.
Would love to see a "bring it back to spec" video.
Thanks
It really does brings back some oldschool memories! :)
Dave, the Voltage offset might be that the Oven/Thermostat/Heater circuit is wonky/ stuck always on or off. The neon bulb is across the heater resister that is series with the thermostat and that goes right across the mains/line/120 VAC. The thermostat might be stuck. You might try driving the heater circuits 120 VAC input with a variac and drop the mains voltage to see how this moves the Supplies DC output voltage around. The thought is the thermostat is stuck on and the heater thus always on and thus the reference Zener is too darn hot.
id love to see you bring this into spec... i am thinking of picking one up and would love to see what kind of repairs i might be getting into
Would love to see a fix video on this.
11:12 That's not a bodge; that's how you soldered a bypass or snubber cap back in the day. We call this "flying lead wiring"; you can still see it in modern valve guitar amps, especially in the booteek market.
R80 is just screaming to be replaced with a nice ~200ohm pot (adjusted via a talented and angled tongue of course). I'd love to see this thing back in spec with all the dried up caps and all intact :D
I'd love to see you get that old man back into fighting shape!
The 'upside-down' schematic could be an indication that it is is primarily a germanium-transistor circuit. Very common to see these drawn with earth at the top and a negative rail underneath. The whole thing looks upside-down if you're used to looking at Si-based circuits because you have PNP where you would expect NPN and vice versa.
Would love to see a video trying to bring it back into spec!
Awesome work Dave!!!
yep i'd love to see a video of you trying to bring it back to spec. I figure you could bodge on a resistor in series with one or both of those trimmer pots you were fiddling with.
I'm assuming you were *adding* more resistance as you turned the pots since you were trying to lower the voltage down, so that's why I'm assuming you should bodge a resistor in series.
Love the old squashed bug germanium transistors on the bottom
One way of troubleshooting this PS is to assume that someone either plugged it into a 220 volt socket, or they overloaded the current.
I think EEVBlog has to tools to check the main transistor, and the input protection circuits.
AT 15:20 those tiny little diodes. Why is the right hand one's leads bent to make it slightly lower than the left hand one? Can't get them to close to one another for some reason? As Dave would say, "Hmmmmmm". Love those pastel colored transistors!
Please bring it back to spec, she deserves it!
I have noticed the "regulate the ground side" on a lot on 1960s broadcast video gear (my vintage interests). They had good NPN power transistors then, like the famous 2N3055 so I don't know why they used this odd configuration in commercial designs? Was there some subtle benefit? Also note the rotary switch wafers are made from FR4 or G10. Not the typical pressed Bakelite junk found in consumer gear of the era.
The Darlington pair is actually a Sziklai pair.Well, they are sometimes called a complementary Darlington pair. The Sziklai pair uses NPN and PNP transistors.
09:50 Turret board.
I was actually going to say eyelet board (Fender used them a lot in their Tweed amps) but you're right, the turrets on the other side make it a turret board. (Eyelets and turrets are both old-school approaches to what eventually became plated-through holes and vias.) Strange that they just soldered everything on the turret side rather than filling the whole turret with solder.
What about the 100uV pot on the front panel - wouldn't it make sense to turn it to 0 position for calibration?
The PNP pass transistor with all the regulation on the low side is a huge clue to me. It tells me that it's probably a Germanium transistor instead of Silicon.
Ge was apparently easier to make in PNP and as such, all the Ge circuits are arse backwards compared to their Si counterparts. You should have seen the look on my face when I found my first Ge transistor based amp after messing with countless Si based circuits.
Test the Vbe drop...If it's around 0.3V, you will know it's Germanium.
The loss of cal is likely caused by carbon composition resistor drift. If ripple is high as well, the old electrolytic caps are almost certainly the cause.
long time since this video was published....but just seen it now and read your comment: nope, these are silicon transistors. The Vbe is written on the schematic as 0.7volt. But since it was cheaper to do pnp wafers in those days, all transistors are pnp, and the schematic is upside down (with our modern npn eyes)...
What a beauty ! It must have costed a small fortune back in the day...
I would love to see how you'd go about troubleshooting something like this.
Nice vintage part. I like it..
Hey Dave! How it goes?! Well, just wanted to voice my opinion once again. I enjoyed your video's but it's just too advanced for the everyday beginner like me. I commend you for being the first TH-camr to introduce me to Electronic Engineering/Design as a hobby but to be honest I need to stick with TH-camrs that are more about electronic design/tutorials for beginners. The Ben Heck Show, Afrotechmods, and other TH-camrs. So it's been enjoyable and I'll still watch some of ur video's but as I've said before, I have a very strict sub list. lol Because I pay attention to my subs watching their video's frequently rather than having 100 and not watch their video's often, making it difficult having a large sub list. Once again appreciate the introduction and I'll still be around! Thanks!
Hobo Maximus No worries. It's simply impossible for me to cater for everyone at every level, and that's the biggest problem of running a relatively broad interest channel like mine. The EEVblog was never envisioned to be a beginner/tutorial channel.
Totally understand and see how this is more useful to the advanced crowd, maybe once i learn more I'll understand you lol. I'll still be to your channel often. Just hard to pay attention to so many TH-camrs!
Any place or person specifically that you learned all of your skills and knowledge in electrical engineering? My current major is EE and I get pretty overwhelmed with all that you talk about in your videos. Thanks.
My god what school do you go to, they teach this in basic electronics,
college level.
MrMac5150 I have not actually got into the meat of the program, I am only going into my second semester this fall and my first mostly consisted of mandatory but unrelated classes. I only say this because I began reading through my Intro to electronics textbook during this summer and I got a little confused just reading and practicing the concepts and formulas. Not having a lab does make understanding the practical parts a bit more challenging. Hopefully actually attending the class that the textbook is related to will increase my understanding and confidence with the field. To answer your question, a community college in New Jersey.
Your DC will be easy, but the AC will twist your head till you get the hang of it, they will teach how to break circuits down to two or three components to look at, makes it a little easier, but I can not do complex circuits my self even with the training I find that hard and not having a schematic with voltage points, I get lost too.
Bum around with stuff long enough and you tend to pick up a thing or two.
CaptmagiKono I may get some hate for saying this, but that's part of the major. EE is geared towards R&D, not practical designs per se. EET (Electrical Engineering Technology) is the major geared towards practical designs. It actually goes back to Sputnik and the need for such R&D...
(disclosure: I'm a senior in EET @ Purdue University's New Albany campus)
With something that old, the caps in that puppy may have dried up a lot causing it to be off spec. Perhaps they need to be replaced. Just a thought.
NICE review Dave!!!
This thing is incredibly beautiful. The view at 11:17 almost makes me cry because of the sheer beauty there ... This piece of equipment is 10 years older than I am myself, and I can say that it has aged WAY better than me.
Dang it! I was in the market for one of these and now the price is going to rise...
Add a series resistor to the potentiometer (the wire wound one), and adjust it to bring the unit back into spec!
It's a 2 minute job considering it's not surface mount.
Peace
You bet that we want this old fellow back in specs :)
Great video. Bring out your ESR and have fun.
Have you checked the jumpers on the terminals on the back? That's one potential source of it being out that I would look at. Another obvious source of issues that comes to mind is any Ge components, some of them have this tendency to grow whiskers that cause them to go off-spec.
Replace the capacitors, clean up the pots and yes, lets calibrate it.
Dave definitely do a video on bringing it back into cal.
Any chance of some high res photos of this one? Particularly, of the cable looms - I do love great cable lacing!
Gabriel Hoffman Want me to email you pics in a plain brown paper bag? :->
:)
I spent a whole month of my electronics apprenticeship at GEC learning to loom properly - 1977 :) So I can appreciate the skill and dedication the assembler put in on this
restore this dave, i know this is quite old by now, but please do it atleast so it will be back in action!
What a gorgeous power supply
I think changing that old electrolytics will help, they lose capacity and ESR can be insane (so it's not that effective at filtering).
This must be a cutting edge tech back in the 60's.
Time to pull out the ol' Dick Smith ESR checker? Those caps could be crusty now. (though the caps in my 1970's oscilloscope are still spot on, lol)
AWESOME!!!! Lovin' my 2020B!
This was my first power supply on my bench. I got it for $20 from a scrap dealer.
I saw a screw on the bottom of the oven that looks like it will let you rotate and pull off the outside casing. Maybe there's something worth looking at in there?
It would have been really cool to see inside of that oven can, it does come off I saw a locking mechanism with a screw on the side of it. Cool stuff, would love to see it put back into specifications though.
what is a oven can though?
@@AtAGlimpse_UB Well you see, an oven can is an oven that is indeed a can.
@@THEGHOSTSLAVE what is even the purpose of that?
@@AtAGlimpse_UB Whatever purpose you can imagine using an oven can for. You can oven it, you can can it, you can oven can it. The possibilities are endless.
I really want to see you get this back into spec.