Rusty and I really enjoyed the video, Terry: Excellent pace, clear narration, and a nice conclusion.....much like a good novel. We give it two thumbs and two paws up. Thanks so much for posting it. Now we're off to check out more of your videos :)
Funny that you mentioned Allen-Bradley. My mother is retired from there as is my Dad and Grandpa. My mother worked in the resistor department back in the late 60's to early 70's. She went to potentiometers after that. Love your videos. Learning a lot.
Nice work. I have Fender Harvard H-00416, Date FH which is August, 1956, built just two months after the one in video. Mine is in excellent cosmetic condition with tweed that looks nearly new, probably because it has an original brown canvas cover to protect it and it sat in a dark closet unused for years. Work done: Replaced bias cap, cathode bypass cap & 3 filter caps (all Astron Minimites); Cord replaced with 3-prong; Disabled death cap; Replaced the rectifier, leaving the original bypassed selenium in place; 2 new 6V6 power tubes, and; Rotated speaker 180 degrees to start gravity working it in the opposite direction for the next 60 years. I saved all the original parts in case a collector wanted to restore it to original, but I prefer to keep these old amps playing well. Fortunately, the signal caps tested well so the originals continue to impart their vintage tone. Anyway, good to another one brought back to life.
old school industrial electricians used to "adjust" the resistance of carbon resistors by grinding away some of the carbon. There were actually boards made with carbon pads on them that the calibration procedure was to saw a slot partially across the carbon pad.
Thanks for the informative videos. I like the way you show what you are doing and not just saying what you are doing. Thanks and keep up the excellent work.
Nice to see this old amp bring up to life! It makes me think that i have to find a variac or i will have problem one of these days ! Thanks for sharing
Hoi Terry, Nice video's! You making tube tech very clear to many people! I'm a also a repair man, but i do not have so much experiance on tube amps. You're video's clear a much questions. Thanks for that, i' m follow you, and watch all your video's! Grz here from Holland, Bart
+ian “valve doctor” forster I agree, it is a nice past time of mine. And yes, it normally doesnt pay. However, the end result makes it well worth the effort.
This was the first video of yours that I was fortunate enough to have come across. I enjoyed observing as you restored that chassis. I have one question. I was surprised that you did not immediately replace that selenium rectifier, it has surely outlived it's life expectancy. Why did you not automatically update it with a properly rated solid state diode? As an old service tech new to guitar amplifiers I'll watch all your related videos! This old dog is full of new tricks!
+Anthony Reo Hello, Yes, you are correct. I would have, however the owner wanted to simply replace the incorrect output transformer. He ended up selling the amp a few weeks later for a nice profit.
D- LAB ON THE VIDEO THAT 4 THOUSAND 700 OHM RESISTOR LOOKED LIKE IT HAD BEEN PARTLY GROUND AWAY IS IT POSSIBLE SOME ONE TRIED TO MAKE THE VALUE 470 OHMS I NEVER EVEN THOUGHT OF THAT UNTILL I SAW THE WAY THAT LOOKED ! ....////
Hey there, another Great video! Just a quick question. I have had a number problems with old selenium rectifiers, is there a reason for not changing them in this unit? Keep up the videos...
Great video. Forgive this basic question: on some forums I read, people insist that the selenium rectifier must be replaced. Or the world will end. You left it as is. I'd be grateful to hear your thinking on the replace of these rectifiers. Thanks!
HI Terry, I see you have Textronix 2235 scope. I have my eye on a 2225 on Ebay for $250.00 including two probes. It is 50Mhz not 100Mhz. Is that enough bandwidth for most tube ans solid state amps? I just found your channel and I find it very helpful. I will be watching more vids in days to come.
+Robert Hurless Hello, Yes, the Tek's are great scopes. Sure are a lot cheaper now. $250.00 would be top dollar for one. I would hope it has the original manuals for that cost. You could get away with a 10MHZ scope for all audio work. I normally recommend a general dual trace Leader or Iwatsu for this type work. Glad you like the videos. I plan to do more when time allows. TD
Klingons: Yes the Praxis resistor IS blown! However we Do NOT require your assistance at this time; maintain treaty boundaries, stay OUT of the Neutral Zone...End Transmission...
Hello Terry- just found your videos and will subscribe. question- I've got several silver face fenders from the 70's (Deluxe Reverb, Twin, Super Reverb and a champ) all of them have RCA power tubes (pre amp tubes all replaced) when it comes time to replace them, do you suggest spending the money to get NOS RCA Tubes? worth the money for the tone? thoughts?
+ContraBand Joe Hey man, There is some magic to the old vintage tubes, however, they can also be microphonic nightmares. I normally buy a nice set of reissue Tung-Sols from the Tube depot. Can't go wrong there.
Thanks for sharing. If you had higher plate current, what would you have looked for next. The big caps were replaced already. If the power transformer had been leaking would that cause low secondary voltage but high primary current flow? I ask because I have a Musicman HD130 410 that draws about 1.5-2 amps when the standby is off. Not sure what's causing it. Tubes and caps have been changed.
Hello, I have seen that issue on older amps. It is a defective power transformer. 1 way to tell is to perform a continuity check from the primary to secondary's. See if you have a current path. If so, you will need to obtain a replacement. TD
Turns out there is no continuity between the pri and sec windings. This trans has 6 leads for 3 separate outputs on the sec and the pri has 4 leads for a single input with 2 additional taps. The additional taps are for high and low power and an extra for a neon light. Because there were the expected low ohms between the primary wires it makes me think there could be a short out on the board. I forgot to mention that the short only or high current only occurs once taken out of standby. The 6.3VAC lines are okay. The plates are only receiving 568v while the spec is 725v. Same with tubes out. Testing the current while lifting the red sec is the same as using the standby switch. It's probably right in front of me.
Hello David. I am always glad to help with vintage electronics questions. I do have a day job, so sometimes I am a bit slow to answer. Let me know what you need. TD
That is the bypass capacitor for the input/preamp tube cathode resistor. I suspect it was deliberately cut. It was an old trick some players, especially harmonica players, used to tone down an amp’s gain. Helped reduced feedback and increase compression. That ol’ Harvard would be one hell of a harp amp!
![ฮักเทื่อสุดท้าย - บอย ศิริชัย [OFFICIAL MV]](http://i.ytimg.com/vi/-1PoPoQ-B-k/mqdefault.jpg)
Rusty and I really enjoyed the video, Terry: Excellent pace, clear narration, and a nice conclusion.....much like a good novel. We give it two thumbs and two paws up. Thanks so much for posting it. Now we're off to check out more of your videos :)
+Uncle Doug Thank you sir. I am honored to have your faith in me
You're welcome, Terry. Your videos are excellent.
YAYYY! D-Lab Terry and Uncle Doug - ON ONE VLOG! It's gonna' be a Great day!
Funny that you mentioned Allen-Bradley. My mother is retired from there as is my Dad and Grandpa. My mother worked in the resistor department back in the late 60's to early 70's. She went to potentiometers after that. Love your videos. Learning a lot.
Finally a tech that knows his stuff with tube amps
Nice work. I have Fender Harvard H-00416, Date FH which is August, 1956, built just two months after the one in video. Mine is in excellent cosmetic condition with tweed that looks nearly new, probably because it has an original brown canvas cover to protect it and it sat in a dark closet unused for years. Work done: Replaced bias cap, cathode bypass cap & 3 filter caps (all Astron Minimites); Cord replaced with 3-prong; Disabled death cap; Replaced the rectifier, leaving the original bypassed selenium in place; 2 new 6V6 power tubes, and; Rotated speaker 180 degrees to start gravity working it in the opposite direction for the next 60 years. I saved all the original parts in case a collector wanted to restore it to original, but I prefer to keep these old amps playing well. Fortunately, the signal caps tested well so the originals continue to impart their vintage tone. Anyway, good to another one brought back to life.
Wow. The Lord was smiling on you, Terry, with that OT! And that 470 ohm resistor, as well!
Uncle Doug and Terry, you guys are my favorite valve amp Gurus! Best wishes from the land down under!
Valuable information. Clear, concise and to the point. Not always the case on TH-cam videos. Thank you, Sir!
Once again Terry; excellent approach to making sure the old girl will run without a hitch.
You ARE a genius!!! I wish I lived around your area to get my vintage Sinmarc amp repaired by you!!
old school industrial electricians used to "adjust" the resistance of carbon resistors by grinding away some of the carbon. There were actually boards made with carbon pads on them that the calibration procedure was to saw a slot partially across the carbon pad.
I think it's great how you take the precautions. Better safe than sorry! Great work!
Hi D-Lab, thanks for your great vids , I watch all your amp repairs and I am constantly learning from them. Thank you.
Thanks man, I appreciate it
Ian Banham I 2nd that comment! Since discovering D-Lab videos, I've been watching as many as I can and learn something from every one!
Thanks for the informative videos. I like the way you show what you are doing and not just saying what you are doing. Thanks and keep up the excellent work.
Nice to see this old amp bring up to life! It makes me think that i have to find a variac or i will have problem one of these days !
Thanks for sharing
Another goodie .I just love close ups and detailed info.very nice.
Hoi Terry,
Nice video's!
You making tube tech very clear to many people!
I'm a also a repair man, but i do not have so much experiance on tube amps.
You're video's clear a much questions.
Thanks for that, i' m follow you, and watch all your video's!
Grz here from Holland,
Bart
Cool deal man. Glad I can be of assistance. More videos will be posted soon. Lots of projects, limited time
First day to watch your videos. They are very helpful for someone like me who plays Fender tube amps.
+Bbendfender Glad to help out. I am located in Battle Creek, MI, the corn flake capital, cereal city, etc
Very nice Young Dave, but come on! your NO Emi!! ha ha!
Always entertaining n veeerrryyy informative! D lab rocks! Keep it up!
tues circuits are so easy and fun love building tube amps
+ian “valve doctor” forster I agree, it is a nice past time of mine. And yes, it normally doesnt pay. However, the end result makes it well worth the effort.
good job! I built one of those from scratch. I love the old Fenders!
James skippinhopper Hello, Yes, this is a nice straight forward design. I enjoyed the repair
I like you terry U MAKE A LOT OF SENCE
No guitar through the amp?! haha, thanks great video
This was the first video of yours that I was fortunate enough to have come across. I enjoyed observing as you restored that chassis. I have one question. I was surprised that you did not immediately replace that selenium rectifier, it has surely outlived it's life expectancy. Why did you not automatically update it with a properly rated solid state diode? As an old service tech new to guitar amplifiers I'll watch all your related videos! This old dog is full of new tricks!
+Anthony Reo Hello, Yes, you are correct. I would have, however the owner wanted to simply replace the incorrect output transformer. He ended up selling the amp a few weeks later for a nice profit.
you're a great American
D- LAB ON THE VIDEO THAT 4 THOUSAND 700 OHM RESISTOR LOOKED LIKE IT HAD BEEN PARTLY GROUND AWAY IS IT POSSIBLE SOME ONE TRIED TO MAKE THE VALUE 470 OHMS I NEVER EVEN THOUGHT OF THAT UNTILL I SAW THE WAY THAT LOOKED ! ....////
Thanks for posting.....love your vids
bmwm3cs Roger that Sir, will keep them coming
I'll bet you that 4.7K resistor was not blown up but was intentionally mechanically ground down to make a 470 ohm resistor. Did you ever measure it?
Hey there, another Great video! Just a quick question. I have had a number problems with old selenium rectifiers, is there a reason for not changing them in this unit? Keep up the videos...
Great video. Forgive this basic question: on some forums I read, people insist that the selenium rectifier must be replaced. Or the world will end.
You left it as is.
I'd be grateful to hear your thinking on the replace of these rectifiers.
Thanks!
He probably works on the principle of 'if it ain't broke, don't fix it'.
sir do you have any idea about mercury in radio please help with regards
HI Terry, I see you have Textronix 2235 scope. I have my eye on a 2225 on Ebay for $250.00 including two probes. It is 50Mhz not 100Mhz. Is that enough bandwidth for most tube ans solid state amps? I just found your channel and I find it very helpful. I will be watching more vids in days to come.
+Robert Hurless Hello, Yes, the Tek's are great scopes. Sure are a lot cheaper now. $250.00 would be top dollar for one. I would hope it has the original manuals for that cost. You could get away with a 10MHZ scope for all audio work. I normally recommend a general dual trace Leader or Iwatsu for this type work. Glad you like the videos. I plan to do more when time allows. TD
i'm with bob barcus. One chord and the rest will come easy!
Klingons: Yes the Praxis resistor IS blown! However we Do NOT require your assistance at this time; maintain treaty boundaries, stay OUT of the Neutral Zone...End Transmission...
Could I send my champ clone to you? It blew a fuse recently after I assembled it
Hello Terry- just found your videos and will subscribe. question- I've got several silver face fenders from the 70's (Deluxe Reverb, Twin, Super Reverb and a champ) all of them have RCA power tubes (pre amp tubes all replaced) when it comes time to replace them, do you suggest spending the money to get NOS RCA Tubes? worth the money for the tone? thoughts?
+ContraBand Joe Hey man, There is some magic to the old vintage tubes, however, they can also be microphonic nightmares. I normally buy a nice set of reissue Tung-Sols from the Tube depot. Can't go wrong there.
Thanks for sharing. If you had higher plate current, what would you have looked for next. The big caps were replaced already. If the power transformer had been leaking would that cause low secondary voltage but high primary current flow? I ask because I have a Musicman HD130 410 that draws about 1.5-2 amps when the standby is off. Not sure what's causing it. Tubes and caps have been changed.
Hello, I have seen that issue on older amps. It is a defective power transformer. 1 way to tell is to perform a continuity check from the primary to secondary's. See if you have a current path. If so, you will need to obtain a replacement. TD
D-lab Electronics
I'll check that. It did fail a ring test while still in circuit. You've given me a good reason to disconnect it.
Turns out there is no continuity between the pri and sec windings. This trans has 6 leads for 3 separate outputs on the sec and the pri has 4 leads for a single input with 2 additional taps. The additional taps are for high and low power and an extra for a neon light.
Because there were the expected low ohms between the primary wires it makes me think there could be a short out on the board. I forgot to mention that the short only or high current only occurs once taken out of standby. The 6.3VAC lines are okay. The plates are only receiving 568v while the spec is 725v. Same with tubes out. Testing the current while lifting the red sec is the same as using the standby switch. It's probably right in front of me.
Shouldn't you get rid of the selenium rectifier? They don't age well from what I hear.
If it ain't broke, don't fix it?
what is the name of the output transformer that you put in? can it be the same as for a 5e3?
are you available for council? it is hard to find a good amp man out in the country. WNC western mountains
Hello David. I am always glad to help with vintage electronics questions. I do have a day job, so sometimes I am a bit slow to answer. Let me know what you need. TD
What does Dumble do to make an amp so much better?
Magic dust. I would assume, high quality transformers. Have never been in one to see the tricks. I hear they are great machines.
How do I remove/replace faceplate on gender twin reverb?
Great video thank you! What became of that disconnected cap?
+activeeq Oops, Yes I did fix the disconnected lead.
It was the preamp cathode cap. Forgot to follow up.
That is the bypass capacitor for the input/preamp tube cathode resistor. I suspect it was deliberately cut. It was an old trick some players, especially harmonica players, used to tone down an amp’s gain. Helped reduced feedback and increase compression. That ol’ Harvard would be one hell of a harp amp!
was that so called death capacitor that had been cut at the start of your video ?
That was the cathode bypass cap for the first tube. Probably cut to decrease the gain of the amp. I believe it's a common mod for harmonica players.
I reckon that background music makin me nervous. Mmm hmm.
FF = june 1956
Its basically a 5e3 Right?
+Tyler Jones Yep, sure is. Crazy how much they sell for
You should learn at least one guitar chord Emaj thanks love the vids
WHY DON'T THE CHINESE CLONE THESE - THEY DON'T LOOK HARD TO MAKE.
what is the name of the output transformer that you put in? can it be the same as for a 5e3?