Thanks for another great video! I recapped and repaired two 450's last year and found them to be excellent receivers, as you mentioned sensitive and delivering a very clean sound. The owner of one commented that it never sounded as good after, someone had cobbled in the wrong replacement output transistors and the current and bias way out. I had a donor set to pull new output transistors from though. Switches were dirty on both but responded nicely to cleaning. All the lights were burned out and I replaced them with LED's by building a DC supply off of the 8 Volt light circuit and soldering two LEDs and resistor across the burned out bulbs, then putting them back in. They are a bit whiter then the originals but should last forever.
great vid Trevor. Like you I like the challenge of getting those "barn finds" back to life, especially those nice 70's style silver faced etc.. For others - a little tip on the foam. I get the "door seal" open cell foam from hardware stores. Comes in lots of various width and thickness with integrated peel back "strong tape". I have used various sizes over the years to refurbish around faceplates etc in these old amps. Simple, works and looks a million bucks and is really cheap- generally on 5 metre or so rolls...
thank you for showing your work, warts and all. every effort you make, successful or otherwise, is of value to me. problem solving is the greatest skill. but also, it shows me which tools are really getting used, and which ones are not really necessary.
Thank you for another amazing vid, this amp is in some ways similar to Marantz 22 receivers, mains tranformer, tuning cap and circuit arangement-wise in general. With the 2238 I was double checking the generator, as that thing barely dropped a notch by the time I was pumping a 0.6MHz sinewave into it! A lot is being said about the warmth and pleasant sound of these, but never about how damn fast these things are, until now at least. I mean, fair enough, I went with Wima polys wherever I could for signal coupling, but hey, if it wasn't for transistors' unity gain into high hundreds of Mhz, it wouldn't even register that high. Thank you once again for the encouragement - "it must have worked before" is a pretty good motto.
I thank ya for a nice vid. Those old Harman kardon receivers well I sent one to my tech thinking he is a little slow returning it, he likes it. Keep em coming.
I really enjoyed listening to this receiver after I finished. After about two or three weeks I figured I better return it to the owner before he calls the police, lol
I have the same model, sometimes one of the channels shorts out. If I pull on either the input or volume knob I can get both channels to work for about 20 mins. I welcome any quick suggestions.
Hi Trevor. I've been watching your 8 track player rehabs and decided to dive in. I picked up a kraco ks 340. So far it looks like I only need to replace the belt (from there I'll check the caps. However, I had a mishap. I lost what I assume is a bushing for "slave" pulley. The large pulley which is belt driven by the motor pulley. I have currently bushed it with a copper tubing sleeve but have no idea what the original looked like. It made several bounces in my shop and disappointed into the ether. Do you know of any place I can get a diagram of this player? Repair manuals are going for double the cost of a working unit and I'd prefer to repair than replace. Any help is welcome. Thank you.
Nobody I know carries repair parts for these old things. I think the capstain shaft is 1/4"? maybe you could find a standard size 1/4" bushing and adapt it to fit. just guessing here
@@TrevorsBench thanks for replying. I kinda figured. I'll probably find some bronze stock with the right OD and center bore it a couple thousandths over a 1/4.
Great episode - and, great channel! While I’m not an electronics tech, i find the processes to revamp things fascinating. I have a 450 that currently sends a voltage surge to the speakers upon power up… capacitors??
The amplifiers should be off and silent for the first 4-8 seconds upon powerup. If there's noise, something is off. Disconnect speakers and check for voltage at the speaker terminals at idle. Should be less than 100mV DC. It's possible there's a failing transistor. If the caps are all original, replacing them can't hurt
@ - thank you for taking the time to reply! I greatly appreciate it! With that said, knowing what you know about this receiver, any suggestions on likely culprit? It doesn’t happen every time - but most of the time (makes the speakers pop). Cheers!!
Hi friend Been watching you for while now and like your narrative and tricks i didn't know Cut story short now I'm retired from electronics I'm planning to do some things in 🇬🇧 UK in my mancave I'm building as we speak so to say I've been out hi/fi game for while and just want to ask what sort of screwdriver set would you recommend only asking as I can't see anything on ebay and screwdrivers in this game are very personal but you already know that Cheers 🍻
Here in Canada we have a retailer called Canadian Tire. They sell tools and have a house brand called Mastercraft. Not saying they are the best but they do sell good quality tools because they have lifetime warranty. If you watch Mr. Carlson's Lab he uses Mastercraft too. I know that doesn't help you in the UK but look for tools that have a good warranty and feel good in your hands. Don't get hung up on brands and focus on tools you like to use. I have my favorites and use them the most. Thanks for watching!
awesome video. man the alignment is still a mystery to me. can you do a video just on how to align a tuner? signal generator - possible to use a phone signal generator?
I get lots of requests for a alignment videos. I've done several videos in the past that detail the alignment but I will make a few more in upcoming episodes. I have some tuners piling up here and want to do more of those, stay tuned. Thanks
Impressive work you have done on this amp Trevor to bring back its glory. What did you use to get rid of all that dirt on the front plate? It looked pretty stinky ;) P.S. Was the power LED glaring? It's hard to see on the video, but perhaps this is due to the lightning on your bench.
I use glass cleaner and a soft cloth on anything front panel. One has to be careful because aluminum is a fairly reactive metal and some cleaners are caustic and will destroy the finish. I also use a ultrasonic cleaner with plain tap water for knobs and other small parts. Surprisingly, this receiver didn't stink even though it looked really dirty. Good eye on the power LED. When I re-assembled the front panel I got the LED in backwards and it didn't light. I had to go back in and reverse the LED before I finished. I'm amazed at what my viewers can pick up on the video, lol
Excellent as always, I hope he did not pay more than $10 for that, 30 watt per channel. I seen it had a dreaded TV Repairman sticker on the back. Hard to believe it is 1979, looks early 80's. I will say this, HK get outstanding FM Reception. Crazy, those trap doors in lieu of lights. Re-string a FM Tuner scares the hell out of me. Zero interest in AM, however thoroughly enjoyed the analysis.
Good job, Trevor. Thanks for taking the time to record and share your knowledge and skill. Always look forward to Fridays! 👍
Thanks for another great video! I recapped and repaired two 450's last year and found them to be excellent receivers, as you mentioned sensitive and delivering a very clean sound. The owner of one commented that it never sounded as good after, someone had cobbled in the wrong replacement output transistors and the current and bias way out. I had a donor set to pull new output transistors from though. Switches were dirty on both but responded nicely to cleaning. All the lights were burned out and I replaced them with LED's by building a DC supply off of the 8 Volt light circuit and soldering two LEDs and resistor across the burned out bulbs, then putting them back in. They are a bit whiter then the originals but should last forever.
Good work Kimmi. I really loved listening to this receiver after I finished. It sounded great!
I’m going to have to keep my eye out for one of these HK 450s those tests looked like it performed really well it’s gotta sound good.
great vid Trevor. Like you I like the challenge of getting those "barn finds" back to life, especially those nice 70's style silver faced etc.. For others - a little tip on the foam. I get the "door seal" open cell foam from hardware stores. Comes in lots of various width and thickness with integrated peel back "strong tape". I have used various sizes over the years to refurbish around faceplates etc in these old amps. Simple, works and looks a million bucks and is really cheap- generally on 5 metre or so rolls...
Thanks Daniel. Good tip on the foam. I keep a variety of sizes here for different uses. Sometime it's used for light blocking on front panels.
thank you for showing your work, warts and all. every effort you make, successful or otherwise, is of value to me. problem solving is the greatest skill. but also, it shows me which tools are really getting used, and which ones are not really necessary.
Thank you for your kind words and feedback. I hope you enjoy the upcoming videos
Hi trevor ,verry nice video ,thanx ,good job!!
Thanks for watching Luke
What a transformation! Great job as usual.
Thanks Mike, good to see you again!
Beautiful work, Trevor.
Thanks Alexis
Thank you for another amazing vid, this amp is in some ways similar to Marantz 22 receivers, mains tranformer, tuning cap and circuit arangement-wise in general. With the 2238 I was double checking the generator, as that thing barely dropped a notch by the time I was pumping a 0.6MHz sinewave into it! A lot is being said about the warmth and pleasant sound of these, but never about how damn fast these things are, until now at least. I mean, fair enough, I went with Wima polys wherever I could for signal coupling, but hey, if it wasn't for transistors' unity gain into high hundreds of Mhz, it wouldn't even register that high. Thank you once again for the encouragement - "it must have worked before" is a pretty good motto.
I thank ya for a nice vid. Those old Harman kardon receivers well I sent one to my tech thinking he is a little slow returning it, he likes it. Keep em coming.
I really enjoyed listening to this receiver after I finished. After about two or three weeks I figured I better return it to the owner before he calls the police, lol
I have the same model, sometimes one of the channels shorts out. If I pull on either the input or volume knob I can get both channels to work for about 20 mins. I welcome any quick suggestions.
Hey so all works except you did not fix the Power LED on top of the Power button. How come? 🤔
Hi Trevor. I've been watching your 8 track player rehabs and decided to dive in. I picked up a kraco ks 340. So far it looks like I only need to replace the belt (from there I'll check the caps. However, I had a mishap. I lost what I assume is a bushing for "slave" pulley. The large pulley which is belt driven by the motor pulley. I have currently bushed it with a copper tubing sleeve but have no idea what the original looked like. It made several bounces in my shop and disappointed into the ether. Do you know of any place I can get a diagram of this player? Repair manuals are going for double the cost of a working unit and I'd prefer to repair than replace. Any help is welcome. Thank you.
Nobody I know carries repair parts for these old things. I think the capstain shaft is 1/4"? maybe you could find a standard size 1/4" bushing and adapt it to fit. just guessing here
@@TrevorsBench thanks for replying. I kinda figured. I'll probably find some bronze stock with the right OD and center bore it a couple thousandths over a 1/4.
Great episode - and, great channel! While I’m not an electronics tech, i find the processes to revamp things fascinating.
I have a 450 that currently sends a voltage surge to the speakers upon power up… capacitors??
The amplifiers should be off and silent for the first 4-8 seconds upon powerup. If there's noise, something is off. Disconnect speakers and check for voltage at the speaker terminals at idle. Should be less than 100mV DC. It's possible there's a failing transistor. If the caps are all original, replacing them can't hurt
@ - thank you for taking the time to reply! I greatly appreciate it! With that said, knowing what you know about this receiver, any suggestions on likely culprit? It doesn’t happen every time - but most of the time (makes the speakers pop).
Cheers!!
Thank you so much! I didn’t see the end of the reply before (or perhaps you just edited it ). But thanks again !!
Hi friend
Been watching you for while now and like your narrative and tricks i didn't know
Cut story short now I'm retired from electronics I'm planning to do some things in 🇬🇧 UK in my mancave I'm building as we speak so to say I've been out hi/fi game for while and just want to ask what sort of screwdriver set would you recommend only asking as I can't see anything on ebay and screwdrivers in this game are very personal but you already know that
Cheers 🍻
Here in Canada we have a retailer called Canadian Tire. They sell tools and have a house brand called Mastercraft. Not saying they are the best but they do sell good quality tools because they have lifetime warranty. If you watch Mr. Carlson's Lab he uses Mastercraft too. I know that doesn't help you in the UK but look for tools that have a good warranty and feel good in your hands. Don't get hung up on brands and focus on tools you like to use. I have my favorites and use them the most. Thanks for watching!
awesome video. man the alignment is still a mystery to me. can you do a video just on how to align a tuner? signal generator - possible to use a phone signal generator?
I get lots of requests for a alignment videos. I've done several videos in the past that detail the alignment but I will make a few more in upcoming episodes.
I have some tuners piling up here and want to do more of those, stay tuned. Thanks
@@TrevorsBench cool thanks trev
Trevor, this was a great video. How can I get a hold of you about a receiver I have that I may want you to have a look at? I am in Alberta as well
Impressive work you have done on this amp Trevor to bring back its glory. What did you use to get rid of all that dirt on the front plate? It looked pretty stinky ;) P.S. Was the power LED glaring? It's hard to see on the video, but perhaps this is due to the lightning on your bench.
I always use simple washing up liquid. Give it a bath as any item in your kitchen, but don't use any solvent or abrasive (pads).
I use glass cleaner and a soft cloth on anything front panel. One has to be careful because aluminum is a fairly reactive metal and some cleaners are caustic and will destroy the finish. I also use a ultrasonic cleaner with plain tap water for knobs and other small parts.
Surprisingly, this receiver didn't stink even though it looked really dirty.
Good eye on the power LED. When I re-assembled the front panel I got the LED in backwards and it didn't light. I had to go back in and reverse the LED before I finished.
I'm amazed at what my viewers can pick up on the video, lol
i don't know if you did it off camera, but it seems that you didn't re-mesh the tuning gang gears for anti-backlash. sorry if i'm being that viewer :(
Excellent as always, I hope he did not pay more than $10 for that, 30 watt per channel. I seen it had a dreaded TV Repairman sticker on the back. Hard to believe it is 1979, looks early 80's. I will say this, HK get outstanding FM Reception. Crazy, those trap doors in lieu of lights. Re-string a FM Tuner scares the hell out of me. Zero interest in AM, however thoroughly enjoyed the analysis.