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Mid restoration regrets?

B

Bob Chieldon

Active Member
DF518665-D8AA-4440-8B1B-2D14943E1EDC.jpeg Anyone get these, especially when taking apart CR 2020s... :D

I love the look and sound of these receivers but by go’s they are hateful, hateful things to work on.

This is my second and first full restoration. It was utterly original, no service bulletin jobs done and hence a bit crispy on the power board. 60% of Pulled caps were reading low capacity and high leakage and so it gets a full refresh. It will be interesting to compare it to the other, basically original one.
A cup of tea and some motivational videos on YouTube I think...
 
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It's mechanically challenging more than anything, much tighter and difficult to work on than the Sansui 9090 I've just finished.

I wanted to get to the tone boards and this involved taking the fascia off and unscrewing one chassis side to free the board they live on enough to get at.

I'm waiting for 22 & 33 ohm PS board resistors to test but but a brief initial test had it sounding very muffled and apparently shirt on gain.
 
Bob Chieldon said:
View attachment 2437614 Anyone get these, especially when taking apart CR 2020s... :D

I love the look and sound of these receivers but by go’s they are hateful, hateful things to work on.

This is my second and first full restoration. It was utterly original, no service bulletin jobs done and hence a bit crispy on the power board. 60% of Pulled caps were reading low capacity and high leakage and so it gets a full refresh. It will be interesting to compare it to the other, basically original one.
A cup of tea and some motivational videos on YouTube I think...
Click to expand...

I feel you. I do endurance mountain bike races and events. Restore projects are the same to me, you just need to keep going. Only way to get it done is to get it done. It's ok to take a break once in a while, but you just have to keep after it. The feeling of finishing is worth it.
 
I have my personal 2020 to go through. When I get around to it.
 
Bob Chieldon said:
I wanted to get to the tone boards and this involved taking the fascia off and unscrewing one chassis side to free the board they live on enough to get at.
Click to expand...

Careful with the preamp section and daughter boards. I completely redid my CR-2020, except for the preamp section and loved it for over a year. I then went to finish the job and do the preamp section. Now I have a CR-2020 shaped door stop as I don't have enough talent to fix whatever happened to it while I redid those little daughter boards. I wound up losing a channel and then in an attempt to fix that, I got it to just sit in protection permanently. The whole experience was so frustrating I put it away and don't ever plan to try to fix it. It was my very first vintage piece of gear.
 
Asmodeus2112 said:
I feel you. I do endurance mountain bike races and events. Restore projects are the same to me, you just need to keep going. Only way to get it done is to get it done. It's ok to take a break once in a while, but you just have to keep after it. The feeling of finishing is worth it.
Click to expand...

An endurance race is an apt metaphor for doing one of these indeed... :D

As you say they are nice when done and this one was in good cosmetic shape.
 
avionic said:
I have my personal 2020 to go through. When I get around to it.
Click to expand...
avionic said:
Fun fun fun .... Not !!!
Click to expand...

Yup,
5zllfe
5zllfe.jpg

There's a reason they get done last. :D

Weird find on one of the tone boards (marked -C on the service manual, page 18), one of the 2SC1213s had been replaced by a TO92 marked "BD184L" which i can find no reference to. Replaced it with a KSC1845 recapped the lot and soldered it back in. Hopefully the resistors for the power board will arrive today and i can power up begin to test the various functions before putting the front panel back together.
 
bobdod said:
Careful with the preamp section and daughter boards. I completely redid my CR-2020, except for the preamp section and loved it for over a year. I then went to finish the job and do the preamp section. Now I have a CR-2020 shaped door stop as I don't have enough talent to fix whatever happened to it while I redid those little daughter boards. I wound up losing a channel and then in an attempt to fix that, I got it to just sit in protection permanently. The whole experience was so frustrating I put it away and don't ever plan to try to fix it. It was my very first vintage piece of gear.
Click to expand...
You have my sympathy, this happened to me on the first CR2020 I partially recapped.

After much buggering around in the preamp section it turned out to be a break in the PCB traces for the driver transistor on one of the amplifier boards. I've noticed that manoeuvring the boards just now has resulted on on the wires from the input sockets at the back breaking, that will need to be soldered back in now before i forget...

Keep at it and be systematic, you'll get there!
 
I feel for ya these are a major PITA to work on. I posted an image of the restro I did on one I had it completely dismantled.
 
avionic said:
Yamaha did not use " BDxxx" transistors.. 2SA,B,C and D only.
Click to expand...
C7611037-6BEF-45A5-9563-B69112E1400B.jpeg

I can’t find a reference to or data sheet for this transistor.

I replaced it, originally for a 2sc1213 in the tone board, with a KSC1845.
I’m struggling to understand why such a transistor in the tone board would have needed replacing in the first place, how do you blow a small signal transistor in a tone board and nothing else?
 
Bob Chieldon said:
View attachment 2439422

I can’t find a reference to or data sheet for this transistor.

I replaced it, originally for a 2sc1213 in the tone board, with a KSC1845.
I’m struggling to understand why such a transistor in the tone board would have needed replacing in the first place, how do you blow a small signal transistor in a tone board and nothing else?
Click to expand...
Looks like the tarnish finally crept up and got inside the body ...
 
Bob Chieldon said:
I’m struggling to understand why such a transistor in the tone board would have needed replacing in the first place, how do you blow a small signal transistor in a tone board and nothing else?
Click to expand...
Probably went noisy....Didn't outright short out.
 
bobdod said:
Careful with the preamp section and daughter boards. I completely redid my CR-2020, except for the preamp section and loved it for over a year. I then went to finish the job and do the preamp section. Now I have a CR-2020 shaped door stop as I don't have enough talent to fix whatever happened to it while I redid those little daughter boards. I wound up losing a channel and then in an attempt to fix that, I got it to just sit in protection permanently. The whole experience was so frustrating I put it away and don't ever plan to try to fix it. It was my very first vintage piece of gear.
Click to expand...

A prescient post, I too lost a channel after recapping the tone boards but managed to find it again in the “L,R,Stereo,LR” switch thank the electronic gods...

I did manage to lose the right hand meter and all the lights in my manipulation of the power supply board and so that needs sorting.
I’ve also stripped and sanded the case veneer ready for staining with oil of alkanet and finishing with boiled linseed oil.
 
Bob Chieldon said:
A prescient post, I too lost a channel after recapping the tone boards but managed to find it again in the “L,R,Stereo,LR” switch thank the electronic gods...

I did manage to lose the right hand meter and all the lights in my manipulation of the power supply board and so that needs sorting.
I’ve also stripped and sanded the case veneer ready for staining with oil of alkanet and finishing with boiled linseed oil.
Click to expand...

Glad you were able to get yours sorted out. I am still pretty bummed about losing this piece. It was my first vintage unit and what got me into this hobby and especially into Yamaha.
 
bobdod said:
Glad you were able to get yours sorted out. I am still pretty bummed about losing this piece. It was my first vintage unit and what got me into this hobby and especially into Yamaha.
Click to expand...


Don't give up!!! Persistence prevails!!!

Nashou
 
Nashou66 said:
Don't give up!!! Persistence prevails!!!

Nashou
Click to expand...

Thank you for the encouragement. I am not giving up forever, but I've given up for now. I've got a few other projects I am more interested in tackling first. As we all know, working on a 2020 isn't actually any fun. I'll get back to it one day, but it'll probably be after I run out of other gear to go through.
 
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