Yamaha CR 2020 41Vdc on outputs!

That mis-marked cap bit me once as well. The panasonic FC bulged and started leaking..Rut Ro shaggy..:biggrin:
 
BTW in that same photo the FG cap you have installed. Don't use a nichicon PW in that position. It don't like it.
 
BTW in that same photo the FG cap you have installed. Don't use a nichicon PW in that position. It don't like it.

I wasn't too sure what to use there, I must admit...
Wondering what the original orange cap was special for, never could find out a special property like low ESR, low leakage, or perhaps low ESL.
The new FG measures better in all those aspects.
But I would still welcome some insight about the original capacitor (labelled "KX")

DSC06808.jpg
 
I have no clue. Other than that orange cap is frequently toast. I've been using KL's primarily for high temp.
 
Well that wouldn't work anymore..... the cable screens really must be connected to outer bushings of the RCA connector (central pin at the back). Otherwise the signal 'loop' is disconnected.

Somebody on eBay is parting out a CR-2020; in case you wish to reinstall a PCB then check out what he has left.

The transparent sleeve is meant as a thermal protection of the signal cables where they near/touching the heatsink

Thanks for the heads-up. I’ve contacted the guy on eBay about my interest in that coupling switch. I’m asking him to confirm that it is still mounted to the PCB. His listing says the switch was pulled from a 1020. I’ll have to do some digging to make sure it’s the same part for a 2020

I feel I need to resolve this missing switch before moving any more forward.
 
Assuming the Yamaha parts list is accurate, both the 1020 and the 2020 use the same coupling switch setup. The eBay guy sent me pictures, it comes complete with the circuit board. Awesome, done deal. And thanks to the Yamaha wiring diagram, shouldn't be any trouble soldering up the right connections.

And then I can get back to, with y'all's help, making progress. :thumbsup:
 
I've replaced the switch in the past with a slide switch from Mouser. Requires a little modification to the switch circuit board. Chances are your going to have to clean the replacement. They are notorious for getting real oxidized and dirty.
 
I've replaced the switch in the past with a slide switch from Mouser. Requires a little modification to the switch circuit board. Chances are your going to have to clean the replacement. They are notorious for getting real oxidized and dirty.

Ah, good point! I will put my De-Oxit to work. Thanks!
 
The new switch came in, I gave it an appropriate DeOxit bath, did the "flick-the-switch-100 times" cleaning, and followed up with DeOxit Gold and more switch-flicking. Installed the new switch, checked my work with the dim bulb (checked good) and then fired it up.

The relay clicked within a couple of seconds. Awesome. (There was no relay clicking when the switch was missing.)

Took readings off L1 and R1. They are:

L1: +5.2 mVDC (took a while to settle there)
R1: -1.3 mVDC

I tried to read the schematic, but ended up scratching my head. Where do those readings point towards? Hey, at least they aren't both reading +41vDC anymore!

Oh, I haven't installed the new resistors yet, I thought I would tackle one change at a time first.
 
L1: +5.2 mVDC (took a while to settle there)
R1: -1.3 mVDC
DC offset,DC balance same thing.. Ideally you want 0.00 volts. This is very seldom the reality. Anything below +/- 10 mv is excellent. As in your case 5.2 and 1.3 those numbers are great.
 
So, original problem solved? Cool. I will move on to the resistors and then the bulbs.

Thanks to avionic, oilmaster, and all for the help. Much appreciated!

- Jeff
 
Thought I would bring some closure to this thread. Thanks to guidance from avionic, oilmaster and mbz, I was able to bring this beauty back to life. All service bulletins complete, new bulbs (5 new 14v lamps from dgwojo), deoxit'd pots and switches...she sounds and looks great!

And obligatory pics, natch!

Thanks again, gentlemen, for all the help!

- Jeff

CR-2020-1overall.jpg

CR-2020-2left-detail.jpg

CR-2020-3center-detail.jpg

CR-2020-4right-detail1.jpg

CR-2020-5right-detail.jpg
 
Yes, in my experience, you can apply moderate pressure and not remove lettering. That seems to be enough to remove the layer of crud and make it shine. I don’t use paper towels, but micro fiber cloths, one to apply and a different one to remove.

I also have a Sansui component with a black face (AX-7) and Noxon worked beautifully on that as well.

I have never tried firm pressure. Thankfully, I haven’t needed it. So far. ;)
 
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