• Please note that there are a few updates and clarifications made in the Audiokarma Rules, mostly relating to advertising and the addition of the new "Paying it Forward" & "Giving back" forums in the AudioKarma Audio Marketplace section.

Yamaha CR-2020 Repair Project

Timothy Flath

Timothy Flath

Well-Known Member
Hi folks
Have started in earnest to attempt repairing a Yamaha CR-2020 that was completely dead. Started with the obvious Power Supply board issues that I have seen posted on YouTube and decided to start with a full electrolytic recap (except the large filter caps) of the Power Supply Board and the daughter E. Cap Board attached to it. Had a minor success yesterday in that I got the relay to wake up as per the following:

 
Last edited:
Register to hide this ad
Following the above I spent a good part of the day today cleaning pots and switches and then wanted to have a further listen to it after it was woken up yesterday. It was late when I shot the previous video so I didn't really do a long sound test so wanted to accomplish that today. Below is what happens with it now (guess I jinxed it?). Anyway, as you can see in the problem video below I can get the unit to turn on and play after the relay kicks in but unfortunately it plays for nicely inly for a short while and then the relay trips again. Thinking it could be any number of things like:
1. Main filter caps are shot - maybe it runs until it drains them after a short while because they are not holding a charge and then causes the relay to trip due to undervoltage (3 of the four smaller caps on the E. Cap Board were at half the rated cap values which makes me suspect that - outwardly they looked good)... Will explore PS voltages in the short Windows I have to do this before it craps out. Seeking ideas so I don't burn anything out trying to troubleshoot...
2. Faulty relay - what makes me suspect this is the fact the relay cover was loose making me believe a previous owner had someone in there monkeying with it...
3. Something downstream ( getting a hum from phono input with no TT hooked up, but Aux, Tape One and FM all work as expected for a brief with a Flac player before the relay trips)

Lamps are all incandescent...
Looking for some suggestions of where to best start tackling this issue:
 
Last edited:
1 and 2 make absolutely no sense, and 3, well 3 is just saying literally anything else.

- The relay drive transistor could be getting tired.
- The sense transistors could also be leaking.
This is assuming you checked the protection circuit is getting uninterrupted voltage, that the amp boards aren't setting it off by actually sending DC, and that you installed all caps correctly.
 
ivandezande said:
Point 1. 1 and 2 make absolutely no sense, and 3, well 3 is just saying literally anything else.

Point 2. The relay drive transistor could be getting tired.
Point 3. The sense transistors could also be leaking.
Point 4. This is assuming you checked the protection circuit is getting uninterrupted voltage, that the amp boards aren't setting it off by actually sending DC, and that you installed all caps correctly.
Click to expand...
Thank you muchly for the feedback.

re your Point 1. Valid points. Just what I'm looking for since, as you can see, I am reaching for straws at this juncture and combing through old forum and Youtube posts for ideas. Yes my point 3 is definitely a shotgun point;)

re your Point 2. Roger that I will pull and check and/or replace.

re your Point 3. Same as above

re your Point 4. Will investigate first two items as best I can. Was planning to do a voltage check around the PS in the little time I have between each relay trip-out. Problem being I may kill some things while I do this with numerous on/off attempts. Just finished a double check on cap installation - pretty sure I got them all correct but it never hurts to triple check . There is the issue I discovered in another AK thread discusssed earlier wrt the E.Cap Board which indicates the board is mis-printed on one of the 1000 uF /50V caps which by this dwg attached I think I have installed it correctly.

Appreciate the starting point
Cheers and thanks again
Tim
 

Attachments

  • 20211220_213213.jpg
    20211220_213213.jpg
    133 KB · Views: 38
Should have mentioned that it looks like someone did previoulsy apply the Service bulletins albeit two of the resistors are not exactly to exact spec - probably installed what they had on hand - the two 33 ohm resistors were replaced with what appear to be 40 ohm wire wound resistors of higher wattage. Fusable resistors were replaced with 22 ohm beefy resistors as well. Regulator trannies were upgraded to the 2SD525 as called out in the bullietins. Those were the first items I pulled and checked with my Peak DCA55 plus TR713 and TR714. Board was a bit of a mess in that area...
 
Last edited:
It would appear from another thread that the manual may be incorrect and I have inadvertantly flipped the left most 1000 uF/50V (blue) cap in this photo of the board I recapped. Wonder why Yamaha has never pointed this out in a bulletin irrespective of age? Oh well, looks like flipping this cap and trying it out is my next order of business tomorrow:confused:

Of course I will check it out first to see if it or anything surrounding it was damaged...
 

Attachments

  • 20211220_211855.jpg
    20211220_211855.jpg
    180.5 KB · Views: 38
Last edited:
You should be good there, I believe it would have promptly exploded if it was in wrong.

I have brand new makes of the e-cap board if you need one.
 
Hard down with a nasty cold for the last few days (Covid Neg thank goodness). Anyway here is my latest test with the Yammy PS. Something is not quite right so focussing in on transistors for now. Thinking of replacing the 2SD525 regulator trannies as a start. Will likely order all the other trannies as I don't have a ton of parts laying around (wish I did)..

 
A little update with some positive progress. Next I have to solve the instant on issue with the relay on power up. Somehow I have interrupted the relay countdown to power up. If anyone knows a possible reason I am all ears. My main concern of course is speaker protection now I have everything else working good (thus far)...

 
Timothy Flath said:
A little update with some positive progress. Next I have to solve the instant on issue with the relay on power up. Somehow I have interrupted the relay countdown to power up. If anyone knows a possible reason I am all ears. My main concern of course is speaker protection now I have everything else working good (thus far)...

Click to expand...
TR702 shorted E-C...
 
You must log in or register to reply here.
Back
Top Bottom