CR-2020 Service Bulletin Mods

[GlobalWarming]

I am sort of "Resurrecting" this thread....

I wanted to look at merrylander's pictures but they do not show anymore; why is that?

 

[merrylander]

My bad, a while back when I was trying to post some photos it said I was at my limit, so I went around old threads deleting photos planning on doing it only in old for sale threads, guess I hit this one by mistake. Since I have two more 2020s in the shop I'll take photos and fill this one back in.

 

[keithpgdrb]

No pics. Sure would hep to resurrect

 

[brutal]

No pics. Sure would hep to resurrect

I recall Rob reposted this another thread with pics. Advanced search for CR-2020 and his ID found it. http://www.audiokarma.org/forums/showthread.php?t=278471&highlight=cr-2020

The SB mod docs are in the AK Yamaha doc database. http://sportsbil.com/yamaha/

Need anything else?

 

[keithpgdrb]

Crap, thought I searched correctly. My bad. I'm trying to see visually if my amp has had the bulletin done. God I hope so.

 

[merrylander]

Just remove the two screws and slide the relay board forward about 1/4" to 3/8" and look for the white fusistors, if they are gone you are probably in luck. Also the two TO-220 transistors should be something other than D234, such as D525, D613 or TIP41C.

 

[icebrian]

I have seen several references to the resistor part numbers (Bourns) that can be used for replacements of the Yamaha parts. What are the specs on the capacitors that need to be replaced? My CR-2020 (1 of 2) has been faithfully in service for over 10 years since purchase and has developed a hum in the left channel that is dependent upon the level of the volume control setting. The higher you set it, the louder the hum. No hum in the right channel. Also, where can I purchase replacement meter and dial illumination lamps? Thanks for all of the help.

Unit #2 is sitting waiting for service. I purchased it used, and it has some issues, and I believe they are also on the power supply board as well. So plan to repair and refurbish the second one as well. These things sound superb when they are working properly.

Brian

 

[avionic]

Welcome aboard Brian - volume dependent hum would be some where prior to the volume control. Most likely in one of the 5 small pre-amp circuit boards.

DGWOJO.Com --Dave can hook you up with the correct lamp kit for the 2020.

 

[bobdod]

There are several threads on this forum that cover 2020 restorations very thoroughly. The 2020 was the first piece I restored, and it was a big job, but not too difficult with all of the info I found on this forum and received from members like @avionic. Search, read, and work slowly. Everything you need to know has already been written.