CR-2020 Service Bulletin Guidance

Thanks a lot. I noticed that too while I was inspecting these boards, "hmm, weird jumper wire here." Is it advisable to add a resistor there? If so, is it a 10ohm 220ma as shown?

I would (re)install a fusible resistor. In theory that would be a 0.5W, and so I did replace it once by new one during a full rebuilt. Yet...a few months later it blew when a happy kid found it amusing to flip the power on-off switch multiple times very quickly.....and that resistor blew.... loosing the -90V rail to the input stages of the power amp PCBs. As such I can imagine that somebody put a jumper in, but it also exposes the capacitor in series with it (the orange one) to a higher operating voltage

It seems that the original white ceramic fusible resistors have much more peak current tolerance than new ones. So for a modern replacement I would resort to a 1W non-flammable type. That is always better than a jumper.

.
 
I would (re)install a fusible resistor. In theory that would be a 0.5W, and so I did replace it once by new one during a full rebuilt. Yet...a few months later it blew when a happy kid found it amusing to flip the power on-off switch multiple times very quickly.....and that resistor blew.... loosing the -90V rail to the input stages of the power amp PCBs. As such I can imagine that somebody put a jumper in, but it also exposes the capacitor in series with it (the orange one) to a higher operating voltage

It seems that the original white ceramic fusible resistors have much more peak current tolerance than new ones. So for a modern replacement I would resort to a 1W non-flammable type. That is always better than a jumper.

.

Thank you! I will look online to try and find that part. Getting a list together!
 
I would (re)install a fusible resistor. In theory that would be a 0.5W, and so I did replace it once by new one during a full rebuilt. Yet...a few months later it blew when a happy kid found it amusing to flip the power on-off switch multiple times very quickly.....and that resistor blew.... loosing the -90V rail to the input stages of the power amp PCBs. As such I can imagine that somebody put a jumper in, but it also exposes the capacitor in series with it (the orange one) to a higher operating voltage

It seems that the original white ceramic fusible resistors have much more peak current tolerance than new ones. So for a modern replacement I would resort to a 1W non-flammable type. That is always better than a jumper.

.

Having a little trouble finding that part. Closest I could find is this one: https://www.mouser.com/ProductDetail/?qs=u4fy/sgLU9NxtutmsXhS/A==

Would that work?

Thank you.
 
OP here, I am getting ready to order parts for the SB as well as a few others that were recommended in other threads. My knowledge is limited. While I am reasonably confident I can replace these parts I am not sure I have selected the right ones. Appreciate any feedback!

Also the unit has just started giving an intermittent buzzing sound in the power supply area on startup. When it does this speaker relay does not click on. If I shut down the unit and then restart the buzzing usually goes away, the relay kicks and the unit functions normally. Based on this new symptom are there any other parts I should looking at replacing (such as the relay)?

Thank you in advance.

SB Parts:

https://www.mouser.com/ProductDetail/610-TIP41C

https://www.mouser.com/ProductDetail/588-93J22RE

https://www.mouser.com/ProductDetail/588-93J33RE

Part found missing on my board:

https://www.mouser.com/ProductDetail/594-5073NW10R00J

Other parts mentioned in threads:

https://www.mouser.com/ProductDetail/647-UKL1J102KHD

https://www.mouser.com/ProductDetail/594-D102K20Y5PH63L6R

Miscellaneous

https://www.mouser.com/ProductDetail/532-56-77-11

https://www.mouser.com/ProductDetail/532-56-77-11

https://www.mouser.com/ProductDetail/567-120-2

I plan to move the transistors off the board for better heat dissipation as seen in other threads. Recommendations for appropriate gauge wire?

Thank you.
 
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OP here, I am getting ready to order parts for the SB as well as a few others that were recommended in other threads. My knowledge is limited. While I am reasonably confident I can replace these parts I am not sure I have selected the right ones. Appreciate any feedback!

Also the unit has just started giving an intermittent buzzing sound in the power supply area on startup. When it does this speaker relay does not click on. If I shut down the unit and then restart the buzzing usually goes away, the relay kicks and the unit functions normally. Based on this new symptom are there any other parts I should looking at replacing (such as the relay)?

Thank you in advance.

Normally I replace the relay(s) as a matter of normal maintenance but considering what you wrote above imho that would move up in priority to an important renovation/repair issue, along with re-soldering every component in that section. Unfortunately I have no experience with your amp (or any other CR/CA for that matter) so can't recommend a suitable replacement relay.

Cheers,
James
 
Normally I replace the relay(s) as a matter of normal maintenance but considering what you wrote above imho that would move up in priority to an important renovation/repair issue, along with re-soldering every component in that section. Unfortunately I have no experience with your amp (or any other CR/CA for that matter) so can't recommend a suitable replacement relay.

Cheers,
James
https://www.mouser.com/ProductDetail/Panasonic-Industrial-Devices/HC2-HP-DC12V-F?qs=sGAEpiMZZMtSzCF3XBhmW8KXvo/AizVD94DI8bzZQpM=

Or..
https://www.mouser.com/ProductDetai...=sGAEpiMZZMtSzCF3XBhmW1uKSon960XE227ogInLziM=
 
OP here, I am getting ready to order parts for the SB as well as a few others that were recommended in other threads. My knowledge is limited. While I am reasonably confident I can replace these parts I am not sure I have selected the right ones. Appreciate any feedback!

Also the unit has just started giving an intermittent buzzing sound in the power supply area on startup. When it does this speaker relay does not click on. If I shut down the unit and then restart the buzzing usually goes away, the relay kicks and the unit functions normally. Based on this new symptom are there any other parts I should looking at replacing (such as the relay)?

Thank you in advance.

SB Parts:

https://www.mouser.com/ProductDetail/610-TIP41C

https://www.mouser.com/ProductDetail/588-93J22RE

https://www.mouser.com/ProductDetail/588-93J33RE

Part found missing on my board:

https://www.mouser.com/ProductDetail/594-5073NW10R00J

Other parts mentioned in threads:

https://www.mouser.com/ProductDetail/647-UKL1J102KHD

https://www.mouser.com/ProductDetail/594-D102K20Y5PH63L6R

Miscellaneous

https://www.mouser.com/ProductDetail/532-56-77-11

https://www.mouser.com/ProductDetail/532-56-77-11

https://www.mouser.com/ProductDetail/567-120-2

I plan to move the transistors off the board for better heat dissipation as seen in other threads. Recommendations for appropriate gauge wire?

Thank you.
Shoulder washers for TO-220 transistors.Need one per transistor.Unless your going to reuse the old ones.The old ones tend to get brittle with heat and age.
https://www.mouser.com/ProductDetail/Aavid/7721-7PPSG?qs=sGAEpiMZZMsiS1%2bJOF5Pn2mwjoA9TbkHK4L90EdbIbI=
 
I did the SBs today, moved the transistors off the board and also replaced 4 additional capacitors and the speaker relay. Overall a success (no mishaps and it seems to work so far!).

I found half a dozen broken traces on the electrolytic cap board. I did my best to make traces and bridge them, it did not look pretty but it is better than it was (three of the SB resistors were just hanging on loose traces with gobs of solder added by whoever last worked on the unit).

One of the 2 existing caps on the electrolytic cap board listed for replacement by another member at 1000uf/50v was found to be actually 2200uf/35v. Is the 1000uf/63v I selected suitable or did I install the incorrect value part?

This was my first real stereo repair. Thanks for the help everyone!
 

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Look for shrunken plastic sleeves on the e-caps.

Thanks, I think I see them, like this one.

I am still getting occasional speaker relay not kicking on but it appears to be happening less frequently than before. Perhaps changing more of the caps will help, appreciate any other suggestions.

Thank you.
 

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