Short story. 15-20 years ago I removed plastic from capacitors in search for better SQ. No components, please 
. I have to replace these capacitors but need help to identify ratings/values for: C18-C23. See schematics.
Yes, I know I have "vandalized" an great Copland amp, but I hope I can restore it with some help. Thanks.
. I have to replace these capacitors but need help to identify ratings/values for: C18-C23. See schematics.Yes, I know I have "vandalized" an great Copland amp, but I hope I can restore it with some help. Thanks.
Many Coplands have roughly the same power supply.
https://www.drtube.com/copland/
has a service manual of the CTA402 with part list.
Looking around at the other schematics should give you a pretty good idea of the values.
Hugo
https://www.drtube.com/copland/
has a service manual of the CTA402 with part list.
Looking around at the other schematics should give you a pretty good idea of the values.
Hugo
Personally , I don't think it's wise to assume this model will use a shared design just because some of their other models do.
Why not measure the working voltage across them . Then pull them and measure the capacitance?
On another tack, the 501 is over 30 years old. You could always contact Copland , let them know you want to restore one of their old classics and ask for the values for those specific parts.
Why not measure the working voltage across them . Then pull them and measure the capacitance?
On another tack, the 501 is over 30 years old. You could always contact Copland , let them know you want to restore one of their old classics and ask for the values for those specific parts.
Hi!
In 2022 I completely replaced the electrolytic capacitors on a friend's Copland CTA301/CTA501 pre-power pair.
I can't say the exact correspondence between the codes of the capacitors in the diagram but the 6 electrolytic capacitors are 3 of 3300uF/16V and 3 of 470uF/63V (I used the Panasonic FR capacitors).
I think I can say that C20-C21-C22 are 3300uF/16V while C18-C19-C23 are 470uF/63V; however, once the old ones have been desoldered, you can check with a tester where to put the new ones that you will replace.
In 2022 I completely replaced the electrolytic capacitors on a friend's Copland CTA301/CTA501 pre-power pair.
I can't say the exact correspondence between the codes of the capacitors in the diagram but the 6 electrolytic capacitors are 3 of 3300uF/16V and 3 of 470uF/63V (I used the Panasonic FR capacitors).
I think I can say that C20-C21-C22 are 3300uF/16V while C18-C19-C23 are 470uF/63V; however, once the old ones have been desoldered, you can check with a tester where to put the new ones that you will replace.
You're welcome!
The complete replacement of the electrolytics is important and gives new strength to a good amplifier like the Copland!
The PCB is good and replacement is not very difficult except for the power supply capacitors; if necessary I can share the components used, taken on Digikey.
One last thing... when you decide to replace the electrolytic capacitors, also replace the resistors R31-R32-R131-R132; they are 10 Ohm and often break - or, worse, subtly fail - due to their low value (1/4 W) and this makes it impossible to regulate the amplifier.
I took the H410RBYA TE Connectivity: 1/2 W it's OK. There is no need for more power (and, actually, it is counterproductive), the quality of the resistors is more important...
Good work!
The complete replacement of the electrolytics is important and gives new strength to a good amplifier like the Copland!
The PCB is good and replacement is not very difficult except for the power supply capacitors; if necessary I can share the components used, taken on Digikey.
One last thing... when you decide to replace the electrolytic capacitors, also replace the resistors R31-R32-R131-R132; they are 10 Ohm and often break - or, worse, subtly fail - due to their low value (1/4 W) and this makes it impossible to regulate the amplifier.
I took the H410RBYA TE Connectivity: 1/2 W it's OK. There is no need for more power (and, actually, it is counterproductive), the quality of the resistors is more important...
Good work!
Excellent!
I have removed all electrolytic capacitors and the "biasing resistors" due to failure. Thank you for your tip I will order same resistors! Also need to replace one tube socket due to bad connection - heat? C33 - C34 - C133 - C134 is not populated on my PCB, should I do something about it?
I have them removed - want to try some fancy audiophile capacitors.As you can see, there are no capacitors in C33 - C34 - C133 - C134.
But ICEL plastic film capacitors are missing in your PCB: why?
Here is the list of codes of the capacitors to be replaced, only C25 is missing which has been replaced with a Mundorf MLytic HV Power Cap (but I don't remember the value... I'll be able to tell you soon).Yes please
MAL211818221E3 - n.3
EEU-FR1C332L - n.3
EEU-FR1J471B - n.3
ALC40A221EC500 - n.2
MAL215919101E3 - n.1
They were chosen for their durability and reliability; regarding the most important ones on the power supply, it will be necessary to remove the old ones that are screwed in and position the new ones using adhesive pads (quite tenacious).
This is the result...
Attachments
Now I have cleaned the PCB and removed the parts I want to replace. I am very grateful for your advice and will order parts form Digikey.However there are some minor differences from your amp to this amp, such as my amp is missing coupling capacitor for HV electrolytic.