ACA - help needed

[Ben Mah]

I think C3 may be the problem, leaking voltage at the input Either the capacitor is faulty or there is a solder bridge.

 

[dovla83]

I have replaced the C3 and it works now but I still have the power up issue. Attached is what I hear when powered on.

 

[tjw59]

“Once turned on, it just "farts" on the speaker, sounds like a 3 second discgarge noise for the lack of better explanation”

Suggests that the amplifier is working because they make that noise (unless you are in the balanced mode) when you turn them on. Thus my suggestion to make sure you are putting something in the input spigot.

 

[dovla83]

It behaves like that with or without any input connected. So that is normal behavior?

 

[tjw59]

Yes: is normal to hear the cap discharge on power up.

 

[Ben Mah]

Read this post and the posts following:

D

Post in thread 'Amp Camp Amp - ACA'

2021-04-01 12:20 pm

Thanks, there's a lot of interesting information in that thread. Most of the power-on burp seems to come from the SMPS trying to deal with the initial current surge.
I like the idea of the capacitance multiplier in #82 although (a) there will be a ~2V drop across it and (b) it will probably not do anything for the power-off thump. So it is not a good solution for the SMPS.

• Dr Quack

 

[dovla83]

Copy that. Did some kits in the past (akitika, pass korg...) and never had that so good to know.

BTW while we're on the subject, any recommendation what caps to use as an "upgrade" for this amp?

Guys thank you all so much for helping troubleshot this, I really appreciate all the help!

Cheers!

 

[dovla83]

@Ben Mah just saw your post, will check it out for sure! Thanks so much on helping out!!!