Yamaha CA 401

[bond.70]

Bought for 42€ few days ago, good overall conditions, connected to my ipod then to Sennheiser Momentum headphones, really disappointed, the sound was flat, without bass, Phil Collins seemed a ghost!...with headphones directly to ipod the sound is big, full of details, crispy and Collins is so real and present!...not only the amp was not able to give me more audio level but it was able to ruin completely the sound!

 

[avionic]

CA-410 perhaps? Bad tantalum caps in the tone circuit.Probably a few electrolytic capacitors past their prime.As well as drifted fusible resistors. Check the idle current/bias.

 

[avionic]

Not to mention dirty switches and controls.

 

[bond.70]

 

[bond.70]

Not to mention dirty switches and controls.

Hi yes sorry CA-410

 

[avionic]

Looks in pretty good shape..

 

[bond.70]

Yes it has only two tiny almost invisible marks around the input selector and one small chip on the wood were I will put a bit of wood putty to fill the imperfection...but as you said I have to check inside and I'm quite sure it needs a full recap!

 

[bond.70]

Opened it and found one of the two big 4700uf caps a bit swallen on top...
All the other caps are Nichicon some tantalum caps around...

 

[amr2]

I would do a full recap. I’m sure it will sound very good once revisted.

 

[bond.70]

first I would put a couple of Nichicon 6800uf 63V in place of the old 4700uf 40V then to follow all the others electrolytics they are Nichicon as well but 40 years old, but what about the tantalums? the tone control board is full of them for example...

 

[amr2]

Personally I don’t like tantalums, they have tendency to create short circuit failures. Depending on the position in the circuit, I usually change them with film or Low Leakage (UKL).

 

[amr2]

But you can leave the tantalums alone

 

[avionic]

Get rid of the tantalums..Especially in the tone board.

 

[amr2]

Get rid of the tantalums..Especially in the tone board.

It's what I would do

 

[bond.70]

What about Wima MKS II in place of tantalums?...

 

[avionic]

What about Wima MKS II in place of tantalums?...

Sure.. 1uf/35v tants.I believe. They remind me of clown fish for some reason.

 

[bond.70]

Have to read all the values convert them and make a list...

 

[bond.70]

Could someone help me to understand the tantalums values?...

 

[mbz]

http://www.csgnetwork.com/capcctantcalc.html
https://www.electronics2000.co.uk/calc/capacitor-code-calculator.php

 

[avionic]

Could someone help me to understand the tantalums values?...

Look over the parts list and the schematic in the service manual.