Please help - Yamaha C4

[Edu1985]

I ve got ready for reccaping my Yamaha c4 when i noticed something fishy on the tone control board.it s a capacitor that i think looks out of place.sometime a long time ago someone replaced the caps on this board only and i think it had made a mistake?or maybe not?can someone look at his headphone/tone control board and tell me if i m right or ..not?pleasee!!and also he put some heatsinks on the headphone transistors

 

[Edu1985]

I m trying to say that he put the cap backwards .it s the only cap on the board that looks putted backwards.what are the chances?even on the board the plus sign it s on the other side

 

[Edu1985]

This is the cap

 

[llwhtt]

Do you have the Service Manual? HiFi Engine has it if you don't. You need to figure out which cap that is and see what it connects to using the schematic. It may be backwards, the silkscreen may be wrong, or the polarity could also be correct and that's the way it was laid out.

Craig

 

[avionic]

This is the cap

Yes, its backwards. All of the electrolytic caps on that board should be oriented in the same direction.
All neg.bands face the front of the board.

 

[avionic]

I've probably recapped 20-30 of these boards. Can almost do them in my sleep.

 

[Edu1985]

Yep,i did put the cap in the right order.i hope it did not damage anything.before it was playing nice.i replaced all the caps except 2 caps in the psu which were bp (and i didn t observe when i maked the list).Avionic,is it normal for the caps on the turnover frec/headphone board to get hotter that the rest of the caps??what s the burn in time of these caps?i read somewhere that silmic are 100h,true?it s working nicely and no boom after 30 min of playing :d

 

[avionic]

i read somewhere that silmic are 100h,true?

I guess whatever the Elna spec sheet says.

 

[avionic]

s it normal for the caps on the turnover frec/headphone board to get hotter that the rest of the caps

Caps get warmer due to the surrounding transistors that run pretty warm.

 

[Edu1985]

I understand..thank you very much Avionic.

 

[Electone]

Those Elna Silmic IIs tend to have a longer "break-in" period than most caps. I used a substantial amount of them in my C4 along with some Nichicon FGs, ESs and PWs. Sounds fabulous.

 

[Edu1985]

How long ia the break in period?

 

[clinic-audio]

5000 hours life time

Your C4 is 35years old unit ....What do you expect ?