Tone control - Panasonic SU bps in place use 2 FG

[MaccAu]

Currently looked at the tone board of my Technics SU-V9 and realised the bipolars are in the signal path of the tone control if go via tone, mostly use Straigth DC and bypass tone though.

I am new to this, but to save spending more, have to either mouser or digitikey being in Australia, i can at RS get Nichicon FG $9 with postage.

replace the electros 4.7uf and bipolars with 47 + 47uf with both - - twisted to get 47uf bipolar - sure the FGs would be much better than the Panasonic SU

Opamp is OPA1642 which I had on hand for a bit of time

?safe to do it this way with biopolars

 

[rayma]

replace the electros 4.7uf and bipolars with 47 + 47uf with both - - twisted to get 47uf bipolar

That's ok, with adequate voltage rating parts.

 

[MaccAu]

Thanks Ray, original bipolars are 47uf16v. I can only get 47uf 50v FG. 47+47 = 47uf do i need 100uf x 2

 

[rayma]

Thanks Ray, original bipolars are 47uf16v. I can only get 47uf 50v FG. 47+47
= 47uf do i need 100uf x 2

Ideally yes. You could use four of your 47uF, and connect two parallel caps in anti-series
with two more parallel caps, to get 47uF total. Takes more room, though.

 

[MaccAu]

Thanks Ray will get 47uf 50v caps or you mean i should get 100uf. Voltage is higher but still will be 16v in the circuit

RS has 100uf is 63v 16v 50v, and 47uf 50v or 63v of Nichicon FG

 

[MaccAu]

Ideally yes. You could use four of your 47uF, and connect two parallel caps in anti-series
with two more parallel caps, to get 47uF total. Takes more room, though.

Thanks Ray, i have to make up 2 x 47uf16v bp caps, so i would take 47+47 and then for the other 47+47uf (should be fine for room)

 

[Iomis]

Hi, Sam,

I would use 47uF film (plastic) capacitors. They're big but I think not bigger then 2 or 4 electrolytics. Check space on PCB. You can try soldering on the copper layer.

Regards,
Cosmin.

 

[MaccAu]

Hi Cosmin
The space is a bit small , if the pin space is small i have a fine drill set so i can easily widen the trace to fit.

Regards
Sam

 

[DF96]

I would use 47uF film (plastic) capacitors.

47uF bipolar electrolytics may have been deliberately chosen so that there is little signal voltage across them and so little distortion. If replacing them with film caps then it may be unnecessary to go for 47uF, which will be large and hence prone to excessive stray capacitance. You will need to analyse the circuit, but 4.7uF or even smaller may be OK.

 

[MaccAu]

Thanks DF96

I got the 47uf FG today- doubled to get 47uf bipolar . Space was somewhat limited as in photos.

not sure if legs should be bent that much, though another possible idea was to lie the caps on the side on some padding

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