Help needed with capacitor replacement

Vaylo

New Member
Hello guys,

time has come to replace one of the filter caps in my tuner and amplifier. Please see below scheme from the service manual, it's marked C901.

4tsttt.jpg


My expectation would be to place an X2 cap here but when i look at the existing cap there's a 'Y' letter stamped on it, which confuses me as then I would expect one of the leads to be connected to the ground rather than to a transformer:

2ur8ew7.jpg


It's RIFA, type PME265MB510, unfortunately I cannot find any datasheet for it to be sure whether it's an X or Y.

In case it's an X-type would this be a correct replacement?
https://www.tme.eu/en/details/mkpx2...olypropylene-capacitors/kemet/r46ki21005001m/

Many thanks in advance for your help.
 
The cap is a snubber cap used to prevent arching when the power switch is turned on. The (larger) filter caps
will be on the other side of the transformer. The cap looks fine to me, why do you want to replace it, it won't improve sound quality.
 
There is probably nothing wrong with the Rifa snubber cap.

Your Kemet selection would be fine.
 
Hi,

The cap is a snubber cap used to prevent arching when the power switch is turned on. The (larger) filter caps
will be on the other side of the transformer. The cap looks fine to me, why do you want to replace it, it won't improve sound quality.

Yup, my bad, you're right, english is not my primary language :)

There is probably nothing wrong with the Rifa snubber cap.

Your Kemet selection would be fine.

Unfortunately it's totally cracked in the tuner (which does not even turn off when you push the power button). I think the one in the amp will follow soon. They are almost 40 years old.

Many thanks for quick replies, I'll go with the Kemet replacement.

Thank you guys.


u0gfc.jpg
 
Unfortunately it's totally cracked in the tuner (which does not even turn off when you push the power button).
Yeah replace the cap however it is not responsible for failed power-on. The snubber will either fail short or open, neither will prevent
power up. Double check fuses.
 
F911, F912,F901 transformer also has a thermal fuse, maybe check for AC on secondary, if no AC check resistance/continuity of
secondary be measuring resistance at power plug active/neutral pins, power switch ON.
 
Yeah replace the cap however it is not responsible for failed power-on. The snubber will either fail short or open, neither will prevent
power up. Double check fuses.

Hi,

there's no problem to turn the machine on. I wrote that the issue is it does not want to turn off :) Only unplugging the socket helps.
 
Thanks again for all the replies. Now a question about those large ones (power supply filter caps). I'd like to replace them as they are 40 years old. Considering their capacitance which is 6800uF, minimum voltage of 40V and lead pitch of 12.5mm it seems I only have three choices (with THT mounting):

Nichicon UVR: general purpose cap, 2000hrs/85C degrees, ripple current 3900mA, 63V
Nichicon UVZ: general purpose cap, 1000hrs/105C degrees, ripple current 2800mA, 63V
Nichicon UFW: "audio grade" cap, 2000hrs/85C degrees, ripple current 3500mA, 63V

Which one should I go for?

Btw we talk about Onkyo A-15 here, 2x25W @ 8 Ohms max output, a pretty lowendish amp but I love it.

Thanks.
 
My expectation would be to place an X2 cap here but when i look at the existing cap there's a 'Y' letter stamped on it, which confuses me as then I would expect one of the leads to be connected to the ground rather than to a transformer:

It is definitely a safety cap, e.g. X2 or Y2. There is a description of the classes here: https://www.allaboutcircuits.com/technical-articles/safety-capacitor-class-x-and-class-y-capacitors/

The schematic doesn't show the cap going from line to ground, so I'd guess it is supposed to be a X class cap.
 
Those Rifa safety caps are notorious for failing like yours has, l have seen quite a few myself.

In regards to your filter caps, how about these Nichicon LS snap in's, they have lower impedance and higher ripple than the ones you mentioned. You can easily "tweak" the 10mm leads to fit your 12.5mm spacing.

https://www.tme.eu/en/details/lls1j682melb/85c-snap-in-electrolytic-capacitors/nichicon/

I am guessing you have enough room to fit 30mm diameter caps?
 
Those Rifa safety caps are notorious for failing like yours has, l have seen quite a few myself.

In regards to your filter caps, how about these Nichicon LS snap in's, they have lower impedance and higher ripple than the ones you mentioned. You can easily "tweak" the 10mm leads to fit your 12.5mm spacing.

https://www.tme.eu/en/details/lls1j682melb/85c-snap-in-electrolytic-capacitors/nichicon/

I am guessing you have enough room to fit 30mm diameter caps?

Hi,

I was considering those as well. As long as it is perfectly 'safe' to add leads to them I'll for sure go with those. And yes, there's plenty of room for them as the old ones are like 40mm in diameter.

Thanks very much.
 
As long as it is perfectly 'safe' to add leads to them

Are these just going through a standard board thickness, ie approx 2-3mm? these snap in leads will have plenty of length for through hole fitment. Depending on what caps are originally fitted you may have to drill out holes/traces in board to 1.0-1.5mm.
 
Are these just going through a standard board thickness, ie approx 2-3mm? these snap in leads will have plenty of length for through hole fitment. Depending on what caps are originally fitted you may have to drill out holes/traces in board to 1.0-1.5mm.

Yeah the board is thin. It's like 2mm at most. I just looked in the datasheet and those leads are 4mm long. So maybe I will not need to drill any holes or add leads as I only need to go like 1mm to each side to fit them in the original holes. Carefully bending them may do the trick.

np3uxl.jpg
 
Many times the through holes are pretty big for filters and you'll find more than enough room to fit a 10mm spacing where there was a slightly wider spacing originally.
 
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