Incorrect cap in a CR-420?

[skidmarks70]

Hey folks,

I started working on my CR-420 again. I actually pulled a couple capacitors in the power supply to try and test them and then realized that my meter wouldn't work on the big ones. Duh.

Anyways, I put them back in (with the correct polarity) and did some more cleaning. Powered up and sounded surprisingly good. For about 5 minutes. Then pop went a fuse. One of the capacitors that I put back died and was blazing hot. So I'm hoping that nothing was damaged and I've started to re-cap the whole power supply.

The interesting thing and what I'm here to ask about is the capacitor that went pop seems to be completely wrong. I pulled it back out and it's 3300 uF, 25V Elna, but the schematic indicates it should be 470 uF, 50V. The capacitor is C511 on the schematic and if I'm reading things right it was completely the wrong capacitor that was in there.

So what should I believe? The schematic or the capacitor that was there? I picked this up at the thrift shop, so I don't know the history.

 

[ConradH]

C512 is a 50V, so I'd expect C511 to be the 470/50 part. No voltages are labeled, but the schematics are usually correct. Naturally you'd check F503, the diode bridge and the single diode feeding the cap.

 

[avionic]

I pulled it back out and it's 3300 uF, 25V Elna, but the schematic indicates it should be 470 uF, 50V

I´d try a 470µf/50v. Make sure the neg. pin is connected to chassis ground. Someone may have installed the 25v cap in the past.Did it look like the cap was original ie. similar make as any of the other caps in the unit ? Solder connections look fresher than the rest of the solder on the board ?

 

[brutal]

I have a CR66-II here, basically the same as the CR-420 and C511 is a 470/50V.

 

[skidmarks70]

Thanks guys, the 25V was the only one in that section that was an Elna. The 2 big 6800 uF ones are also, but the rest in it's neighborhood were smaller, purple/violet ones that I didn't see a manufacturer on. I wouldn't say the solder looked any different, but I didn't really pay attention before pulling it. Sounds like 470/50V is the way to go.

I've pulled all the electrolytic caps from the power supply board now. All but one of them tested 20-30% high on capacitance. Just going to replace them all on principle. Is there any particular brand/type that's recommended for the power supply? Keeping in mind that this isn't a top end piece of kit, I don't see a huge need to put super premium parts in, but I don't want to put in junk either.

Thanks for the help!

 

[avionic]

I usually go with Nichicon PW´s.

 

[brutal]

I usually go with Nichicon PW´s.

Yup, this for power supply.

I think that particular 470 was only available @ 63V when I ordered mine, which works just fine.

I used FG's for most everything else. There were a few I didn't have so I just used available KW or KT's.

For the low leakage caps (mostly the orange ones you will find) use the KL series. I think they all had an "RB" designation on the schematics.