Will a snap-in cap fit an old Soundcraft PCB ?

[jnashguitar]

I'm replacing the caps on an 800B power supply (SC 1218).

Most of the large caps available from Digikey are the snap-in type. The lead spacing on the snap-in caps is 10mm, which measure about right, but does anyone know for sure that the leads will fit in these Soundcraft PCB holes ?

Specifically, I was planning to replace the 4700uF/50V caps with Panasonic ECO-S1HA103EA (10,000uF/50V). Are these a reasonable choice and does anyone know for sure whether or not they'll fit ?

Thanks!

-James

[MrMegaEli]

How about this? 4PCS Nichicon MUSE FW Audio Capacitor 4700uF 50V NEW | eBay

EDIT: I don’t believe audiophool caps, but this is all I could find.

[Ike Zimbel]

As always, it depends. If the circuit board is single sided (copper traces only on the bottom), there's no reason why you can't enlarge the holes a bit. BUT, you do need to be careful about doubling the amount of filtering as it can place an extra load and stress on the bridge rectifiers and transformer as well as the mains fuse. Sometimes just going to the next size up, in this case 5600uf, can be a good compromise.
Best,
Ike

[jnashguitar]

Originally Posted by Ike Zimbel

As always, it depends. If the circuit board is single sided (copper traces only on the bottom), there's no reason why you can't enlarge the holes a bit. BUT, you do need to be careful about doubling the amount of filtering as it can place an extra load and stress on the bridge rectifiers and transformer as well as the mains fuse. Sometimes just going to the next size up, in this case 5600uf, can be a good compromise.
Best,
Ike

Thanks, Ike! I saw several posts recommending replacing the 4700 with 10,000, but maybe that's not always a good idea ? Is that mostly dependent on the circuit design, or the parts quality ? I'm attaching my PSU's schematic in case you can tell from that.

I haven't looked extensively, but so far, haven't found a 10,000uF cap (with leads) that would fit in this case, anyway--they're all too tall--maybe that's a cosmic hint I should stick closer to the original values ? :-)

-James

[jnashguitar]

Related question: I'm noticing that with many of the caps, Nichicon for example, there's a choice between a rating of 2000 hrs at 85ºC or 1000 at 105ºC. Any rule of thumb there on longevity under normal studio conditions (I'm hoping it will never get anywhere near 85ºC inside the PSU case) ?

-James

[Ike Zimbel]

One year is 8760 hours. Those ratings are just how long the part type has been tested for. In general 105 degree caps tend to be kinder to audio for a whole bunch of reasons which have been documented and discussed elsewhere on this forum and the net.
best,
Ike
p.s. 85C is 185F, which is really, really F'ing hot. Again, the temp ratings are what the cap has been tested to, not what you can expect to encounter inside a piece of gear.

[Ike Zimbel]

Originally Posted by jnashguitar

Thanks, Ike! I saw several posts recommending replacing the 4700 with 10,000, but maybe that's not always a good idea ? Is that mostly dependent on the circuit design, or the parts quality ? I'm attaching my PSU's schematic in case you can tell from that.

I haven't looked extensively, but so far, haven't found a 10,000uF cap (with leads) that would fit in this case, anyway--they're all too tall--maybe that's a cosmic hint I should stick closer to the original values ? :-)

-James

You could replace the two 4700uf caps on each rail with ONE 10,000uf. Or, stick to the design value, as you said. Once you've done that, I think you will get more bang for your buck by installing a pair of decoupling caps of 4700uf or a bit more inside the console frame at the power supply connector.
best,
Ike

[jnashguitar]

Thanks again for all the advice!

One more cap question... I need 2.2 and 10uF 50V caps for each channel. Panasonic FM is not available in those values, so I tried FCs in my test channel. Sounds fine, but does anyone think it's worth spending the bucks for Wima polyester (only 15mm seems to be available--$5 each) or Kemet tantalum ($10), or any other recommendations ?

Thanks!

-James

[jnashguitar]

OK, after much searching--since I need something <1.75" tall--the best PSU cap options I could find are:

4700uF Nichicon VZ, 105ºC
4700uF Nichicon VY, 105ºC
6800uF Nichicon VR, 85ºC

More important to upgrade the value or go with the higher temp rating ? And I searched around and couldn't find any info on the VY vs. VZ models if anyone has advice.

Thanks for helping me with all these somewhat mundane and tedious questions!

-James

[Ike Zimbel]

I'd say go with the stock value. With this and your other cap question above, you are starting to wander into the gray area of re-capping vs. upgrading. The answers to "should I use this, or this?" start to get more complex...and more time consuming to type. The short answer is when in doubt, use the same or next closest value.
best,
Ike

[jnashguitar]

That makes total sense, Ike--thanks!

The only cap I'm having trouble finding is the fader cap, originally a 2.2uF electrolytic. I'm using Panasonic FM for all the other audio path caps, but the lowest value available in the FM series is a 22uF. I haven't found a 2.2uF electrolytic that gets decent reviews around here.

Several have reported upgrading their fader cap from 2.2 to 10. Is there any harm going up to a 22 so I can stick with the FM series ?

Thanks so much for your time, Ike!

-James

[jensenmann]

Long time that I´ve been into an 800B. IIRC 2,2uF were used in the peak detector circuit. Stay with that value.
Original large PSU caps are snap in, at least in the PSUs we used to have, same with 400B and 200s. It´s not so easy to say one parameter is important, others are not. They all interact, in the end you need to consider everything. But let´s not make it too scientific. You can´t go wrong with the original value/voltage rating and 105deg temp. rating. If you can fit in mechanically a higher capacity cap with same voltage and 105deg then go for it.
Forget about tantalum caps everywhere except timing and Neve circuits.

[jnashguitar]

Thanks, Jensenmann!

Sounds like there's some variability. In my PSU, the large 4700uF caps are standard radial lead (I removed one to confirm).

And in my modules, there are two 2.2uF caps, C28 and C25. C28 is for the peak detector, and I'm replacing with identical. But C25 looks like coupling between the 10k fader and the 5532 amp. I think that's what's called the "fader cap" ? Any harm in increasing its value to 22uF so I can use a Panasonic FM ?

Thanks!

-James

[jensenmann]

22uF is fine.

[jnashguitar]

Thanks, Jensenman!