recapping my console, bigger caps?

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Baltimore

Well-known member
Joined
Nov 19, 2005
Messages
268
Location
Baltimore, MD - the Charm City
I'm about to recap all the power supply caps in my auditronics. It has 10uf tants for power supply decoupling. Should I up the value of these..something like 100uf lytics? They should easily fit the board. Or should I stick with 10uf lytics?

Kevin
 
To be safe, we need to know how many cards you intend to replace the caps on.

If it's only a handful, I can't see a problem. However, if your PSU is slightly underrated or has sensitive over-current sensing or suchlike, you could have a problem when replacing more than a handful of caps.

If you increase the size of a whole load of caps, it can appear to the main PSU as if it's a direct short... There's also the issue I discovered when I fitted massive caps, whereby the inrush current / inductance from the caps charging is so large that it blows your rectifier diodes across the room...bit of a fire risk! It won't necessarily happen immediately either, so it could happen when you least expect it, i.e. a burning diode could land on the skirt of the lead singer - major bummer!

I am being conservative btw, but it pays to be careful.

Justin
 
It is a 26 channel frame but only loaded with 16 channels right now, but I will add channels as I find them. There are 13 10uf tants per channel, but it looks like 6 are for power supply decoupling - 2 per routing module and 4 per channel, Plus a bunch for all the master section. The rest are in the signal path and I will probably bump those up to a higher value.

Kevin
 
[quote author="Baltimore"]It is a 26 channel frame but only loaded with 16 channels right now, but I will add channels as I find them. There are 13 10uf tants per channel, but it looks like 6 are for power supply decoupling - 2 per routing module and 4 per channel, Plus a bunch for all the master section. The rest are in the signal path and I will probably bump those up to a higher value.

Kevin[/quote]

6 caps x 90u (extra) x 16 channels = 8,640u of extra capacitance for your PSU to charge on start-up...

Does it have a soft-start circuit? I'd advise caution if not...


Justin
 
Decoupling caps shouldn't be unecessarily large. Larger electrolytics have internal series resistance and inductance. Because of this they aren't as good a bypass at higher frequencies and can affect stability of the gain stage. Unless you are driving low impedance loads there really isn't any benefit to be gained.
 
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