My Soundcraft CPS 150 power supply took a big hit during a storm and the +17 and -17 volts of the supply are GONE. 48 volts looks fine.
The surge protector didn't.
I have noticed some brownness around BR1 & 2 (bridge rectifiers), they look small and probably shouldn't run so hot.
Turned over the board and it's a crap solder job under br's there, looks like it was burned last time it was fixed.
I need help.
Any suggestions till I get it up and running. I'm so pissed off I can't think.
HELP!
HELP!
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RodC
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Prob lost the rectifiers.
I would unhook the transformer connections and check the AC supplies. If they are OK check out the Bridges using diode check or a good ole analog meter. Then check the regulators (If it has them.)
I would unhook the transformer connections and check the AC supplies. If they are OK check out the Bridges using diode check or a good ole analog meter. Then check the regulators (If it has them.)
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Brian
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Looks like it's the bridge rectifiers AGAIN, they are prone to fail if you don't tie the negative terminal to the star ground with an extra wire, which didn't happen ;last time they were fixed. Looks like I'll beef this sucker up while it's down so I can recapp the board and SW-Op-amp-it. Get it, swap??
Regulators look intact.
Book says the TL783C is supposed to be isolated from the heatsink also and the sink is to be tied to ground, BUT, it isn't, so. yet another noise effecting thang to fix.
Regulators look intact.
Book says the TL783C is supposed to be isolated from the heatsink also and the sink is to be tied to ground, BUT, it isn't, so. yet another noise effecting thang to fix.
Harumph!
i remember seeing the magic smoke escape from the power supply of an Emulator II+HD back around 1988...it stank really bad.
tech at the studio cracked the case and the diodes that comprised the bridge rectifier had all melted to the board and i think an electrolytic had burst as well.
over the phone, someone at Emu talked him thru replacing them as well as a few other bits and testing it (this would never happen today!).
good as new within 30 minutes, but i am told the smell lingered for a week or two.
personally, i was surprised the hard drive didn't get trashed by the whole ordeal.
tech at the studio cracked the case and the diodes that comprised the bridge rectifier had all melted to the board and i think an electrolytic had burst as well.
over the phone, someone at Emu talked him thru replacing them as well as a few other bits and testing it (this would never happen today!).
good as new within 30 minutes, but i am told the smell lingered for a week or two.
personally, i was surprised the hard drive didn't get trashed by the whole ordeal.
?What need is there to weep over parts of life? The whole of it calls for tears.? -- Seneca
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Brian
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OK, this is what I learned:
1, the rectifiers in a CPS 150 need to be 20 to 35 amps,
2, the filter caps need to be at least twice the size provided to handle the ripple, at least 10,000uf,
3, the R32 needs to be 1/2 amp,
4, all the zero volt terminals and those of the filter caps need to be star grounded.
All of this will very significantly reduce hum in the supply, if you have one you know, and any noise in the power.
More later
1, the rectifiers in a CPS 150 need to be 20 to 35 amps,
2, the filter caps need to be at least twice the size provided to handle the ripple, at least 10,000uf,
3, the R32 needs to be 1/2 amp,
4, all the zero volt terminals and those of the filter caps need to be star grounded.
All of this will very significantly reduce hum in the supply, if you have one you know, and any noise in the power.
More later
Harumph!
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Brian
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IF you are talking about the CPS150,,yes, that is what I'm describing.
They come from the factory underpower. Voltage and power starving the board is not a good thing. It makes the board sound foggy in the mids and loose on the bottom and noisy too. That nasty cumulative fogginess effect from using the same pre's on everything is worsened by this.
This gets rid of that.
They come from the factory underpower. Voltage and power starving the board is not a good thing. It makes the board sound foggy in the mids and loose on the bottom and noisy too. That nasty cumulative fogginess effect from using the same pre's on everything is worsened by this.
This gets rid of that.
Harumph!
hey all,
my cps 150 died a week or so ago. this thread was very helpful in fixing it. thanks Brian! thought i would post a pic of the new bridge rectifiers flown out and fixed to the case lid. also here is a link to the parts I ordered from Mouser.
http://www.mouser.com/ProjectManager/Pr ... 13ccb99029
one thing to watch out for, in the thread above it is mentioned to tie the negative rails of the rectifiers to star ground. i tried this and it created a short in the circuit. i test it first with a dim bulb limiter so no damage occurred, but definitely not something you want to try under full AC voltage.
photo(2)
my cps 150 died a week or so ago. this thread was very helpful in fixing it. thanks Brian! thought i would post a pic of the new bridge rectifiers flown out and fixed to the case lid. also here is a link to the parts I ordered from Mouser.
http://www.mouser.com/ProjectManager/Pr ... 13ccb99029
one thing to watch out for, in the thread above it is mentioned to tie the negative rails of the rectifiers to star ground. i tried this and it created a short in the circuit. i test it first with a dim bulb limiter so no damage occurred, but definitely not something you want to try under full AC voltage.
photo(2)
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