Memphis 16-MC1.2500 protection issue.

[rhempz01]

i just rebut this me. ppl his amplifiers power supply. also Q404-403 were burnt as well as the trace on the under side of the board. I got the power supply up and running fine.
The outputs all tested ok.
When i first tested this amplifer, everything seemed fine. It had audio now protection.
i thought a cap was missing from here. c219 or c219. But I'm not sure it just looked like legs were snapped off in the solder joints.
I am in much need of help for this one.

 

[rhempz01]

pcb

 

[rhempz01]

ps1

 

[rhempz01]

c219-c218

 

[rhempz01]

output side.

 

[Perry Babin]

Al of that carpet and possibly that plastic you have around your bench could be sources of static electricity that may not be enough to feel but could be enough to destroy FETs, simply by touching their gate.

Is it trying to oscillate before the relay?

Is it producing DC voltage before the relay?

Is it producing the various rail and regulated voltages?

 

[rhempz01]

its definitly trying to oscillate before the relay.
only has +- 30v of rail on the output.
my regulated voltages are not present at my opamps.
It only stays out of protection long enough till.the relay engadges then protection.

 

[rhempz01]

its strange now its running with full audio at the outputs and +-12 at the op amps.
+-87vdc of rail.
It was almost as if something like a timing capacitor was off. it like clicks and protects of starts.

 

[rhempz01]

power supply drive. doesnt look right at the fets.

 

[rhempz01]

the drve at the fet.

 

[rhempz01]

i think the problem is with the low voltage supply.
q221 the rail voltage take a long time to build up. Once its up the amplifier will stay out of protection a work properly. now i was testing at q221 and slipped at hit the cap c213 and it blew the q221 and possibly the capacitor as well.
anyone know the value of c213?

 

[Perry Babin]

This amp is similar. If no one has a definitive, maybe you can find the corresponding part (don't expect the circuit board designations to match).
http://www.bcae1.com/temp/soundstreamxxx6500.zip

 

[rhempz01]

got that fixed but its still slow to build its rail voltage tk stay on. any ideas on what would likely cause this?

 

[Perry Babin]

I don't know what that's supposed to read but you need to check the voltages on the driver IC and look at the waveforms there to see if something is strange when there is a problem.

 

[rhempz01]

i was trying to relay the actions of this amplifier. It reminds me of the 1500.1

Rail voltage slowly rises, once it gets high enough the amplifier will run and produce clean audio.

i just dont know what or where to look. Would rectifiers cause this?

 

[Perry Babin]

The rectifiers, unless shorted, aren't likely to cause this.

Did you look at the diagram and determine what part of the protection circuit was shutting it down?

 

[rhempz01]

i tried perry. i just couldnt fiqure our much.
both of the 494 voltages match.
pin 5 of one of them.seems to bring the amp to start up if i test for voltage 1.406vdc

 

[rhempz01]

It reminds me of what the 1500.1 did when i repaired it with your help. same

 

[Perry Babin]

Wasn't the 1500 a completely different type of amp?

You're going to have to find the reason it's not powering up and find why that is being triggered.

 

[rhempz01]

same make and model. 16-mc1.1500 same black heat sink model. It was i had to make a circuit to get it to power on after using the 31n20 in the output section. It did the same thing just kind of on and off, current then none, and back again. it will.dk this and go into protect until.the rail.voltage reaches over 70v and then it will just come on. If i dont discharge the caps. even if you shut it off, and power it back upit will then just come back on.