Eclipse 3121 questions

[spooney]

I've got an eclipse amp here with a couple issues.The previous owner told me that the amp worked fine and then one day just quit working.I find it kind of hard to believe as both power supply fets (stp50n06) and both rectifiers are shorted.Is there anything that could suddenly go bad in a normally functioning amp that would cause this kind of damage?Also there is a couple diodes (zeners i believe) on the underside of the circuit board(smd device) that appear to be damaged.There is absolutely no markings as far as a part number on these things.Just the normal stripe marking the cathode.How would i go about determining a value to replace the bad diodes?

[jol50]

The fets is normal since they run parallel once one blows it overloads the rest and trashes all of them, maybe. I don't know as much about the diodes/rectifiers as far as the various causes that blow them, they don't blow near as much as the fets. Of course if a diode shorts it can make a mess.

[Perry Babin]

Did you pull the rectifiers to check them? Shorted ral caps can make the rectifiers look bad and can also cause the rectifiers to fail.

The diodes are probably MELF components and won't have any markings. You will probably have to determine how they are being used (zener, rectifier...) to find a suitable replacement. If they are being used simply as a rectifier or to prevent current from flowing back into a circuit, virtually any replacement switching/rectifier diode will work. If it's being used as a zener in the regulator for the op-amps, it's probably a 16v zener.

[spooney]

the fets and rectifiers were trashed and i'm reading no shorts on the rail caps. I replaced the power supply fets and the rectifiers and the amp is now able to power up and make rail voltage(approximately + 21 volts) .The amp does not have any output though.I've yet to address the problem with the diode.I'm still in the process of figuring out exactly what its for.One end of it is tied to the outer legs of the rectifiers but i'm not sure where exactly it goes from there.

[jol50]

Is there more than one? I have an amp here with two power supplies for lack of better description, it has the dual to-220 rectifiers and a set of 'old style power' diodes on the board that also run off the transformer but they are not that big.

[Perry Babin]

Does the amp have regulated power supply voltage (±15v) on all of the op-amps in the audio section?

[spooney]

yes it does perry.actually about 14.1 volts.Is that too low?

[Perry Babin]

That's not too low. Anything over ±10 would be enough. I said ±15 because that's what most amps use.

If you have both plus and minus rail and regulated voltage, the power supply seems to be working.

At this point, you'd have to begin tracing the signal and/or checking op-amps.

I couldn't find any information on this amp. If you could post a couple of photos (of both sides of the board), they may be helpful.

[spooney]

I was unable to find any info.I even got a hold of the company eclipse recommends for repair work and they told me a service manual is no longer available for this unit.I will get some pics in a few minutes.

[spooney]

Pics of the top and bottom of the board can be seen
here
The missing diode is in the upper right hand corner of the bottom of the board pic.It is labeled CR7