Digital Designs Z2

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I got this amp in for repair and well someone tryed repairing it themselfs.

I pulled all of the power supply fets out of the amp and the output driver board also .

With the power supply fets in the amp the amp trys to power up and the Transformers start squealing like crazy.

With the power supply fets out of the amp heres what i have for gate signals
There are 4 banks of fets first pic is bank 1 and pic 2 is 2nd bank Pic 3 is the 3rd bank and last is the fourth bank. If you notice 1 of the banks deflects much higher then the other 3 and another bank doesnt look the same as the other 2

ANY Ideas?


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Lets see some pics of the hardware, what do you see first that looked like it was touched? Check your joints, and dont be lazy, verify all the resistor value's fall in line with the color bands, and make sure you dont have any obvious shorts on any switching devices. Whilst wave forms and signals rule the logic world, amp repair can be done at the lowest level, verify no shorts (open or closed) and check your discrete components...

as my father once said, "what happens on one end is likely caused by a problem on the other end!"
If that's the case, then disconnect the smps from the amp side, and, as you say "get it up and running" aka remove the final rectifier's and you shall obtain your goal, strange change in amplitude on the 4th pic, hows that op-amp look? voltage look good?

also, that BNC connector on your scope looks jacked up... might want to fix that.
I understand that i need to get the Power supply up and running first off. The gate drive signal dosent look right on 2 banks of the power supply fets. I dont know what pulling the rectifiers would do besides eliminate the output section which is already done THe problem is with the Power supply drivers or driver card
the entire output section has power if the final rectifiers are in-place, pulling them in most cases, will isolate the smps in it's entirety. Old amps had the V+VgV- isolated down to just the 3 traces, seporateable by jumpers in most cases, so isolation was easy, these days and on some amps, making isolation a priority, can be a pain! But were here to help :)

so, I have to ask, whats "big" to you, Mike? I have fixed hifonics xxx's in the 10kw range, I dont see much larger then that these days, do you work on industrial RF heaters? cause that stuff's way neat! My most complex is my millet 300b 5.x system for my home theater.

Or the Intel itanium ES machine's I have to evaluate sitting @ my office.
Wasent trying to be rude to you at all I havent seen your name on here til like a few days ago And wasent sure if you were one of thoose people that thinks they know everything about amps by reading a couple of threads on here.

I respect the fact that you have a degree and you know your stuff was just making sure .

I pulled the rectifiers out and the bank that deflected the most is normal now only have a wierd signal on 1 bank yet. wondering if this would cause a problem or not?


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You have come to the same conclusion you had in the start, that the smps was fine, and your issue was in the output stage, So, as we discussed in the last iteration, how is the health of the op-amps? can we get a scope shot of there input/output and voltage?

To be honest, Perry owns this section, and has these templates he likes people to use when showing measurements, so really, I'm waisting your time, Perry is who you want.
well you would do that to unload supply, if something is worng with amp. What I would go is, go from drivers back and see if there is any good signal, as it should be... in the end something on driver card could be dead or not working ok

I tend to blame the drivers first, They just have a way of going bad... especially in the amps that use 16+ driven's, in the to-220 and bigger package, with 4 to-92's per side, holding the rein's :( give me good old to-220 on to-220 and to-243's for the out's, tip35 and 36c's still grace my finest amp's.
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I know what you mean, but as long as amp work, those drivers are ok, most times drivers go at the same time as fets do, so they are really "at the heart of the action"... but if they fail, then even ICs "up the stream" can be damaged.

expect everything to be damaged, but do see, what is ok and what is for sure not

This z2 and z1 are only amps, way too big to work inside a car in those conditions that they most of the times are
Well I found a big problem when i started removing the driver transistors ,

The legs on the C3228 is broken and someone did a number on this amp the pads are burnt very badly.

This amp to me is pretty much unrepairable. I will take pics in a few and show you what i mean.

Is there a good replacement for the C3228's Like the C2383's or should i order something else"?
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