HIFONICS ZXi 1008 car amp stuck in protect mode

[tscr2015]

.706 out of circuit, protect light ON

 

[S Merlington]

Ok we will start from the beginning ..

Clean all of the pads for the components you removed ..

Install all of the components that you removed in the amp..

After that's done report back

 

[tscr2015]

ok, everything is back in place. Where do we start?

 

[S Merlington]

Ok if the amp is in protection mode pull the rectifiers and only the rectifiers .

Is the protection light still on ?

 

[tscr2015]

Ok, while I am getting ready to do this. Can you explain to me what we are trying to accomplish? Just trying to learn more as I do this. I have a smaller amp that works to compare results to. I can tell when I hook up my meter to one of the diodes on that amp that they switch on and off real fast. In the amp that we are working on nothing happens at all. I assume that is because of the PROTECT. Is there anyway to disable protect to see what happens?

Thanks
Tom

 

[tscr2015]

According to the manual, Protect is only supposed to engage if the outputs are shorted or if there is a DC offset in the output correct?

 

[tscr2015]

Is there anyway to seperate the power supply(s) from the rest of the amp to just test and repair the power supply without the rest of the amp circuit hooked up?

 

[Perry Babin]

Did you replace the burned resistor near the output transistors?

 

[tscr2015]

yes, pulled rectifiers, still in PROTECT mode. Now what do I check?

 

[tscr2015]

yes, pulled rectifiers, still in PROTECT mode. Now what do I check?

never mind this. I found a short under one of the recifiers that I pulled. I eliminated that short and now the amp is out of protect mode. So when the rectifiers are in that is when it goes into protect mode so what does taht mean?

I will be waiting to hear back on this.

Thanks
Tom

 

[tscr2015]

Tested the rectifiers, with the center legs out of circuit, and I get +45vdc and -45vdc out of them so I guess that means that the rectifiers are good and so the power supply FET's are good. When I hook the center legs up to the circuit that is when it goes into protect.

 

[tscr2015]

I got a question regarding the designation of pin 1 on the circuit board. Is it usually a square shaped pad and the other are round or is that not standard?

 

[S Merlington]

That's normal ..

Ok so the amp is all together correct?

If not solder everything back in the board ..

Next take the outputs and drivers out of 1 channel at a time only 1 channel at a time and power it up does it protect?

 

[tscr2015]

one channel has all of the drivers and outputs out of it and it still protects. There are 4 ceramic disc capacitors that connect between the pins of each of the rectifiers (1 between pins 2 and 3, and between pins 1 and 2) when on do try t connect pin 2(center pin of the rectifiers) to the circuit I get a small spark and the power supply shuts down. I traced the center pins of the rectifiers and seen that they supply the collectors of the outputs for both channels which I don't understand can you explain to me why they would do this.

 

[tscr2015]

all drivers and outputs out of circuit. hook up rectifiers 5 seconds later goes into protect.

 

[tscr2015]

looks like one or more of the FET's are bad. How can I test them to make sure?

 

[tscr2015]

What would cause this amp to go into protect?

 

[Hexhclass]

post the voltage of the 494 IC when it is in protect ,black probe on main ground.That might indicate something.

 

[tscr2015]

See post #90

 

[tscr2015]

ok. Checked everything downstream of the rectifiers cannot find anything shorted. When I try to plug in the center pin of the rectifier, i get a spark, does that mean that one of the caps is shorted out?