HIFONICS ZXi 1008 car amp stuck in protect mode

[tscr2015]

do I need to take the zener diodes off the board to test them or can I leave them in the circuit?

 

[Perry Babin]

At this point, I think he just wanted you to see if they were shorted or leaking badly. You can do that in the board. If one shows very low readings (much lower than the other), you'd remove it to check it more definitively.

 

[tscr2015]

What would be a good reading for the zener diodes. I think the last time I tried to test them they gave open line in one direction but in the other it showed like a capacitor was charging up because the readings keep changing. I will check again and then report back what I find.

 

[Perry Babin]

If both read the same, they're likely OK. If you remove them to check them, they will likely read about 0.7v one way and open with the probes reversed (meter on diode-check). With the meter on ohms, they would read open one way and 3-4M ohms with the probes reversed (but that depends on the meter).

 

[tscr2015]

almost forgot to mention there is like 4 to 8 of these just around the area of the transformers and driver board for PWM-OSC. There are others for the voltage amplifier that goes to the drivers.

 

[Perry Babin]

There should be two diodes connected to the 4 large resistors in the center of the board. Those are the ones you need to check.

 

[tscr2015]

both read .7 volt on diode check one way and open the other, but on ohms setting they read open in both directions, is that right. I did notice that when this unit was partially working that those for big resistors (R60, R61, R62, R63) were extremely hot to the touch.

 

[tscr2015]

Ok assuming they are bad what kind do I need to order to replace it with?

 

[Perry Babin]

They appear to be OK.

 

[tscr2015]

I found 4 diodes next to the PWM-OSC board and they show about the same voltage drop in each direction so I am guessing that they are bad (refer to the 4 diodes next to the PWM-OSC driver board)?

 

[Perry Babin]

Did you test them out of the board?

 

[tscr2015]

Without "easter-egging" this thing any more, what is the best way to test this amp to figure out what is wrong with it and if it can be fixed relatively inexpensive? As of right now there are no output transistors or driver transistor for the output in the board and all of the rectifiers for the power supply have been removed. There is 12 vdc going to the mosfets of the power supply but the protect light is still on. Did I miss checking something?

 

[tscr2015]

Almost forgot to mention: IF these are independent power supplies (ie one for each channel), is there a way to hook and test each of them individually? Sorry for all the questions, but I really want to get this thing repaired and back to my friend.

 

[Perry Babin]

Did I read it wrong previously? I thought that you stated that there was no protect after removing the rectifiers.

The supplies are not independent if the center legs of the rectifiers for one supply connect directly to the center leg of the corresponding rectifier on the other supply.

 

[tscr2015]

disregard post #72. The correct state with rectifiers out there is no protect light on tested for about five minutes and still no protect light. Quickly explain to me if you will about the power supplies. Is one generating rail voltage for the output and the other generates the 15 volts for the opamps?

 

[S Merlington]

Can you post a high quality pic of the area around the power supply driverboard ..

I may have a suggestion for you to try but I need a better quality pic of the amp around the driverboard area

 

[tscr2015]

you need the driver board or just the area around it?

 

[S Merlington]

The area around the driverboard in front of it and in back of it ..

 

[tscr2015]

The area around the driverboard in front of it and in back of it ..

Hopefully this is what you need. I can take a shot of the bottom side as well just PM me.

Thanks
Tom

 

[S Merlington]

Put the rectifiers back in the amp ..

Remove U1 that sits behind the driverboard ..

Insert a 10 amp fuse in series with the B+ wire ..

Try powering the amp up dies this allow the amp to power up?

Only try powering it up for a few secs since it may draw current so remember to insert a 10 amp fuse in the B+ line