HIFONICS ZXi 1008 car amp stuck in protect mode

[tscr2015]

Is there anyway to isolate the power supply part of the amp from the other stages for testing purposes? This is a testing project to learn from. If I cannot get it to work at least I can gain some knowledge from the information that I learn.

I want to thank you for your help while working on this. There doesn't seem to be a lot of information about this amp anywhere on the internet is that because it is considered a "throw away" amp?

 

[Perry Babin]

If you leave it on for 10-15 seconds, does the protect LED remain lit?

Pull the rectifiers and clean ALL solder pads to ensure that there are no bridges. Does it still go into protect mode?

 

[tscr2015]

With powered up protect light stays on. I will pull the rectifiers, clean the solder pads and report back to you what I find.

Thank you again for the help. I know this is a pain when there is no schematic available.

 

[tscr2015]

rectifiers are out, pads clean

Result = No protect light, just green power light

tested rectifiers voltage drop

HERF1004GA = .406 V
HERF1004G = .406 V

Is that correct or should it be higher like 0.6 V?

datasheet says that this is an Isolation 10.0 AMPS, Glass Passivated High Efficient Rectifier. I looked at the datasheet but I cannot find the voltage drop unless it would be the same as a normal diode?

 

[Perry Babin]

The diodes are OK and not the problem. They are simply not providing supply voltage to the protection circuit in the output stage.

Do you read 0 ohms between the output legs of the rectifiers on both sides of the board (positive to positive, negative to negative)?

 

[tscr2015]

Do you read 0 ohms between the output legs of the rectifiers on both sides of the board (positive to positive, negative to negative)?

Should I put the rectifiers back in or leave them out to test this?

 

[Perry Babin]

Leave them out. This is to determine if the power supplies are independent or parallel.

 

[tscr2015]

ok, not quite sure if I did this right but if I measure with the meter leads on the outer legs of where the rectifiers were on the board:

component side = 0 ohms
bottom side = 0 ohms

each channel has its own transformer with dual primary and secondary if that helps out

 

[tscr2015]

When I removed the rectifiers I removed one set on left side of board, clean up and tested still had protect light, when I removed the set on the right side of the board cleaned up and tested the protect light went out but I noticed that I did not have the 15 volts going to the op amps anymore.

 

[Perry Babin]

I should have been more clear. I need you to measure from the center pad of one positive rectifier to the center pad of the other positive rectifier in the other row of components across the board.

 

[tscr2015]

reads 0 ohms when the dmm settles down reads about .2ohm when first connect the leads

 

[tscr2015]

were you able to figure out what is wrong with the amp from the info that I have provided you thus far?

 

[Hexhclass]

check the zeners

 

[tscr2015]

what symptoms would this cause? Right now Perry said the protection circuit is not receiving the correct voltage.

 

[Perry Babin]

I've been too swamped to answer any questions that take more than a few seconds to answer. I'll check back when I get more time.

 

[tscr2015]

Ok, thank you for the reply, I will check the zener diodes and see what I can find. Be waiting to hear your response when you have some time, and always thank you for the help.

 

[Hexhclass]

I repaired a ZRX hifonics amp this week with independent supply.When i pull a particular rectifier the amp came out of protect .I left it long enough to realize the resistor supplying voltage to one of the zeners was extremely hot because of a bad zener.I replace the zener and that was it,

 

[tscr2015]

ok I will check the zener diodes and report back.

 

[tscr2015]

can't find anything wrong with them and nothing seems like it is getting hot. What else to check? Anyone with a schematic that is similar to this model please PM me.

 

[Perry Babin]

Not much can get hot with the rectifiers removed. Taking them out of the circuit disconnects 2/3 of the amp from their power supply for this amp (from what I can see from the photos).

Did you use a multimeter to check the Zener diodes?