Hertz HDP4 Oscillating output

Good day. I am working with a Hertz HDP4 4 channel amp a couple of day now. It uses 4 IRS2092s drive chip which drives 2 IRF14019H dual mosfets in parallel in each drive. In my initial repair, i replaced 4 of the mosfets and 2 drive ic that where burned and deffective. Upon power power on , I see the gate and output signals clean and good from the mosfets but after a couple of seconds the signal becomes distorted kind of oscillating too much wherein no signal is fed yet. All of the channels have same issue, I tried to feed an 50 hz signal but not seen any signal output. I checked the mosfets and drive chips , in my opinion are all good. Am i having an issue on the output section or in the preamp section? First time i encounter this oscillating issue. Please need help from guys who have same issue on Hertz amps. I will post later the output signal from the mosfets if you need them. Thank you very much.
 
Sorry for the term oscillation that I had used, Yes i was wrong, After power on the relay clicks normally and I am getting a good gate square wave signal for the hi and lo of the dual mosfets on each channel but after a couple of seconds the signal beacomes distorted. Then the overload orange led lits up and the relay clicks off. I checked the output components because there is still no load and seems they are all good. Double check the Mosfets as they are all good. Is there a problem with the preamp section or the output section maybe? Please any insight with this design? Thank you Perry again for the prompt response.
 
HI, usually when this behavior occurs, it can depend on one or more secondary voltages or even on the rail.

If at the beginning, the RAIL and all the auxiliary voltages are present, the 2092 works well, but if the RAIL goes down gradually, at some point the 2092 stops working.

The same happens if the 12V (referring to the negative rail) disappears or if it is too low for some reason.

The same happens if the +/-5.6v (for the internal logic of the 2092) is low or absent or becomes unstable after a short time from the start of the operation.

My advice is: keep an eye on the rails during operation and when it stops working.

Are the rails stable? do they go down gradually?

Same thing, keep an eye on the 12V (2092 pin 12) (referring to the negative rail).

Same thing with +/-5.6v referring to secondary ground (pin 1 and pin 6 of 2092).

Usually, however for convenience, the +/-5.6v is generated from the +/-12 or 15v which is used for the pre-amp section, so keep an eye on those as well.

The thing is very simple, if the amplifier works when switched on, but stops after a few seconds (on all 4 channels) and it is not an overcurrent condition, there must be something wrong with the power supplies.

Is this "gate distortion" condition common to all channels?
 
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Thank you. Mario, for your info. I will monitor the voltages you are referring to. However with your question, the distortion of the gate signals doesn't occur on all the channels as I looked deeply last night, 2 channels are having a clean hi and lo signal gate. the others 2 channels have distorted signals. Does it mean I am having problem either the drive chip or the mosfets? I replaced the chips 2092s with new ones before and I checked the mosfets again but seems they are all good.
 
In this period it is very difficult to find IRS2092, where did you buy them?
With the advent of the "broker" boom, a flood of fake chips or chips that have not done a correct backing procedure (or factory rejects) are going around the world.
The same thing goes for your Dual Mosfets.
Can you make sure they're sourced reliably?
Especially IRS2092.
 
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I got the dual Mosfets from Arrow electronics, I believed a reliable source. Yes your are correct IRS2092s .I can't find it a reliable source in US, However I doubt the IRS2092s, I got it from my friend who ordered from Hongkong with good review according to him.
 
I work in a company that produces top-level electronic boards.
Many times, the components that compose them are not available from reliable suppliers, so we are forced to fall back on brokers or suppliers of whom we know little or only "hearsay". 80% of the time, the components aren't good, even though a friend who buys said it has good reviews.
Trust only your sources, the reliable ones, never those of others based on their experiences.
 
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I believed then that I got IRS2092s that are not original. Because not all the channels are having a distorted output. Let me source out these components again form a legit seller and let me get back to you. Any recommendation where I can find other legit stores? At the moment I am ordering parts from Digi-Key, Mouser and Arrow electronics, but sometimes they don't have the parts as well. Any Legit sellers you can recommend bro? Thank you again for your responses. I appreciate it.