Hi everyone.
I have 2 pioneers gmd8601 with ps blown. I replace the driver section, 2 2gm and 2 1gm transistor, i have 4.5v on all gates. The problem is when i take off the remote, just like power off the headunit, the ps blown.
I take off the rectifiers, same problem. On one amp i replace tl494, same problem. Test with another mosfets, irfz48, 50n06, etc and the same thing. The amp can power up and sound, but if you power off by the remote bum, ps blown.
When the remote is take off i have 0v on the gates, when turn on rises slow up to 4.15v. 0v between both banks gates. I dont have scope at the time.
I have 2 pioneers gmd8601 with ps blown. I replace the driver section, 2 2gm and 2 1gm transistor, i have 4.5v on all gates. The problem is when i take off the remote, just like power off the headunit, the ps blown.
I take off the rectifiers, same problem. On one amp i replace tl494, same problem. Test with another mosfets, irfz48, 50n06, etc and the same thing. The amp can power up and sound, but if you power off by the remote bum, ps blown.
When the remote is take off i have 0v on the gates, when turn on rises slow up to 4.15v. 0v between both banks gates. I dont have scope at the time.
The problem is that the supply voltage on pin 5 is being pulled down too quickly (before the 494 stops producing output). The capacitor pulls down pin 4 with it. I'm not exactly sure what your circuit is like. I'm using the D9605 diagram which is likely different.
I've seen this in other amps where it happens but without problems unless the FETs are changed (from a weaker to a more robust FET). When all of the FETs are in the circuit, the FETs aren't damaged but you can see a surge on the DC power supply when powering down.
The solution may be to install a pulldown resistor across the 100uF cap that connects across pins 8, 11 and 12, to ground if it causes a problem with all of the FETs of the original part number installed.
I've seen this in other amps where it happens but without problems unless the FETs are changed (from a weaker to a more robust FET). When all of the FETs are in the circuit, the FETs aren't damaged but you can see a surge on the DC power supply when powering down.
The solution may be to install a pulldown resistor across the 100uF cap that connects across pins 8, 11 and 12, to ground if it causes a problem with all of the FETs of the original part number installed.
The 1k resistor would go from pin 8, 11 or 12 to pin 7 on the 494. You can connect it across the capacitor that is across those points (C708 on the D9605 diagram).
A smaller cap on the soft start can be an option but you'd have to reach a compromise between no soft-start and malfunctioning. Also bear in mind that there are many millions of amps that work perfectly fine with no soft start. If you change the cap and the soft start isn't as slow, it's OK.
A smaller cap on the soft start can be an option but you'd have to reach a compromise between no soft-start and malfunctioning. Also bear in mind that there are many millions of amps that work perfectly fine with no soft start. If you change the cap and the soft start isn't as slow, it's OK.
Solved. I try with originals 3205 pulled from another amp, same thing.
Then i try this:
Change pulldown resistor for the output pins of tl494, from 2.2k to 1.5k ohm.
Put a 1k ohm resistor from pin 7 to 8 of tl494, supply voltage.
Gets down gate resistor from 47 ohm to 22ohm.
Irf3205 pulled from another amp.
Amp plays fine, nothing hot.
Then i try this:
Change pulldown resistor for the output pins of tl494, from 2.2k to 1.5k ohm.
Put a 1k ohm resistor from pin 7 to 8 of tl494, supply voltage.
Gets down gate resistor from 47 ohm to 22ohm.
Irf3205 pulled from another amp.
Amp plays fine, nothing hot.
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