Ok thanks my parts i ordered from ebay got lost in the mail so im gonna order from digi key or mouser later on today. Thanks perry
I have a ? I found that the big gate resistor r263 is bad. I thought the only one that was bad was the small surface mount one r20 on power supply. But found this that i thought i already checked. Anyways these are .3 ohm on my amp, the schematic says .1ohm my ? Is are they 3w or 2w and can i substitute a .1 out of my punch 60 dsm thats for parts?
R263 isn't a gate resistor. Gate resistors are the resistors in series with the gate terminal of an FET.
R263 is a source resistor.
With most multimeters, you will see a resistance of about 0.2 ohms when you touch the probes together. Part of this 0.2 ohm reading is the resistance of the leads. When reading low value resistors (like 0.1 or 0.2 ohm emitter/source resistors), you can touch the probes together for a few seconds and subtract that from the value the meter gives you when you measure the resistance across the low value resistor.
R263 is a source resistor.
With most multimeters, you will see a resistance of about 0.2 ohms when you touch the probes together. Part of this 0.2 ohm reading is the resistance of the leads. When reading low value resistors (like 0.1 or 0.2 ohm emitter/source resistors), you can touch the probes together for a few seconds and subtract that from the value the meter gives you when you measure the resistance across the low value resistor.
Sorry for my ignorance yes it toggles between .4 and .5 when measuring a good one. The 1 in ? Measures up in k range cant remember exactly it has black orange silver gold stripe pretty sure that is .3ohm. If i tried putting a .1 in there would it hurt anything or would i need to replace all of them?
The black, orange... is a 0.03 ohm. The 0.03 and 0.1 aren't interchangeable. The photos I have of a 250a2 have 0.03 ohm resistors.
There are no parallel source resistors so you only need to replace the failed one.
The 0.1 may serve to allow testing at low levels but it's not going to allow the amp to produce full power because it will make the protection circuit much more sensitive.
If the source resistor opened, there may be damage to the protection circuit. Check R261 and R262 while the source resistor is out of the circuit.
There are no parallel source resistors so you only need to replace the failed one.
The 0.1 may serve to allow testing at low levels but it's not going to allow the amp to produce full power because it will make the protection circuit much more sensitive.
If the source resistor opened, there may be damage to the protection circuit. Check R261 and R262 while the source resistor is out of the circuit.
Im sorry i misread the color chart. In that case the possible replacement resistor is a .01 ohm. I swear the schematic said .1 on it which i know doesnt match my board #. I will check those other res you mentioned earlier when i get home.
Ok i will get some .03 ohm resistors you dont happen to know the part # for them do you? Thanks for dealing with me.
Ok Perry I replaced all known bad components. The ps was replaced with 3205's with 47ohm gates. When powered up the light comes on then about 2 or 3 sec later tmy ps drags down to 8.5v i ammediately pull power what that happens. Is there something i need to check now?
My ps is a pyramid ps-12 12amp
My ps is a pyramid ps-12 12amp
Set the bias pots fully counter-clockwise. Does that eliminate the excessive current draw?
You should have everything tightly clamped to the heatsink (with heatsink compound applied) to prevent anything from overheating.
You should have everything tightly clamped to the heatsink (with heatsink compound applied) to prevent anything from overheating.
Ok thank you i did not have it clamped to heatsink i will do that b4 i do anything else thank you. I will get back with you as soon as i try that.
I tried that perry i think the current draw was less voltage dropped just a little and ps started singing a little then i heard what sounded like a static snap. And i seen what looked like a arc from closest cap (c22) from there to heat sink ?
There could have been a strand of wire under the cap.
I don't know what to expect measuring resistance from B+ to ground. 0 or very low resistance would be bad. Nearly 10M doesn't tell me anything.
I don't know what to expect measuring resistance from B+ to ground. 0 or very low resistance would be bad. Nearly 10M doesn't tell me anything.
Pretty sure diode d7 is bad it needs replacing i hope it wasnt caused by somethink i did. I hope it was from original failure.
Im gonna pick up a diode it said radio shack had them when i looked up number. i will check again to make sure no trash got under there. Could have that diode cause the whole failure to begin with?
That diode, when it shorts, typically causes the amp to have engine noise. If the diode opens, it can cause there to be DC offset at the output. Neither is likely to cause any further damage to the amp.
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