This amp came in with one bad output FET.I remove it and power the amp.
The amp powers up with 60v rail but FET 260 is getting hot.It tested ok out of circuit. LED 399 is on and LED 238 comes on about 10 sec later.The amp is drawing excessive current .I remove that one bank of outputs but no change.Any ideas?
The amp powers up with 60v rail but FET 260 is getting hot.It tested ok out of circuit. LED 399 is on and LED 238 comes on about 10 sec later.The amp is drawing excessive current .I remove that one bank of outputs but no change.Any ideas?
FET260 runs hot normally. It's a regulator that's dropping quite a bit of voltage. The two 1000uf caps on the edge of the board sometimes fail and can cause the regulators to run hotter.
Does it draw excessive current before LED238 comes on?
Does it draw excessive current before LED238 comes on?
yes it draws current before LED 238 comes on.I have a light bulb lmitter and it is very bright when
i power the amp.I will check the caps tomorrow.
i power the amp.I will check the caps tomorrow.
I change the caps and re-solder some bad connection.The amp is drawing about 4 amps at idle.
is that ok for this amp?
When i power this amp up with the limiter LED 238 keeps blinking.I remove the limiter and tried it for audio with one output still missing and it had good audio.
any good sub for the outputs? IRFB42N20D
is that ok for this amp?
When i power this amp up with the limiter LED 238 keeps blinking.I remove the limiter and tried it for audio with one output still missing and it had good audio.
any good sub for the outputs? IRFB42N20D
These amps are sensitive to the output transistors used. I'd suggest using the originals. Even then, there's no guarantee that they will work. I'd suggest keeping the originals that you have until you find some replacements that work. It may get to a point to where you don't know if the replacement transistors are the problem or if it's something else. If you keep the original FETs, you can reinstall them and determine where the problem is.
I have an 81000d here that doesn't have all of the outputs installed but before it switches on the output stage, it draws about 0.6 amps. After the output stage is switched on (LED238 on), it draws approximately 2 amps.
I have an 81000d here that doesn't have all of the outputs installed but before it switches on the output stage, it draws about 0.6 amps. After the output stage is switched on (LED238 on), it draws approximately 2 amps.
Before LED 238 comes on amp draws about 3 amps so i guess it still has problems.I will try a different amp-meter to make sure.Sometimes i hear a little squell in the power supply.
Before LED238 is lit, all current is from the power supplies (low voltage, regulators and rail). You can confirm that there is no current flowing in the audio section by measuring the DC voltage across the shunt resistors near the output transistors. You can prevent the output section from switching on by shorting the capacitor shown in the photo. The jumper in the photo was cut to allow normal operation.
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