The rectifiers don't seem to be the problem.
I wouldn't be concerned about any noise that occurs after the power supply has been switched off.
What is the current rating of your power supply?
To save time (if you plan on repairing other amps) please edit your signature file to indicate whether you have a scope or not, what meter (make/model) you're using and the current rating of your power supply. Others should do this also if they're asking for help with repairs.
I wouldn't be concerned about any noise that occurs after the power supply has been switched off.
What is the current rating of your power supply?
To save time (if you plan on repairing other amps) please edit your signature file to indicate whether you have a scope or not, what meter (make/model) you're using and the current rating of your power supply. Others should do this also if they're asking for help with repairs.
Pulled them, tip36c seems to be fine, resistances between legs (multimeter set to check continuity) either 1 (more than meter can display) or 950, hfe 45.
tip35c resistances either 1 or 205, when testing hfe my meter shows me 1 (again more than meter can display) and battery sign in the corner lights up.
35c has then kind of shorted but not entirely and is letting so much current flow through that it trips my supply?
tip35c resistances either 1 or 205, when testing hfe my meter shows me 1 (again more than meter can display) and battery sign in the corner lights up.
35c has then kind of shorted but not entirely and is letting so much current flow through that it trips my supply?
Tried to switch the amp on today without these tip35c and tip36c. Power LED turned on, limiter lamp did not glow, does not draw excessive current anymore? Produces audio with other channels. So now I have to replace the tip35c and tip36c. One of them was OK, but to match them I need to replace them both, yes?
Defective FET was IRFZ44A local store does not carry those, options are here:
https://www.elfa.se/elfa3~ee_et/elfa/init.do?query=irfz44
IRFZ44NPBF and IRFZ44A are both 60V 50A, but power dissipation differs: NPBF - 250W, A - 126W. Is that a suitable replacement? If it is then do I have to replace all 6 of them to match them?
Defective FET was IRFZ44A local store does not carry those, options are here:
https://www.elfa.se/elfa3~ee_et/elfa/init.do?query=irfz44
IRFZ44NPBF and IRFZ44A are both 60V 50A, but power dissipation differs: NPBF - 250W, A - 126W. Is that a suitable replacement? If it is then do I have to replace all 6 of them to match them?
Only parallel components need to be matched. The TIP35and 36 are not in parallel. That said, it's good practice to replace all outputs in a channel when one fails.
The IRFZ44NPBF is a good choice. I've never seen a Z44 with an A suffix. If it's the original Z44, it's a good choice also. The suffixes generally mean that there are different versions of the same part. For power supply FETs in car audio amps, the suffixes aren't generally important. The PBF suffix means that it's lead free.
The IRFZ44NPBF is a good choice. I've never seen a Z44 with an A suffix. If it's the original Z44, it's a good choice also. The suffixes generally mean that there are different versions of the same part. For power supply FETs in car audio amps, the suffixes aren't generally important. The PBF suffix means that it's lead free.
Many thanks Perry Babin for walkthrough. If you dont mind I will ask a few questions more to understand what we did rather than just mechanicly do what I am told to do.
First stop we removed rectifiers that is to narrow the search only to power supply part of the amplifier? Amp without rectifiers drawing too much current has a fault in power supply? After removing defective FET we had 5 still going, what does removing one do to amplifier? It will limit the maximum current to output? With FETs removed we confirmed that power supply IC has voltage on its 9 and 10 pin, that means that transformer has not shorted because otherwise there would be no voltage on these pins and my supply would trip? After reinstalling rectifiers supply tripped again that told you that we had a malfunction in output as well? Why did 2 resistors have higher voltage across them if only one transistor was defective?
First stop we removed rectifiers that is to narrow the search only to power supply part of the amplifier? Amp without rectifiers drawing too much current has a fault in power supply? After removing defective FET we had 5 still going, what does removing one do to amplifier? It will limit the maximum current to output? With FETs removed we confirmed that power supply IC has voltage on its 9 and 10 pin, that means that transformer has not shorted because otherwise there would be no voltage on these pins and my supply would trip? After reinstalling rectifiers supply tripped again that told you that we had a malfunction in output as well? Why did 2 resistors have higher voltage across them if only one transistor was defective?
First stop we removed rectifiers that is to narrow the search only to power supply part of the amplifier?
**** Yes.
Amp without rectifiers drawing too much current has a fault in power supply?
**** Generally, yes.
After removing defective FET we had 5 still going, what does removing one do to amplifier? It will limit the maximum current to output?
**** It reduces the current that the power supply can produce reliably.
With FETs removed we confirmed that power supply IC has voltage on its 9 and 10 pin, that means that transformer has not shorted because otherwise there would be no voltage on these pins and my supply would trip?
**** Removing the FETs prevented the damaged FET from causing excessive current draw which was dragging the voltage down and prevented you from measuring the voltage. With the amp receiving ~12v, the voltage on the output of the IC could be measured. The ~5v on pins 9 and 10 indicated that the IC was producing output pulses. With only a multimeter, it's a guess but pretty reliable. 5v of DC on the meter could mean that you actually have 5v of DC (not good) and not the desired 10v (peak) 50% duty-cycle sine wave.
After reinstalling rectifiers supply tripped again that told you that we had a malfunction in output as well?
**** It means that something beyond the rectifiers is causing excessive current draw. It could be shorted rail caps, solder bridges, shorted/leaking outputs, shorted/leaking driver transistors or a number of other things. Shorted outputs are, by far, the most common fault that causes excessive current draw.
Why did 2 resistors have higher voltage across them if only one transistor was defective?
**** The transistors are essentially in series. The resistors are in series between the transistors. One transistor pulls the voltage toward the upper rail. The other pulls the voltage towards the lower rail. If one shorts, it applies its rail voltage to the speaker output. This is a problem because the amp wants to have 0v (with no signal) on the speaker output. To correct the voltage error, the amp's differential amp corrects by driving the non-shorted output fully on to try to eliminate the DC offset. It's not possible so the amp either goes into protect mode or fails.
**** Yes.
Amp without rectifiers drawing too much current has a fault in power supply?
**** Generally, yes.
After removing defective FET we had 5 still going, what does removing one do to amplifier? It will limit the maximum current to output?
**** It reduces the current that the power supply can produce reliably.
With FETs removed we confirmed that power supply IC has voltage on its 9 and 10 pin, that means that transformer has not shorted because otherwise there would be no voltage on these pins and my supply would trip?
**** Removing the FETs prevented the damaged FET from causing excessive current draw which was dragging the voltage down and prevented you from measuring the voltage. With the amp receiving ~12v, the voltage on the output of the IC could be measured. The ~5v on pins 9 and 10 indicated that the IC was producing output pulses. With only a multimeter, it's a guess but pretty reliable. 5v of DC on the meter could mean that you actually have 5v of DC (not good) and not the desired 10v (peak) 50% duty-cycle sine wave.
After reinstalling rectifiers supply tripped again that told you that we had a malfunction in output as well?
**** It means that something beyond the rectifiers is causing excessive current draw. It could be shorted rail caps, solder bridges, shorted/leaking outputs, shorted/leaking driver transistors or a number of other things. Shorted outputs are, by far, the most common fault that causes excessive current draw.
Why did 2 resistors have higher voltage across them if only one transistor was defective?
**** The transistors are essentially in series. The resistors are in series between the transistors. One transistor pulls the voltage toward the upper rail. The other pulls the voltage towards the lower rail. If one shorts, it applies its rail voltage to the speaker output. This is a problem because the amp wants to have 0v (with no signal) on the speaker output. To correct the voltage error, the amp's differential amp corrects by driving the non-shorted output fully on to try to eliminate the DC offset. It's not possible so the amp either goes into protect mode or fails.
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