Both resistors are within tolerance 10 Ohms, and my DC voltage across them are:
Resistor in front of 7812: +12.25 DC volts
Resistor in front of 7912: -18.35 DC volts
Resistor in front of 7812: +12.25 DC volts
Resistor in front of 7912: -18.35 DC volts
That's not possible. The AC component is confusing your meter.
Do you have approximately 25v on the input pin of the 7812?
Do you have approximately 25v on the input pin of the 7812?
Correct, I posted both the input and output readings. Two posts back to back, sorry for the confusion
Sorry. I hit the last post button so I only see the last post.
Insert a 1 ohm resistor in series with the output of the 7812. Measure the voltage across the 1 ohm resistor. The voltage will be the same as the current (1.2v = 1.2a). If the current is greater than the rated current of the regulator currently installed, use a regulator rated for higher current. If the current is less than the rated current, replace the regulator. I'm assuming that the installed regulator is equal to the original if you replaced the original regulator.
Insert a 1 ohm resistor in series with the output of the 7812. Measure the voltage across the 1 ohm resistor. The voltage will be the same as the current (1.2v = 1.2a). If the current is greater than the rated current of the regulator currently installed, use a regulator rated for higher current. If the current is less than the rated current, replace the regulator. I'm assuming that the installed regulator is equal to the original if you replaced the original regulator.
Ok, I Re-installed the original regulators, 7812A and 7912PI.
I replaced them during the repair, while troubleshooting, but I don't believe anything was wrong with them so I re-installed them. I'm now reading +11v and -13v of DC voltage on the op-amps? Closer in value but still not equal. I should see positive and negative DC voltage of about ~15, correct?
Tested the amp again for audio output but it still clicks in and out of protection when I attempt to play any sound?
I replaced them during the repair, while troubleshooting, but I don't believe anything was wrong with them so I re-installed them. I'm now reading +11v and -13v of DC voltage on the op-amps? Closer in value but still not equal. I should see positive and negative DC voltage of about ~15, correct?
Tested the amp again for audio output but it still clicks in and out of protection when I attempt to play any sound?
I replaced all the output transistors, both IRF9640's and the IRF640's. I also replaced all the power supply FETs, IRF3204's. All parts were purchased from Mouser.
I posted 2 posts in a row again, I'm not sure if you read post 48 or not? Hopefully this info. will be helpful in figuring out the issue? Thanks Perry
I saw it.
If you run it out of the heatsink for a few seconds and allow it to go into protect a few times, does one group of outputs heat up quicker than others? If so, which ones.
Side note, you wrote 3204s. They're 3205s. This is just to prevent confusing others that may find this thread.
If you run it out of the heatsink for a few seconds and allow it to go into protect a few times, does one group of outputs heat up quicker than others? If so, which ones.
Side note, you wrote 3204s. They're 3205s. This is just to prevent confusing others that may find this thread.
I ran the amp out of the heat sink and none of the FETs get even slightly warm. As the amp switches in and out of protection, there is a synchronized pulsing noise coming from the center of the amplifier, see attached image....
I'm using a sound generator app on my iPad to apply audio through the RCA jacks. As I lower and raise the Hz Output, the "frog" like noise changes too, lower and higher in pitch based on the lower or higher Hz I select.
I hope this makes since. I tried to track down where the noise is emitting from but I can't pin point the exact component. Don't know if this is any help with tracking down the issue or not?
I'm using a sound generator app on my iPad to apply audio through the RCA jacks. As I lower and raise the Hz Output, the "frog" like noise changes too, lower and higher in pitch based on the lower or higher Hz I select.
I hope this makes since. I tried to track down where the noise is emitting from but I can't pin point the exact component. Don't know if this is any help with tracking down the issue or not?
Attachments
Are you seeing a pulsing (or steady) rail-rail oscillation on the center legs of the output transistors?
It's pulsing, it reads approx. +/-56 DC volts and it drops and rises ~5V when switching in and out of protection.
When I lower the volume to zero, the amp comes out of protection and all of my readings appear to be normal, except the positive and negative DC volt difference on the op-amps.
When I lower the volume to zero, the amp comes out of protection and all of my readings appear to be normal, except the positive and negative DC volt difference on the op-amps.
Perry,
I'm Sorry to resurrect an old thread but would you happen to know the value or part the part numbers of the resistors in the output section of this Memphis 2000D?
I believe these are part of the protection circuit. I do know that there are two different values but I'm also not sure where the different values belong? It's been a while since I attempted to repair this amp so I can't remember the details about these resistors.
I'm Sorry to resurrect an old thread but would you happen to know the value or part the part numbers of the resistors in the output section of this Memphis 2000D?
I believe these are part of the protection circuit. I do know that there are two different values but I'm also not sure where the different values belong? It's been a while since I attempted to repair this amp so I can't remember the details about these resistors.
That's a 0.04 ohm resistor. Those are likely in series with the source leg of the P-channel FETs. The N-channel FET likely have a 0.02 ohm resistors in series with their source leg. R922 is a 0.04 ohm. You should be able to use that to confirm the statements above.
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