The output stage is related to the amp in the attached diagram and some of the PS components are similar.
I removed all of the outputs and the rectifiers and replaced all of the 3205's on one side of the PS. Pin 16 of the 594 is driving pin 3 high. I grounded pin 3 and the power supply runs fine without any problems.
Some of these amps have a protection circuit that will shut the driver IC down if it doesn't see rail voltage. You can either find the protection circuit transistors or install the rectifiers.
There are variations but the attached is one version. You'd remove/lift Q87.
There are variations but the attached is one version. You'd remove/lift Q87.
Attachments
Last edited:
Thanks Perry! I installed the rectifiers and it runs with no problem. Drawing .8 Amps. Working on these things can be humbling.
Feel free to ask questions.
Wait until you get a Brazilian type amp that uses an MCU to control everything and all coding is proprietary... and many replacements must come from Brazil... and they do fail. To make them even more fun, many deface the semiconductors and to make it just a bit more fun, the over-current protection is (supposed to be) matched specifically to the output FETs. Failure to make the calculations and circuit mods will not allow the over-current protection to function. They also have two different protection circuits per driver IC that require different calculations. AND that's virtually all that's being sold because they're cheap and that's the most important aspect of an amplifier for many people. For the larger amps (power rating), they can take 900+ amps of current to run up to full power.
What do you normally repair?
Wait until you get a Brazilian type amp that uses an MCU to control everything and all coding is proprietary... and many replacements must come from Brazil... and they do fail. To make them even more fun, many deface the semiconductors and to make it just a bit more fun, the over-current protection is (supposed to be) matched specifically to the output FETs. Failure to make the calculations and circuit mods will not allow the over-current protection to function. They also have two different protection circuits per driver IC that require different calculations. AND that's virtually all that's being sold because they're cheap and that's the most important aspect of an amplifier for many people. For the larger amps (power rating), they can take 900+ amps of current to run up to full power.
What do you normally repair?