Hi! I recently went and modified the analog stage in my Pioneer PD-10 SACD Player, here's what I did for clarification:
-Electrolytic caps replaced with Panasonic FMs and a couple Nichicons FW when I didn't have correct values of Panasonics
-OpAmps (5532) replaced with LM4562 (I haven't yet bypassed them, but I was planning to put a 100nf cap on them)
-Voltage regulators replaced:
-Positive 15V swapped from JRC 78M15A to LM2940CT-15
-Negative 15 swapped from JRC 79M15A to LM2990T-15
Positive 5V swapped from JRC 78M05A to LM1085IT-5.0
Here's what I KNOW I screwed up:
-at first, I put 2 positive 15v regulators instead of a positive and a negative
-lifted a few solder pads here and there, but none of them seem to be disconnected, so I just soldered over them and they hold in place.
The result is: noise. Just noise. Nothing else. The analog out just emits a hiss, doesn't react to any disc being played, any operation being done, it just hisses from the time I turn it on, to the moment I turn it off. It didn't change even after putting in the correct 15v regulators (I changed both positive and negative) and I don't know what to do next. I got my hands on a service manual, but I'm more comfortable working with it and the advice I get from people, so any help will be much appreciated. Thank you and have a good day! (Please somebody help)
-Electrolytic caps replaced with Panasonic FMs and a couple Nichicons FW when I didn't have correct values of Panasonics
-OpAmps (5532) replaced with LM4562 (I haven't yet bypassed them, but I was planning to put a 100nf cap on them)
-Voltage regulators replaced:
-Positive 15V swapped from JRC 78M15A to LM2940CT-15
-Negative 15 swapped from JRC 79M15A to LM2990T-15
Positive 5V swapped from JRC 78M05A to LM1085IT-5.0
Here's what I KNOW I screwed up:
-at first, I put 2 positive 15v regulators instead of a positive and a negative
-lifted a few solder pads here and there, but none of them seem to be disconnected, so I just soldered over them and they hold in place.
The result is: noise. Just noise. Nothing else. The analog out just emits a hiss, doesn't react to any disc being played, any operation being done, it just hisses from the time I turn it on, to the moment I turn it off. It didn't change even after putting in the correct 15v regulators (I changed both positive and negative) and I don't know what to do next. I got my hands on a service manual, but I'm more comfortable working with it and the advice I get from people, so any help will be much appreciated. Thank you and have a good day! (Please somebody help)
You can stick to hope but if you reversed the voltage you are pretty much done with this thing. I suggest you start by measuring the actual voltages to confirm they are reversed or not.
@A 8 i already swapped the regulators, so now it should be okay, if I didn't fry the board. I'm counting on the reverse battery protection in the regulator to work properly and shut it down before something happened, I replaced both the positive and negative regulator just to be sure, I'll swap the incorrect pinout 5V regulator for the original JRC one and see if it works
If you did does it work now? Don't know what you refer to as "reverse battery protection" but if its relevant and you have changed the regulators it should work, right?
I don't think it will though as there is typically not much protection built in for more than max .7 volts of reverse voltage in any circuit.
I don't think it will though as there is typically not much protection built in for more than max .7 volts of reverse voltage in any circuit.
Thou shalt check voltages!
Measure the supply voltages everywhere they appear, i.e at all the supply pins on all the chips. Pray that it's missing somewhere and that that's the problem.
Putting in a positive regulator where a negative should be isn't going to reverse the voltage, but it might have blown the regulator and worst case put unregulated voltage on the rest of the circuit.
Measure the supply voltages everywhere they appear, i.e at all the supply pins on all the chips. Pray that it's missing somewhere and that that's the problem.
Putting in a positive regulator where a negative should be isn't going to reverse the voltage, but it might have blown the regulator and worst case put unregulated voltage on the rest of the circuit.
@A 8 it should work, but the circuit has 2 voltage rails - 5V and 15V, and as @Monstercore pointed out, the 5V regulator I used doesn't have the same pinout as the original one, thus I have no idea if the circuit works, because one of the voltage rails was basically cut off. "Reverse Battery Protection" is something I've read in TI's LM2904 datasheet:
"Designed also for vehicular applications, the LM2940-N/LM2940C and all regulated circuitry are protected from reverse battery installations or 2-battery jumps.During line transients, such as load dump when the input voltage can momentarily exceed the specified maximum operating voltage, the regulator will automatically shut down to protect both the internal circuits and the load. The LM2940/LM2940C cannot be harmed by temporary mirror-image insertion.Familiar regulator features such as short circuit and thermal overload protection are also provided"
I don't know if it's relevant here, but it sounds like it is
"Designed also for vehicular applications, the LM2940-N/LM2940C and all regulated circuitry are protected from reverse battery installations or 2-battery jumps.During line transients, such as load dump when the input voltage can momentarily exceed the specified maximum operating voltage, the regulator will automatically shut down to protect both the internal circuits and the load. The LM2940/LM2940C cannot be harmed by temporary mirror-image insertion.Familiar regulator features such as short circuit and thermal overload protection are also provided"
I don't know if it's relevant here, but it sounds like it is
Good luck! But as reference for next time: Measure, measure and measure. Hook up your meter to the rail. Power up. Look at the meter. If it doesn't look right, IMMEDIATELY turn the power off.
Okay, so the noise is gone, but it doesn't output sound at all now, I'm having a hard time measuring any voltage, including anything from the power plug to the pcb, where it should be 17V, there's hardly any
It’s supposed to be 17V from the power plug? How could that be possible? You mean from the transformer? Did you measure that with the meter in AC mode?
What about if you measure directly on the transformer secondary outputs? Is there a single secondary windings? Where is the rectifier located? On a separate board, I presume?
Here's how the transformer board looks like, from the top, the first three pins go directly to the analog stage PCB, I just noticed that the elements between the large transformer pins and connector pins are actually fuses, and both coming to the analog stage are blown, and there is 18V on the transformer's secondary
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When you messed up the regulators you probably shorted the entire power supply and the fuses did what they’re supposed to.
Before you change the fuses, make sure all the regulators are in the correct place and correct orientation. Use the diode mode to check for shorts across the regulator terminals. THEN change yhe fuses and power on.
Before you change the fuses, make sure all the regulators are in the correct place and correct orientation. Use the diode mode to check for shorts across the regulator terminals. THEN change yhe fuses and power on.
@njswede okay, I think I have something that might have caused the issue, the LM2990 has a metal plate at the back of the package, and while on the 2940 it's ground, on 2990 it's voltage input, and I think that the heatsinks are grounded, so the 2990 shorted voltage input to ground thus blowing the fuses
Nope, not that apparently. Swapped the LM for JRC and the fuses still blow. I gotta get some more fuses and then I'll try just getting all of the original regulators back in place
Take a step back and a deep breath.
Done?
Now bring out your multimeter and start measuring for shorts and checking the components. Are there shorts between the legs of the input/output and ground on the regulators? If you remove the regulators, are there shorts between the input/output pads and ground? Desolder and test capacitors for shorts. And so on… Double check again that the orientation of the components is correct.
Changing random things and blowing fuses is the worst possible method of troubleshooting. You’re risking (and probably already have) blowing more components. If you power it up, do so on a current limited supply. What you’re doing now is just a magic smoke fest.
Done?
Now bring out your multimeter and start measuring for shorts and checking the components. Are there shorts between the legs of the input/output and ground on the regulators? If you remove the regulators, are there shorts between the input/output pads and ground? Desolder and test capacitors for shorts. And so on… Double check again that the orientation of the components is correct.
Changing random things and blowing fuses is the worst possible method of troubleshooting. You’re risking (and probably already have) blowing more components. If you power it up, do so on a current limited supply. What you’re doing now is just a magic smoke fest.