I checked c1, c2, q1, and q2 on both boards, and all of them seemed to be responding to the multimeter the way the rest of the components did. I couldn't find any shorts, and all of the parts look to be in good condition. I also checked over the rest of the capacitors on the amp boards and they looked to be in good shape.
It looks as if c2 and c5 have been previously replaced on both amplifier boards, c5 is yellow in color and c2 is orange, although they have the correct values and look to be in good condition.
Hopefully I'll be able to get replacements for the capacitors on the power supply board on monday and see what they add to the adventure.
Chris, if you'd like, I can scan and send you the diagrams for the "Stabilizer" board.
Thanks again!
It looks as if c2 and c5 have been previously replaced on both amplifier boards, c5 is yellow in color and c2 is orange, although they have the correct values and look to be in good condition.
Hopefully I'll be able to get replacements for the capacitors on the power supply board on monday and see what they add to the adventure.
Chris, if you'd like, I can scan and send you the diagrams for the "Stabilizer" board.
Thanks again!
Hi Mike,
Sure, fire it over. BTW, you can't trust an ohmmeter test on caps unless they are very leaky. You can measure the DC voltage on each side to look for leakage. The better your meter is, the more accurate this test. I have a $6,500 LCR meter for measuring caps and inductors (+ resistors). Many times substitution is the best test, since the component is out call it replacement.
-Chris
Sure, fire it over. BTW, you can't trust an ohmmeter test on caps unless they are very leaky. You can measure the DC voltage on each side to look for leakage. The better your meter is, the more accurate this test. I have a $6,500 LCR meter for measuring caps and inductors (+ resistors). Many times substitution is the best test, since the component is out call it replacement.
-Chris
I just replaced c1, c2, and c13 on the stabilizer board. c1 and c2 were originally 220uf/80v, I replaced them with 330uf/100v parts I scrounged from a tech at school. c3 was 1000uf/25v, I replaced it with 1000uf/35v again from school. The replacements brought the DC voltage on the speaker output down to 24 from 28.9, so I think it was a mild improvement, although the other channel is still jumping between .015 and about -.007.
Any more suggestions on where to look for these problems would be greatly appreciated.
Chris, I emailed you the schematic for the stabilizer this evening. Thanks again for all of your help!
Mike
Any more suggestions on where to look for these problems would be greatly appreciated.
Chris, I emailed you the schematic for the stabilizer this evening. Thanks again for all of your help!
Mike
I just replaced C1 on both amplifier boards with 5% tolerance caps I got from the technician at work. The replacements brought the voltage down to 22.3vdc on the speaker output, which is an improvement of another volt or two. I am going to re-check the offset and see where that takes me, but things are still not quite back to functional. I am encouraged by my progress, however.
Thanks again to everyone who helped me! I'll be updating again once I check the offset.
Mike
Thanks again to everyone who helped me! I'll be updating again once I check the offset.
Mike
The Mystery Continues
Chris,
I just checked, both pin 3s (one on each amp board) start out at about 64.8v and then slowly go down to about 62 or so. Both pin 5s and pin 6s are attached to ground. I also checked the offsets and they were all the same as they were before.
Just to make sure, c1, the cap that you said to replace, was 1uf 100v. I replaced both of them.
Thanks again,
Mike
Chris,
I just checked, both pin 3s (one on each amp board) start out at about 64.8v and then slowly go down to about 62 or so. Both pin 5s and pin 6s are attached to ground. I also checked the offsets and they were all the same as they were before.
Just to make sure, c1, the cap that you said to replace, was 1uf 100v. I replaced both of them.
Thanks again,
Mike
Mike,
If you can, remove the relay. Check the resistance through the coil. Your service manual should have a spec for it. If it's ok and you have a variable power supply, slowly apply power to the coil untill the switch closes. Does it close at the proper voltage? After closing, check for resistance in the switch contacts. You may have either a weak coil that can't hold in the relay, or a resistive load in the contact. Either way, it will arc and cycle.
Roger
If you can, remove the relay. Check the resistance through the coil. Your service manual should have a spec for it. If it's ok and you have a variable power supply, slowly apply power to the coil untill the switch closes. Does it close at the proper voltage? After closing, check for resistance in the switch contacts. You may have either a weak coil that can't hold in the relay, or a resistive load in the contact. Either way, it will arc and cycle.
Roger
Mike,
If you can, remove the relay. Check the resistance through the coil. Your service manual should have a spec for it. If it's ok and you have a variable power supply, slowly apply power to the coil untill the switch closes. Does it close at the proper voltage? After closing, check for resistance in the switch contacts. You may have either a weak coil that can't hold in the relay, or a resistive load in the contact. Either way, it will arc and cycle.
Roger
If you can, remove the relay. Check the resistance through the coil. Your service manual should have a spec for it. If it's ok and you have a variable power supply, slowly apply power to the coil untill the switch closes. Does it close at the proper voltage? After closing, check for resistance in the switch contacts. You may have either a weak coil that can't hold in the relay, or a resistive load in the contact. Either way, it will arc and cycle.
Roger
I'm not sure, but it does look exactly the same, only with a black face.
On another note, a newbie question: Can I take the amp board out of the chassis, attach the connectors for pins 1-6, power up the amp, and then test the voltages? That would make everything a lot easier and less time-consuming, but I don't want to hurt myself or the receiver.
As always, thanks a lot!
Mike
On another note, a newbie question: Can I take the amp board out of the chassis, attach the connectors for pins 1-6, power up the amp, and then test the voltages? That would make everything a lot easier and less time-consuming, but I don't want to hurt myself or the receiver.
As always, thanks a lot!
Mike
Hi Mike,
Yes, if you use diodes to simulate the output transistor B-E connections. Don't attempt to set bias. If you can take out the heatsink as well you can run the whole lot out of the case. Pins 12 and 15 need to be connected in that case. Also pin 14 if it is connected.
RogerG and planet10, check post #26. Mike has DC offset. The protection circuit should keep the relay open.
-Chris
Yes, if you use diodes to simulate the output transistor B-E connections. Don't attempt to set bias. If you can take out the heatsink as well you can run the whole lot out of the case. Pins 12 and 15 need to be connected in that case. Also pin 14 if it is connected.
RogerG and planet10, check post #26. Mike has DC offset. The protection circuit should keep the relay open.
-Chris
can some please help me I am new and I guess learning the hard way I bought 1250 reciver Pioneer the receiver has a problem that I was unable to figure out, but then I'm not a tech, allow me to give you the good first, the aux input works, the phono 1 and 2 are working, the tape 1 and 2 are working, all the controls and switches are working, the dial lights are working, the receiver sounds excellent, the bad, none of the indicator lights come on, the tuning meters are not working, and the AM/FM is completely silent, the signal is not being passed to the indicator lights and meters, I believe that there is a cold solder joint on the selector board, I was inside the receiver, the fuses are good, and the parts look good, no burned parts, also there may be a connection problem, I know the receiver sat unused for a long while, I'm sure a tech knows what's wrong by simply reading my description
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