So we don't get connectors mixed up just go directly to pin 3 (output) of IC02. Measure between pin 1 (gnd) of IC02 and pin 3 (IC02). Put red probe on pin 1.
Craig
Craig
OK, the output of IC02 is NOT shorted to gnd, IC02 must be kaput. Replace it and you should be to go. They do fail but not a very common problem in my experience of 40 or so years.
Craig
Craig
Thanks Craig.
I’ll be ordering this IC02 from DigiKey.com and minimum shipping is $8. So can I order some other components for the power board and replace them?
If yes, then please let me know which ones.
Warm Regards,
Ash
Maybe capacitors C03,4,5,6. I usually use Panasonic FC in power supply positions. There are various diameters with different lead spacing so measure and order the correct size. That might get you close to $8. Maybe order a couple of each of the regs.
Craig
Craig
check the temp on the regulators after some time, if they get quite hot and aren't heat sinked, you might try adding a small amount of heatsinking if there is room. You could maybe squirt the offending regulator with an inverted "duster" aerosol spray can and see if it trips back to operational. I think I saw a thread on here where an amp's regulators got hot enough to desolder themselves?
Last edited:
Hi Craig,
Once again, thanks a million for the help, advice and troubleshooting the problem.
Once I get the parts changed and the Amp is up and running, I’ll get in touch with you.
Until then
best regards,
Ash
PS: I wasn’t that bad a newbie, was I? 😀
At least you had meter. I've been doing for so long with all of the test equipment it's hard to help somebody with no knowledge and/or test equipment. I have my ways of doing things just out of habit. Not having the unit in front of me makes it harder too.
If you learned anything here CHECK YOUR POWER SUPPLY VOLTAGES FIRST THING, if it will power up.
Second if the same thing is happening with both/all channels it's usually something in common to both channels, THE POWER SUPPLY.
You aren't done yet, did the regulator just crap out OR did something take it out. You'll find that out when you get it back together.
Craig
If you learned anything here CHECK YOUR POWER SUPPLY VOLTAGES FIRST THING, if it will power up.
Second if the same thing is happening with both/all channels it's usually something in common to both channels, THE POWER SUPPLY.
You aren't done yet, did the regulator just crap out OR did something take it out. You'll find that out when you get it back together.
Craig
I replaced C03 and C04 with Nichicon from digikey part#493-4612-ND so you don't have to guess at those.
Enjoyed this thread and learned a lot as a newbie. Had my AS200 open, looking at everything you pointed out to try and test.
Much appreciated for the step-by-step.
Enjoyed this thread and learned a lot as a newbie. Had my AS200 open, looking at everything you pointed out to try and test.
Much appreciated for the step-by-step.
I'm shocked you didn't bring up horses, cowboy hats and six-shooters! Austin is its own country unlike Dallas or Houston.
I, I Captain!
I don’t know how you did it without the actual Amp in front of you. You are Genius I should say. Hats off to you my friend.
In fact, you taught me a big lesson in Solid State electronics.
Yes, I too is keeping my fingers crossed for this Amp. I know what you mean. 🙂
By the way, I do have a hobby of restoring vintage tube radios but its becoming harder and harder and expensive to get good tubes and parts, so decided to slowly quit this hobby. In fact, I was thinking of playing with Arduino Projects which are compact and less lethal. 🙂
Have a great day
Regards,
Ash
Hi Craig,
Just a little concern. I have taken out the power board and can see a over heating stain under IC01 & IC02. I have checked all the resistors, they are very accurate to the values. And I’ll be replacing caps C03, C04, C05, & C06 along with IC01 & IC02.
Is there any thing else you want me to do?
See the pic.
Regards,
Ash
Attachments
Hi,
I already have put HeatSink on both regulators.
Thanks for the advice. Now that AMP is not tripping amy more, but Regulators are running HOT. I can hold them but the heat hurts my fingers. Are these supposed to Run that hot?
Ash
Hi Craig,
An Update:
I replaced 4 Caps C03,4,5,6, IC01 and IC02. Added HeatSink to these.
Amp is not tripping any more (tested for an hour) without input or speakers.
In spite of installed HeatSinks IC 01, & 02 are running quite HOT. I can touch these but it is quite hot.
Do these run this HOT? If yes, can I connect speakers and input to test the AMP?
Voltage at -15V and GND is (-)14.97V and at +15V & GND is (+)14.70V
Please advise.
Thanks,
Ash
Attachments
The heat dissipated depends on a couple of things, the input voltage to the regs and the current draw from the regs. I tried looking for a way measure the current draw but there are no series resistors to measure. Those regs are rated for 1A so if all of the opamps add up close to that they may run hot. Both are the same temp? Now with it running correctly go ahead and do a finger test on all of the opamps to see if there is a warm one or if you have an IR thermometer use that.
Let it cook for a while then try using it, if the same problem occurs you already know the protection circuitry works.
Craig
Just looked at the pictures, can you flip the heatsinks around to get some of the fins in free air? You can see the outline of a heat sink silk-screened on the PCB, I wonder why there wasn't one installed at the factory. That's a clue they run on the warm side.
Let it cook for a while then try using it, if the same problem occurs you already know the protection circuitry works.
Craig
Just looked at the pictures, can you flip the heatsinks around to get some of the fins in free air? You can see the outline of a heat sink silk-screened on the PCB, I wonder why there wasn't one installed at the factory. That's a clue they run on the warm side.
Last edited:
1. I tried HeatSink fins the other way but its not possible because of those 100µF caps. Thats why I have put these as per the documents. I wish I can get a thicker Dual adjustable HeatSink.
2. Temp at IC01 reaches to 74ºC (165ºF)
3. Temp at IC02 reaches to 54ºC (129ºF)
4. All the OP AMPs are running at room Temp, then I tried touching all ICs and Transistors.
5. Q204 is running at 44ºC (111ºF) and QA204 is running at 39ºC (102ºF). Rest of the Amp is fairly stable at room temp.
Your advice please!
Ash
Attachments
- Status
- Not open for further replies.