Kiowa

I found the issue. When I replaced the MOSFETs I attempted to read the part numbers off of the parts removed and replace with the same parts. I got the Q13 and Q19 wrong. Instead I replaced with the following and all is working now: Q14,Q20,Q7=IRF530 and Q13,Q19=IRF9Z14 or IRF9530. Like to see the pot tuning video. I don't have an expensive set of 8ohm resistors to sink the amp into. Can you cover tuning with conventional setup just using the speaker connected?

With the PDC removed I get 150V out of the D6 rectifier so that portion of the PSU is working now that the inrush limiter has been replaced. I did a full rebuild of the PDC with the schematic and parts listed in this thread. When I measure across the body of U4 and U5 according to your video I should see ~30V. I am only seeing 2.5 volts (with a lot of wild variation on the meter) and my AC limited supply bulb is pulsing bring/dim. Do you have any suggestions on how to better validate operation or troubleshoot the PDC board? here is a quick video: Video Update (even thought it looks like this thread is pretty much dead): The problem was having the BASH board removed during testing let the Gate Drive that feeds Q7 float and damaged Q7. I also noticed Q14 was shorted as well (Both had been replaced during my rebuild once already). Removing both Q7 and Q14 (both IRF530). Then replacing Q7, puts the amp in working condition from a power supply perspective. No more pulsing AC bulb. I see ~22VDC across the body of U4 and U5. I see the 5VDC across R70 and R71. Everything looks good. I verified the BASH board is getting 15VDC as well. Problem: The problem is when I populate Q14 (IRF530) the flashing AC limiter bulb is back and the board is unhappy again. Not sure what to troubleshoot on the Q14 side. The PDC and BASH seem to be working to me. Would this be an indicator of a bad U3 opamp? Thanks

Sub-10: After a full recap, MOSFET, THC, Q5, Z1, and TH3 replacement I went to test the PSU via your video @59:00. I am only seeing 20VDC. I have removed the yellow glue from any visible parts that it could cause a short between. My current limited AC supply bulb is pulsing bright/dim. Also, I see very little voltage between R70 and R71 as you tested @59:43. From this forum I believe you are saying the issue is the BASH board or PDC. What would cause the +15V_M and -15V_M at (U4 Pin3 & U5 Pin3) to be limited to 20VDC instead of 25-30VDC and is this acceptable? I removed the PDC and BASH boards and I no longer see a pulsing bulb on my AC limited supply. How do I troubleshoot these two boards to determine where the fault is? The DB1 BASH3010A IC on the BASH board. If that is faulty, where can I find a replacement chip? I plan to put a single row female socket 8P and 12P header on the board so that I can more easily remove the PDC and BASH sub-boards for troubleshooting until I can figure out where the problem exists.

I am also having trouble finding parts and following this thread. I have compiled the fragments of information and I am attempting to build a straight forward list of components that are often abbreviated with "Amp was recapped, replaced TH3, FETs, and Q5" "amp was fully recapped with Nichicon caps" We now have a suggested manufacturer, Can we get a list of the caps and values? "I use GE silicone 2". Good to know, will add that to materials list "I had to clean and rebuild the PDC" Ok, what did that entail? Parts list please? "replace the fets". Can we get a list of PNs? "and TH3". OK, back to the original problem. Where does one find a "TH3"? Do we have a manufacturer and part number? Suggested Parts list with links: 1) Q5 is SOT-23, it needs to be replaced with a TO-92 2N44011 2) TH3 (DSP104) replaced with ???? 3) PDC parts for rebuild. What is all involved in a PDC rebuild? Parts?? 4) FETs replaced with ??? 5) GE Silicone 2 If you can help fill in the blanks I can edit this post and include links for the parts.