AB100 Class AB Power Amplifier

This is a second amp, busy with chassis stuff that is the most work. 5mm solid copper bar to connect 3 separate heat sinks together.Needs to be polished.


  • IMG_20240316_160213.jpg
    483.7 KB · Views: 183
  • IMG_20240316_160222.jpg
    445.2 KB · Views: 182
  • IMG_20240316_160328.jpg
    494.4 KB · Views: 182
  • Like
Reactions: 2 users
I unfortunately will not be building one of these amps due to other projects yet to be finished due to ongoing health issue's BUT I always find your (Mr. Pass) generosity amazing. You have provided folks with SO many projects without ever asking for anything, and then also all the time to reply to all the questions thrown your way. Very nice man indeed!
  • Like
Reactions: 3 users
Goodness, its the last time that I clad a frame, using 3mm aluminum, it is such a lot of work, measuring, drilling, tapping, screwing together, and the same sequence over again and again and some more, plenty plenty of times... But getting there soon !;)


  • IMG_20240421_141839.jpg
    355.9 KB · Views: 79
  • IMG_20240421_141204.jpg
    293.9 KB · Views: 69
  • IMG_20240421_141151.jpg
    367.9 KB · Views: 74
  • IMG-20240420-WA0046.jpg
    168.7 KB · Views: 83
  • IMG_20240416_180742.jpg
    508.8 KB · Views: 77
  • Like
Reactions: 4 users
Joined 2014
Paid Member
The left channel of my AB100 let the smoke out after about a year of playing in my garage. The day it quit, the temperature was 78 degrres in the garage and the stereo was playing at a moderately high volume level. I heard the left channel quit and went to check it, the left channel was hot.
When I removed the cover, I found the two rail fuses blown. I use 5 amp fuses on the rails. I replaced the two fuses and powered it up and it smoked R16 in the diagram below. See also the picture.
I then checked all the outputs for shorts to ground and to verify they were still good using a meter on diode check.
I then checked R6 and R5, both good.
I then checked T6, T7, T1 and T2, T8, T3, all good. I checked these by removing and checking with a meter on diode check and in a cheap chinese tester.
I also checked C5, it shows high resistance across it and correct capacitance.

It's pretty obvious to me that the issue is in the front end, but so far everything is checking out.

Does anyone see something that I have missed? To smoke that large Vishay resistor I would think something would be very obvious, but I'm not finding anything.

Scan20240422120321.jpg 20240422_113908.jpg 20240422_114020.jpg