HA 3500 Hartke Bass Amp Power Amp Get Hot Inmediately After Power On

Thread Starter

Bass Player

Joined Nov 12, 2015
  • Im not an electrician expert but like to do some repairs by myself as long as easy tasks can be performed. I got two identical HA 3500 bas Amps. One of them (amp # 1) start to do some creepy crackling popping sounds. After several times the amp stop to sound. I thought it was dead. The second amp(amp #2) was working good until it stop to sound too. I open the second amp(amp #2) just looking and found that when I tap one big olive green capacitor (Sam WHA/ 4,700uf /100wv/HM 85C) The sound come back. I read in some other forums that cold welding points could be causing the problem. I proceed to resolder the capacitors. After re assembling I try to turn the amp on and a very strange sound came out from the speakers. Inmediately I turn it off. I recheck the solder points and re do soldering taking care all solders are ok. I tried again to turn on the amp this time there was no strange sound but almost immediately the part of the amp where the output transistors are located got very hot. I turn the unit off inmediately.
  • I open amp #1 that I thought was dead. I tap the same capacitors but no sound came out. I tap an electrical component that got some kind of aluminum harness and sound came out. I resolder this part and the amp got back to life. Is working beautiful now.

  • Amp # 2 is still dead. I think is time to take it to a professional technician.
  • Any ideas to explain the heat problem. Needs help.