stevie

Thanks for the advice, Dave. Most helpful. Stephen

Anyone familiar with the old OHM GA125 bass combo? I recently acquired one that was crackling. I resoldered a few connections on the PCB and managed to fix it. Resoldering and replacing components is about my limit, I'm afraid. The amp seems to be working now but I am concerned that two of the wirewound resistors on the preamp board are getting very hot. The amp is split into a preamp section (front) and a power amp section (back) with an umbilical cord between them which seems to carry the power from the power supply (on the power amp board) to the preamp. The two resistors are the first components in the preamp circuit at this point. The original resistors were 470 ohm, 5W wirewound, but as they were visibly burning the board, I changed them to 10W wirewound and spaced them away from the board. However, even these ones are still getting very hot. By hot, I mean you can touch them but you can't keep your finger on them for more than a fraction of a second. Is this normal? Second question for the experts. I have taken the amp out of the combo and installed it in an amp sleeve. The graphic section of the preamp is now closer to the mains transformer and is picking up losts of hum. Moving the preamp away from the transformer reduces the hum. So, I've turned the preamp round 180 degrees so that the input section is next to the transformer and the hum has gone (the power amp is now upside down in the sleeve, if you follow me). I'm not very happy about the power amp being upside down. I would have thought that the input section of the preamp would be more susceptible to hum than the graphic section. Any ideas what I should be looking for here, or is this normal? Finally, the compressor operates very oddly and degrades the sound of the bass. It's basically unusable. Is this also par for the course? Taking the amp to a repairman would cost more than the unit is worth. Any help in saving it from the landfill would be much appreciated. Stephen