Hi all-
Working on a 9505 (2nd generation, I think - XLRs at the bottom, bananas at the top, & SMD input stage). It warms up and gets noisy.
I've found comments that the drivers are the prime suspect here - MPSA06/MPSA56, Q14 thru Q17.
Seems simple enough to swap but happy to hear from anyone who's been here before? Thanks.
Working on a 9505 (2nd generation, I think - XLRs at the bottom, bananas at the top, & SMD input stage). It warms up and gets noisy.
I've found comments that the drivers are the prime suspect here - MPSA06/MPSA56, Q14 thru Q17.
Seems simple enough to swap but happy to hear from anyone who's been here before? Thanks.
I would troubleshoot, not shotgun. If a thermal problem, some freeze spray should identify it real easy like.
4 output pairs. Must have been a monster! Curious schematic. I may have to play with it some.
4 output pairs. Must have been a monster! Curious schematic. I may have to play with it some.
Also resoldering connections and replacing discolored resistors should be first.
Try poking around with an insulated tool, while using junk speakers.
Try poking around with an insulated tool, while using junk speakers.
I posted an explanation of what is going on with this things a few years ago. Search for my post. K9bf73@gmail.com. Replacing the driver transistors will not fix the problem for long. The bais current throgh them is way to high. Good luck
Also check for SMD resistors. Usualy the soldering ends breaks and the solder to the PCB too. Some may get their values severely increased or open completelly. A common problem in old SMPS.
I'll save you some trouble. BigFooToo's ink is here: https://www.diyaudio.com/community/threads/hafler-9503-9505-repair-information.376251/