yes clean the filter, lots of people ran these amps with the filters removed, this enabled evn more dirt to cycle through the amplifier and clog up the internal heatsinks.
you need to lift the lid and very carefully remove the output modules (ONE AT A TIME!) and clean them, there are very small heatsink fins that clog with dust.
usual safety precautions, power off mains unplugged let amp discharge for a few hours, and clean one at a time....
or mark modules and chassis so you know which module came from which of the four positions........
apart from that fan usually runs half speed....and as i remember there were problems with early amps.
check out the info on this site in the legacy amps section, schematics and mods sheets etc etc
Well I cleaned out the clogged filter and checked inside - which was surprisingly clean! I blew out the dust with a can O air and it's run without problems or fan cycling since!
4 JBL 4311's powered by the PSA-2 is the LOUDEST I've EVER HEARD INSIDE! That Telarc 1812 recording really BOOMS!