I use to repair these when they were current. The issue is that the -5v required by the RAM is generated by one of those transistors. Unfortunatly the only way to reset is unplug the power. If the LC circuit was at the wrong charge it would blow the transistor. Which would then cause a cascade failure of the RAM chips. (If no -5v turn off immediatly) Those boards are not nice to work on and I realy honed my soldering skills socketing the RAM.
Well done Dave 😃
I use to repair these when they were current. The issue is that the -5v required by the RAM is generated by one of those transistors. Unfortunatly the only way to reset is unplug the power. If the LC circuit was at the wrong charge it would blow the transistor. Which would then cause a cascade failure of the RAM chips. (If no -5v turn off immediatly) Those boards are not nice to work on and I realy honed my soldering skills socketing the RAM.
Yeah these boards are tough so easy to pull up traces when desoldering ram