Message
Re: Refurbishing my SDS1000
2016-10-01 by spr@...
Are you 100% sure the 8051 is dead. It needs pulses from IC2 to work correctly. Check pin 12 with a scope and make sure it's getting pulses from IC2 pin 3 - otherwise it will play dead. Also worth checking pins 18 & 19 to see if the clock is running - crystals and ceramic caps can go bad.
Before you go much further, check the supply - there should be 5v and +/-6v. I've seen the regulators fail, giving out raw +/-12v. This will cause a lot of damage - probably toasting the CEM3394s and other stuff - and cause enough damage to upset IC2 and freeze the 8051. The cost of replacing three blown 3394s would be similar to the cost of a working SDS1000.
Steve