Be warned that IIRC the orientation of the ICs on the earthy CPU board isn't consistent - pay careful attention to the markings on the silkscreen
Also the order in which the EPROMs are installed isn't exactly what you might expect ... Check most carefully David -----Original Message----- From: volt-nuts [mailto:[email protected]] On Behalf Of Rick Bale Sent: 20 April 2020 19:32 To: [email protected] Subject: [volt-nuts] Solartron 7081 I's been a while since I last posted on my 7081. I needed to wait to receive new earthy CPU and DMA chips. They are cheap and easy to swap. So far, with Joe's help, I've replaced the earthy side PROMS. Also new is all the RAM, DMA and microprocessor. I also went back and rechecked all the power rails. I found a little extra noise on the +5v & +40v power rails. I corrected this by replacing C56, C57, C58 filter caps. They all measured about 50% or less of their original uF. The 12v filter C59 was okay. I have the same symptom of all LED stuck on and nothing on the screen. I feel like I need to check the data during boot up. Probably means decoding the logic. Maybe it's hung on a reset since all the LEDs are on. It would seem reasonable that they would all come on during boot up or on a reset. The problem is I don't have a logic analyzer or probe but mainly don't really know where to start in the circuit. Does anyone have any suggestions on where to start. Do you think I should move the conversation to the Solartron Group? Thanks, Rick _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/volt-nuts_lists.febo.com and follow the instructions there.
