On Wed, 04 Jan 2006 23:15:48 -0600 (CST), you wrote: That was only referring to the transistor that drives the POK signal. It survived. I had also found that the "upside-down and backwards" hookup places two 75113 drivers in contention - but they are not fried either. Unlikely given that all read tests pass and the system boots... and the Write Data and Write Gate signals are making it to the logic board in the RL02, by direct measurement. I missed the fact that the error code returned by the toggle-in program (102210) actually has WDE (15) as well as WGE (10) set. I am not sure which came first (i.e. the write data error resulted versa). But the problem could also be on the drive's R/W board. There is some logic there that can cause a WDE. I'm not sure what fault happens if there is a bad steering diode or write current source. More as I investigate... I may have to fix the faulty p/s on my Tek 7403 so I can plug in the logic analyzer! That will tell me for sure which line is first. -Charles