I'll outline where I'm trying to go. The SM is oddly silent trimming offset adjustment to drive servo amp output to about 0V. Maybe that's what this +/- 3V is all about.
Oh right, so you're saying that the dc offset
TP404 is pin 1 of IC401A.
So it appears in my mishap before a couple of pcb tracks got smoked. I'll repair them this eve, but surely I've cooked something else!
TP403 is the 0VRB side of R451.
TP404 is pin 1 of IC401A.
So it appears in my mishap before a couple of pcb tracks got smoked. I'll repair them this eve, but surely I've cooked something else!
DC offset on the Left is 6mv. On the right it is 750mv....way too high...doesn't seem to change with adjustment...
So the manual does address the issue, just a bit obliquely.
After confirming power supplies, I invariably measure amp output, input (eg. R301), feedback (NB), and servo output. That usually points the direction.
I remember as a young engineer (ca 1975) damaging a $400USD A/D. That was serious money in that era. I felt awful.
After confirming power supplies, I invariably measure amp output, input (eg. R301), feedback (NB), and servo output. That usually points the direction.
I remember as a young engineer (ca 1975) damaging a $400USD A/D. That was serious money in that era. I felt awful.
I've confirmed PSU, but I'll struggle to do much this week as I'm packing up to move house...and workshop 😛
Thanks for your help. I made a mistake several years ago in my career, that cost a client hundreds of thousands of dollars. I thought I was done. I barely even reacted with emotion as I knew my career was done. But, after investigating the incident, they determined that at no stage did I commit a safety breach and furthermore, nobody at the plant was trained to correct the incident...So they thanked me for highlighting shortfalls within their operating procedures. Hahaha...ah...
Thanks for your help. I made a mistake several years ago in my career, that cost a client hundreds of thousands of dollars. I thought I was done. I barely even reacted with emotion as I knew my career was done. But, after investigating the incident, they determined that at no stage did I commit a safety breach and furthermore, nobody at the plant was trained to correct the incident...So they thanked me for highlighting shortfalls within their operating procedures. Hahaha...ah...