2 Nov
2015
2 Nov
'15
3:17 p.m.
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Mattis Lind
Sent: 02 November 2015 21:44
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Testing H7864 (MicroVAX II) PSU With No Load
2015-11-02 22:05 GMT+01:00 Robert Jarratt <robert.jarratt at ntlworld.com>:
Thanks for spotting the drawing mistake. I have noted an apparent short before, and I have
some notes I made at the time, but that was so long ago (almost a year!), and the notes
don't seem to conclude whether I found the short or not. I think I may have put it
down to some of the transformers at the time, but I can't be sure. I will investigate
this further as this is quite promising, but it looks like I will need to desolder some
components...
Regards
Rob
I have just uploaded all the corrections. So the connector names on
the risers should now correspond. I have also corrected the area on
the primary control module around C403 and R407.
Regards
Rob
Checked the new one. There are still something weird. The base of Q301 it is
short circuited to the emitter (which if that is true would of cause your
problem). But I think this is a drawing mistake. The base signals goes to the
D405 diode which is connected to emitter Q405 and emitter Q406 which is then
connected to emitter Q301... Please check this again. Maybe there are a short
circuit component that makes you trace it wrong (if you do it by ohm-meter)
/Mattis