5 Apr
2015
5 Apr
'15
9:02 a.m.
I suppose that is possible, but not sure that would
explain the dead stop, although I suppose it isn't impossible. I
Bad connections rarely do anything you expect :-)
was nowhere near it when it happened. Do the signals I
posted look right to you? Would you expect inconsistent
triggering on the scope on just one of the FET outputs?
More seriously, have you tried swapping the FETs round to see if the dodgy signal goes
with a particular
transistor?
-tony
5 Apr
5 Apr
9:52 a.m.
Not tried swapping them as they are firmly attached to a heat sink. If I have further
problems will try this.
-----Original Message-----
From: "tony duell" <ard at p850ug1.demon.co.uk>
Sent: ?05/?04/?2015 17:03
To: "General Discussion: On-Topic Posts" <cctech at classiccmp.org>
Subject: RE: RD54 Stopped Spinning
I suppose that is possible, but not sure that would
explain the dead stop, although I suppose it isn't impossible. I
Bad connections rarely do anything you expect :-)
was nowhere near it when it happened. Do the signals I
posted look right to you? Would you expect inconsistent
triggering on the scope on just one of the FET outputs?
More seriously, have you tried swapping the FETs round to see if the dodgy signal goes
with a particular
transistor?
-tony
9:57 a.m.
Oh, are you SURE these are FETs? At that vintage, they
could much more likely be Darlington bipolar transistors.
The waveforms would make more sense that way, too.
Jon
3:15 p.m.
On 04/05/2015 09:02 AM, tony duell wrote:
More seriously, have you tried swapping the FETs round
to see if the dodgy signal goes with a particular
transistor?
That reminds me--about a year ago, I powered up an XT 1140 and it was
working well, then after about half-hour, it started spinning (audibly)
slower and slower over a period of about 3 minutes, then refused to spin
at all.
It's not important to me, but has anyone else ever seen this happen?
--Chuck
3549
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