12 Apr
2020
12 Apr
'20
11:30 a.m.
This machine acts oddly. After powering it off, you usually can't power it
back on again for about 30 seconds or so, it just seems to ignore the power
switch. Similarly, if it has been switched off at the front power switch, it
will switch itself on after maybe a minute of two of being switched off. In
all other respects the machine seems fine. I have not opened up the PSU at
all, just wondering if anyone has ever seen this and might know what the
problem is?
Thanks
Rob
12 Apr
12 Apr
11:49 a.m.
s?ndag 12 april 2020 skrev Rob Jarratt via cctalk <cctalk at classiccmp.org>:
This machine acts oddly. After powering it off, you
usually can't power it
back on again for about 30 seconds or so, it just seems to ignore the power
switch. Similarly, if it has been switched off at the front power switch,
it
will switch itself on after maybe a minute of two of being switched off. In
all other respects the machine seems fine. I have not opened up the PSU at
all, just wondering if anyone has ever seen this and might know what the
problem is?
Guessing: Check electrolytic capacitors.
/Mattis
Thanks
Rob
12:20 p.m.
This machine acts oddly. After powering it off, you usually can't power it
back on again for about 30 seconds or so, it just seems to ignore the power
switch. Similarly, if it has been switched off at the front power switch, it
will switch itself on after maybe a minute of two of being switched off. In
all other respects the machine seems fine. I have not opened up the PSU at
all, just wondering if anyone has ever seen this and might know what the
problem is?
Not quite the same thing but I have noticed that many DEC power supplies
will sulk for a while if their overload trip is triggered. Switching them
off and on again straight away is not enough to reset them even though the
overload is cleared. The H7821 seems to need to be switched off for around
16 seconds minimum before it will contemplate coming to life again. I have
come across similar behaviour with the power supplies in various other small
VAX and Alpha machines but I have not measured the exact time period
involved in any other cases.
Regards,
Peter Coghlan.
1498
days inactive
1498
days old
2 comments
3 participants
participants (3)
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cctalk＠beyondthepale.ie -
mattislind＠gmail.com -
robert.jarratt＠ntlworld.com