13 Aug
2016
13 Aug
'16
9:51 a.m.
On 13.08.2016 11:37, Rik Bos wrote:
For what it's worth a small warning about the HP 9825 series computers.
The power supply doesn't have a crowbar(over voltage protection), so a
transistor failure in the Psu can be catastrophic.
On the other hand the two 9835's I have, which uses the same form factor and
almost the same power supply layout are HP modified with crowbars added.
It seems to be good practice to add some ov-protection to the HP 9825 supply
because the switching transistor and 723 voltage regulators don't have the
eternal life.
And there no certain prediction in how they fail, short or open circuit, I
found out the hard way several years ago.
-Rik
The same is true of the PDP8/L. I also found out the hard way....
That L is still not running, but the PS now has a crowbar !
Jos