I think in this design an overcurrent on the +15 operates through the B section of the op-amp and pulls down the +65 as well.
I'd look to see if there's a there's a short on the +15.? Just because.
Not that there couldn't be shorts on other supplies.
Harvey
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On 3/24/2022 10:15 PM, Raymond Domp Frank wrote:
On Fri, Mar 25, 2022 at 02:30 AM, James55 wrote:
Until, after replacing the A5 Trigger Generator and Sweep Logic board, the
voltages on the +65v, +15 and +5v rails all went to almost zero.
The +140v is on 72 volts, whilst the minus 15 is around -3v and the minus 8
rail being around -7.4v
Remember that +65V is needed for all other voltages to be ok, including +140V (a shorted +65V would pull down +140V to +75V, about the voltage across VR1718 in the LVPS), so a short between +65V and ground would seem enough to cause this.
Raymond
