With a sensitive enough voltmeter you can measure the voltage drop on the
PCB traces and figure out where the current is going.
3 1/2 digits won't be enough.
On Fri, Mar 25, 2022 at 12:28 AM David Templeton <vexorg.calibra@...>
wrote:
You don¡¯t need more than 3.5 digit for fault finding and to get it working
David
On 25 Mar 2022, at 01:56, Harvey White <madyn@...> wrote:
?I'd like more than 4 digits, but you take what you can get. You'd
generally want to replace the "failing" rail with power from the supply
(other supplies not needed), current limited to about 100 ma. Somewhere
around here we've talked about voltage drops across parts when looking for
shorted capacitors.
Harvey
On 3/24/2022 9:30 PM, James55 wrote:
Situation update...
Measurements were taken as each disconnected part was reconnected and
all was going fine.
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
A quick check seems to show that none of the tantalums are short, and
nothing is obviously burnt or damaged, so tomorrow I shall repeat what
worked for the A6 main interface board.
That is, I'll get prints of the component layout and of the schematic,
then I'll colour the components of the failed rails (in a separate color
for each rail), whilst working through the schematic, taking and recording
the readings of each component in turn.
@ Harvey
There is a 15v 2A current limiting PSU here and the DMM has four digits
The questions will come as I look closer.
