Hi again Lenny,
I know what you mean about the "hot bridging" technique. It's not
for the faint-hearted! There's also a fairly high risk of damaging
semiconductors in the circuit, as I seem to remember happening to me a
long time ago.
Regarding the idea of adding extra diodes for protection, this is
what I wrote about it in the Mark 2 kit instructions:
"Heavy-duty protection.
To provide greater protection
against connection to charged electrolytics,
some kit builders have
connected an inverse-parallel pair
of 1N5404 (or similar) high-power
diodes between the test lead sockets (jacks).
If you’re the kind who’s likely
to connect the meter to the
120uF input filter capacitor of a
240V-powered switching power
supply without checking that it’s
been properly discharged, this
modification is for you.
Reportedly, this protects the
meter quite well, although it can
result in the probe tips being blown
off by large charged capacitors.
The resulting surge current can
also damage the charged capacitor
and the power diodes themselves.
However, without the diodes, the
resulting 600A current spike
destroys the microcontroller (IC2)
and damages C6."
Anatek Corp was selling a little protection board for the DSE ESR
meter, and probably still is. It's much kinder to the meter and
capacitors than the above brute-force idea. On the down side, it adds
a small amount of resistance to the test lead circuit, making it
essential to use high quality low resistance test leads.
I hope this gives you some ideas to think about. I'm delighted that
the meter's been assisting you for so long.

Regards,
Bob




" wrote:

Hi Bob
I built your kit a few years ago and it has been a great addition to my
shop. It still amazes me the dead sets I get working without a
schematic by just poking around a SMPS and finding a high ESR cap.
Prior to getting this meter I would resort to other tricks. I would try
powering up and after fifteen minutes or so feel the caps around the
power supply. Sometimes a warm one turned out to be the culprit. Then
there was always the hot bridging method. Lots of sparks and excitement
At least once you will inadvertently reverse polarity. I wiped out a
regulator and scared the crap out of my wife that day. With my meter
though it doesn't lie. Among many other things we do here, I rebuild
apartment house intercom amplifiers. These things sit in a lobby wall
for twenty years and will suddenly start sounding like crap. I find
dried up electrolytics with my meter almost every time. Its a quick
profitable repair. and the building managers love it too as I rebuild
their equipment at a fraction of the cost of new. One serious concern I
have though is that on more than one occaision I have discharged caps
through the meter . Apparently, and luckily these were not charged
enough to damage it but seeing an arc even a small one through my meter
sure disturbed me though. I read somewhere in this thread about the
installation of two diodes. Could you please tell me the specifics of
this modification? Thanks very much and best regards, Lenny Stein,
Barlen Electronics.