Re: Asteroids/Asteroids Deluxe - Current Tracer for shorts

HP 547A Current Tracer

Ignore the insane price on this page, these can be had really cheap from
eBay or used test equipment shops..
I have one of these but haven't actually needed to use it yet! So I can't
comment first hand on using it for this problem.

They can be immensely handy, put the appropriate current in the track/node,
and follow it down where it goes with the little sense head, there's a
current sense intensity light in the head.

http://www.skolnik-tech.com/for_sale.htm

http://pdp-8.org/tools.html
HP 547A Current Tracer
“The HP 547A Current Tracer is a hand-held probe which enables the precise localization of low-impedance faults in electrical
systems. The probe senses the magnetic field generated by a pulsing current internal to the circuit or by current pulses supplied by
an external stimulus such as the HP 546A Logic Pulsers. Indication of the presence of current pulses is provided by lighting the
indicator lamp near the Current Tracer tip. Adjustment of probe sensitivity over the 1 mA to 1A range is provided by the SENSITIVITY
control near the indicator. The probe is self-contained and requires <75 mA at 4.5V to 18V, from any convenient source.”
I don’t use this very often, but when I need it, I really need it. It’s used for finding things like shorted input gates, stuck
tri-state buses and broken/shorted traces.

http://www.google.com/search?q=hp+547a
http://www.google.com/search?q=hp+current+tracer

Marc

----- Original Message -----
From: "Evrovski, Andrew" <andy@cyberplex.com>
To: <vectorlist@synthcom.com>
Sent: Friday, August 24, 2001 11:51 PM
Subject: RE: VECTOR: Asteroids/Asteroids Deluxe

> Again, folks, thanks for all of your help. I managed to locate the short in
> one of the boards (but the other two I cannot really make heads or tails).
> The resistance value changes are so small, it is really tough to gauge
> sometimes. I have a really nice fluke graphical multimeter, but it only
> measures to 2 decimal places and I find only .01 changes in resistances in
> the other boards and they don't seem consistent (ie. sometimes I probe a
> particular section and get a value, and go back to that same row later, and
> it has changed slightly, go back again and it is slightly different again...
> very tough when changes are so minute).
>
> Is the tool more sensitive to resistive changes (more than my $1500 Fluke
> multimeter?) I may try the overload method.
>
> Thanks Folks
> Cheers
> Andy
>
> -----Original Message-----
> From: peter jones [mailto:highwayman2000@mail.ru]
> Sent: August 24, 2001 06:51
> To: vectorlist@synthcom.com
> Subject: Re: VECTOR: Asteroids/Asteroids Deluxe
>
>
> power the bitch up with a p.c. power-supply for 5 seconds, OR until
> something goes bang/you smell burning.
>
> then touch each i.c. until you burn your fingers.
>
> this trick works great with defender pcb's when hunting bad ram chips!
>
> the reason to use a p.c. supply is simple, they give out 18-35 amps!!!
>
> if you use a game psu you will just blow fuses/damage the loom/psu.
>
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Received on Fri Aug 24 07:38:01 2001