Re: Vcc buss rails being pulled down.

The caps were my first thought, however, the board has
has a hang tag that states "caps replaced, board comes up
04-20-1998" The caps look fine.

What is this 'milliohm meter' method you
speak of ? I have a digital bench meter
but I'm not sure of it's sensitivity.

----- Original Message -----
From: "Rodger Boots" <rlboots2@gmail.com>
To: vectorlist@vectorlist.org
Sent: Sunday, October 16, 2011 4:04:20 PM GMT -06:00 Central America
Subject: Re: VECTOR: Vcc buss rails being pulled down.

First step, disconnect electrolytic capacitors and tantalum capacitors conected Vcc.  If you have a very good ohmmeter you may be able to trace it to an area.
On Oct 16, 2011 4:38 PM, < litterbox99@mchsi.com > wrote:

I'm working on a Slot machine MPU, with
similar 74xxx components like our arcade
games.

The Vcc buss is being pulled down to about 50mv.
The LM340T5 runs very warm, so were keeping the
power on time very low.

Besides removing the IC's one at a time (and
of course their not socketed ) is there a way
to ID which component is at fault ?

We've removed the IC's that are socketed, and
checked for warm or hot components.

Todd

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Received on Sun Oct 16 18:48:29 2011