Actually, I just picked up an HP comparator too. I had deferred getting one, mostly because of kev's comments:

http://users.erols.com/mowerman/bugtrap.htm

(This is a "Bug Trap" but I believe it's pretty much the same concept).

I'll be very interested to hear how you make out. I tend to use a logic probe for checking most of the 74xxx chips, but there are a couple chips, like shift registers, that I can't test that way. I'm hoping that the logic comparator can help.

--James Bright
www.QuarterArcade.com
Restored Arcade Games for your Home

----- Original Message -----

From: Chris Toseland

To: TechToolsList (E-mail)

Sent: Monday, July 28, 2003 8:24 AM

Subject: HP Logic Comparators

Hi All,

This Weekend I've been trying to use my HP Logic Comparator to help fault find some boards and am getting some very hit and miss results.

What I'd like to know is are there certain chips that this equipment won't test correctly?

I know that if an output is onto a bus it'll read bad but what about simple stuff like 74ls04 it fails that then works fine with a 74ls08. It definately doesn't like 74ls283's.

I have tried 3 or 4 different comparison IC's so it's not down to a bad one of them.

It even fails chips on known working boards that I'm using for signal comparison with the scope.

I'd like to use it so I can some of my backlog out of the way but it seems just to unreliable for serious fault finding.

Do I just put it down to tarnished IC legs or something? Any of you have any input?

thanks

Chris

http://www.muppzlab.co.uk