Trouble Shooting Boards

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chuckphd53
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Trouble Shooting Boards

Post by chuckphd53 »

I was watching Adrians Digital basement, his recent episode fixing Comodore units...

He does pretty good diagnostics, and then swaps chips to remedy suspsect issues..

I learned a trick with TTl chips (even works for CMOS) years ago, many many years....

When you have chip that is suspect, you first remove it then replace it and 'power up".

An easier way that mostly works, not always, but is a great way to first try before removing a chip, which can be a real pain, is to
Clean the 'outside' of the suspect chips legs, removing oxidation, I use an exacto knife to get them shiny again.
Next take a known good chip ( same flavor of course) and clean the 'insides' of this chip with your exacto knife...

Yes you probably figured out by now, you PIGGYBACK the good chip on the old chip, making sure you have a tight fit by bending the good
chip leads in a little so when you press it on the suspect chip all the pins mate to clean surfaces on each chip...

Power up and see if you get any better results...
This typically works good for memory chips, as some chips you may get one data line that is not bad but weak and the new chip will
act as an aid to help pull up the signal enough to show positive results...

This method saves lots of shot gun type replacements and possible damage to the Main board, especially on these older systems with old solder..

I wanted to share this with Adrian, but as usual the youtube folks are hard to find an email address to drop a line, Twitter, Facebook... NOPE
not me, dont do those 'anti'social boards...

So if someone wants to share this with Adrian please do, he has about 6 more Comodores he will be fixing, could be a timesaver for his troubleshooting.

But at the very least try this technique when you get into your basement and start fixing your favorite new addition picked up at the fleamarket bargin bin...

hope this little trick save you some time on the repair bench.

chuck
“I never commit to memory anything that can easily be looked up in a book.” (AE)
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