HP 71b repair advice - won't power on with batteries or on AC adaptor

[dmh]

(06-11-2021 06:40 AM)KimH Wrote:  

(06-11-2021 05:47 AM)dmh Wrote:  Ok, I've opened up the worse looking of the 2 units (in case I broke anything) and the photos are below. It came apart quite easily. Even the rubber feet are still intact (but will need double sided tape).

https://www.dropbox.com/sh/ljsoop5ggt43l...ee7ea?dl=0

Thoughts?

Worth trying to repair by soldering wires?

The Zebra connector doesn't appear to want to move, is this just pulled off away from the board or do I lever each end?

Pretty much what I expected it would look like.

Some gentle application of vinegar to get rid of all the corrosion (watch out for possible bridging between traces and components, use a loupe).

The “flange” for the zebra is probably held by corrosion as well, again vinegar is you friend.

Then on to the soldering…

I have repaired at least a handful that way, none failed to work.

Tip: use two different colors of wire alternating, it helps avoiding mistakes in the sequence.

Hi KimH,

So I opened my other dead 71b and it is very clean with only slight damage to the zebra and barely any corrosion and have soldered the 2 halves together with wire wrap wire but still no go.

Do you have any other suggestions / advice?

Thanks