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

[KimH]

(06-08-2021 04:19 AM)dmh Wrote:  

(06-07-2021 07:29 AM)KimH Wrote:  If you had been in Germany, I would have said "come on over and let's look at it" - but that's obviously not an option...

You can find the repair manual with the link below, that should help you with how to open and peek inside. Some electronics experience is required if you want to repair!

AND a Torx 6, don't try without!!

Documentation

I have repaired a few of these after corrosion - Battery-Leak - and it can be very tricky.

You can have anything from Copper traces being corroded to oblivion or the ZEBRA which connect top and bottom on the Plastic-Back model - and many more, peeking should give you some hints.

The ZEBRA can be replaced with soldering short wires from top to bottom "clam", if you are good with an iron and have the kit to solder "thin" wires on small pads.

If you like you can drop a photo of what you find here on HPMUSEUM and there will surely be some commentary from the 71B experts on this forum

Thanks. After looking at the photos popping over is still tempting :-).

That Zebra connector looks very fragile!

I only have a T10 and T15 so will need to source a T6.

Is there much risk of damaging anything else if I open to have a look? Just evaluating whether it is worth it. I don't have soldering tools or experience.

The images from Etienne are very good for you decision.

The Zebra images show how they should NOT look, they are supposed to be the same shining thin gold connections from one end to the other.

The one with the flex-cable is the metal back version - lots more screws to hold things together and in place. Not like what you have.

If you don’t have the experience - or know one who has - you will likely see what is in the pictures plus the corrosion (green) which you can clean with vinegar. But that’s the end…

The likelihood that they would recover from a repair is actually quite high, as mentioned a have done a few, mainly fixing corrosion or modifying module configuration RAM/ROM, I have yet to see one I couldn’t recover (unless display was dead… that one is hard)