Re: [oldcalculatorforum] Digest for oldcalculatorforum@googlegroups.com - 1 update in 1 topic

38 views
Skip to first unread message

David Ramsey

unread,
Jun 4, 2024, 9:23:18 AM6/4/24
to oldcalcul...@googlegroups.com
My only guess would be that the power switch has oxidized or dirty contacts. I’m not sure how easy it is to disassemble an SR-52 (all my calculator restoration work has been with HPs); hopefully you can get to the switch without drilling out plastic rivets!

On Jun 4, 2024, at 04:35, oldcalcul...@googlegroups.com wrote:

"M. S." <mirkosc...@gmail.com>: Jun 04 12:11AM -0700

Hi All,
Recently I obtained a TI SR-52 calculator that look still in pretty good
shape. The only thing is I have to rebuild the batttery pack as was to be
expected.
I already connected the calculator to external recheageble battery pack and
the leds did not light up. Also with charger attached no sign of life.
What would be the first things to check for malfunction or defect in order
to find out if this calculator can be brought back to life or not...
Does anyone have experience in this, or a check list of frequntly occuring
issues related to that?
Please let me know so i can try to revive this beautiful piece of history
:-)
 
Thanks, Mirko
You received this digest because you're subscribed to updates for this group. You can change your settings on the group membership page.
To unsubscribe from this group and stop receiving emails from it send an email to oldcalculatorfo...@googlegroups.com.

David Ramsey

unread,
Jun 6, 2024, 9:33:31 AM6/6/24
to oldcalcul...@googlegroups.com
The problem is almost certainly a failure in the “zebra connector”— an elastomeric pad with embedded connectors that’s held by compression between two of the internal circuit boards in the calculator. Over the decades the elasto- part degrades, leading to intermittent or failed contacts that can result in the dead display you’re seeing.

Fortunately the HP-41 series is held together with screws, not sonic welds, so it can be disassembled and often repaired. However, the zebra strip is not the only thing that can degrade with time— the plastic of the case can become brittle and the posts the screws tap into will often fracture and fail with repair attempts.

You have three choices that I can see:

1. The best choice is to simply buy a Swiss Micros DM-41X. It’s a modern interpretation of the HP-41 running as an emulator on an ARM CPU. With a stainless steel case, giant multi-line display, a great keyboard that reproduces the classic HP keyboard feel, and about a zillion times the performance of the original, it’s the go-to choice for engineers and hobbyists that actually use their calculators. The downside is that it’s rather expensive at almost $300.00:


2. Send your existing calculator in for professional repair:


3. Buy a modern replacement for the zebra strip and repair it yourself:


I’ve worked on some old HP-41s in the past and depending on the condition of the plastic— specifically how friable it is— such repairs can range from “Gee, that was easy!” to simply throwing up your hands and accepting that it’s a total loss. There are some techniques that can save even badly degraded cases but they’re beyond my minor technical skills.

In any case, good luck with whatever you choose.

By the way, did you know there’s an annual conference for users of HP calculators?


— David

On Jun 6, 2024, at 04:35, oldcalcul...@googlegroups.com wrote:

hossnerbiz <hossn...@yahoo.com>: Jun 05 10:23AM -0700

After 40 years of daily driving, my trusty HP broke. After some checking,
I determined it is the display that isn't working - it is blank. I
confirmed that the CPU etc is working by blindly keying the BEEP command,
which resulted in the familiar 4 tone chime.
 
Anyone here with experience with these calculators? What typically goes
bad? The display driver? The display? Cracked solder joints? I assume I
might need a parts unit and a tricky remove and replace - with another 40
year-old part. Better to just get a working unit and eulogize the old one?
 
Thanks in advance!
Steve in OR

David Ramsey

unread,
Jun 7, 2024, 12:21:08 AM6/7/24
to oldcalcul...@googlegroups.com
My apologies; the link in that previous reply should have been:


Reply all
Reply to author
Forward
0 new messages