HP 32E Battery compartment tabs

[KD8TZC]

Hi all, I picked up an old non-working HP32E, when I received it, and looked in the battery compartment I saw what may be the issue. The two metal tabs that connect from the power board to the battery were missing. I'm hoping the flex cable is also not broken.

My question is this though, what is the easiest way to fix the two missing metal tabs? One thought I had, and it wouldn't be the prettiest, but it should work. Could I just solder two wires onto where the old contacts would have been, and then solder them to the batteries?

[ThomasF]

Hi,

Maybe the easiest way is to order a replacement ...

http://www.panamatik.de/html/spice_batte...ector.html

Cheers,
Thomas

[KD8TZC]

I have seen that, but at $53 shipping, that's a bit steep. I could always go the slow boat route, and only pay $13 for shipping, but that seems steep too. I've ordered things from India via DHL and it was only about $10 I believe. I'm not sure why shipping from Germany is so much more.

[BillBee]

I've used the sticky copper conductive tape. Folded over a few times, stick to riviet and bamn a working 32E. While yes, not a pretty fix it worked.

If you do some digging in the archives you will find some creative solutions. IIRC a small screw in the rivet hole holding a new tab.

-Bill

[KD8TZC]

(06-06-2022 06:45 PM)BillBee Wrote:  I've used the sticky copper conductive tape. Folded over a few times, stick to riviet and bamn a working 32E. While yes, not a pretty fix it worked.

If you do some digging in the archives you will find some creative solutions. IIRC a small screw in the rivet hole holding a new tab.

-Bill

Can you share a picture of that? I'm having a hard time visualizing this.

Also, there are a few "holes" on that board, so I'm assuming I want to use the two holes that are closest to the bottom of the calculator (and near the notch)?

The small screw is an interesting idea if I can get enough pressure on the battery pack. Although, I could always wedge some paper or a foam nose pad for eyeglasses between the bottom of the battery on the opposite side.

[BillBee]

I don't have one here at work but its a fairly simplistic job. Instead of jamming tinfoil between the battery ends and contacts you fold over a strip of the copper tape and stick it to the contacts. Not really a picture worthy concept.

This assumes the only issue is the contact tabs.

-Bill

[KD8TZC]

Thanks BillBee, I think I understand now.

I did try the small screw method since I did have some around. It can now make contact, and when I hook a voltmeter to the two screw posts, I do get current when I plug in the charger. What I don't have though is a good battery pack, so I ordered one. I seem to recall that HP's won't run without a battery, so I'm hoping that is why the LED's don't come on when plugged in and powered on without the battery. I'll find out in a few days.

[Steve Simpkin]

(06-07-2022 09:12 PM)KD8TZC Wrote:  Thanks BillBee, I think I understand now.

I did try the small screw method since I did have some around. It can now make contact, and when I hook a voltmeter to the two screw posts, I do get current when I plug in the charger. What I don't have though is a good battery pack, so I ordered one. I seem to recall that HP's won't run without a battery, so I'm hoping that is why the LED's don't come on when plugged in and powered on without the battery. I'll find out in a few days.

Yes, unfortunately the HP-2x (aka "Woodstock") and HP-3x (aka "Spice") series of HP LED calculators used the batteries to regulate the voltage from the charger. You should never try to power one of these models from the AC charger without a good working set of batteries installed that also have a good electrical connection between the batteries and the calculator electronics. Doing so may damage the circuitry of the calculator. The HP-3x Spice models seem to be a bit more likely to survive this but it is still very risky.

Here is a link to the English version Owner's Handbook for the HP-33E. See page 76 for information about battery charging.
https://literature.hpcalc.org/community/...hpg-en.pdf

[BillBee]

(06-07-2022 09:12 PM)KD8TZC Wrote:  Thanks BillBee, I think I understand now.

I did try the small screw method since I did have some around. It can now make contact, and when I hook a voltmeter to the two screw posts, I do get current when I plug in the charger. What I don't have though is a good battery pack, so I ordered one. I seem to recall that HP's won't run without a battery, so I'm hoping that is why the LED's don't come on when plugged in and powered on without the battery. I'll find out in a few days.

I wish I knew you were going to plug a charger into it, as like Steve said, its a big "no-no" with a dead or missing battery. There is a guy on the Bay (warerhosko IIRC) where the battery packs are pretty good.

If with the charged battery it doesn't light up - you can push around the spaces between the keys. Some of the Spice series have non-soldered connects which need some "encouragement to reconnect.

Taking them apart is a whole different adventure and I hope you do not have to go there.

-Bill

[vassilisprevelakis]

(06-06-2022 07:52 PM)KD8TZC Wrote:  Can you share a picture of that? I'm having a hard time visualizing this.

Hi,

here is a picture of my battery compartment. In my case the flex cable was also damaged, so I replaced it with ordinary wires leading from the back of the battery compartment to the power supply.

Vassilis

http://www.series80.org

[KD8TZC]

Well, I did order a new battery, and that arrived today. I was told that the battery would arrive fully charged. When I put the battery in and connect the power supply and then turn it on, a very faint red dot appears in the lower left side of the display. Any idea what that means? If I disconnect the charger, I don't see anything.

[KD8TZC]

It looks like there may be damage to the ribbon or the contacts for the battery compartment. I cannot get continuity across the two contact points, so I believe I will order the kit that is out there. My question though is once I have the calculator opened, there appears to be a plastic cover that the ribbon goes into where the keys would be. How do I get that cover off. I see 6 plastic tabs, but I also see some metal looking tabs. I'd appreciate it if someone could help on how to get that off so I can see where I need to reconnect this ribbon. Also, once I remove the plastic cover, I thought I heard that some of the HP calculators didn't have chips soldered on, but just held in place by these covers. Is this one of those calculators?

[vassilisprevelakis]

(06-13-2022 07:10 PM)KD8TZC Wrote:  It looks like there may be damage to the ribbon or the contacts for the battery compartment. I cannot get continuity across the two contact points, so I believe I will order the kit that is out there. My question though is once I have the calculator opened, there appears to be a plastic cover that the ribbon goes into where the keys would be. How do I get that cover off. I see 6 plastic tabs, but I also see some metal looking tabs.

Hi,

If the picture is of your calculator, then the chips are NOT soldered, they are kept in contact by the pressure of the plastic back and some foam under a foil with traces on. The plastic tabs hold the plastic module with the chips and all against the keyboard, so you have to CAREFULLY bend them to remove this assembly. The metal tabs are in two strips, one for the left side and one for right side. I don't think you need to mess with them to access the power supply module. I think that if you remove the complete assembly, you get access to the power supply which is where the ribbon from the battery ends up. I have just replaced the ribbon with wires leading to the battery connector. I left the external power supply connection disconnected, as I prefer to charge the batteries away from the calculator.

If you end up removing the metal clips, be VERY careful not to let the ICs fall off. Or at least make sure you know where each one goes and its orientation.

The construction is very fiddly and once opened it may be a devil to get everything working again because the foam is no longer springy and if disturbed may not apply the same kind of pressure as before. In fact this may be the real problem with your calculator, and not the power.

Let us know how things progress.

Cheers

**vp

http://www.series80.org

[teenix]

(06-13-2022 09:31 PM)vassilisprevelakis Wrote:  If you end up removing the metal clips, be VERY careful not to let the ICs fall off. Or at least make sure you know where each one goes and its orientation.

I can tell you, that placing these IC's in reverse then applying power will instantly destroy them so it is worthwhile triple checking on reassembly.

It is also wise not to handle the IC pins with your fingers either, as static electricity charges on your body can also destroy the tiny circuitry inside them. Use can use tweezers to handle them by lightly gripping the ends of the plastic case only.

cheers

Tony

[KD8TZC]

Thanks all... I don't think I will be removing that assembly then.

The picture I posted is not from my calculator, but an image I found online. I guess what I don't understand then is how/where do I attach the new ribbon if I don't take off the cover? I can't see under that slot very well, but am I just supposed to cut the ribbon someplace easy outside of the slot in the plastic, and then somehow connect the two ribbons together?

[BillBee]

http://www.panamatik.de/html/download.html

The site is marvelous and great reading.

http://www.panamatik.de/html/spice_batte...ector.html

Look at the manuals to get a feel for calculator's construction.

-Bill

[KD8TZC]

Thanks Bill... so it looks like I cut the old ribbon and then have to get the resists off to expose the traces. It says though that you need three small copper wires to join it. Is there a better/easier way to get the wires onto the traces than having to scrape the resists off?

[BillBee]

I personally would expect the worst. The Spice series is known for having the chips fry when using the adaptor with dead/or no batteries and you did this multiple times.

On the other hand, there is no better learning experience and aside from cost its not like you are going to trash say a 34C.

Regarding the wires: That's what I read too and that guy knows his business.

I wish you the best and each success brings hope to others.

-Bill

[Steve Simpkin]

(06-15-2022 11:06 AM)BillBee Wrote:  I personally would expect the worst. The Spice series is known for having the chips fry when using the adaptor with dead/or no batteries and you did this multiple times.
...
-Bill

Regarding the risky, low-cost charging system used in the Woodstock and Spice models. I wonder if the ICs used in Spice models were slightly better able to withstand the high voltage applied to them when using the charger without the batteries installed. I have heard so many cases where the ACT chip was fried from this in Woodstock models. I have heard other cases where this was done to a Spice model and it survived the experience. The warning messages in the Owner’s Handbook about operating the calculator on the adapter without batteries installed also changed between the two series. The warning is much more dire in the Woodstock manual (first picture below) than in the Spice manuals (second picture). Not that I am advocating that anyone try using the AC charger without known good batteries installed. Just something I have observed.

   
   

[KD8TZC]

Thanks all... being that I got this as a steal (just the price of shipping) if it's dead, it's dead. Maybe it can be parted out somehow.