Reparing a power supply 82002A

[Le Babou]

Hello.

I need your knowledge.
I've just bought a hp-35 NOS.
The power supply is a 82002A model and doesn't have a big switch 110/220v under the pins.
So, I didn't made attention (stupid I am !) and I power it on.
After few seconds, it stopped working. It was set to 110 and of course it's 220v in France :\
I looked carefully and the voltage switch is a little one on the left bottom side.

The calculator has no damage.
As it's NOS, I'd like to keep the original power supply.
Can it be open to be repaired ? If so, how to do it ? If not, is there a place to buy a new NOS one ?

Sorry for beeing so long and thanks a lot for your help.
Xavier - stupid handyman...

Edit: here is a photo of the power supply. It's the first time i've seen one like this. You can see the voltage selection in the lower left corner.

[Le Babou]

Hello.

Nobody to tell me if it can be opened and repaired ?

Thanks. ☺
Xavier

[Maximilian Hohmann]

Hello!

Can't offer much help apart from this: This charger must be very rare. I have a box full of HP chargers but I have never seen one like this. Nor has google's image search.

From your photo it looks as if it can't be opened without damage. There are several other chargers like that from HP which are welded/melted together. To open it, you must break that weld somehow and I doubt it is possible without leaving visible traces. And even if you manage to open it, the only possible repair would be a replacement of the transformer. Other similar chargers (again: I never saw this one before) have a fuse somewhere between the windings which is not accessible or replaceable. This one might be different but I doubt it, otherwise they would have used a fuse accessible from the outside.

What I would do is keep this charger for completeness of your calculator and keep looking for an identical replacement. I know no other place apart from eBay where to look for that, especially if you want NOS parts.

But I have one curious question: How did you manage to connect this thing with your 220V outlet? The plugs are completely different... For my vintage calculators I have a 220V/110V transformer which has the U.S. type plug on the 110V side. They cost almost nothing and save you from trouble like this one. Even if you have set the 220V/110V switch wrongly, nothing will be damaged.

Good luck with your search!
Max

NB: I just did another search for LR 21061 (that's the second type number below 82002A) and there are quite a few search results. Obviously the same charger was used with Casio and Texas Instrument calculators as well, but with a different cable and plug. So there might be a source for spare transformers! But none of the pictures show it in opened state and I still doubt that it can be opened without damage.

[TomC]

The LR number is just a safety type acceptance code. Has NOTHING to do with the charger type.

[Maximilian Hohmann]

(09-16-2016 11:28 AM)TomC Wrote:  The LR number is just a safety type acceptance code. Has NOTHING to do with the charger type.

Oh, I didn't know that! But it is still worth googling for that number because other people don't seem to know either. E.g. this (unfortunately expired...) eBay-auction 131490402297 lists the missing transformer under it's LR number.

[Le Babou]

Hello Max.

Thanks a lot for your answsrs.

As I buy a lot of material in the states, I have plug adaptators US to EU and also transformators 220v to 110.
So I use a plug adaptator, i read quickly instructions and tought the voltage selection was automatic as on a lot of power supply AND IT WORKED for 2 seconds. I'm now called official stupid of the year.

Best regards.
Xavier

[Le Babou]

(09-16-2016 10:41 AM)Maximilian Hohmann Wrote:  This charger must be very rare. I have a box full of HP chargers but I have never seen one like this. Nor has google's image search.

I could carrefully open it. It was lightly glued.
But now, I don't know what to do because I'm not an electronician...
If it's so rare like you said, do you think I can get a good price on EBay to finance a new working one ? Or do you want to make an exchange ?
I can add photos of the interrior. Nothing seems to have burnt

Best regards.
Xavier.

[Maximilian Hohmann]

(09-16-2016 05:37 PM)Le Babou Wrote:  I can add photos of the interrior. Nothing seems to have burnt

Do you have a (digital) multimeter? If you can post some photos, someone on this forum might be able to tell you what measurements to take in order to determine the fault. Maybe it can somehow be fixed... (I'm gone for today but will look back tomorrow.)

Regards
Max

[Dieter]

(09-16-2016 10:41 AM)Maximilian Hohmann Wrote:  What I would do is keep this charger for completeness of your calculator and keep looking for an identical replacement.

That's the obvious solution. But the replacement does not have to be identical. AFAIK there are several suitable chargers for the Classics. A good reference is Kees v. d. Sanden's website. So what about an 82010A or 82022A/B ?

Maybe someone else can say a bit more about this.

Dieter

[hibiki]

Hi all ! I am new in the forum. My First post.

Hi Xavier ! I am an electronic technician and will try to help you with some hints.

If you have a multimeter, the first step is check the transformer coils continuity. The primaries coils should not present infinite resistance between their terminal wires. The same for the secondary coil (lower resistance). If some of them are open circuit, you should replace the transformer.

According to the schematic seen in the Van der Sander page, check if your power supply has a fuse that could be open due to the overvoltage applied. If it is ok, check the voltage rating marked in the capacitor C1 of 400uF and if it is intact (not blown, electrolitic capacitors do not support overvoltage applied, but nevertheless, it can be replaced as its age is very old). The diodes 1N4002 are rated 100V reverse voltage and 1A of current, so they should be ok. Other parts that could be damaged are the zener diode D5 and transistor Q1. It is and old form of voltage regulator, that is better replaced with a 7805 ic regulator plus a diode in series to supply the 4.2Vdc.

But if you could post some pictures/photos we could give you better advices.

[Duane Hess]

Not posting to help you with the repair because I do not know how. But to raise your awareness of the charger you have.

Unless I'm greatly mistaken the unit you have was the very 1st classic charger model (the *original* 82002A). i.e. most all other classic charger units are follow-on models of the 82002A you have. That in itself makes your charger a gem of a find.

When chargers the same as the 82002A you have sell on TAS they get a significantly higher price.

Unfortunately, I have no idea how to open the unit. However, the posts you've received so far do have good points. Checking the functionality with a meter to get an idea of what to do is quite reasonable.

If you search on this site, on the right side is a list of items. "Repairs & Batteries" shows some charger data possibly useful to you. General searches on forum postings may produce info.

I do not have the specific charger unit you have. Have seen it listed in sales. Personally I wonder whether the case snaps together. i.e. with careful tools, prying you can get the cover off. But that is totally a guess on my part.

The action I'd recomment? WAIT! I have no doubts there are several collectors on this forum who have that charger or know about it. Many people do not log on every day. Personally I'd wait about a week and see what posts you collect in order to avoid becoming anxious and end up cracking or marring the case of the charger.

Mainly, I'm trying to impress upon you that you have a rather RARE charger unit. I believe it was the 1st one ever released with the HP-35 and a relatively small number of that specific 82002A units were sold. Shortly after the HP-35 introduction, follow on models of the 82002As were sold. (the ones with the screw together case) I do not know why the later style chargers with screws were sold. Likely engineering changes. Wouldn't surprise me if the change was made as screws made it easier to service.

For what its worth.

[Duane Hess]

See I'm stupid also! I didn't notice your post that you were able open the unit.

Glad that worked out.

I'd still wait however, as I'm sure, numerous collectors check the forum only once or twice a week.

Not to promote TAS sellers. But I have had communications with sellers who are obviously HP calculator sellers and refurb units before sale. I have asked them about possibly repairing items. In my case it was re-celling a battery unit of a non-HP calculator. The worst that can happen is they tell you no. Some sellers do perform minor repairs.

If you want a name, please PM me. I have no afficiation with any sellers other than being a buyer and don't feel it appropriate to suggest people openly.

[Duane Hess]

I wish my brain worked & could get it all together in one post. I need to get to the local farmer's market before they close.

If HP collecting appeals to you, I'd recommend retaining the charger whether you can repair/get it repaired or not. Mainly as I'm 99.9% sure you have a version of the very 1st classic charger sold. Personally I would not sell/exchange it unless you get another working 1st in the classic series power adapter.

Don't know if there are date-codes inside a charger but if collecting appeals to you it may be worth examining if you have one of the 1st of the 1st off the assembly line.

After being a buyer on TAS for about 7 years my recollection is seeing only about 8-12 of the charger types you have. Compare that to the screw together cases of the later 82002A charger models. At least a 100-fold more of the later models have been sold on TAS over the years. Of course, I don't check TAS every day but the comparison is valid.

If you want a working charger the screw together cases are fairly cheap. Personally I'd keep the model you have as its rather a rarity.

I'm going out the door now! Hopefully no more posts from me.