Hello, I recently dug out my "repairs" bin, full of semi-working machines.


First to take the dive was a Toshiba BC-602L whose keyboard was stuck thanks to some caffeine and sugar-based beverage generously spilled on it (of course was sold to me as "working" on eBay...). Actually, itt took the dive as all it needed was a bath in soap water, careful rinsing and some hair dryer care. Came back in full shape, I love those strange "6 digits with 12-digit calculating capability" machines as G.Ball says !


Second to show its innards was a Technico 77SR, and here I need help. To my surprise the display is a 12 digit bubble stick made by HP (so this is not 100% OT) ! It is marked as "made in Singapore", has some slight corrosion which can be cured.

Everything else looks good, I'll check a possibly bad capacitor, but my problem is another component which is square, about 3x3x1 cm, marked :

BEST CHOICE

DC - 2415E

7510

TAIWAN


What is this ?? I don't want to test / desolder it without further knowledge. For the record, the single LSI is marked "A4802CB", "7615", and has a logo I don't know. Do you know its maker ?


I hope you don't mind these questions, as I know there are several engineers carrying screwdrivers...

Bonjour Gérard,

Le seul DC 2415 que j'ai rencontré est un convertisseur CC/CC encore vendu par Peak et référencé Ici.

Cordialement

Etienne

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Hello,

The only DC-2415 I've met is a DC/DC converter still sold by Peak and referenced here.

Best.

Etienne

Thank you, I am impressed !

The component I see in the machine has 3 pins only, one at each corner (but one).

I will probably pass on this one.

I understand your point.

However, if you check the link to the referenced DC/DC component you'll see that:

- Not all pins are connected: 4 & 6 are omitted
- of the 4 remaining pins, only the ones needed for specific voltages are to be connected.

This is a multi-voltage DC/DC converter, therefore, if you can assess the needed voltages (DC input & DC output) in your calc, you can choose:

- the component variant you need between:
P6LU-0505E
P6LU-0512E
P6LU-1205E
P6LU-1212E
P6LU-2405E
P6LU-2412E
P6LU-2415E

- Which pins to connect between the 4.

That's the best I can propose.

Good luck & cordialement.

Etienne

Thank you Etienne,

I am not sure I have the necessary skills to go further on this one, I'll check voltages and if unsactisfactory will desolder the component, then test it. Its shape is really different, here it is square and a quite unimpressive molded blob.

I have turned my interests into making a working Omron 86SR from one with a broken VFD tube and a working 86 (not SR). It's a pity to destroy a working machine, but I want to make the better model work again. Not opened yet, so I don't know if it will fit.

Regards, and sorry for the bandwidth.

Depending upon the VFD, you can find several of them on Ebay. Search for "ITRON", "NORITAKE DISPLAY", "FUTABA DISPLAY". Also, check your local Goodwill store. The ones here always have TI, etc desktop calculators with VFD displays for under $5.

Thanks, I searched as you said and was surprised to see results, but as I expected there is about as many kinds of tubes as there are calculator models. Also, the price od the offered stuff is way higher than what I paid for the Omron 86, whose display is a much more likely replacement for that of the 86SR.

Strange times when we have to cannibalize good machines to repair better ones. Replacing capacitors is easy with alternate parts, but when (or if) times come to replace faulty ICs (see the EPROM discussion), there will be tough decisions to take... Nothing lasts forever