HBI-55 4k RAM cartridge exploration

By Astuck

Supporter (8)

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19-01-2022, 04:11

Hi guys,
I've received my HBI-55 for a Sony HitBit HB-75F. The first test is ok, well recognized by the "OS".
I've tried several functions with a basic program : SAVE "CAT:" and LOAD "CAT:"

It worked well 5-6 times until the BASIC respond with "direct statement in file",
then no cartridge recognized even with cold reset. And it came back 5 minutes later.
Doing some research, some talks about CR2032 3v battery, some talks about cold solder joints on the pcb and computer's port,...

I decided to cut-open the 4k cartridge back sticker in 3 points to open it "cleanly".
Here's the opened beast and the battery was tested at 3.3v, incredible for a 40y old battery, no ?


And the case with details on the plastic clips :



It was sold 265FrF in 1984.
Any help would be much welcomed ! Thanks

Astuck

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By hamlet

Scribe (4096)

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19-01-2022, 15:35

Change the battery. Although it provides the 3V for your messurement, it can't keep it up when in use.

By Astuck

Supporter (8)

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24-01-2022, 01:46

Hi,
I'm wondering, is it a regular CR2032 3v lithium battery or a rechargeable one ?
Thanks

By hamlet

Scribe (4096)

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24-01-2022, 06:31

By gdx

Enlighted (5352)

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24-01-2022, 09:41

On the battery it is written "CR2032, 3v". So it's a non-rechargeable battery. You must use an CR2032 or BR2032 battery. CR lasts a longer time. You need 1HS or HFN models. They are with PCB Pins look like on your picture. (Not sure, you must measure the distance between the two pins)

The equivarent rechargeable batterie are ML2032 or VL2032. These batteries don't work long without a charger controlling the charge.

Be careful not to overheat the battery when soldering it. Put on safety glasses.

By Jipe

Paragon (1549)

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24-01-2022, 14:23

By Astuck

Supporter (8)

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24-01-2022, 18:11

Thanks for your help !
CR2032 is on its way but can't find the exact Sony replacement.
I ended ordering a SNES cartridge battery, same yellow model as Hamlet proposed,
I'll just have to bend the negative stripe to match width.

While the box is open, I'll refresh all solder joints with fresh new lead solder.

Cheers !