About that HP37E I am trying to fix



#7

As I posted a while ago, I got a faulty 37E. The powersupply is not working.
Now I got annother spice, a 32E, (the 37E was my first one) and I used the 32Es powersupply to test the 37E. It still did nothing. Then I realized that the LEDs were badly corroded inside too, and after swaping those too it works!!
The powersupply should not be a big problem to repair, as I have that working one to look at and measure on (Thanks to Luiz for the excelent pictures and enlightening me on that jumper :)). But do you have any suggestions on how to restore the LEDs?

Regards, Harry (Germany)


#8

Harry:

I am am afraid you need a spare part. Any solderless spice display will work.

If you can repair it post the solution. I have two of those "internally corroded" displays.

Best Regards

Jon


#9

Hi Jon, Harry (I wrote your name wrongly in my e-mail; sorry)

Just to add to Jon's correct note that if you find a working LED module in one soldered Spice and you are carefull enough removing it without dammaging it, it will work fine as well. I have already done that...

About restoring the "corroded" microscopic 7-segments LED blocks: I completely agree with you, Jon; I cannot see a better way than using a spare LED module. Harry, be patient and you'll surely find a "donator". Spices are not so rare.

Good luck, Harry. And let us know what happens. (thanks for mentioning the drawings; my pleasure)

Luiz (Brazil)

#10

If the connecting pins are corroded you can clean them with alcohol and lightly sand them with extra-fine grit sandpaper. Treat the pins with a corrosion inhibitor if you can find it. This should get the display up and running.

VERY occasionally the corrosion can get up under the LED lens and affect the bonding wires to the LED chips. This usually only affects a small portion of the display. It is not repairable.


#11

That is exactly what happened to my LEDs. I can see crystals arround all the boding wires through the lenses.

I will keep the calculator for spareparts...

Regards,
Harry

#12

Dear Harry,

I have a spare 32E at hand, which is corroded, but LEDs seem fine. I don't have time and pations to give it a try. If you want it for free, please drop me a line. In case it works out, I would be pleased to receive a bottle of beer of your home town as reward.

Best regards,

Stephan

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