HP 75D power supply

[zixingcheche]

Hello

Just a question about the recharger for HP75D, according to the service manual, it outputs VAC 9.9~13.3.(AC) it should be same as HP97 desktop calculator. is that right?

but I found a description here (https://thimet.de/CalcCollection/Calcula...ntents.htm)
HP75's recharger is DC 8V. please check the picture attached.

Just to confirm this, I thought it should be VAC output.

BR,

[teenix]

(09-26-2024 09:25 AM)zixingcheche Wrote:  Hello

Just a question about the recharger for HP75D, according to the service manual, it outputs VAC 9.9~13.3.(AC) it should be same as HP97 desktop calculator. is that right?

but I found a description here (https://thimet.de/CalcCollection/Calcula...ntents.htm)
HP75's recharger is DC 8V. please check the picture attached.

Just to confirm this, I thought it should be VAC output.

BR,

The compatibility will be determined by the VA ratings of the 75/97 charger transformers. If the charger serial numbers are the same, then they should be compatible, if not you will have to do the AC output test as outlined in the 75 service manual to make sure the AC voltage drops to the listed value when under load.

I don't know much about the 75 except that the manual states an AC output charger. The internal 75 battery charge circuit rectifies and conditions the charger voltage. You could still use a DC output charger as long as the operating voltage and current capability is compatible with the AC one.

cheers

Tony

[KimH]

(09-26-2024 09:25 AM)zixingcheche Wrote:  Hello

Just a question about the recharger for HP75D, according to the service manual, it outputs VAC 9.9~13.3.(AC) it should be same as HP97 desktop calculator. is that right?

but I found a description here (https://thimet.de/CalcCollection/Calcula...ntents.htm)
HP75's recharger is DC 8V. please check the picture attached.

Just to confirm this, I thought it should be VAC output.

BR,

HP Collection take a look - it is the 82066B for 220/230 for Mainland Europe and marked 8V-AC & 2,5VA - I use this. I see you're registered as in China and this is a bit more complicated (or can be) as there are 3 main Plugs in use, but you obviously know this already.

[rprosperi]

The normal HP 82059B/D works for both the 97 and the 75C, as well as the 91, 92, nearly all the HP-IL peripherals, etc.

A good summary of the various models by country be found here, under "Topcat, Sting and Coconut Series chargers":

https://www.keesvandersanden.nl/calculat...argers.php

So, yes the 75C uses a 8-10VAC power supply, that webpage is simply wrong. Many people assume that all such wall-warts put out DC for electronic devices, and publish such assumptions as fact.

I'm not EE-nough to say if a special DC supply might work OK, but HP didn't supply one.

[Martin Hepperle]

... and the same AC block is also used for the HP-110 and the HP Portable Plus ...

[zixingcheche]

Thank you all for your comments about this.
I understand it now.
Thanks a lot!