HP 75D power supply

[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