General Category > Lisa Troubleshooting and Repair

Help needed for Apple Lisa PSU Transformer 120VAC resistance

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patrick:
120 and 230V PSUs have different transformers. The main regulator can be converted by moving a jumper  (change from voltage doubler to bridge rectifier), but the standby transformer must be swapped. Its pin configuration is uncommon, at least in Europe. Therefore I made adapter PCBs from prototype stripboard.

So yes, you cannot use the EU transformer as a spare part for an US PSU and vice versa.

greniu:

--- Quote from: patrick on August 04, 2023, 05:14:13 pm ---120 and 230V PSUs have different transformers. The main regulator can be converted by moving a jumper  (change from voltage doubler to bridge rectifier), but the standby transformer must be swapped. Its pin configuration is uncommon, at least in Europe. Therefore I made adapter PCBs from prototype stripboard.

So yes, you cannot use the EU transformer as a spare part for an US PSU and vice versa.

--- End quote ---
Hi Patrick,

Thanks a lot for clarification. Do you know any equivalent of T2 to swap? Or any workaround for it to make PSU to  work. My two T2 have definitely failed because they show OL in multimeter. I need to fix it to work in 220-230V.
Greg

patrick:
You need something with 2x 9V secondary, approximately 3 VA. For example RS Components 121-3833
However, as the pin spacing does not fit you have to build an adapter PCB from a piece of prototype board.

greniu:

--- Quote from: patrick on August 04, 2023, 05:58:31 pm ---You need something with 2x 9V secondary, approximately 3 VA. For example RS Components 121-3833
However, as the pin spacing does not fit you have to build an adapter PCB from a piece of prototype board.

--- End quote ---
Hi Patrick. Thank you. I will try with this RS transformer.

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