TI replacement power supply

[TI replacement power supply]

Thanks for the offer. I would need an european Powersupply (240V) anyway and also the internal one.

 

If this is stable I see no reason to change back for now. Voltage Input is universal, too for the Meanwell supply.

[TI replacement power supply]

Hi,

I recently aquired a TI99/4a and had the problem with a missing external Transformator and also the internal PSU board didn't look too healthy.

 

So I came up with my own solution using mostly off the shelve parts.

 

I used a Meanwell IRM series powerbrick 12V 1.8A and etched my own replacement Board with an additional 5V Buck regulator and MAX660 in voltageinverter mode for the negative -5V Rail.

Then I replaced the old 4Pin Powerplug with a Connector from an old Deskjet Printer which fits almost perfectly.

So now I can connect it directly to the mains.

 

Works and seems to be stable and not getting too warm.

 

I also reuse the original powerswitch and LED.

 

Attached are some photos of the setup.