Mac Plus power supply

[eyal-a]

Hello,

I am looking for a way to safely test the mac plus power supply outside of the computer chassis without connecting it to CRT or logic board. All power supply test examples on YouTube and blogs seem to be done with the board installed - loaded with CRT and logic board.

I tried it, but the board's protection circuit (Q8, CR18, R32, R33) clicks repeatedly and shuts down the supply as over voltage is detected.

I tried loading the 12v rail (with resistors or the logic board/diskette drive), but probably don't have sufficient load without the CRT(?)

Does anyone have experience or suggestions on how to test the power supply board independently?

EA,

PS. my end goal is to remove the high voltage fly-back transformer and CRT and go with this RGB-to-HDMI https://retrohackshack.com/product/rgbtohdmi/ and an 9" LCD panel

 

[pinto_guy]

Do you have a spare HDD ? It should drain enough power to get the AB going

 

[Johnnya101]

If/When you do remove the flyback and CRT, DO NOT throw them out, please list them here for sale if you don't have any other uses for them!

 

[eyal-a]

Thank you. I only have a logic board and a diskette drive in my possession. I tried a small ATX power supply and that powered the logic board up to a "bing" sound. My goal was to retain as many original components but I eventually decided to replace the AB with an ATX supply and RGB-to-HDMI connected to a 9" LCD panel.

I have a CRT to spare. Would I simply post to the "Trading Post" area when ready?

Happy New Year!

 

[Johnnya101]

Yup, just post there when ready. Use caution while handling, and when shipping, encase the back of the tube with something to protect it, and use a block of foam on the pins if possible.