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Old 01-06-2022, 03:54 PM   #1
Join Date: Jan 2022
City & State: Edmond, Oklahom
My Country: USA
I'm a: Knowledge Seeker
Posts: 20
Default Need some help with Epson Printer Power Supply C655 MAIN

Here is the back story. This printer had been sitting for about two years not used. I removed the print head to clean it (completely dried out). I cleaned it and reinstalled in. Powered the printer on, the printer started going through it's normal start-up procedure and part way through it was like the power just shut off. No sound, not lights, no error messages, it just went completely off. I suspect the power supply.

At any rate, the schematic for the power supply is included.

There is a lot going on on the low voltage side that I am not able to make heads or tails out of! I believe the stand-by power is derived on the low voltage side.

I have tried doing some initial testing with the supply removed and could not really tell much as I was not able to get it out of stand-by mode. The fuse is good and I'm getting power into and out of the rectifier.

One thing I have discovered, if I reconnect the supply to the processor board, I hear sort of a high-pitched "beep" sound from the supply. I believe the supply is attempting to start up but them shuts down. After doing more testing last night, I discovered that R12 looked "chalky" colored, I believe it was blue, or light blue at some point. I pulled it and it measured 1.2 ohms. According to the schematic, it should be 0.3 ohms. I didn't have a 1 watt resistor so I had to order one.

On the output I have nothing, no +42v, no +5v and no +3.3v.

Can you folks help me get this supply working again? I would greatly appreciate your help.
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