C253 repair

[rugby_mihe]

Hello everyone,

I recently got a c253 for free. It worked until a power surge, and now does not do anything.
The service manual does not give any flowchart about the internal electrical checks, so
what is the best way to sort out which board is broken and needs repair or replacement?

I suspect the power supply board on the left side, but I dont want to buy a replacement
board without a check if its really broken or not.

Any suggestions?

Thanks,
Michael

[doinbox]

If you've tried a new power cable and are getting no lights or anything at all then it is very likely the power supply.

[Cantechman]

Hello everyone,

I recently got a c253 for free. It worked until a power surge, and now does not do anything.
The service manual does not give any flowchart about the internal electrical checks, so
what is the best way to sort out which board is broken and needs repair or replacement?

I suspect the power supply board on the left side, but I dont want to buy a replacement
board without a check if its really broken or not.

Any suggestions?

Thanks,
Michael

The manual would say what to check on the power supply board to see if it's getting any power at all and it would also show you how to check if power is coming out of it.

[rugby_mihe]

Thank you for your replies. I have now found the service manual, which describes how to check the internal
connectors (24V, 5V supply). Will do that later. If 24V and 5V are provided, its most likely not the DCPU, ... I
will come back with the results.

[rugby_mihe]

Its the DCPU board that fails. No 24V output. I tried to find some broken parts, but visually inspected everything looks fine. I could follow the
primary voltage from the rectifier to the transformers, but afterwards the secondary voltage disappears. Fuses are good and conducting.
As I dont like to repair SMPS, I will try to find a power supply board from a broken machine. Should not be too challenging and expensive.

[copyman]

I have a few working C253 I can take parts from. Will ship to USA address.

[Markks]

Hello everyone,

I recently got a c253 for free. It worked until a power surge, and now does not do anything.
The service manual does not give any flowchart about the internal electrical checks, so
what is the best way to sort out which board is broken and needs repair or replacement?

I suspect the power supply board on the left side, but I dont want to buy a replacement
board without a check if its really broken or not.

Any suggestions?

Thanks,
Michael

Its great that you got the machine for free. Just be aware that this machine reached end of life in June of 2017 which means that KM no longer makes parts for that machine. But the good news about the older KM machines is that you can use boards from other machines unlike the new modles

[rugby_mihe]

According to the previous owner, the machine was lightly used by him, so I guess its mechanically
in good shape. I gave it a good cleaning and removed all the dust inside and around the fans. As I
am not a technician for KM machines, I dont have any idea about them, in general. I repair radios
and tv's since decades, so I know more about electronics than how this unit works.

Thanks also for the offer for parts, but I dont live in the US, I live in Europe.