Bizhub 423 - Powers on - blank screen - faint high-pitched noise from DC power supply

[Fritzy]

The adventure continues...

This morning I powered on the Bizhub 423 I've been refurbishing (with an significant amount of help from the community here). The power light illuminated, the start button glowed orange, but the screen remained dark and the start button never turned blue. I could hear cooling fans spinning, and the developer made it's usual start up cycle churning noises but that's all that happened. After the startup cycle completed I could hear a very faint high-pitched whine from the DC power supply that I had not previously noticed. :confused:

I've tried leaving it unplugged for 30 minutes, restarting it, trouble-reset mode, unplugging the HDD (since that was the last thing I worked on), but each time I start the Bizhub it does exactly the same thing as I experienced this morning.

I didn't find much in the KM forum that looked similar to the issue I'm having. The high-pitched whine makes me think a power supply issue has cropped up. Before I pop open the power supply to take a look around (bad capacitors?) I thought I would check in to see if anyone had some other suggestions.

Thanks for the help!

[blackcat4866]

The power supply is the most likely choice. =^..^=

[Hansoon]

Never had ANY power supply go bad on our several machines of the 283/363/423 series, but it is still possible since your power supplies might be different from our 230VAC here over the pond.

Hans

[Fritzy]

Thanks blackcat4866 and Hansoo. I have no idea what happened here. Last night the bizhub was working fine and this morning it was kaput!

I pulled the power supply, visually it looks fine (photo attached). No leaking or bulging capacitors and there is nothing burnt or odor of magic smoke.

[rrrohan]

Thanks blackcat4866 and Hansoo. I have no idea what happened here. Last night the bizhub was working fine and this morning it was kaput!

I pulled the power supply, visually it looks fine (photo attached). No leaking or bulging capacitors and there is nothing burnt or odor of magic smoke.

ive had faulty touch control panels do this

[Fritzy]

ive had faulty touch control panels do this

Thanks for the suggestion. I'll re-install the power supply and take a closer look at the control panel.

[Fritzy]

The bizhub is back!

I'm not entirely sure how or why it is working again.

I re-installed the power supply and powered it on, but still had the same result as before. Then I proceeded to unplug everything from the MFP Board including:

Hard Drive
Memory
Fax board (USB and wiring harness)
All ribbon cables.
Power connector
Control panel connector


Plugged them all back in, powered it on, the control panel display lit up and it started like nothing was ever amiss. :confused:

I'm keeping my fingers crossed that this was just a bad connection and is resolved now.

[blackcat4866]

These switching power supplies have the ability to "heal" themselves. Just powering off, and unplugging the device for an hour can reset the power supply.

Keep in mind that it's a sign of age, and it can only "heal" so many times. =^..^=