L8-01 Driving me up the wall!

[Innov8tive1]

ARM450U copier with network option installed. L8-01 which indicates no full wave signal. The full wave signal is present both at the power supply and at the PCU board (CN14 pin 1). I replaced the PCU PWB with one right from Sharp to no avail. I replaced the DC power supply with one from our used/parts inventory to no avail. I removed all options thinking perhaps something was loading down one of the power supply voltages, no luck. I went around unplugging as much as I could from the PCU board while still enabling the machine to boot and I get the same code every time. The display comes up normally for startup, then one fan comes on then shuts off, when it does the display contrast goes very bright and the L8-01 comes up. I can press the custom settings button or any of the keys but the touch screen is unresponsive. In speaking with Sharp (Canada) tech support they tell me of a Tech Tip from the States in which the MFP board is to blame.
Has anyone ever dealt with this issue before?

[bonnie750]

never had this exact fault but when fuse on the motherboard goes it causes many different faults. usually normal display at first and almost immediately nothing except the fans running..worth a look. Also had weird faults caused by the ribbon cable from the main drive assembly damaged or poor contact.

bill

[mojorolla]

TT-20084.pdf See attached. This reads exactly as you describe.

[Dark Helmet]

another tip i found:

L8-01, New AC/DC Power Supply Board Is Different

AC/DC harness has been changed too.

If you need to replace your AC/DC Power Supply Board for any reason and your machine is older, please note the part # of the board your machine is equipped with and order exactly that number (you will find it on the rear side of the board, near CN2).
If your machine is older, the board may be an RDENC0002FCZZ. This is now substituted by RDENC0020FCZZ or FCZ4 on which CN2 has 7 pins, while on the old 0002FCZZ it had 6 pins.
You will also have to order and replace the AC/DC harness (Section 13, item 20 in Parts Guide), old part # DHAi-3289FCZZ (for RDENC0002FCZZ), new part # DHAi-3430FCZZ (for RDENC0020FCZZ or FCZ4).

[Innov8tive1]

The last one I have seen but I did verify that the replacement power supply was the exact number as the one that came out. All the plugs on the wiring harnesses did match up.

As far as the Tech tip which describes a faulty harness, I will look into that. It does seem odd that this would happen all of a sudden. Thank you for all the replies.

[Innov8tive1]

Found the solution. The "mother" board that the MFP plugs in to which has ribbon cables going to the PCU PWB has a 12V regulator on it which supplies 12V to an op-amp on the PCU board. The regulator was dead, had 24V in but only 0.4V out. The op amp in question takes the full wave signal from the power supply and compares it to a known voltage and outputs that to the cpu (far as I can tell). If the FW signal is not there it throws the L8-01...............but if the 12V supply is not present on the op amp then it can't do it's job to tell the cpu that the FW signal is present thus it throws the L8-01 code.
Hopefully nobody else has to deal with this because the board is very hard to get at. But for those who do come across it, this might save you some troubleshooting time and a few (more) grey hairs!

[ZOOTECH]

Thanks for the update, I hope I'll remember this for the next time it happens here.

[Dark Helmet]

It's in a very special spot isn't it.

Actually a lot of things on that machine are special to take out. Thats what happens when you put a 45 ppm copier in a 2x2 cube.

Glad you got it fixed.

[Innov8tive1]

Yes, many may things are "special"..........that's what happens when you make a 45ppm printer into a copier..........no, even in printer form it would be a pain!