Mimaki UCJV300 "Error 1db" - Need help diagnosing and fixing

[HGdesign]

Thank you everyone for this great forum!

- I purchased a used ucjv300 as our first uv printer. When its powered up, it displays "Error 1db" "Station IV PCB V48"
- Looking this up in the mainatnce manual; it says - check and replace the power supply, and then an additional step, notes to replace 3 PCB boards.
- For background: The previous owner said they used the machine lightly, and then stopped using it about 14-18 months ago. The last effort to run print test on the head several months ago led to this happening..

My question is if any of you have had this "error 1db" and know what can cause it, and how you were able to resolve it?
- It seems odd that a significant amount of boards all failed at once
- Does the maintenance manual entry ( attached) mean that both the power supply and the boards all need to be replaced, or each of these steps normally independent, one or the other?
- Do these boards ever have a simple problem that be fixed; for example: fuses on board are blown?
- Can letting the machine sit unused for 14-18 moths cause such a problem

Looking like this error may be significant expense to get parts:
- Are there ways to source boards, power supply, and parts like this at a reasonable price, or am I likely looking at full Mimaki prices on spare parts.
- I would love to hear about your experiences with this type of error, and advice on diagnosing properly, and then ordering parts reliably, and hopefully, economically, at reasonable prices. , etc.

Thank you so much!

 

[Smoke_Jaguar]

The RWS1000B-36R is the big 36V power supply in the back of the printer under the main control board (EPL3 or 5 depending on age) that has the USB and network control ports on it. Big silver box, 2 huge terminals with some beefy wires bolted to it. Check that voltage with a meter. Note that those power supplies can be adjusted with a small potentiometer from around 30 to 40 volts if they have drifted. Not common to go bad, but easy to test. Best bet is test where you and only order parts when you confirm them to be bad or have reasonable suspicion.

Power supply is a stock unit, but they are pricey. Mimaki's boards are mostly custom, so typically not many good deals to be had unless you score one cheap on eBay.

 

[HGdesign]

Thank you. I hope to begin testing per your suggestions tomorrow, God willing.
I will report back. Thank you

 

[Smoke_Jaguar]

Not sure how well god will work, but I recommend a multimeter.

 

[HGdesign]

- I powered it up, it displayed the Mimaki logo with boot up for a little while, and then went to the error screen with the 1db error.
- The entire time, the power supply fan ran at what seemed like a high speed. But I am not familiar with the normal operating sound of this so not sure if that is normal, or if the PS varies it's fan speed as needed.
- I checked the voltage across the output terminals on the power supply in the back, and it measured 35.92V. Does this mean the power supply is not the issue? Or are there additional measurements / tests I should do with the power supply?
- Looking at the various PCB's in the back cabinet, I noticed that the main PCB on the left, had a number of red LED's lit up. (see photo), However no lights on the station IV PCB, or the CT PCB below it.
- I then opened up the top panel as well on the back to access the UV Drive PCB. It also had no LED's lit up, and the small fan next to it on the right was off. The area around that fan, and about 1/3 of the UV PCB was covered in dust pulled in by the fan
- With power off, I tired to carefully clean up the UV PCB
- I check the fuses on the stations IV PCB, and on the bottom of the UV PCB for continuity ( while leaving them installed on the boards) . All beeped on my tester and seemed to be ok
- I then tested the boot up again, same boot screen, followed by error 1db
- No lights on the 3 boards ( Station IV PCB, CT PCB, UV Drive PCB)
- I'll attach some photos
- Are there other tests I can perform, or isolate certain boards to see if errors change, etc.
Thank you !

 

[HGdesign]

 

[Smoke_Jaguar]

Voltage is fine, might be a bad board or fuse. Note that some boards have fuses on both sides and they might not be referenced in the service manual.

 

[HGdesign]

Voltage is fine, might be a bad board or fuse. Note that some boards have fuses on both sides and they might not be referenced in the service manual.

There is also this orange connector that is not connected to anything. Is that normal?
- Can you recommend any techniques or tests I can do for narrowing down which board it may be, or do you think I will have to replace all 3 together as per the service manual.
- Is there a way to boot the machine into some type of service mode where it possibly gets further before getting hung on this error?

 

[HGdesign]

 

[Smoke_Jaguar]

There will be a good dozen or so connectors not used in the printer, this is normal. Used for optional items, or items removed due to revisions, etc.

As for boards, mark connections and remove them, look for damage and check fuses on bottom side if any. If board isn't lighting, that's a bad sign.

 

[HGdesign]

- Is it normal for boards to go bad. In this error 1db case: 3 PCB's at once.
- My concern is if I replace boards, and the issues that caused them to fail, causes the new ones to fail again
- And are some of the established sellers on Alibaba reliable to source boards from, or am I limited to mainly Mimaki, and eBay?

 

[Smoke_Jaguar]

Some boards get power off of adjacent boards and the power is typically a fused connection. If no power, connections, fuses and power supplies are most common issue. Going to have to start probing to see if they are getting power and if so, where it's dropping. Not super easy, but basic electronics troubleshooting skills. Most techs just replace the boards though.

 

[HGdesign]

I have not been able to find a clear issue yet. Checked a number of cables, and fuses. Traced some power connectors back to main powersupply and they have 36V as well. But no lights on those 3 boards, so it seems to get cut off.
I pulled out the Station IV PCB completely to be able to take closer look and check back side. Attached are some photos of an area along the right under-side where CN2 and CN5 FFC cables connect. There is some subtle discoloration and distortion visible. I can't make out what it is yet, almost like a clear coating that has yellowed slightly; something that was just on the surface. Have you seen anything like that? I angled the board into the light to make the distortion look more obvious in photos, so it looks more exaggerated. But in reality, it is very subtle, and the circuit traces underneath look intact.

 

[Smoke_Jaguar]

Just looks like solder flux from board manufacturing, might just be a bad board. Going through chip-by-chip troubleshooting is something I don't have the patience to do remotely.

 

[HGdesign]

I did not mean to ask for so much of your time to go chip by chip. The main thing I am trying to understand, is being a newbie to Mimaki machines, is whether I can just follow the service manual and confidently replace the parts noted, and expect to resolve the issue?
- My concern is that this error 1db says, replace 3 PCB's at the same time ( Station IV PCB, CT PCB, and UV Drive PCB). Is it common for 3 rather pricey boards to all fail at once, or would that mean that something else is up and simply replacing the boards would just result in a repeat of the new ones getting damaged again. I am not sure if these boards are common failure points and simply replacing is the solution, or if a failure of a board generally points to a issue downstream that should be carefully checked, before a new board goes in. ( For example, could a pump or motor be seized that caused a board to actually go bad, but unless I fix the pump, the new board will be damaged again)
I am not sure if that makes sense.
Thank you for all your help. It is greatly appreciated.

 

[Smoke_Jaguar]

The connector diagrams offer some help in seeing what connects to what. 3 boards down hints at power not going through. Section 2.1's block diagram is a bit convoluted, but it shows what connects to what. 2.1.2 shows most of the fuses as well as the family of codes that can trip because of blown fuses. Section 2.3.# are board diagrams, not super detailed but still great reference.

 

[Smoke_Jaguar]

No lights means no power. Will changing the boards change that? Maybe. We don't know where power is dropping. Power can be lost at the board early on, or it can be an issue of what is supplying the power to it in the first place. Without being there to trace out power, no amount of guess-work will give you an accurate response. We can guess and we can give instructions. The service manuals aren't perfect, but they show where to look. Error codes are just guidance. If the machine was working before acquired, it could be something as simple as a loose cable. Check the cable connector lists and make sure each one is plugged in. Each board has its ports labeled and diagrammed in the manual. Some extra connectors on the board will be there, and some cables aren't used. But those that are will be documented.

If you want to know if a light bulb is burned out and the switch is off. You cannot tell without checking to see if it is turned on.

If you want to repair issues where a board is unpowered (no LEDs), you either have to figure out where power is dropping and only replace that particular problematic part. If you skip troubleshooting, you can just throw boards at it until it works. This is a case where a tech who can scope things out is probably your best bet. If that's out of the budget, you might just have a write-off on your hand.

 

[HGdesign]

I do want to make my best effort to troubleshoot first. I am new at this, but technically competent, and do try to learn
I understand that I need to trace where power is and where it ends either at or before the board.
- Trying to focus first on Station IV PCB, as it seems to be first after the main PCB, and the other 2 boards depend on it
- I like to simplify things when trouble shooting. Im trying to think how can I minimize the number of variables, but uncertain if Mimaki require all cables to be connected
- In this case, can I eliminate all the connections going to / from Station !V PCB and ONLY connect the bare minimum necessary to confirm power is at the board
- Looking at diagrams you noted 2.1, and 2.1.2: Am I correct that there are only 2 inputs, CN24 is from the power supply, and CN1 is an FFC cable from the mani PCB
- CN24 measures 36V at the connector itself when powered up, and does not switch off even after the error appears
- Should I be able to disconnect everything else to station IV PCB, and still see its light up at least 1 LED on the board to indicate power?
Thank you

 

[Smoke_Jaguar]

Check your 5V power supply as well.

 

[kehall]

echo Smoke_Jaguar's comments - 5V is going to be necessary here for most of the logic and control to operate (and therefore LEDs).

I am not familiar with your model having only worked on my UJF-3042, however Mimaki do seem to like to have their own 5v supplies on each board, and check for connections through the FFCs before enabling power to downstream boards through said FFCs. Have you checked fuses on the upstream board? Having just read that it has a separate power connection though, I'm doubting it's done that way on your model.

Definitely check for voltages on coils around buck/boost converters (the dark round ferrite materials with white lettering and two legs to the board) - these will likely have voltages on of various magnitudes for 5v, 3.3v, 1.8v (for any microprocessors) etc. It may help narrow down (or could be another rabbit hole).

As mentioned in the other thread, FFC cables are cheap - and I'd start with the one to the upstream board. The main board will communicate with the sub-boards and if no response (or something else it doesn't expect to see), it will error... First things first, expected voltages, particularly 5V...