Repairing a Toshiba e-Studio3005AC

Over the past few months I’ve been dealing with the printer or demon known as the Toshiba e-STUDIO3005AC. Turns out repairing things you’re not meant to repair without being a tech isn’t a pleasant experience.

Sometime in Mid-2023, I acquired this beast from the land known as Craigslist. It was larger than expected and I didn’t have any good way of transporting it other than on its side in an SUV, so that’s what ended up happening. foreshadowing Half the reason I picked it up was because it came with toner; a full CMYK set in the printer, and spare CMY in the storage compartment. Toner is expensive, though I would later find, there were other expensive consumables. Anyways, I spun it up, and it whirred along and did its thing, until it soon decided to spit out an “empty waste toner” message. Yay. Off to find the service manual, I go. Which is hard to find by the way, but not super hard. The important thing to know is that there are multiple printers included in the manual, so it’s listed as “e-STUDIO2505AC/3005AC/3505AC/4505AC/5005AC”. Some sources will say something is for the 2505AC, or for the 5005AC, but most stuff is for the entire range of printers. “es5005AC_SM_EN_0004” will net you the service manual, by the way.

Problem 1

You’re not supposed to empty the waste toner box, and I don’t want to buy one. In reality, the waste toner box isn’t particularly full. What had happened is that when the printer was tipped during transport, the waste toner in the box fell and covered up the clear plastic that is near the sensor that detects the status of the box. Either way, I decided to empty it. But I didn’t understand the principles of the box. You see, the box has 5 entrances. Each for the CMYK developer units, and 1 for the transfer belt. So, any toner that comes in has to come out from there. I naively just flipped the box and shook it, and it made the error go away. All was fine, right? For a bit. Then the paper started jamming. How was that related, you might ask? Time to actually explain how things work.

[5] is the waste toner box. It is where waste toner is deposited and commingled together, from all colors. It gets there by way of some cleaning blades on the drums (part of [10], [11], [12], and [13]), and on the transfer belt, which is between the process units on the bottom and the toner cartridges on top. The “latent” image (as unused toner) is transferred from the process units’ drum to the transfer belt, which on the right (unpictured), there is a roller that pinches the transfer belt against the paper to transfer the image to the paper, after which it is sent to the fuser, where the toner is melted and the process is complete. So, all you really need to know is: process unit makes toner image, transfer belt transfers the image to paper, 1st transfer roller helps pinch and transport paper against the TB, and the fuser melts the toner. The roller that made contact with the paper had become critically dirty with toner after further inspection. I cleaned it, to no avail as the issue near-instantly came back. Inspecting the transfer belt, it didn’t look like it was getting cleaned by the blade, so I decided to take a look at the cleaning blade. Doing this requires one to remove the waste toner box, and it is available by a simple latch. It wouldn’t pull out and felt jammed. Through some fiddling, I managed to get it out, and realized to my dismay what had happened: the spring that the blade uses as an auger to deliver toner to the WTB had slipped out and wedged itself between the transfer belt and the casing above it. The transfer belt itself is made out of a plastic-like coated material that’s almost definitely delicate. Removing it required me to remove a side panel to get further access (not that it helped much), and just being careful. The spring was somewhat fatigued and ruined, but still usable enough. Reassembling the unit that contained the cleaning blade was painful as the spring wanted to escape, but I managed to get it good enough eventually. The belt was luckily not damaged. What I theorized happened was this: By improperly emptying the WTB, most of the waste toner simply piled on the left side near the transfer belt unit. The sensor is on the opposite side and can’t identify such a situation. The toner built up after some regular usage, and piled up inside the transfer belt cleaning blade unit, after which it found itself unable to clean the transfer belt properly. Thus, the roller got dirtied, and it stopped being able to grip paper properly. I should also note that the pages that it did manage to print had streaks on them from the excess uncleaned toner. It was quite painful, but pales in comparison to the issue I’ve finally (believed) I’ve fixed.

Problem 2 (the big one)

It began intermittently freezing. It’d usually be in its sleep mode, but then just refused to wake up. Cutting the power and restarting it usually revived it, but it would sometimes freeze early in the boot process (Stage 2/9) on its loading screen, or do absolutely nothing at all. I discovered a vaguely documented function where holding the energy saver button clears something (probably at least DDR calibration data), and that sometimes got it back running. First, I should probably take a step back and explain the hardware that drives this. It uses an embedded Intel Celeron (or Atom) of some kind, and has a RAM slot with 2GB of DDR3. Digging through firmware update files, it runs coreboot with a heavily customized grub payload, that boots an old linux kernel + initrd. Everything appears to be signed, but I would suspect it’d be possible to break it somehow and boot regular linux. There is a 320GB encrypted hard drive, which appears to be proprietary (though uses SATA). Both are updatable, though not automatically (intended to be done by a tech, which I am very much not). The kernel + initrd are meant to boot the main part of the OS on the HDD, but the initrd also contains a minimalistic recovery/service mode (known as HS mode). There also appears to be a mode that (appears to be) accessed via removing a jumper on the SYS board which can sideload an kernel+initrd off of a usb (with the text “Starting Recovery Mode”.

There is also the mislabeled “SRAM” which is really non-volatile ferromagnetic RAM on the SYS board (main x86 stuff going on, plus an ASIC) and the “EEPROM” which is the same IC, but on the LGC board (seems to handle most printer operations, got more ASICS and FPGA-like stuff on it). Anyways, there are some diagnostic LEDs on the SYS board, and of course they were no help to me. The code was described in the manual as a SYS board issue, which is way too vague for my purposes. I decided to attempt to remedy the issue by reinstalling the firmware. That’s a good idea, except for the part where I needed firmware to install. If the service manual was hard to find, the firmware was about 10x worse. I found it by searching for what the manual said the name of the folder was, and found it in the description of a facebook post that linked to a mediafire link, and on a Polish hamster themed download site that wanted me to pay. I installed it, wiping everything that was on there, are per the procedure, and it appeared to kinda work for a bit, but it did begin freezing again, to my frustration and dismay. When it did work after some fiddling, it seemed to work, until it didn’t want to really work at all anymore. It either wouldn’t get turn on, got stuck, booted into that recovery mode screen, spewed grub errors, or booted straight into the HS mode and desired firmware updates.

I tried to update (same procedure as reinstalling minus formatting the HDD) the firmware again, but this time got the this wondrous error:

But this update was perfectly fine the last time I tried it?! The hint that came to me was this from the SM: “When H05 error occurs and it does not clear after a USB media check, replace the main memory (DIMM)”. The manual doesn’t use the best English, but I interpreted it to mean that if the issue isn’t with the files on the USB or the USB itself, it’s something RAM related. I decided to take the printer apart once more, and give it a closer inspection. Rust. Weirdly concentrated rust. Here’s an overall picture (with the SYS board cover removed)

And here’s what I’m talking about:

The RAM was corroded. The legs on the SRAM ic were corroded. The SYS board had various bits of corrosion on it. The RAM was hit the hardest, and was probably the source of the various memory errors. I suspect rust came in through humid air, as it was stored in a garage when I picked it up, as the affected area is next to the CPU FAN. Replacing it was a bit tricky since I needed a close replacement, but sticking to DDR3L 1Rx8 12800S worked. 2Rx4 made the printer bootloop after 2/9 in the boot process. But, it works. For now

Update: yeah, it gave up the ghost. rip. probably the corrosion did a number on it again. might dump the bios flash and see if its particularly messed up, and inspect more thoroughly.