Needing Some Help W/ Logs

I’ve got the orange button at startup, and rather than going through GF and waiting a week for them just to tell me I need to send my machine in for $200 and then bill me $800 for who knows what, I thought I would see what you tech savvy guys think.

When the machine turns on, the fans whir up, but the lens will not focus. The button turns orange and stays that way. in the GFUI it says that the machine is Focusing, which, it never accomplishes. Here is the log to my machine. At this point, I assume that it’s the board sitting next to the exhaust, but I can’t be certain. I’ve taken the machine apart and have inspected the board, but there aren’t any obvious signs of issues. GF Logs

When the GUI tells you that it is focusing, that is just their abstract term for the entire initialization process. Your particular GF is never making it to the actual focusing routine as it is experiencing a problem during the hardware initialization.

Specifically, it appears that the control board is not able to establish I2C bus communications with the head.

Relevant parts of glowforge/current:

2019-12-31_03:00:43.89880       8196 DEBUG: head_accel_abort: setting to 0
2019-12-31_03:00:43.89881       8196 ERROR: i2c_transfer: ioctl failed (9: Bad file descriptor, src/i2c.cpp:26)
2019-12-31_03:00:45.73493      10034 ERROR: i2c_transfer: ioctl failed (9: Bad file descriptor, src/i2c.cpp:26)
2019-12-31_03:00:45.74710      10040 ERROR: fused_temp: could not read head temp sensor (src/sensor_task_peripherals.cpp:397)

The lid, head, and accessory boards all have their own distinct I2C buses, and the errors indicate that the lid and accessory board buses may be working properly. The head bus is not.

The head I2C utilizes PCA9600 bus extenders (datasheet) - there is one on the GF head board (U19) and the GF control board (U40). These convert the 3.3 VDC I2C bus signals to 12 VDC for transport over the wires between boards, and back to 3.3 VDC.

You can see the basic circuit for this in the OpenGlow schematic, sheet 4, grid A5. (Note: This is the schematic for the OpenGlow, NOT the GF, but the bus extender circuits are essentially identical)

All this being said, my first suggestion would be that you check that the head connector is OK. The pins have a tendency to get bent. Make sure to check, and re-seat, both ends of the flat cable - the one on the head board (J2), and the one on the accessory board (J1).

If those are good to go, the next step would be troubleshooting the operation of the electronics.


Awesome, that gets me in the right direction. I have a second machine coming and I’ll try swapping the heads to see what happens and then go from there.

I’ve checked the pins and they seem to be fine, as does the cable, so until the second machine shows up, it’s hard to troubleshoot.

Alright, I’ve confirmed that the head of the laser is working by connecting it to my second machine, I don’t really have a way to test the connecting cable since I’m not willing to rip my new machine apart to grab that cable. Are there replacement cables like that that I would be able to pick up somewhere?

There are not “off-the-shelf” parts, but it is a pretty standard cabled that could be assembled by laymen. The cable connectors are TE 1-487545-7, with a 20 conductor 1.27 mm (0.05") spaced FPC cable. The cable is 1290 mm (50.75") long. The FPC cable might be the hardest part to source, given its length.

Though, if you’re not willing to disassemble the unit, you won’t be able to replace that cable. It meanders throughout the device on a rather long path.

Since I have 2 machines, I was just meaning I didn’t want to take my second machine apart to pull the cable out to test on the broken one. I’ll see if Glowforge is willing to send me the part, they’ve sent me the circuit board for the lid black ribbon cable, so possibly they’d send me another weird part that no one ever asks for…

Semi great news, I swapped the accessory board from my second machine into the broken one and was able to get it to work. I just asked GF if they could source me a replacement, and they said they would look into it. They did send me the board that the black lid cable connects to, so I’m hoping they’re able to get this one to me, as well.

Thanks for pointing me in the right direction, I’m not sure if I would have eventually started trying to swap parts to diagnose my machine or not, but you mentioning that the board having communication failure narrowed it way down.