Screen Tablet malarky => Heyaaaalpppp => Topic started by: procersapientiae on October 03, 2018, 05:02:40 PM

Title: Advice on a repair with a DTK-2100
Post by: procersapientiae on October 03, 2018, 05:02:40 PM
I am trying to get some advice on a DTK-2100 (Intuos-4 style Cintiq 21-UX)
This appears to be a very common issue, as evidenced by this related thread:

Here is a snippet from the email I sent to Wacom (It would be so much easier if I could just buy the board new......)

I did some investigation into my repair issue with the DTK-2100s and I tried replacing the Wacom W4027F chip (this was a suggestion in the other topic) (taken from a functional Intuos 4 Small) to see if it resolved the issue, which it did not, there was no change in behavior), I then proceeded to gather test voltages from several of the test points on the board, I noted the ones that were off by a substantial amount and was hoping I could get adviced on the repair, if not I will have to proceed with replacing many components in the region until something works. Here are the Test points that do not work on my CON-348(X) board, Note, it also has a Qisda P/N of 5E.0VJ41.001 (of ironic note, of the 3 boards I have only the one from JAN 2011 is functional, while the ones from May and Feb 2011 have failed...)
Test Point : Good Voltage (on active functional board) : Bad voltage (on BOTH non functional units).
TP62 : Good (-)10mV : Bad (+)2mV
TP65 : 2mV : 0mV
TP71 : 1.75V : 5V
TP63 and TP64 : ~1mV : ~30mV
TP68 : 3mV : 0mV
TP6 : 11.5V : 12+V
TP3 and TP83 : 22V : 24-25V

The most obvious aberration was that TP62 clearly had a low negative voltage in the good board, and TP71 was not at 5V in the good board, indicating it's voltage seemed to be uncontrolled in the bad boards.
It was also unusual that TP6 and TPs 3/83 had higher voltages in the bad boards, I am uncertain if that was just coincidence though, as I assume there's flexibility in the 12V line and in the voltage after the doubler, or maybe it caused the cascade of failure.

It's really sad that these failed so early I bought them broken back in 2016, that's only 5 years after they were manufactured. Assuming they weren't put to use on day one, they had less than 5 years of use. I just want to restore them to glory, any help is appreciated.

Will try to upload a high res scan, but... my scanner is not that great...... It's canning now and looks mad blurry.

For immediate reference, here was the other guy's scan. (same board)

Title: Re: Advice on a repair with a DTK-2100
Post by: procersapientiae on October 10, 2018, 08:26:47 PM
I found 30KOhms of stray resistance between the clock and ground due to a faulty inverter at position "U50" it's responsible for part of the clock signal going to the Wacom QFP chip. The faulty chip is labeled W62, and appears to be a common source for why the DTK models will not respond to input. I replaced it with part SN74LVC2GU04DCKT and the issue was resolved. You can see more on the issue here if desired. I leared a loooooot about how the digitizer works while playing with a scope and looking for this issue.

I figured I'd post the answer here since you guys may bump into this sort of problem.