SOLVED: vertical sync interlace flickering problem
Zitat:
Zitat von
SailorSat
Hm... I've seen that problem myself.
Infact my 33" Polo has exactly the same line problem.
It looks like it hat the fields swaped -> line 2 -> line 1 -> line 4 -> line 3 etc.
However I have yet to find a solution as only THIS monitor hat the problem.
My various smaller screens don't have this "bug".
OK, with the help of a professional arcade monitor engineer I have finally solved this problem. It is caused by a ground loop on the sync input pin of the TDA1675 (vertical amplifier). It is a pcb design fault of Polo and other monitors. I have a Selti monitor and it has this problem too. It is not noticeable unless you use interlaced resolutions.
The ground loop is caused by a filter capacitor placed between the sync input of the TDA1675 (pin 5) and ground (pin 8). In order to fix this, there are two options:
- connect the end of the capacitor that goes to GND directly to pin 8 of the TDA1675 by means of a very short insulated wire
- if this doesn't help, remove the capacitor completely
On my Polo 28" 15 kHz I had to remove the capacitor (C136 on my chassis) to completely fix the problem. Now the image is PERFECTLY stable and correct even with interlaced resolutions (no flickering at all).
I wanted to post this also here for everyone to benefit as it was a very annoying problem and damn hard to fix.
All the best,
Matteo