Nanao MS8-26SG, vertical collapse after recap [SOLVED]
Posted: February 23rd, 2021, 3:13 pm
Hi guys, I am at an unexpected situation after giving a recapping with parts from arcadepartsandrepair to one of my 2 Nanao MS8-26SG.
The monitor was working "well" before, a bit out of focus, but having recently acquired it (it is part of an Aero City cabinet), I decied to recap it as many recommend to do with such old electronics.
After the job I plugged it in and found a better sharper image, but after a few minutes, where I was also adjusting the size/position with the pots, the image started "collapsing" until being a single line at the middle. It vibrates sometimes (video https://imgur.com/a/Tt8w8xf ), but it is pretty random, no pot wiggling or pcb poking could make the line vibrate more or less than I can say.
I've doing some stuff to the chassis with no success, neither worse or better, that is:
-Brushed and cleaned the board with compressed air
-Reflowed all suspicious joints I could see, there were some on the neck board (not related to this vertical collapse problem I guess), and some on the pcb around hot components.
-Contact-cleaning and reflowing all front pots, and some vertical (V-LIN and S.P.C.) pots.
-Replaced many 1/2w resistors with 1w ones, (when I took them out I measured them and besides being ugly and some cracked, they were fine, replaced them anyways)
-Same thing with many 1/8w resistors on the vertical oscillation town (all measured fine but were replaced) with 1/4w ones
-Put a IC socket at the HA11423 place and put a new HA11423 that I got locally (unnecesary but done)
-Put a IC socket at the PC501 (TLP521-2 octocoupler), tested the octocoupler and seemed fine.
-Took out q401, q402, q534 (D1138 transistors), measured fine with IC tester, soldered them back in because couldn't find replacement and didn't seem necessary
-Same with q451 q452 q453 (small C1740 transistors)
After all this work, the monitor still works exactly the same...
What can I do? Maybe measuring the input oscillation signal from where it originates and follow it around? Don't exactly know how to do it, this is my 1st crt chassis repair, would like to hear suggestions please!
I've got this cheap oscilloscope that can be useful, but I'm a little worried about connecting it to a high voltage point and frying it.
Thanks!
The monitor was working "well" before, a bit out of focus, but having recently acquired it (it is part of an Aero City cabinet), I decied to recap it as many recommend to do with such old electronics.
After the job I plugged it in and found a better sharper image, but after a few minutes, where I was also adjusting the size/position with the pots, the image started "collapsing" until being a single line at the middle. It vibrates sometimes (video https://imgur.com/a/Tt8w8xf ), but it is pretty random, no pot wiggling or pcb poking could make the line vibrate more or less than I can say.
I've doing some stuff to the chassis with no success, neither worse or better, that is:
-Brushed and cleaned the board with compressed air
-Reflowed all suspicious joints I could see, there were some on the neck board (not related to this vertical collapse problem I guess), and some on the pcb around hot components.
-Contact-cleaning and reflowing all front pots, and some vertical (V-LIN and S.P.C.) pots.
-Replaced many 1/2w resistors with 1w ones, (when I took them out I measured them and besides being ugly and some cracked, they were fine, replaced them anyways)
-Same thing with many 1/8w resistors on the vertical oscillation town (all measured fine but were replaced) with 1/4w ones
-Put a IC socket at the HA11423 place and put a new HA11423 that I got locally (unnecesary but done)
-Put a IC socket at the PC501 (TLP521-2 octocoupler), tested the octocoupler and seemed fine.
-Took out q401, q402, q534 (D1138 transistors), measured fine with IC tester, soldered them back in because couldn't find replacement and didn't seem necessary
-Same with q451 q452 q453 (small C1740 transistors)
After all this work, the monitor still works exactly the same...
What can I do? Maybe measuring the input oscillation signal from where it originates and follow it around? Don't exactly know how to do it, this is my 1st crt chassis repair, would like to hear suggestions please!
I've got this cheap oscilloscope that can be useful, but I'm a little worried about connecting it to a high voltage point and frying it.
Thanks!