Neotec NT-3602 Horizontal Failed, Need Help Please

Jerry Scaduto

Member
Joined
Jul 30, 2010
Messages
76
Reaction score
0
Location
Miami, Florida
Hello All. I am working on a Arctic thunder with a NT-3602 in it. The screen is showing a thin brite vertical line in the center. I have spent much time on this and not gotten anywhere. I have swapped out the flyback with a known working fly, neckboard, Q402 (HOT), re-flowed the 4 pins for the yoke. I know the tube and yoke are fine because I pulled the chassis from it's twin and put it in there to verify. I have those 3x headband goggles and have verified every square inch of the section.

One wierd thing: I am measuring 90 volts on the B+ (which I think should be 120 or so volts)and 15 volts on the other diode (which should be around 25 volts) on the power supply. When I raise the voltage, the voltages drop! I think something is loading down my board, but I cannot figure this out because I have neck glow, I have high voltage.

The heatsink where the Q402 (HOT) is mounted to gets VERY VERY HOT to the touch quickly! No other components get hot. I swapped the HOT, but the same results.

I heard that a forum member on here has a neotec troubleshooting guide, but I could not find it. I contacted neotec, and they emailed me a poor copy of the schematics. I did find a 27E book in my drawer, and it seems to be almost the same.

I appreciate any help that can be offered.

Thanks
 
Well. I found the problem. The Polyster dark red (brick colored) capactitor was bad. Located just next to the horizontal ouput pins. Set my meter to capacitance and sure enough it measured bad.

AWESOME
This made my day, maybe my week!
 
Well. I found the problem. The Polyster dark red (brick colored) capactitor was bad. Located just next to the horizontal ouput pins. Set my meter to capacitance and sure enough it measured bad.

AWESOME
This made my day, maybe my week!
Good Job!
The High voltage safty caps do change there value
and may get very dark because they are out of range.
They may split open and increase the ESR or short or Open and cause the HV
to be excessive and or cause the HOT to short.
Inmost cases the fly is good but is still replaced because of intermitent
focus symptoms found in the past. If never replaced before.
In your case the cap was killing the B+ to a lower run voltage.

The Power supply caps need to be replace if they
haven't be replaced before or you will get the chassis
back soon,per my experince.
Alot of the nt chassis look alike.
Visual inspection of these safty caps first can lead to
a fast repair,if it looks bad it probably is!
they are not included in a cap kit.
Other notes;
Tatung has a version of the NT-3501 Vga
claims to be a high res instead of med res.
Heres some of NT models res for large tubes.
Nt-3500 for 15khz res
Nt-3501 for 25khz res
Nt-3602 for 31.5Khz Vga
Good Luck on your next repair!
 

Attachments

  • tat_nt-3501.jpg
    tat_nt-3501.jpg
    34.6 KB · Views: 36
Back
Top Bottom