No Red on a Neo-TEC 2701

[NightWolfx03]

What do I need to check if I seem to have an absence of red. The screen almost looks like it's a big blue / green fire.

I don't have a service manual or schematic for this monitor.

[NightWolfx03]

Actually I think I spotted a shorted transistor / FET on the neck board. I wonder if it ruined anything else or not. It's looks like a drive transistor, it's emitter and base seem to be shorted.

[grantspain]

most common issue when missing colour is the drive transistor

[Kevin Mullins]

Swap transistors from one of the other colors to verify.
Have the tube itself checked too....the Zenith ones that came with those like to crappy color guns.

[lilshawn]

sometimes the video amp chip goes. if swapping the transistors keeps the image the same, it's probably the LM1203N (IC901)

if swapping the transistors yields a red/blue or red/green image, your transistor is dead.

NOTES:

transistors fail in one of two ways:

SHORTED...

if your image is completely bathed in a color, you have a transistor shorted causing the color to stay on 100%. it is not uncommon for 1 transistor to short out and cause a 2nd to short as well. the heat generated from the shorted transistor overheats the next one closest to it.


OPEN...

if your image is simply lacking a color(s) then you have an open transistor. replace it.

[NightWolfx03]

Yeha I pulled the transistor off the board, I have a dead short between the emitter and the base. waiting for the replacement to come, now I need to get the k7000 finished, there's a newer thread about it.