Hantarex MTC9000 Red is Purple [RESOLVED]

[Cyberwhiz]

This one has me confused. I have a MTC9000 that I recapped and repaired (purchased non-working) and everything works and looks great, except that my red is purple! Any adjustments to the red pots just increases/decreases the "purpleness". Would the same components identified as potentially faulty for missing or too much color from the Fromm chart apply to this problem as well ?

Thanks

[grantspain]

run a colour test to see whats missing

[StephenH]

Do some color tests.   Red being purple indicates to me that likely there is some problem where the blue color is on when it should not be.  I would first make sure there is not a short between the blue and red inputs.   The next test I would run, is diconnect the blue input and see if the problem goes away.  If this is the case, I would connect the red wire to the blue input and see if it is all blue where the red is or purple.  If it is purple, you have identified the problem. 

The other cause of it being purplish is a lack of color in the green channel.   I would run a test displaying some green images and see if they appear black or incorrect colors.  If they appear black, blue, purple, or some other color you have a problem in the green circuit.

[Cyberwhiz]

Sorry, I should have been clearer. When I said everything else looked good, that included the color bars pattern test (color test?) from my SF2 board. Green and Blue look perfect, red is the only color not working right. I'll try disconnecting the blue.

Thanks

[grantspain]

can you upload a photo of screen shots?

[qrz]

wouldn't by chance have the red xistor shorting against the green xistor ?

i ask due to having one monday with a bad pic.
looked like it was in dire need of degaussing . colors all wrong  !
 deguassing didn't help ... further testing revealed  the g/b signals were reversed  - at the input connector 
correcting the connection restored proper color.

qrz

[Cyberwhiz]

Update:

1. Disconnected blue input - Blue color bar disappeared completely, no change to purple (red) color bar
2. Disconnected red input - Purple (red) color bar disappeared completely, blue and green were normal
3. Checked for shorted components or traces, everything appeared fine
4. Checked neck tube connections, all looked fine
5. Posted picture

Again, I haven't changed anything on the neck board except for the cap in the kit. I also tried another game board, no difference. I have tried another monitor with my test rig, all the colors worked fine. I can't test the tube because I don't have the right adapter and this is the only MTC9000 monitor I have.

I appreciate the suggestions so far.

Thanks

[StephenH]

I would try manually degaussing your monitor.

[SirPeale]

I would try manually degaussing your monitor.

I was going to suggest the same thing.  At least in that picture it appears to be some variety of magnetic interference.

[qrz]

orig description made it sound as if the issue was uniform .

pic indicates need for deguassing (and per 2 prev posts )

qrz

[Cyberwhiz]

Son of a gun ! I did not see that, it looked uniform to me because the green and blue seemed unaffected, only the red. I fired up the drill and magnets and voila, red is red again ! Another lesson learned. 

Thanks again for your help!

[Kevin Mullins]

Now the question is why doesn't it auto degauss ?

Or does this monitor have the manual degauss button type setup?
(I'm not familiar with the MTC9000)

[Cyberwhiz]

True, I'm working on that now. It has a connector that you can plug a button into for manual degaussing. From what I understand from the manual and looking at the schematics, it should have a jumper plug for automatic operation (it didn't). I removed the connector and soldered in a permanent jumper. I'll just have to see if it holds.

Thanks

[SirPeale]

Now the question is why doesn't it auto degauss ?

It probably does, but the problem was too great for the onboard to overcome it.

[qrz]

i STILL find the "magnet on a drill bit" funny.......but hey , can't argue as the principal is valid.

one could likely spin a magnet on a string for the same effect........may just try it for fun ! 

and not everyone has ready access to a proper degaussing coil....

qrz