Hantarex MTC 900/e very dim screen; screen control=no effect, color bleeding

[Pac-Fan]

I picked up a supposedly working Hantarex MTC 900/e chassis off eBay 6 months ago.  It was very clean, appeared to have a very recent cap kit (looked like a LizardLick kit with black caps with blue writing that I've seen before from them vs. the light blue cans that Bob typically uses)  I connected it up to a known good tube that worked fine with another 900/e (that had VLIN problems).

The results are that if there is no input signal, no amount of control cranking (Screen, Brightness, Contrast, RGB Drive and Cutoff controls) produces ANY visible glow on the screen.

With a signal, then only if brightness and contrast are cranked, and you significantly raise the drive and cutoff controls past midway do you get a dim picture.  When it gets to about-quarter normal brightness, then of course the amount of gain is too high and all 3 colors significantly smear horizontally.

Interestingly enough, the screen control has virtually no effect on the brightness (maybe 1% swing?), but the focus control actually affects the brigthness more (at the same time making it a blurry blob or bringing it really sharp.

So basically the chassis seems to work and display fine, just doesn't do it bright enough.

I suspect it's a flyback issue, and perhaps something wrong with the screen/focus assembly or something similar.  I haven't checked connection in the socket of the screen wire, but assume if it was disconnected, there would be no picture at all, right?

Interestingly the flyback appears visually different than my other 2 900/e's..  Plus this board has a daughter board with 3 pots, some caps, a heat sink and stuff  on it behind the flyback that I've never seen before.  THere are empty holes on my other 2 boards for it, but this is the first one I've seen populated.  Any idea what the change is there?

Is it possible this is intended for 13" instead? Though all other ones I've seen easily go between 13 and 19 without problems.  Also this board has a brown PCB on the signal processing (left) side and a green board on the high voltage/deflection side. My others have green boards throughout.

Thanks for any suggestions on this one.

[grantspain]

i have seen that many years ago when someone put a 10" flyback in a 20" chassis,you will need to check the flyback number

[SirPeale]

Sounds a lot like the issue I have with a MTC900.  When I first got it it wouldn't do anything except display a yellow picture.  In it's current state, all it does is display nothing.  I've isolated it to the brightness circuit, but not what part.

[Pac-Fan]

Looks like grantspain may be right...   The flyback physically matched the one in my 13" Hantarex but was visually different than the ones in my 2 19" 900e's.  Unfortunately the number stickers have fallen off these for an exact comparison

That seems odd that most other chassis work from 13-19 without problem.  So apparently Hantarex used a 10-13 and then a 19?

Does anyone have information what the differences are on the 13" vs. 19" MTC 900/e chassis?  Is the only part that's different the flyback or are there other components that are different? I really don't want to walk through every component and compare if I decide to swap in a different flyback from a dead 19" chassis, but may have to.

(I have another 900/e chassis that works on 19" but has significantly weird problem with psuedo-retrace lines duplicating certain vertical rows a few rows down but otherwise works--will post a new thread with pictures on that one if anyone has an idea what's up there!)

Thanks grantspain, will do some more digging and try it on a 13" tube and see if it has enough juice for that.