Issues with Hantarex MTC9000

[Nipedley]

Hey guys

It's been a loooong time since I was last here. I just moved house and dug my arcade cab out of storage (been in there for 3-4 years), everything is great except a couple of monitor issues

This is a Sega Megatech cabinet with a Hantarex MTC9000 (ish) chassis in it, recently recapped, recent new flyback, transistors, the works

Issue 1. The colours are way off, attached is a picture of Sonic 2 on my LCD tv showing correct colours and then on the MTC9000. Is this something just the RGB pots on the neckboard could sort out ? Everything seems to have a blue tinge to it.

Issue 2. There's some sort of blooming / heartbeating / shimmering effect going on, all of the colours burst in intensity and then drop again every second. I've linked a video where you can kind of see this, if you focus on the blocks of the floor Sonic is standing on you can see it get bright and then darker and then bright again, this happens continuously. Also on the video you can see the screen 'refreshing' as it scans down, you can see that with the naked eye as well. This 'blooming' seems to happen in time with the refresh scanning down. What could cause that?
Video: https://vid.me/M8MT

Help/hints/advice very much appreciated. Thanks! 

[baritonomarchetto]

Check your neckboard first: is it well inserted in the CRT?
Then, try toying with the contrast pot: this could solve the colors issue.
About the "blooming": check your b+ ... is it stable?

[grantspain]

the pre brightness pot can cause issues like this
I don't think its b+ as the picture is not changing size-you can check it with a meter and it should be about 130vdc
contrast pot is a possibility

anything sitting around for a long time will have problems with pots and connections

[Nipedley]

Thanks guys, I'll pull the chassis and replace the pre-brightness pot and also will be checking R90 and the neckboard. Where would I need to look to measure B+? It's an MTC9000/A chassis I believe

I never got the degauss working (the wires were cut when I got the cab), could that be something to do with the thermistor? Worth ordering a replacement do you think? Fuse was good and I'm fairly sure I checked the wiring (it was many years ago), but I will do so again.

Also I have a feeling if I remember rightly that a couple of the metal clips that hold some of the transistors to the heatsink chassis are missing. Anywhere I could get these or something I could whip up as a bodge?

Grantspain many many years ago it was you that helped me get this thing going in the first place, many beers are owed ! 

[Nipedley]

Okay, so today I fired the machine up and things were a bit different. There was no shimmering or the visible refresh rate issue from earlier, the colours were still off but the picture looked perfectly stable. It did however resize itself, maybe 3 or 4 times over about a minute. I didn't leave it on long enough to see if this was just during it warming up or whether it would have continued

I haven't done anything to the monitor yet as still waiting for parts, could that be the B+ as grant said earlier it's unlikely as it wasn't resizing?

[grantspain]

get a multimeter and test b+ on pin 3 or 4 of deflection coil plug (red probe)and heatshield (black probe)
b+ should be around 130vdc,a couple of volts change is normal but nothing more