Hantarex MTC9000 vibration

[arcadaen]

Hello,

Recently I got an old cabinet and started my first arcade project, but I can get to fix the Hantarex MTC9000 monitor it has.
The picture on in keeps vibrating horizontally.
I have been following Randy Fromm flowchart and have already tried the following without success:

• Replace every electrolytic capacitors
• Replace transistors TR10-TR13
• Replace IC2 (TDA2595)
• Replace flyback
• Try to adjust everything on the control board

But the picture is still the same as in the very beginning.
I'm using a gbs-8100 and a computer to feed the input signal. Anyway, when I remove the input signal I can still see the vibration on the screen.

I don't know how to continue to fix this monitor.

Any ideas?

[grantspain]

sounds like the supply regulation has failed,what is the b+ reading?

this fault is normally down to tr20 and tr19,you should check the resistance of r105
check diodes 19 to 22
desolder the degauss ptc 1

[arcadaen]

I remember B+ was 132V or 133V. I thought that value was OK and didn't give any importance

I don't have the monitor at hand, just the chassis. I will check those components and double measure B+ .

[arcadaen]

My cheap multimeter says R105 is 350 Ohm. Is that an acceptable value? It is supposed to be 330Ohm, Right?
Diodes 19 to 22 seem OK.

I have not been able to check B+ again. Should I be worried if I get 132-133V?

[grantspain]

My cheap multimeter says R105 is 350 Ohm. Is that an acceptable value? It is supposed to be 330Ohm, Right?
Diodes 19 to 22 seem OK.

I have not been able to check B+ again. Should I be worried if I get 132-133V?

all ok

it still could be tr20 but i would suggest unplugging the degauss coil first and see what happens

[arcadaen]

I tried unplugging the degauss coil but it had no effect. So I'm gonna replace tr19 and tr20.

It seems tr20 (tipl762) is hard to find. The guy at the shop offered me a BUW11A as equivalent, I'm being looking at the specs but I'm not completely sure.

Do you know if that transistor is OK? Any other equivalent one?

[grantspain]

we used to use bu508a if tipl762 was not available

[grantspain]

forgot to say,check R110-it should be 33k

[arcadaen]

r110 looks OK too.

I found and ordered a TIPL762 on ebay, pricey though. Looking forward to replace it and give it a try.

[grantspain]

see if you post up a video of the issue if the transistor does not cure it

[arcadaen]

I'm not sure what fixed it but it did. The problem is I broke it again and now it is worse than at the beginning.

After replacing the transistors I didn't see any difference. So then:

• I checked B+, it was 134V DC.
• Checked the output of the isolation transformer. It was 134V AC
• I changed the input connections of the isolation transformer (It has -15, 0, +15 connections). The output lowered a bit to around 128V. Nonetheless, the vibration was still there
• I played with the gbs-8100 switches and unexpectedly  got a stable image

I was thrilled I got a stable image for the first time, but was also sure I had tried all of those things in previous occasions, so I didn't know what was the thing that fixed it this time.
Curiosity was killing me so I had to verify B+ again to check if I was getting a value closer to 130 now that I had manipulated the isolating transformer and that was the cause. But here came my mistake. I was about to check B+ at SP4 connection of resistor R105 but the probe slipped, it touched the metal part of the chassis it short circuited with a big spark and everything was gone... 

Now I get no image and a B+ of around 170V. So I guess I'll have to start from the beginning again.

Any idea on where to start at this point? I know for sure I short-circuited it at SP4 connection of R105 resistor.

[grantspain]

sounds like you have taken out TR15 and/or TR20

look on the bright side,at least you are getting some good experience

[arcadaen]

I replaced every transistor in the power supply part and now it is up and working.

Thanks