Repair of a broken MTC900 chassis

[ckong]

A loooooong time ago, in my early days of arcade collecting, in fact during my (dark) Mame years, I bought a generic cab with a not so good monitor in it. I also bought a tested and working tube with a MTC 900 chassis at the same day.

In those days I thought that electricity is electricity and I had never hear the word 'isolation transformer'. A few days after the purchase of the generic cab I decided to swap the monitor. I made the swap, noticed the little sticker mentioning that the monitor works on either 128V or 220V (yes, you may laugh now), knew that my wall socket produces 220V, connected the monitor to the wall socket and ...... it was dark in house!!!    I of course knew right away that something was wrong. Not knowing what (at that time) I just stored the monitor in the attic where it has been for 6 years or so.

But next week I want to test some Hantarex chassis that I got from Blanbek and I want to give the 'old one' another try also.

However, I guess I first need to repair that one. What gets normally broken after a stupid action like I did?  I already checked the 3 fuses on the power board of the 900 chassis but they are OK.

[Etienne MacGyver]

My knowledge of that does not reach that level, but i have heard that operating without an isolation transformer can serious f#ck up the chassis...

[italiandoh]

The MTC900 does not work on either AC voltages you mentioned, but requires BOTH. 128 V AC is for the normal operation, 220 V AC is for the degauss circuitry. You need a 220 V -> 128 V AC stepdown transformer to operate it. If you plugged 220 V AC into the 128 V AC input you more than likely fried something into the power supply section of the chassis.

Matteo

[ckong]

The MTC900 does not work on either AC voltages you mentioned, but requires BOTH. 128 V AC is for the normal operation, 220 V AC is for the degauss circuitry. You need a 220 V -> 128 V AC stepdown transformer to operate it.

Yes,  I know that for quite some time now,  but not 6 years ago  .

[ckong]

Double post

[Etienne MacGyver]

Did you hookup the 220 part to the 220 in on the monitor connector?

If yes, then maybe only the degauss circuit my have damage as the 220 is only used for the degauss and you 128 "monitor part" is unharmed..

If you connected the 220 to the 128 volt input, then i think the chassis has serious damage.

I would say, try it in a zacc, that has the right connectors and transformers.
I would disconnect the game pdb though 

[ckong]

Did you hookup the 220 part to the 220 in on the monitor connector?

If yes, then maybe only the degauss circuit my have damage as the 220 is only used for the degauss and you 128 "monitor part" is unharmed..

If you connected the 220 to the 128 volt input, then i think the chassis has serious damage.

I would say, try it in a zacc, that has the right connectors and transformers.
I would disconnect the game pdb though 

Yep,  I did 220 to 220 and yes,  will do 

[vernimark]

As italiandoh mentioned i think you damaged the power section only... if you are lucky...
If you have another chassis compare component of that part

[ckong]

As italiandoh mentioned i think you damaged the power section only... if you are lucky...
If you have another chassis compare component of that part

I have blanbeks chassis to compare,  will do that when my vanguard is returned from Hilversum,  as Etienne said,  it is much easier to test all chassis with a Zacc cab on hand.

[Etienne MacGyver]

You should have mentioned it before, i have a spare zacc powerbrick i could bring to EC14...

too late for that now  

EDIT:

Looking at the schematics of the MTC900, it looks like the degauss circuit is isolated from the other circuit. (wich makes sence ofcourse  )

so i think if you blow something, its only in the degauss circuit and the other part is unharmed.

[vernimark]

Last month I tried to repair a MTC900 chassis but every time I plugged it (in the right way) the security switch powered off.
I thought the problem was related to the ground or something similar but checking the degauss circuit I discovered the board had been hacked in order to work with 128VAC only.
Please check any hack, as a fuse removed or disconnected and 2 tracks after the power connector short circuited.

Just an idea...

[level42]

You could also ask Grantspain on the BYOAC forum. He's a real Hantarex expert.

[nilfisk]

About 10+ years ago, when I was in my early days too and knew nothing about monitors, too, I once accidentally swapped the 220 vac input with the 110 one on a MTC9000 chassis. Big bang, room fuse went off.

I checked my wiring, discovered the fault, swapped out the cables and put on power again .... and the monitor is working to this day

So not always will something like a swapped power line kill the monitor - but I agree that I was very fortunate, and this is probably a rare example.

[ckong]

not really topic related, but ...

I have a MTC 900E (europe version) with a NE04 neckboard. I read somewhere that a Videocolor A51-420X tube fits, but does a Videocolor A51-421X fits also (the pins on the neckboard matches with the connector on the neck, but I don't dare to power the monitor on yet)?

If not, then I will have to swap the tube for a 231X

[Etienne MacGyver]

maybe this helps :

http://tubular.atomized.org/

compare the tubes and connections, and maybe they are compatible