Dead mct 9000

[brianc]

Hi!

Recently I got 2 old arcade cabinets, but the monitors are dead in both!

I searched the net and came across this great forum.

I'm not skilled with monitor repair, but can handle a soldering iron, and have fixed a few tellys by following repairtips before.

well - I have only looked at one, which is a Hantarex mct 9000 monitor.
There is no neck glow - actually I belive the neck did glow the first time I turned the thing on, but now there is nothing.

The 130v B-voltage at tp-10 reads about 157 volt. 

I have removed the tr20 transistor, but dont know how to test it. (I did a diode test with it, and it reads .54 and .47 or something)

R90 is dead!

Any ideas?

Regards

[grantspain]

the mtc 9000 hantarex monitors are really old and they suffered from common faults
i have posted a lot here various pointers to problems but every case is different
when i started as a trainee the mtc9000 chassis had just come out and even though it was pretty new they all threw up some common problems
r90 is open circuit on ohms?probably not
the common faults are tr20,tr15,th2(flyback),r216,all the electrolitic capacitors
a real good tip is see how hot tr15 and r105(the bloody great big load resistor)get-don't touch though as i actually burnt the skin off my hand checking that resistor when i was a kid
also you need to be careful around the power supply circuit
check your 130v at sp4
here is a link to the schems to help you
http://www.freeinfosociety.com/electronics/schemview.php?id=2245

[brianc]

Hello!

well did some more testing today.

TR15 + TR20 appears to be good.
R105 does not get hot!

Resistor r72 has been very hot once and measured wrong - have been replaced now.
Resistor R90 and R91 was blown and had been replaced.

The 12 volt for the tda2595 (thats the oscillator - right?) only reads about 5 volts.
I lifted pin15 on the tda2595 from the board and measured 12 volt!!!
Does that mean that the tda is dead or are anything else pulling the current down?
ZD1 appears to be good and I replaced c16.

Regards Brian

[grantspain]

difficult to say for certain but it looks like the flyback is shot judging from the components that have been replaced

[brianc]

hmmm - any ideas that could narrow it down a bit?

btw, there is a service note on the frame, saying that the lopt has been changed in 1999!

I have a dead polo 25" aswell (I only get faint clicknoises) - do you know if the flyback is the same - sure it could be dead, but it wouldent take long to try it!

Regards Brian

[grantspain]

different lopt mate,the polo is likely to be the hdt transistor(bu508af)
mtc9000 were well known for the lopt failure,your +130v reading proves there is no load so the logical conclusion is flyback failure but its like all things electronic-it might be the problem then again it might not