Solved Hantarex MTC9000 retrace linea jumping around.

[Georgian2]

Hello,

Here I have another fault that I cannot fix.
Diode D25 is lifted so the fault could be better seen. No video signal, flyback turned almost all the way up. The retrace lines should be visible and stable but the image sort of rolls. It dose stabilise at some point but it starts again.

If you have any ideea, please do let me know.
Here is an video of the problem.

Thank you.

 

[gunblade]

brave man running a chassis with xray protection disabled
whats the issue when you have signal connected

 

[Georgian2]

I doubt that the x-ray protection ia deactivated. The blanking is deactivated, I hope I'm not wrong.

With a signal connected, briliant image but the top is shaking left and right a little. Like 1cm on the top. In this 1cm are the trace lines visible if the blanking is activated. Many people won't notice anything but it'a killing me...

I might be wrong but the retrace lines should be visible when flyback screen is turned up and should be stable, right?

 

[gunblade]

my apologies on d25, not something i have ever needed to do on a 9000 chassis - i mistook for d10 which is what everyone seems to do
whats the voltage like to the vertical ic, have you replaced the vertical ic yet
whats the b+ reading
have you checked the eht level
Not all chassis show solid raster so i think thats the wrong way to go about tracing the fault

 

[Georgian2]

Not all chassis show solid raster so i think thats the wrong way to go about tracing the fault.
All the ones I have and work show stable lines if the flyback is turned up. If screen is dark then no lines at all.

So this MTC9000 was from factory with an 15" CRT paird. I got it with an blown flyback. Since it is a very clean chassis I decided to get it serviced and get it to work with an 20" CRT. The C40 was 5.6nF and I replaced it with an 6.8nF. R38 was 8.2k and I replaced it with 12k. I did not find any other differences on other componnets. I put an Flyback that I scraped from an 20" Chassis (I don' know it it worked well before). The neckboard had an different layout for the CRT Socket (mini neck) so I swapped it for another with proper socket. I grabed the best 20" CRT that I have (used to be with an MTC900E Videocolor A51-421X) and the jurney began.

So IC1, IC2, TR15, TR17, brightnes pot, all the elektrolytic caps are new. Diodes test good (the zener ones I did not test).

It's hard to get a video of the problem when video signal is applied but I'll explain: with an dot cross hatch pattern the very top horizontal line, along with the vertical lines move right and left just like the wipers on the car's windshild, maybe 1mm to the left and 1mm to the right. This is happening only on the top most row.
Mybe there are some other components that are specific to 15" CRT? I have no clue and I hope you guys understand what is going on.

 

[gunblade]

maybe there is a resistor needs changing, what is r46 reading?

 

[Georgian2]

1.7-1.9 Ohm in circuit.

 

[Georgian2]

I pulled an TDA2595 from an known working chassis and it's got a stable picture now. Just to confirm, I put the other 2 back in and same problem with shaking top. I guess I have to restock on horizontal ICs now.

Where can I get the clips that hold the ICs on the heatsink? They almos always break when removed.

 

[gunblade]

loads of fake ic on the market if the first 2 tda were new

 

[Georgian2]

loads of fake ic on the market if the first 2 tda were new

Yes, I bought them as new... You never know what you get. At least I can fix one more fault now.

 

[gunblade]

i bought in a batch of tda1675a and tda1771 and they were fakes, loads of high voltage transistors on the market are all fakes. if its not difficult enough to fix a chassis this crap is thrown in for good measure.

 

[pinballaction]

At moment I buy only used original and all good , in China, reference dismantled machines
I bought chassis for pieces too.

 

[Georgian2]

At moment I buy only used original and all good , in China, reference dismantled machines
I bought chassis for pieces too.

I buy poker and gambling machines. I already know which ones have an hatarex inside and most of the time they are very cheap.

 

[Ace`]

You wouldn't think there was a large enough market for them to bother faking the TDA transistors, but nothing is safe even common TTL is getting faked / remarked now.

 

[big10p]

I took a punt on a batch of 6522 VIA chips from China. They were being sold as new. When they arrived, I was actually quite relieved to find that they were used. They all tested as working.

 

[TheDaddy]

There is lots of caps that are Faked , They all work just voltage is out of spec. Not sure how you are suppose to tell half the time and many faked stuff works !! Granted not sure for how long. Its a nightmare for spares IMO.

Dave.

 

[pinballaction]

Today arrived , 2 weeks, 2sc5446, second hand , 1€ each with shipping, to japan chassis , top