Build Your Own Arcade Controls Forum

Main => Monitor/Video Forum => Topic started by: arcaic on October 03, 2007, 04:53:25 am

Title: Hantarex MTC9000 - F1 blowing... can anyone help?
Post by: arcaic on October 03, 2007, 04:53:25 am

Hi all,

Got an 20" MTC9000 thats blowing fuse F1.

According to some info on here diodes D19 - D22 can often be the cause but they check out fine. I replaced them anyway but no difference, fuse still blows. I cant see any signs of physical damage or shorts and the monitor did work about a year ago and has been in the cab its in ever since.

What should I check for next?

Please be precise if possible as I'm not a monitor expert, I'm aware of the danger so not likely to stick my fingers in the back with it on and am handy with a soldering iron, but have no experience of fault finding in monitors. I have schematics for the MTC9000.

Thanks

Andy

Title: Re: Hantarex MTC9000 - F1 blowing... can anyone help?
Post by: grantspain on October 03, 2007, 09:59:56 am

it might be the degauss coil or the ptc component that switches it,disconnect the degauss coil first then if the fuse still blows desolder the ptc component(its a white square thing with 3 legs near the degauss plug)

Title: Re: Hantarex MTC9000 - F1 blowing... can anyone help?
Post by: arcaic on October 04, 2007, 05:09:18 pm

Thanks for the reply Grant.

I've got the schematics and the degauss circuit is on fuse F2. I've been testing with the degauss disconnected and it still blows. Could this still affect F1?

Schematics are here ... http://www.freeinfosociety.com/electronics/schemview.php?id=2245 (http://www.freeinfosociety.com/electronics/schemview.php?id=2245)

Another source said to decouple the power regulation side of the chassis from the rest and see if it still blows. I did this by not connecting the coil connector at CM and by lifting one end of R100. Fuse still blows.

So next I removed R99 which according to the schematics just leaves the initial group of diodes and capacitors that might be bad. Fuse still blows.

I've already changed the diodes so this just leaves 4 caps. I'm trying to find out where to get them from.

Is the above methodology I've followed sound?

Thanks in advance for any help.

Andy

Title: Re: Hantarex MTC9000 - F1 blowing... can anyone help?
Post by: grantspain on October 04, 2007, 05:31:52 pm

yes see what you mean about f2,i should have checked the schem first
if pulling r99 isolates the rest of the circuit then logic says that something is dead short to ground in the intial
how badly is the fuse blowing,is it blowing crapless?
have you metered the ac input on pins 1 and 2 yet?

Title: Re: Hantarex MTC9000 - F1 blowing... can anyone help?
Post by: grantspain on October 04, 2007, 05:49:30 pm

be real careful around those diodes,there are some serious voltage there

Title: Re: Hantarex MTC9000 - F1 blowing... can anyone help?
Post by: arcaic on October 05, 2007, 03:01:00 am

One of the first things I did was monitor the voltage on pins 1 and 2. Its 240v. Not what it says on the schematics but this is a UK cab and another Kortek Chassis works ok from it so I assume its correct.

Andy

Title: Re: Hantarex MTC9000 - F1 blowing... can anyone help?
Post by: grantspain on October 05, 2007, 03:06:42 am

the voltage is wrong it should be 120v pins 1 and 2 for the monitor power supply and 220v pins 3 and 4 for the degauss circuit
the kortek works because it is a free range monitor and works from 90v to 240v
there is a good chance that you may blown the diodes again
remove one side of each diode and check on diode test if all is good then repower using 120v ac input pins 1 and 2
you may have blown some caps further in to the power supply of the monitor but you never know your luck

Title: Re: Hantarex MTC9000 - F1 blowing... can anyone help?
Post by: arcaic on October 05, 2007, 04:56:34 am

Hi Grant

Swapped the PSU and it works now. Thanks for the help.

Inexperiance and assumptions = lots of wasted time. I live and learn.

Andy