Hantarex MTC900/E

[BaldiGit]

I have got an Hantarex MTC900/E that doesn't show any signs of life. I have a cap kit on order for it, but I had to make up a custom list as the 3 PCB's in it aren't the common US versions. And I got all excited  when I found an old posting on this forum where Ken Layton give a link to his repair guide for the said monitor. But the link is dead.....  , does anyone know if I can get a copy of it?

[Ken Layton]

All of my guides are now located here:

https://sites.google.com/site/mtpacifico/kens_korner

The specific one you want is this:

https://docs.google.com/viewer?a=v&pid=sites&srcid=ZGVmYXVsdGRvbWFpbnxtdHBhY2lmaWNvfGd4OjNmNGNjYTE2NTEzOWE2N2M

[nburgmeijer]

Not sure why you ordered a cap kit. It's dead you say. Highly unlikely it's a cap problem.

Also that repair guide is not going to help you

- Did you check if there's any mains voltage on the board?
- If there is, does the flyback produce the High Voltage for the tube. Just listen if the tube crackles when you start it up.
- etc, etc, etc

[BaldiGit]

Thanks Ken, I'm so glad it still exists. I have downloaded the US manual but it doesn't cover the circuit boards in mine. There seems to be plenty of help for the US version, but not the European one.

And thanks for the comments nburgmeijer. I bought the capacitors because I want to get it working and the capacitors are over 30 years old (plus a few are obviously leaking). Yes I have checked there is voltage at the board; it has 220v and 110v inputs. And I have a B+ of 156V, but I have no guide as to what it should be, which is why I was after Ken's guide. The degauss coil fires, but there seems to be no HV or neck glow. I have checked the 2 chassis transistors on either side and they check out ok. But I want to change the dodgy capacitors before I go any further. I’ve yet to discover where the HOT is and of course the flyback could be in question.

Any help or ideas are very welcome. Thanks for the help so far.

[BaldiGit]

Just had a quick look at the list...... Mine is very different    . There are 34 capacitors on mine that vary quite a lot from Ken's list. I have a deflection board PE06, an Interface board DF04 and a Neck board NE04.
If it would help anyone else I have made a detailed list of the capacitors, there positions and dimensions in a word document.

[nburgmeijer]

Here's the european manual:

http://www.arcade-museum.com/manuals-monitors/Hantarex_MTC900-E_Europe.pdf

B+ should be 126 Vdc so yours is high. The HOT is TR17.

Good luck!

PS. I see you have different named boards. I suppose they don't differ that much.  Why not identify the caps yourself and order them seperatly?

[BaldiGit]

Thanks for the info and TR17 is one of the one's on the chassis to the right that I already checked, so that's ok. When I've done the caps I'll dial down the B+. And the list mensioned above was compiled for ordering the capacitors and they're already on order (all 34  ).

So it's not looking good for the flyback..... 

[grantspain]

i expect the fault is the horizontal drive transformer open circuit on either one or both windings

[BaldiGit]

Ahh, I have a pinout for the transformer in my new manual from "nburgmeijer". When I get 5 minutes I'll desolder it and test it.
Thanks for the advice.

[grantspain]

should be 1 ohm one side and about 70 ohms the other side,the 70 ohms will be open circuit-the winding wire is so thin that it corrodes at the contact posts

[BaldiGit]

Great, thanks for the info. I haven't had the time to get it out but I'll have a go now. 

[BaldiGit]

Hmm.... Well looking at the diagram of the flyback here

http://www.arcade-museum.com/manuals-monitors/Hantarex_MTC900-E_Europe.pdf

Checking each winding from it's ends I get:

Pins 4 to 7                             2.2Ω
Pins 6 to 9                             0.8Ω
Pins 5 to 10                           1.4Ω
Pins 8 to HV on neckboard    5.4MΩ

Which on the surface of things looks OK and makes sense of the diagram. But I get nothing from the Anode cap to any of the pins 
Is this right? Or have I found a fault?

[BaldiGit]

I have just interogated an old but known working flyback that I changed on my WG K7000. And again I can get no reading between the Anode cap and any of the pins/wires.
So maybe it's right.....!!!!! 

[ed12]

between the anode cap and pins on the flyback had better = 0 open

ed

[BaldiGit]

  Ah... good 

[grantspain]

th2 was the transformer i was referring to,the flybacks on these are extremely reliable

i have repaired a few hundred of these chassis and th2 is open circuit in 90% of them

[BaldiGit]

My Bad....... Sorry Grantspain. I assumed the flyback was the only transformer on the board (or boards...) DOH........

I think you are spot on there. I've desoldered TH2 and I get 0.3Ω one side and open circuit the other.   

My next question is where do I get a replacement..??

(Sorry..... I love these emojies)

[grantspain]

replacements are very hard to find,what i do is find the break and then join a single strand of wire to it and then the other side back onto the post
its very very delicate and you will require a magnifier,you have to very gently scrape the insulation from the original wire before trying to solder together.If you don't get this right you end up breaking the wire further down

your other option is to find another chassis and salvage the transformer from that

[BaldiGit]

Your right about the wires, they have crumbled. One side is still there but the other has gone all the way into the coil itself  .

Looks easy enough to rewind I suppose, as long as the wire is intact enough to count the number of turns..... 

[BaldiGit]

I'll put out a post to see if anybody has one first. 

[BaldiGit]

Update..

I have managed to get a 2nd hand TH2. But that had suffered the same fate  . So I unwound the outer winding on mine, soaked the insulation in thinners to loosen it and removed the insulation. Managed to find the ends and got 75Ω. Re insulated with special transformer high temp insulation. Extended the brocken ends and reconnected. rewound outer winding and re varnished with insulation varnish and double checked for shorts...... All OK 
                                                       Plugged it in and it's as dead as ever.........

HELP........ Any ideas chaps??

[BaldiGit]

OOH.... Forgot to add, replaced all 36 capacitors on all 3 boards. Checked and double checked value and polarity is correct too.