Author Topic: Hantarex MTC 9000 tube swap (Read 7408 times)

nburgmeijer · « **on:** November 10, 2016, 02:40:28 pm »

Hello there fellow arcade enthousiasts,

So I recently acquired a Hantarex mtc 9000 arcade monitor for free.
When i removed the neck board i noticed a crack in the neck, bummer!
Now I want to install a replacement tube.
So I read up on it and found that Samsung tubes can serve as replacements.
Now I only managed to find 1 tube near me with the right socket(CR-23). It's a A51EER133X tube connected to a S15a chassis.
The yoke resistances aren't compatible so I swapped the Yokes.
Is it possible to do it this way? Before I start anything up and blow myself up?

Kind regards,

Nick

princess prin prin · « **Reply #1 on:** November 12, 2016, 04:55:13 am »

That tube is an inch bigger than the old one and will not fit the frame.

Other than that, yoke swap is possible but it is an unnecessary complication in this case as replacement tubes for this monitor are commonly found in most TVs.

nburgmeijer · « **Reply #2 on:** November 12, 2016, 05:52:39 am »

I noticed the size difference. I have a stable picture but a horrible pincushion problem. I suppose this has to do with the size difference? And for some reason my mtc9000 chassis is missing it's pincushion circuit. While all the manuals show is there.
Could you point me to some common tv sets with compatible donor tubes?
I live in Europe btw.

princess prin prin · « **Reply #3 on:** November 12, 2016, 06:19:14 am »

Only some tubes require pin cushion correction, that's why you don't always find the daughterboard fitted.

Which country, Holland?

nburgmeijer · « **Reply #4 on:** November 12, 2016, 06:38:18 am »

Yups Friesland Holland

princess prin prin · « **Reply #5 on:** November 12, 2016, 08:35:31 am »

OK, one more question: what's the number on the old tube label? It should be something like A51-231X, A48JRV70X12 or similar.

nburgmeijer · « **Reply #6 on:** November 12, 2016, 08:52:36 am »

The original tube was a videocolor a51 437x

princess prin prin · « **Reply #7 on:** November 12, 2016, 09:08:18 am »

What kind of socket do you have on the neckboard, first or second?

nburgmeijer · « **Reply #8 on:** November 12, 2016, 09:17:17 am »

Top one. Female cr-23

princess prin prin · « **Reply #9 on:** November 12, 2016, 11:07:01 am »

nburgmeijer · « **Reply #10 on:** November 12, 2016, 11:33:52 am »

Wow that's just awesome! Thanks man!

So you can tell from the pictures that those tv's have rounded corners?
And what about the socket? What would the chance be that the tube doesn't have the CR-23 socket?

Also if I were to build myself a pincusion board from the schematics, would I be able to fix the pincusion problem on the Samsung tube?
You see I allready build my cabinet and atm I have a B&O MX4000 mounted in it. And that one is also 51 cm like the samsung tube. So getting a smaller 20 inch tube means I would have to build a bracket to make it fit.

I'm using crt-emudriver 2.0 to drive the MX4000 which works well. Just wanted to try a real arcade chassis(which cost me nothing). Not sure if i'd get different results though.

princess prin prin · « **Reply #11 on:** November 12, 2016, 11:59:36 am »

Quote from: nburgmeijer on November 12, 2016, 11:33:52 am

So you can tell from the pictures that those tv's have rounded corners?
And what about the socket? What would the chance be that the tube doesn't have the CR-23 socket?

Yeah, after cracking open almost 6000 TVs my eyes are well trained. The only TV that in all likelihood will not have a CR23 socket is this:

http://www.marktplaats.nl/a/audio-tv-en-foto/tv-s-overige-tv-s/m1105567064-zanussi-tv-televisie-vintage-retro-kleur.html
(this was made in my town, Pordenone Italy, early 80s probably a CR24).

All other models will have a CR23 or a CR31 (if it's one of those Orion tubes I mentioned).

Quote from: nburgmeijer on November 12, 2016, 11:33:52 am

Also if I were to build myself a pincusion board from the schematics, would I be able to fix the pincusion problem on the Samsung tube?

Hard to tell. The fact is that it's old tubes that needed this board (you can read about that in the MTC manual), newer tubes didn't needed it. And of course it was always necessary with bigger tubes (25"-28") but then there were other chassis differences (in fact it was called MTC9110).

Was the geometry good with the original tube?

Quote from: nburgmeijer on November 12, 2016, 11:33:52 am

You see I allready build my cabinet and atm I have a B&O MX4000 mounted in it. And that one is also 51 cm like the samsung tube. So getting a smaller 20 inch tube means I would have to build a bracket to make it fit.

I thought you had a MTC9000 complete with frame (for a 20"). If you don't then yes, you'll have to adapt it somehow.

princess prin prin · « **Reply #12 on:** November 12, 2016, 12:13:08 pm »

OK, you said the original tube was cracked...

Then it's possible that there is a problem in the east west circuit. Check TR16, TR17 and all the resistors/capacitors connected to them and D12, D13.

Does the horizontal size adjustment (H. AMP pot on remote board) work?

nburgmeijer · « **Reply #13 on:** November 12, 2016, 12:52:18 pm »

It dit not come with a remote board. Frame was also missing. I never got the see the original tube since it was allready cracked.
H.AMP does work on the chassis though. I suppose the degausing coil does not interfere with the geometry?
I used the MTC 9000 degaussing coil but it doesnt quite fit the bigger crt.
I also thought the geometry problem was caused by the bigger screen.

princess prin prin · « **Reply #14 on:** November 12, 2016, 01:34:41 pm »

Tubes from 14" through to 21" have the same deflection angle (90°) and work with the same chassis. Bigger tubes (25"+) have 110° deflection and need several changes. So a 21" is basically the same as a 20". If the H.AMP pot works then the EW circuit works and the signal from TR17 is fine. I would still check D12 and D13.

BTW what were the yoke measurements on the 21" original yoke?

nburgmeijer · « **Reply #15 on:** November 12, 2016, 01:48:51 pm »

I took the yoke from the videocolor tube and that one read 2,4 and 15 ish. Thats the numbers i keep bumping into as well online.
The yoke from the samsung was 3 and uhm 9 i think.
I did in fact do the yoke swap.
I'll check D12 and D13 tomorrow. Do you know if there's any residual voltage over D12 and D13 when chassis is disconnected?
And TR16 is ok as well?
Might as well build the E/W board on a breadboard tomorrow and test the pincushion trim.

Maybe you could tell me what to measure on what TP?

P.S.: The dude that supplied me the mtc9000 bought a cab for just 85 euro's with this monitor in it. He never tested it properly and immediatly put an LCD in it for a MAME computer. So I suppose there was something wrong with the EW correction circuit when he bought it.

nburgmeijer · « **Reply #16 on:** November 13, 2016, 10:18:23 am »

Small update.

Turns out it isn't a mtc9000 chassis. It's a C&AG vi2000.
Could've fooled me. Identical components except for the flyback. I replaced most caps on the board with new ones.
Still getting pincushion problems. Also the right side is slightly wobbled. I think I will make the pincushion daughter board since the components are really basic.
The high voltage diodes D12 and D13 measure fine.

Btw, the pincushion also occurs top and bottom.
Also the flyback whistles from time to time. Don't know if this is bad.

Here's some pictures.

https://goo.gl/photos/t64MaZ7C6NTMVgBo8

princess prin prin · « **Reply #17 on:** November 13, 2016, 01:41:18 pm »

Try with the Samsung yoke.

nburgmeijer · « **Reply #18 on:** November 13, 2016, 01:53:07 pm »

The samsung yoke is 2.9 and 9.4 ohm. Isn't that too far off?

princess prin prin · « **Reply #19 on:** November 13, 2016, 02:37:15 pm »

Horizontal inductance will be like 2.2-2.3mH which is OK. Vertical inductance will be around 20mH (original would be 29-30mH) which can still be within tolerance. You're not going to smoke anything.

nburgmeijer · « **Reply #20 on:** November 13, 2016, 03:46:36 pm »

Nice! That worked. Geometry is way better. It's not perfect but it's getting there. Now to set the convergence. Bloody samsung screen has 6 rings. ....

princess prin prin · « **Reply #21 on:** November 13, 2016, 09:38:24 pm »

Good stuff

If you had left the yoke/rings on as they came from factory I imagine the picture would now be as good as it gets. Mixing yokes and tubes from different manufacturers may give so-so results.

nburgmeijer · « **Reply #22 on:** November 15, 2016, 01:39:01 pm »

Hmpf, now I got a power regulator circuit problem i think. I started getting a wavy picture, lines and other weird stuff with brightness.
So I measured B+ and some other points.
First of all all voltages are too low.

B+ = 96-102 Vdc depending on the brightness control on the flyback. Should be 130 Vdc
TP1 = 18,4 Vdc should be 24/25 Vdc
TP12 = 11,5 Vdc, should be 12 Vdc
TP13 = 19,9 Vdc, should be 25/26 Vdc
TP14 = 154,3 Vdc, should be 200/210 Vdc

Isolation transformer measures 125 Vac. Smoothing cap measures 152,1 Vdc. I expected around 125 * 1,414 = 176 Vdc.

Voltage across R105 (the big 30W resistor) = 52 Vdc. I calculated that to be 8 Watts, but it sure gets hot.

TR20 measures just fine.

Any other components I shoud look into?

I read C34 can get leaky. I'll replace that tomorrow .Also R110 could go short. I'll look into that as well.

nburgmeijer · « **Reply #23 on:** November 16, 2016, 03:57:31 am »

One more thing. I tested the inductance on the horizontal coil. This is the yoke from the donor tube. It measured 0.15 mH. That's quite a way off from the 1.9mH on the original yoke, actually less than 10% of the original value...
I measured the original yoke as well and it measured 1.9mH as expected.

Now I was wondering if this low inductance coil could've faulted my board(see last post)?

princess prin prin · « **Reply #24 on:** November 16, 2016, 05:36:42 am »

Regarding the tube, if the resistance is 3.0ohm the inductance can't be that low. I would expect it to be around 2mH. With 0.15mH the resistance should be less than 0.5ohm. On VGA monitors you have that kind of values or on 100Hz TVs but those are only bigger sets (25" and above). And yes, such a low H yoke wouldn't do any good to the chassis but you would notice that immediately.

What's the TV model it came from?

As for the chassis, disconnect it from the tube and solder a light bulb to ground and the common side of R111/R112/R118, turn on and measuer the voltage at the same time. If you don't have 130v there is a problem in the power regulator circuit.

nburgmeijer · « **Reply #25 on:** November 16, 2016, 05:41:06 am »

It's definitely not a big 100hz TV.
I'll replace all the high voltage caps first later on. Need to pick those up.

By disconnecting from tube you mean disconnect the yoke?

princess prin prin · « **Reply #26 on:** November 16, 2016, 06:06:27 am »

Yes, disconnect the yoke.

nburgmeijer · « **Reply #27 on:** November 16, 2016, 09:28:56 am »

So all caps are now replaced.
No avail.

Connected a lightbulb and measured 117.5 volts.
So still too low.
Mind you it was a 230V bulb.

I replaced all the electrolytes in the regulator circuit.
I measured tr20 and r110. All fine. Gonna check the other 3 transistors now

nburgmeijer · « **Reply #28 on:** November 16, 2016, 10:24:47 am »

Found the culprit. Tr20 is toast. Now to find a replacement.
Any suggestions?

I tested the horizontal coil on the yoke again with a different inductance meter. It measures 2.11 mH and 2.7 ohm. So it's fine.

princess prin prin · « **Reply #29 on:** November 16, 2016, 12:27:29 pm »

Quote from: nburgmeijer on November 16, 2016, 10:24:47 am

Found the culprit. Tr20 is toast. Now to find a replacement.
Any suggestions?

You can use a BU508A (or the insulated versions AF or AFI), same transistor as the HOT (the other way round wouldn't work). Or any of the usual BU508A replacements:

BU2508AX
S2000AF
S2000N
BUH715

Quote from: nburgmeijer on November 16, 2016, 10:24:47 am

I tested the horizontal coil on the yoke again with a different inductance meter. It measures 2.11 mH and 2.7 ohm. So it's fine.

That's reassuring. How about the vertical yoke?

When you're done, before connecting the chassis to the tube I would do a light bulb test on the HOT, i.e. connecting the bulb to the collector and emitter. HOT needs to be off circuit or in circuit with base grounded.

nburgmeijer · « **Reply #30 on:** November 16, 2016, 12:36:12 pm »

Vertical measures 9.2 ohm and 20.36 mH

Quote

HOT needs to be off circuit or in circuit with base grounded.

Not sure what you mean by that. 2 options?

1: Take the HOT out and connect the bulb where Collector and Emitter used to be?
2: Leave the HOT on the board, connect bulb between collector and emitter and ground the base(so connect D28 to GND?)

And what is the reason for testing this.

P.S. Just read about lightbulb tricks for CRTS and found this:

When putting a lightbulb in the B+ circuit or in series at the mains

Full brightness: short circuit or extremely heavy load - a fault probably is still present.
Initially bright but then settles at reduced brightness: filter capacitors charge, then lower current to rest of circuit. This is what is expected when the equipment is operating normally. There could still be a problem with the power circuits but it will probably not result in an immediate catastrophic failure.
Pulsating: power supply is trying to come up but shutting down due to overcurrent or overvoltage condition. This could be due to a continuing fault or the light bulb may be too small for the equipment.

I guess one would want to limit the B+ current through the HOT?

princess prin prin · « **Reply #31 on:** November 16, 2016, 02:28:35 pm »

Quote from: nburgmeijer on November 16, 2016, 12:36:12 pm

Quote
HOT needs to be off circuit or in circuit with base grounded.

Not sure what you mean by that. 2 options?

1: Take the HOT out and connect the bulb where Collector and Emitter used to be?
2: Leave the HOT on the board, connect bulb between collector and emitter and ground the base(so connect D28 to GND?)

Yes, either 1 or 2. I always do 1.

Quote from: nburgmeijer on November 16, 2016, 12:36:12 pm

And what is the reason for testing this.

After fixing the power regulator circuit there could still be problems in the deflection so you test the B+ as far into the deflection as possible: B+ goes through the primary winding of the (inert) flyback and ends at the HOT collector. If there are shorted components connected to that line you will know that as the bulb won't light up and the HOT will be safe.

nburgmeijer · « **Reply #32 on:** November 16, 2016, 06:20:49 pm »

Replaced the transistor with one i found in a switch mode power supply.
B+ is around 130 Vdc now. Problem I have now it's not stable at all. Screen blooms like mad. Even with contrast turned down.
When a game is running i can see the B+ voltage changing up and down. Also when i turn the brightness on the flyback the voltage changes. Somewhere between 128Vdc and 131 Vdc.
Seems to me the regulator circuit isn't regulating very well.

When I hook up the yoke from the donor tube I hear a audible hum, and the flyback starts to give that annoying high pitched sound.
If use the original yoke that came with the MTC9000 that's gone.

Do these chassis have bad regulation or is there still something wrong?

P.s. I replaced the transistor with a e13007f2

grantspain · « **Reply #33 on:** November 18, 2016, 01:43:11 pm »

blooming could be caused by a fault in the brightness circuit
if you have a modern multi game board running they always do this the various degrees depending on monitor

a drop on the b+ with screen brightness changes is quite normal if its less than 5 volts or so

nburgmeijer · « **Reply #34 on:** November 18, 2016, 04:07:27 pm »

Hmmmm so I found that TR18 is toast and rv7 brightness control pot measured 90k instead of 220k.
Gonna get some replacements for those. Anything else I should replace there? Like ZD2? Can't measure that zener since its 100V

grantspain · « **Reply #35 on:** November 18, 2016, 06:39:20 pm »

r90
r89
all the 1n4148 diodes near tr18
just check they are good with a meter-remove one leg from circuit

nburgmeijer · « **Reply #36 on:** November 19, 2016, 06:58:58 am »

I also noticed there's 2 service manuals for the mtc9000 on the net.
Couple of difference i noticed:

- One has a 3 position switches for contrast control the other a lineair 3x1k pot in one package

- One has a Coil/Capacitor/Resistor for beam current limiting, the other has just a Resistor

- Some small changes around the brightness control and the blanking circuit.

The one with the lineair pot for contrast is the newer one I suppose? (has the same layout as the MTC9110 chassis)

I have the version with the 3 position switches.

Would it be useful to adapt my chassis to reflect the newer board?

And another thing I find strange. TR18 has a absolute maximum Vce rating of 100V and a typical rating of 80V. But the parallel Zener ZD2 is 100V. Feels underdimensioned? Or is it there for protection or Voltage clamping?

nburgmeijer · « **Reply #37 on:** November 26, 2016, 05:17:30 am »

So after fiddling around more and more the strain had finally killed the LOPT. Now I'm looking for a replacement. Since its not a true mtc9000 chassis but a CA&G clone it's not a 1:1 replacement with a mtc9000 LOPT. Not sure what the model number for my chassis is. Something like VI2000 or VI2100?

Anyways here's a picture of the serial number on the LOPT.
https://goo.gl/photos/UG2mZg6RFS7V44QdA

I suppose it's a HR 7211? As seen here?
http://m.donberg.ie/catalogue/line_output_transformers/hr_7211.html

If anyone got one lying around i'd be much obliged.

Edit: I also read somewhere that a mtc9000 lopt works but you had to cut a track because of a short to ground. I think this has to do with either pin 4 or pin 5 being ground?

princess prin prin · « **Reply #38 on:** November 26, 2016, 02:49:41 pm »

That number on the flyback means nothing, it's just for the focus/screen pot piece which is not even made by the flyback manufacturer.

That's an Eldor flyback, the code is on a sticker that often comes off. I had one of these CA&G clone chassis a while back and the sticker wasn't there anymore but that HR replacement might be the correct one. It crosses with Eldor 1105.0938. You can probably find neither at this point. You could use a MTC9000 flyback if you cut pin 4 and bridge 4 and 5 on the chassis PCB (assuming pad 5 is unused).


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