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Author Topic: MTC 900 - orientation of C94 - repair anode-cap - color problem  (Read 1336 times)

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sollima

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Hello,

After the repair of my MTC9000 I bought a second arcade cabinet with a MTC900 monitor (although that is what the label on the chassis says (vaguely)). The picture on the new one is dominantly green. But shifts from time to time to redish and greenish. I noticed the ceramic capcitor near the green wire was chipped off.
So I thought, first of all --> fullcap kit including the chipped off ceramic capacitor. I made pictures of the chassis before installing the new capacitors.

My problem is:
- The monitor worked. Although the colors were shifting and the picture looked like it stretched and shrunk from time to time, overall not stable. But it funtioned(ish). But when I was applying the cap-kit I got to C94 and the negative side was oriented in direction of the + symbol on the PCB (see picture). So I looked at some manuals of MTC900 (/e) and all the C94 say it should be the other way around.

I am afraid if I do orient it the way the manual says, I will fry my chassis. (because my monitor worked(ish)). And I sometimes read that there are sometimes errors on the chassis and in the manuals.

Can someone confirm the orientation of C94 for me? It would help me a lot. I added a picture of my chassis with the original orientation of C94.

Thank you in advance for your help

EDIT: Changed the title to different subjects that were adressed in this thread
« Last Edit: March 15, 2018, 01:02:29 pm by sollima »

baritonomarchetto

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Re: MTC 900 - can someone confirm the orientation of C94
« Reply #1 on: March 14, 2018, 01:36:12 am »
There are silk screen issues on those chassis. Place the cap with negative lead to ground.

sollima

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Re: MTC 900 - can someone confirm the orientation of C94
« Reply #2 on: March 14, 2018, 03:03:11 am »
Thank you baritonomarchetto for your answer.

I do not know what 'silk screen issues' are or if my monitor shows symptoms of 'silk screen'.
But I can see that the positive side is connected to the 'ground' at the moment. From what I know the negative side should be connected to the ground. So I guess you confirmed it.

But shouldn't the capacitor have burned or exploded when it is connected the wrong way around?

I followed the + lining on the PCB and it connects to the horizontal phase (which connects to the horizontal freq, see faint red-striped line on picture). When I started a game the screen was far too wide. I couldn't correct it with the potmeters so I thought it could be adjustment of the width coil or capacitors near the width coil like the last time.

Could it be that wrong orientation of the capacitor C94 is the cause of not being able to correct the width with the potentiometers?

When writing this post I came across a color picture in a manual of the MTC900 it shows the capacitor oriented like you said. If the pictures in the manual, schematics in the manual, forum members and commen sense are in line, I think that I can safely change the orientation of the capacitor.  Right?

« Last Edit: March 15, 2018, 01:02:49 pm by sollima »

baritonomarchetto

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Re: MTC 900 - can someone confirm the orientation of C94
« Reply #3 on: March 14, 2018, 12:12:07 pm »
Go for it!
With "Silk screen issues" I refer to errors in the silk screened simbols on the PCB :)

sollima

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Re: MTC 900 - can someone confirm the orientation of C94
« Reply #4 on: March 14, 2018, 12:36:34 pm »
 [emoji1303]. I did it. Regained control of the most left potentiometers. Looks good.

But (of course) the next problem occures. There is a crackling sound comming from underneath the anode cap. I think that when I removed the cap the metal clamp has partly come loose from the wire. The metal clamp feels loosely.

Is it possible to strip the wire and resolder the metal clamp? Is there a specific manner to solder (does the wire consist of two seperate wires for instance)?
Is it possible to replace the suctioncap entirely?
Or do I have to buy a complete new LOPT?

Thank you for the help.


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baritonomarchetto

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Re: MTC 900 - can someone confirm the orientation of C94
« Reply #5 on: March 14, 2018, 02:02:59 pm »
After discharging the CRT remove the cup and carefully clean the area underneath. Pay attention not to remove the aqadag (black conductive paint).
Take a closer look to the clip (second anode) when out.
« Last Edit: March 14, 2018, 02:04:31 pm by baritonomarchetto »

princess prin prin

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Re: MTC 900 - can someone confirm the orientation of C94
« Reply #6 on: March 14, 2018, 02:38:45 pm »
There are basically two types of anode contacts. Those used in the west (and hence also in Hantarex monitors) have a ferrule crimped around the hook contact and the wire so it's difficult to remove it and reuse it. The second type is used in Taiwan/Korea/Japan, doesn't have the ferrule and it's very easy to remove and use as a replacement. Every PC monitor has this type. If you can't find one I have lots.

sollima

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Re: MTC 900 - can someone confirm the orientation of C94
« Reply #7 on: March 14, 2018, 04:23:37 pm »
There are basically two types of anode contacts. Those used in the west (and hence also in Hantarex monitors) have a ferrule crimped around the hook contact and the wire so it's difficult to remove it and reuse it. The second type is used in Taiwan/Korea/Japan, doesn't have the ferrule and it's very easy to remove and use as a replacement. Every PC monitor has this type. If you can't find one I have lots.

I think you are right. I had difficulty removing the anodecap. It went easily with my MTC9000 but suprisingly hard. After it came loose there was a small black hook like ferrule that came loose. I did not know how to put it back. I figured it was a piece to make the connection to the monitor more stable, but with the two metal clampwires to the sides sticking out, I figured I could tuck them back in the anode hole and the suctioncup would give enough stabilisation. When I looked at the soldering connection of the clamp, it was very wiggly and I think to see that not all the wires of thick cable are soldered to the clamp.

I would not know where to aquire a new one. I would like to ask you if I could aquire one from you?

 

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Re: MTC 900 - can someone confirm the orientation of C94
« Reply #8 on: March 15, 2018, 01:42:57 am »
It's not safe to replace the second anode. The same is true for the high tension cable, if you are not used to.
I always go the cheapest way, but in this case (if and only if the anode actually came loose) i would suggest to replace the whole EAT.

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Re: MTC 900 - can someone confirm the orientation of C94
« Reply #9 on: March 15, 2018, 06:25:05 am »
Hi Barito, it's Michele here. Replacing the anode contact+cap is perfectly safe and easy (and cheap) if done the right way.

Sollima, your description sounds a bit complicated to me. The two types I mentioned are shown below. I'm sure the first is what you have on your monitor. The ferrule keeps the hook contact from moving and breaking the solder joint. With the second one you simply put the contact onto the stripped wire and solder (rubber cap needs to go in first). If you want it PM me.

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Re: MTC 900 - can someone confirm the orientation of C94
« Reply #10 on: March 15, 2018, 06:46:03 am »
Ah, it's you! Nice to read you here too [emoji106]

sollima

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Re: MTC 900 - can someone confirm the orientation of C94
« Reply #11 on: March 15, 2018, 07:44:04 am »
Thank you Princess Prin Prin for your offer and help.

I added a few pictures of my EAT cap. When removing the cap the clip came loose so now I have seperate parts. But seeing your caps and parts I wonder if mine is repairable. If not I would be gratefull if I could aquire one from you and I will send you a PM.

I am trying to get it back together in the right way. I've added some pictures, but it looks promessing, I think.
Which one (if one) would you go for?

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Re: MTC 900 - can someone confirm the orientation of C94
« Reply #12 on: March 15, 2018, 08:38:52 am »
I've never seen one with that plastic bit, always metal. I wonder if the flyback is a Chinese knockoff. In any case you put it together the wrong way. The hook is the same as the first type I posted so it must have the same orientation.

sollima

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Re: MTC 900 - orientation of C94 - repair anode-cap
« Reply #13 on: March 15, 2018, 01:01:57 pm »
Thank you Princess Prin Prin (for your help and cap-offer, it's appreciated  :applaud:). Repair of the anode-cap is what you said straight forward. I made sure the pins were in the right direction and they are kept in place by the ferrule. The solder is also protected by the ferrule (and the cap of course).

Maybe my flyback is a Chineese knockoff, but it does not strike me as one. Even the shape, ridges and slit on the two knobs are consistent with the silk on my chassis and my MTC9000. But it delivers picture for the moment, so I hope my color problems are chassis related.

I did a full cap kit. Even the poly-caps. I have a B+ (measured at the yokeplug? between the black loop wire in the plug) of 130.4V.
I have almost no control over the colors with the potentiometers on the neckboard. My black have a reddish glow over them. The colors are not krisp, but dim. Upping the brightness on the chassis does not bring much. It feels like it is being held back. (Not enough voltage?).

When I turn the brightness full open on the flyback it brings a bit more colors, but when I turn it down a bit red and green seem to dissapear an blue becomes dominant. But I don't think this is the right way to adjust.

I have resoldered all the connections on the neckboard.

At this point I am planning to replace all the potentiometers on the neckboard. Can someone tell me if I am on the right track? Or point me in the direction of color 'krispiness'?

Thank you

« Last Edit: March 15, 2018, 02:33:58 pm by sollima »

sollima

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #14 on: March 16, 2018, 04:40:29 am »
Small update

I measured SP10, SP11 and SP12. Those are the input points of the Red, Blue and Green from the chassis into the neckboard. I wanted to know if the neckboard received signal. They all gave between 2,9V and 3,1V. I can't find the values of SP10-12 in the manual, but my blue is dominant and bright and the green is present, so I think that the other value (Red) should be OK.

I think the Red gun in my tube is OK, because I see a faint reddisch glow on the monitor and when I adjust the flyback, horizontal red lines appear.

That makes me think the problem is that the signal is not going correctly through the neckboard to the tube. I will try to buy new transistors and potentiometers (now the open metal ones are installed) and see what happens when I install them.


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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #15 on: March 16, 2018, 07:34:14 pm »
are you missing red gain?
do red cut off work?

sollima

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MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #16 on: March 17, 2018, 02:10:51 am »
are you missing red gain?
do red cut off work?

Both red gain and cut off give no significant change when I turn them. I measured both potentiometers and they seemed OK. (They are the old open kind and my screwdriver seems to get stuck in the slot sometimes, so I will replace them with new incapsulated ones). Because of the voltages on SP10, SP11 and SP12 were roughly the same (2,9V-3,1V), and my control of cut off and gain on blue was good, I thought my problem might be in the red circuit on the neckboard.

I read in another thread "Hantarex 900/E display problems" your answer to user 'SJP0tato' who had trouble with his green:

yeah do a job lot so change the following
r146 3k3 0.5w
tr31 bf871
tr30 bf871
tr29 bc237
d11 1n4148
d31 1n4148

check with meter r137 and r134

use solder braid(wick) on these components as the tracks will be delicate

I deducted the transistors and diodes for the red circuit. (see picture with faint colored lines). I will remove and measure R141, TR32,TR33, TR34, D19, D32, R138 and R135.

To be sure I will do the same for green.

Hope I'm approaching this problem from the right angle.
« Last Edit: March 17, 2018, 02:15:07 am by sollima »

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #17 on: March 17, 2018, 04:28:45 am »
yes I have had issues like this on mtc900e in the past and the fault could be absolutely anywhere on the colour circuit not just the neck card

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #18 on: March 17, 2018, 04:32:14 am »
Do you have an alternative place for me to look, or should I just replace all the transistors in the color circuit for starters?


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sollima

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #19 on: March 17, 2018, 01:09:56 pm »
I haven't replaced the transistors/resitors on the neckcard yet, but I have been thinking. What if someone switched the power connector to the chassis with the color/HV connector. The both have the same number of pins.

Then 130V (B+) would be connected to pin 3 of the CA socket-connector. Connector-pin 3 is the red signal. But because of the loopwire on the power-connector-plug it would also be directly connected to pin 4 which is ground on the CA connector socket.

But could it be possible that components behind pin 3, the red circuit, could be damaged because of the 130V dispite the loopwire to ground?
And would TR11 be the first to go? Or will the potentiometer RV3 be the first to go? Or could several resistors have burned through? Or is that very unlikely?

« Last Edit: March 17, 2018, 01:11:46 pm by sollima »

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #20 on: March 17, 2018, 01:58:10 pm »
easy to prove the issue tbh- on the main chassis you see each colour wire goes to small spade terminal- swap the red and green over, if your red starts to function correctly then the issue is related probably to transistors on the main chassis board

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #21 on: March 17, 2018, 02:45:07 pm »
easy to prove the issue tbh- on the main chassis you see each colour wire goes to small spade terminal- swap the red and green over, if your red starts to function correctly then the issue is related probably to transistors on the main chassis board

You're right. My experience is still limited. I appreciate the input. I switched both wires (see picture) and red was the dominant color. Green was absent (only a little bit of gain and cut off, just like red used to have) (see picture).

So, as you suggested, the neckboard is OK. The problem is between CA connector and the loop wire. Before I read your post I already replaced TR11, so that's not it. I replaced all the electrolytic capacitors, so maybe a ceramic one? Or a resistor, or transistor?

I will try to deduct the possible problem components from the schematics? In your experience, do you have a suggestion where to look first?

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #22 on: March 17, 2018, 04:26:25 pm »
think you have the wrong schem, my 900e schem shows red and blue opposite so I would be looking at tr8,12,15,18,21

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #23 on: March 17, 2018, 04:45:36 pm »
Ok Thank you. I used this manual. The foto shows the corresponding TR numbers with my board, but the schematics have different TR numbers and descriptions.

But I see what u did. It's like a vertical line of transistors over the chassis that should be replaced. Although the transistors u mentioned correspond with the numbers of my chassis they follow the vertical line with the blue wire and B symbol on the chassis.

But I will replace all the transistors you mentioned and the ones in line with the red wire. Then it should be OK.

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #24 on: March 17, 2018, 06:30:39 pm »
I am half way. I replaced the transistors in the red line. I have full control of red cut-off now, but no control over the gain. The picture still has no red. Could the transistor on the neckboard TR32 be faulty?

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #25 on: March 17, 2018, 06:49:43 pm »
that could be the pot or one of the transistors on the neck card
does the contrast pot affect the red at all?

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #26 on: March 18, 2018, 12:14:29 pm »
I think the colors are fixed. Thank you again grantspain for your help and time  :applaud:. I went transistor-replace-postal and replaced all the transistors on the interface-board. (minus two TR5, TR6). Replaced the transistors on the neckcard in the red lane (TR32, TR33, TR34) and measured the resistors and diode D19. All looked good.
I thought I was ready to go. Hooked up the chassis, no red. That can't be. That's when I thought of the thread in which a guy wiggeld is JAMMA connector. I thought what if the game board has become faulty. It works perfectly in my other cabinet with the MTC 9000.

Luckily I have not sold my other arcade cabinet with a Street Fighter JAMMA board yet. Hooked it up, set it to maintenance mode and voila. See picture. All the colors are there and fully adjustable. Wohoo!  ;D

But of course... another problem occured. Where the other game (Knights of the round) is easy to adjust the settings (horizontal/vertical etc) I can't get this game (Streetfighter II) to get stable. Even with a stable picture like the maintenance screen near the white you can see it bending off. In reality it is 'wobbleing/unstable'

- The colors are off. They look a bit like when I turned the little switch on the chassis of the MTC 9000. The colors look like 'in negative' (see picture number 2)
- When I do get it a bit stable when scenes change it becomes blurry/moving again.
- When 'stable'  the screen looks wobbly

Could this be a ground issue? If so, should I solder extra wires to the ground points on the PCB and connect them to the chassis? And/or should I connect the DC-COM of the JAMMA powersupply to ground?

The 'negative' colors: should I connect the jumperwires on the chassis to the pins with the - symbol (or is this for vertical monitor orientation?

Could it be a PSU problem?

Does someone know what to do?
Thank you in advance.
« Last Edit: March 18, 2018, 12:19:34 pm by sollima »

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #27 on: March 18, 2018, 02:38:48 pm »
where is the video ground going to on the jamma connector?

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #28 on: March 18, 2018, 03:01:37 pm »
Ground 1+2 go to the PSU. I don't know (yet) what happens under the PSU cover. Ground 27+28 are used by the controls. The controls are extended through a new plug.

The PCB-board voltages (+12/+-5) look like they are too going to the PSU, but I think they are forwarded to the JAMMA powersupply

I added pictures.

You think it's a groud issue? Not a Sync-polarity problem - instead of the + it is now?

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #29 on: March 18, 2018, 03:29:43 pm »
some game boards need video ground to go to pin 14 on the jamma, yours looks like it is there- cps2 do strange things if the video ground goes to a different pin or common

check your +5 volts

 I doubt the picture would lock on if it were on the wrong sync polarity

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #30 on: March 18, 2018, 03:42:47 pm »
you sure that the contrast is not far too high and the brightness too low?

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #31 on: March 18, 2018, 04:10:42 pm »
I measured the following values:
I can see that the ground of pin 14 goes to the connector of the color-input on the chassis.

I measured the following voltages:
JAMMA-pin
3 + 4 = 4,65V
5 = 0V
6 = 13,4 V

I am missing the -5V. It is not connected to the JAMMA-psu, the slot is free. I know that the voltages are a bit high (13,4V) and somewhat low (4,6V). I adjusted the JAMMA-psu to remove artifacts in the game. (like the upsidedown Ryu in the upper left corner of the test function, see picture few posts back). On the MTC9000 I had artifacts in the sprites and saw that upping the voltage a bit (not much because the game stalls and reboots) the artifacts dissapear.

When trying to lock the picture I tried everything. Low/high brightness, low/high EHT, Low/high chassis voltage, low/high contrast. I noticed that when it is set not too high it gets a bit better to find a stable screen. But when the scene changes (player choice to fighting) the picture gets more colors and it gets out of sync and starts scrolling.

Do you think that missing the -5V is at the root of my sync problem?
« Last Edit: March 18, 2018, 04:12:59 pm by sollima »

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #32 on: March 18, 2018, 04:32:52 pm »
whats the b+ reading?

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #33 on: March 18, 2018, 04:42:29 pm »
B+ = 128V (measured at the plug between the loop wire)

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #34 on: March 18, 2018, 04:51:47 pm »
yeah b+ is ok,
-5 missing on some boards affects normally sound but on others is affects video( like cruisn' exotica)
cps may well use -5, does your other cab that works ok have the -5 connected?

your +5 should be about 5.05 at the edge connector

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #35 on: March 19, 2018, 02:49:43 am »
That "wobbly" picture reminds me of an old repair where i had a similar problem. The cause was the filter capacitor gone out of spec. In this case, if i have understand well, it happens only with one pcb so it' probably not the case.

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #36 on: March 19, 2018, 08:06:00 am »
@baritonomarchetto: Thanks for the input. I replaced all the caps on the board. The big capacitor too. I don't think it could be it.

I made things worse I'm afraid. I thought to rule out sync-polarity I swithed all the colors to - instead of + also the FS8 (horizontal) to -.
I got picture and locking it went fine. More easily than with all the connectors set to +. Although the colors were still not correct. I returned it to the original settings.
When I got home from work I wanted to see what the effect would be on my other game. So I set everything to - and booted up the game. When the picture was stable it was bright with hardly no game visible.
I returned everything to the original settings (+) and put my Streetfighter game back in. When I booted up the screen has scanlines, starts blue-ish and after 1-2 seconds goes to reddisch (see picture).

I think I broke something. I do have a new HOT (Tr17) could that have been broken?

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #37 on: March 19, 2018, 12:25:19 pm »
Small update.

I took the chassis out and replaced some transistors. The HOT (I think) Tr17 (the big one on the side of the heatsink) and Tr6 near the filtercapacitor. (I had one laying around, maybe it would help)

The result was that the screen now is white(ish) and can be focused. So the scanlines are white and stable. Only thing missing is the picture. I can not use contrast or brightness, only the pods on the other mainboard.

I removed the game-pcb and the picture stays the same. I concluded that video signal is not getting through from CA to the end anymore. To rule out game-pcb failure I tried connecting my other game and Pi with Pi2Jamma. The result is the blank (only scanlines) screen.

I measured the Jamma plug and set my 5V pins to 5.03V, but still no picture.

I think I messed up  :(


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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #38 on: March 19, 2018, 06:48:35 pm »
something has died on the 200v video b+ line
I will look at the schem

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #39 on: March 19, 2018, 06:51:54 pm »
check r131 10ohm safety resistor- directly on pin 4 of flyback
r145, solder on c52- these on neck card

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #40 on: March 20, 2018, 10:21:51 am »
Again you are right  :applaud:.  R131 read in the mega Ohms so I guess it went out. I bought a new one and there was somewhat picture again  :D. The same as before it went white. I desoldered R145 and C52 the both were good.
All the transistors on the interface board are replaced now. I also replaced all the BF871 transistors on the neckcard.

I connected the raspberryPi with Pi2Jamma and got a good picture. A bit dim, but a good stable picture (see picture). I don't think a Pi makes use of the -5V. So that is probably the problem with the gameboards. I remember giving the PSU a cap-kit and after measuring the molex-connector which gave -5V. So I am confident my other cabinet uses -5V. But I will verify that.

I was not totally satisfied with the colors so I connected the Streetfighterboard in Testmode. I got the same colored barrs again.
I started tweaking the neckboard and suddenly the screen became redder and the scanlines appeared. Just like before
Then the screen went white with scanlines and I was back where I started.
When I turned the cabinet off and on again the screen was still white with lines, but I heard crackling. I looked and saw spraks comming from R131 to the heatsheald next to it. Turned the cabinet off immediately.

I think something is overloading R131. I soldered everything with great care. The only thing that gives me doubts is the broken ceramic capacitor I replaced. It's 50V but it is so small I am not sure anymore if it's right. (see picture).

Could it be that connecting without the -5V could cause an overload?
Do you know where I can look to solve this?

« Last Edit: March 20, 2018, 10:40:52 am by sollima »

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #41 on: March 20, 2018, 10:36:38 am »
maybe there is some short component on the neck board- did you change the red pots?

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #42 on: March 20, 2018, 10:38:55 am »
Yes I did. Should I replace them?

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #43 on: March 20, 2018, 11:09:22 am »
be interesting to see what happens if you replace the resistor- see if the red is up high again
this of course could be the red gun in the crt itself, but they usually go super bright with flyback lines in one colour or no colour at all

a white screen with flyback lines is normally video b+ missing

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #44 on: March 20, 2018, 11:34:23 am »
I will buy several resistors and new pots tomorrow. I will not change the pots yet and film the effect of loosing the resistor. Then I will report back and see if I can detect a short on the neckboard.

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #45 on: March 21, 2018, 12:02:17 pm »
Bought new resistors today. Replaced the broken one.
I cleaned the neckboard and connected the -5V to the JAMMA-plug.

So when I booted up it looked good. But then I heared the crackling noise. I saw sparks flying from R131 to the heatsheald. But sometime they stayed away and the screen was 'giving picture' (see movie 100MB)
When scenes changed the picture went out of sync again.

I did capture a time when the resistor almost broke. On second 3 of the movie you can see the scan lines and reddish glow appear. Movie2 100MB. At the end of the movie you can see picture going out of sync. Sadly I was too late for the final burn through, but it looked like second 3 of movie but the screen went white with scanlines.

I think the spraks were getting worse when I tried to adjes RV17 Vert Lin.

I really hope you can help me.


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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #46 on: March 21, 2018, 12:58:24 pm »
its acting very strange, could be flyback- you did reconnect the crt earth to the neck card?

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #47 on: March 21, 2018, 02:07:47 pm »
I did reconnect the earth to the neckcard and to the clip connected to the metal wire that goes around the tube.

I hope it's not a broken flyback because that would mean a big finacial investment. Is it worth it? Is there a way to rule out if it is the flyback?

Could it be that IC2 is broken? Or that components on the interfaceboard probably got broken and cause an overload?

This thing is worrying and keeping me up. I would love for it to work properly.

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #48 on: March 21, 2018, 03:11:39 pm »
I read the repair guide from Ken Layton. Here It's for the 900E but the boards are very similar. Does this comment on the bottom of page 1 apply to me?

Quote from: Hantarex MTC 900/E repair guide
No vertical deflection problem: Check for an open or burned resistor R56 (6.8 ohm, 1 watt) on the deflection board. If the resistor is found to be bad then you must also replace the IC3 vertical output (TDA 2653A or NTE 1804).

Is this the same resistor as R87 1.5 Ohm 1W of my board? Or am I way off?


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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #49 on: March 21, 2018, 05:22:08 pm »
you have far too many odd faults, these chassis are fix after fix as they are old but is incredibly rare for the repairs to fail like yours
do you have a european 900e or usa 900e?

you may find you are throwing money at this, how do you know your tube is good btw? did you test that chassis on the mtc9000 tube(neck pinout allowing)

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #50 on: March 22, 2018, 02:22:58 am »
 :( that does not sound promessing. To be honest I do not know if the tube is good. It gives three colors and some picture, so I assumed it is good. Can I assume that you think the failing of the resistor should be the reason of the neckcard or up to the tube?

Sadly the crt-connector of the MTC900 is different from the MTC9000. My MTC900 has some kind of sleeve the MTC9000 has a female plug like connector. Is it possible to just switch the connectors and test?
The sticker to identify my monitor is missing so I can't say or sure.

The sticker on my chassis says MTC900. But searching the manual online it looks more like a MTC900/e. Although the manual I found online has a different silk numbering of the interface board. From discriptions I read I think I have a MTC900/e version2. But I don't know if it is a European or USA version. But because I live in the Netherlands, I assume it is the European version.
Is there a way to indentify it for certain?

Can I assume that testing the tube is the first priority before chasing IC or interfaceboard or flyback?

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #51 on: March 22, 2018, 04:13:31 am »
you can swap the crt socket but tbh you don't want to start messing with a working chassis- I would buy a replacement crt socket
euro 900e has 1 x 6 pin green connector for rgb and a 4 pin green connector for 120/230- usa version has same connectors you find on stuff like g07, there are some minor differences in the components and design of the chassis

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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #52 on: March 23, 2018, 10:29:53 am »
Thank you for your answer. Then I definitly have a european version. I will try searching for a crt socket.

I will report back when I know more.


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Re: MTC 900 - orientation of C94 - repair anode-cap - color problem
« Reply #53 on: April 21, 2018, 08:08:55 am »
Yesterday I got around to switch the tubes of my MTC9000 (A51-427x) and my MTC900-e (unknown missing sticker).

I switched the CR23 plugs on the neckcards and placed both the chassis.

I think I have two issues.

1. The MTC900-e (with the failing of R131) failed again with the new tube. When booting up the picture was in sync, sharp, bright. I thought I deducted the problem as the monitor. But after a reboot the screen went white again with the scanlines. R131 was blown again. Dispite the tube change. --> my conclusion is that there is a build-up to a short in the neckcard. A component gives slowly which causes R131 to blow.
Does someone have a tip on which one it could be?

2. The working chassis of my MTC9000 was connected to the other tube (of the problematic MTC900e). I got the same results when connection the game. No way to correctly sync the game. Picture stays blurry, scrolling. The same as with the MTC900e.  (Strangely, when connecting a Pi with Pi2scart, the picture comes up nicely). Looking at the neckglow there is one filament glowing brighter than the others.
So I concluded that the tube is also faulty. (The same chassis MTC9000 together with the other tube gives a stable picture). Would one say that this is a fair conclusion?

Thank you for your help
« Last Edit: April 21, 2018, 08:14:20 am by sollima »

  
 

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