Hantarex MTC9000 chassis help

[qjuk]

I recently picked up a cab with a Hantarex MTC9000 chassis and a Samsung tube.

I’ll hold my hands up here, this is the first time I’ve worked on a MTC9000. When I first powered the monitor up the screen looked like a blurry rainbow effect. I originally thought the degauss wasn’t working as the colours were all over the place.



I removed the chassis to take a closer look. There’s nothing obvious that looks like any part is possibly dead. The chassis has been previously worked on before and I noted some caps have been also been previously replaced (no idea how long ago though). Also, the solder joints to the LOPT have been reflowed or the LOPT replaced previously.

I noted when I removed the green yoke connector that it wasn’t pushed down firmly on the chassis. Also, the pins to the neck of the tube looked a bit manky when I removed the neck pcb, so I cleaned them using WD40 and a nylon toothbrush.

I put the chassis back in and got the same rainbow blur picture as above, so I thought I‘d get my iPad to take a photo so I could post it here asking for some help. When I got back to the monitor the picture had improved a bit and I could actually make out the PacLand game running, even though it was out of focus.



I tried adjusting the focus on the LOPT but it didn’t make any real difference, even though there was a change, it still remained blurred and out of focus.

I left the monitor running for a few more minutes and I noticed the picture quality was very slowly improving. I adjusted the focus again on the LOPT and this time I got a perfect picture, however I could hear a clicking sound coming from the chassis. Even thought is was now a decent picture, the screen was a bit wavy, very slightly jumpy and a few white lines would appear every time the chassis made a clicking sound.

I powered off the monitor off as I didn’t want to potentially cause any other damage.

Looking again at the chassis, the cap at C53 looks very slightly bulged at the top.



The cap also looks original and does not look like its been previously replaced (judging from underneath, the solder joints look untouched). Info from Swallow Amusements says a wavy image can be caused by the C53 cap - so I intend to replace that.

My question is, any there any other things that I should look at that could have possibly cause the above issues?

 

[Ace`]

Slowly getting better suggests bad caps and not just the filter cap, you should replace them all. The flyback might also be bad if it's arcing (the clicking sound). Also NEVER use WD40 on pcbs, it's flamable and leaves a nasty residue.

 

[gunblade]

at first sight it looks like damaged shadow mask but that would not resolve itself so i am sure you can discount that.
clicking from neck when adjusting focus is sometimes down to corroded crt socket or focus pin, can you show a photo of the crt socket
i would suggest replacing the crt socket first to see if it resolves the issue then look at replacing a few of the critical caps( 54, 56 , 34, 45)
c53 going bad would cause a problem in voltage regulation circuit and the picture would have a serious wobble, like a degauss being permanently engergized

 

[Lurch666]

Maybe this can help?

 

[tb2000]

Yeah it looks like a crt waking up from a long slumber but as Gunblade says i'd go for the neck socket before anything else, if it's not letting through the focus voltage properly you'll get an out of focus blurry image. It woudn't hurt to do the caps as said above, there's a couple that normally go bad, the little 1uf 250v down by the brightness preset is nearly always dead and also C34 if I remember correctly (22uf 200v, by the big filter cap) usually is getting tired even if it still works (especially if it's the original factory fitted cap). The big filter cap is more than likely fine. Most i've seen have got a domed top. Best way to see where the ticking is coming from (if it's causing an arc) is to carefully look in the cab at the chassis when it's dark and see if you can see an arc. Either that or you've got a bad solder joint in the HV area that's starting to arc when it warms up. Or it's the neck socket arcing - if I remember correctly there's a 'spark gap' inside which can cause problems if it's going bad. If you're still getting a wavy image after the caps then i'd check the voltage reg, B+ should be a steady approx. 130v.

 

[qjuk]

Thanks guys for all your input above, some great advice to help point me in the right direction.

I powered up the monitor again today from stone cold and we are back to the psychedelic colour display. There’s no clicking from the chassis. I left it for a couple of minutes, no change. I then powered it off.


I’ve removed the chassis. Here‘s a picture of the CRT socket.


I’m not sure exactly how you remove the white cover to the focus wire? I didn’t want to force the cover off incase I snapped it. I’d like to look inside and check as Lurch666 suggested.

I certainly do think this chassis needs another recap. I’ll go through later and make a note of the cap values. I’m not sure if the cap kit from Swallow Amusements will cover everything I need? I’ll make a note the caps that gunblade and tb2000 suggested for sure to make sure they get done.

I note this chassis is the earlier BZ version, so it looks like the HR7025 LOPT is the right one for this pcb. It’s been previously been replaced/reflowed, the solder work looks a bit messy but the solder connections seem solid.



Just out of interest, if I do end up needing a replacement flyback, where can I get one? They appear to be unobtainable now

 

[gunblade]

its unlikely flyback but you can use 1105-E048
its either the crt socket or the tube itself on its last legs

 

[qjuk]

Thanks gunblade. I’ll start by looking at the CRT socket (I’ll probably just replace it) and do the caps, then see where I’m at.

 

[big10p]

Might be able to get them cheaper elsewhere, but I can vouch for these from Tecknoservice in Spain.

Transformer EHT Flyback HR7107 - 1105.E048 - HANTAREX MTC 9000 - 9110 | eBay UK

Tovoid Flyback Damage, Replace The Capacity Between The Hot Collector and Ground. Note: As The 7107 is out of production, A Fully Functional Compatible Transformer Will Be Sent To You Institute of The 7107. The New Transformers Were Kept in Tests For More than 10 Days, Verifying Eser...

ebay.us

Donberg in Ireland also make them still, but the one I had from them was crap.

 

[tb2000]

Yeah every flyback i've had from Tecknoservice so far has been fine (although the ones they do for the Sanwa 29e31s aren't 100% perfect but they acknowledge that and they do get the chassis working again though which is the main thing!) It's worth mentioning that those ones at Donberg seem like they are actually original HR ones, with some you can get actual orignal HR ones that were made in Spain (like the 2 I got a while ago for a couple of Microvitec Cub chassis), others have been what look like Chinese made ones with HR stickers on them. Big10p, can I ask what was wrong with your one? From what I read some time ago, HR said themselves that they continue to produce flybacks, although whether that's still the case I don't know, it could be that they get them made if there's enough call for them. I've got original HR ones though that came from HR that appear to not be made by HR themselves, despite the original HR stickers. The ones i've got from HR came from them some years ago, I remember I had a HR7717 which had a duff focus pot or focus voltage output out of the box, but another (presumably from the same batch as they were bought at the same time and were identical) from them was fine. I've also got HR6020 lopts that came from HR several years ago, but they're actually a different part number (I forget which one) which due to them having electrical specs which are "close enough to work" and an identical pinout layout and spacing have been relabelled as HR6020 by HR themselves - and they do work fine in the 900/E chassis.

Edit: By the way, you might be able to use a HR7508 in the 9000, and Donberg are selling original Spanish made ones from HR by the looks of the pics on their site. I remember you could use a HR7025 in a MTC9000A by cutting a pin (I forgot which one, it's been ages since I repaired an MTC9000A!) so i'd have thought the reverse is true, that you could use a 7508 in a 9000 chassis. Might be worth checking the specs first but the pinouts look the same enough to work.

 

[big10p]

Yeah every flyback i've had from Tecknoservice so far has been fine (although the ones they do for the Sanwa 29e31s aren't 100% perfect but they acknowledge that and they do get the chassis working again though which is the main thing!) It's worth mentioning that those ones at Donberg seem like they are actually original HR ones, with some you can get actual orignal HR ones that were made in Spain (like the 2 I got a while ago for a couple of Microvitec Cub chassis), others have been what look like Chinese made ones with HR stickers on them. Big10p, can I ask what was wrong with your one? From what I read some time ago, HR said themselves that they continue to produce flybacks, although whether that's still the case I don't know, it could be that they get them made if there's enough call for them. I've got original HR ones though that came from HR that appear to not be made by HR themselves, despite the original HR stickers. The ones i've got from HR came from them some years ago, I remember I had a HR7717 which had a duff focus pot or focus voltage output out of the box, but another (presumably from the same batch as they were bought at the same time and were identical) from them was fine. I've also got HR6020 lopts that came from HR several years ago, but they're actually a different part number (I forget which one) which due to them having electrical specs which are "close enough to work" and an identical pinout layout and spacing have been relabelled as HR6020 by HR themselves - and they do work fine in the 900/E chassis.

Edit: By the way, you might be able to use a HR7508 in the 9000, and Donberg are selling original Spanish made ones from HR by the looks of the pics on their site. I remember you could use a HR7025 in a MTC9000A by cutting a pin (I forgot which one, it's been ages since I repaired an MTC9000A!) so i'd have thought the reverse is true, that you could use a 7508 in a 9000 chassis. Might be worth checking the specs first but the pinouts look the same enough to work.

The one I got from Donberg wouldn't focus fully, and was very noisy. I swapped it out for the one from Tecknoservice and got a great picture and runs silently.

 

[wheeeeel]

For what it's worth I bought a HR 7025 from donberg a few months back and its working fine in my MTC 9000.

I have the earlier (even earlier than yours qjuk) MZ revision though.

You have the BZ revision with the large 9W ceramic resistor next to the flyback at R81, which I do not have on mine. For that board I would echo what others have said and recommend a HR 7107 from technoservice in your case (if you do need to replace it).

 

[qjuk]

For what it's worth I bought a HR 7025 from donberg a few months back and its working fine in my MTC 9000.

I have the earlier (even earlier than yours qjuk) MZ revision though.

You have the BZ revision with the large 9W ceramic resistor next to the flyback at R81, which I do not have on mine. For that board I would echo what others have said and recommend a HR 7107 from technoservice in your case (if you do need to replace it).

Thanks for the additional info.

The reason why I questioned/mentioned the flyback is because of a comment made on Arcade Parts and Repair recently:-
Be aware there are two flybacks for the MTC 9000; the flyback was changed in later revisions.
This flyback is for the later boards (MZ revision). If you have an earlier board (BZ revision), HR 7025 is what you require instead of this one.

I’m not at the stage of knowing if I actually do need to replace the flyback yet. I’m awaiting a replacement CRT neck socket, so I will try that first.

The socket on my neck PCB is a Pressac branded one. I managed to remove the focus cover without breaking it


It doesn’t look pretty. Someone else has previously worked on it. The spark gap contacts also look oxidised. I previously mentioned the tube neck pins were manky so chances are all/most of the pin sockets are probably in a bad way too.
I’ll be glad when the replacement arrives.

 

[Lurch666]

Try reflowing and adding solder to the focus connection (the end of the red wire with the brown burn marks around it) and see if that improves anything.

 

[qjuk]

Replacement parts arrived late yesterday, so I’ve been working on this today.

The original neck pcb had some broken tracks and has been previously repaired using jumper wires (I had already started to desolder 4 pins on the neck socket when I took the photo).


I replaced the neck socket and tidied up the broken tracks…


I also recapped nearly all the caps on the chassis (with the exception of C22 and C53).
C22 in the cap kit was underrated at 50v (original in board was 100v, manual is saying 63v) so I put the original back in the pcb as I haven’t got any spare 1uF 63v or 100v caps to hand.

I also left in the original C53 filter cap since the feedback comments were saying it was unlikely to be causing the issue I originally reported. I did order a replacement so will keep it with my spares.

Powering up the monitor, it starts off a bit blurry and a bit out of focus, but after about a minute the picture comes into focus and looks reasonably good..


There’s no clicking or noises from the chassis. If you look to the left side of the screen, there‘s a bit of the screen that’s a bit off. No amount of adjustment seems to cure it. There’s still a very slight bit of shimmer/waviness to the picture. Nothing major, kind of like a lot of machines I used to play on BITD

Considering it takes about a minute for the picture to warm up from cold, I’m thinking maybe the tube is possibly on the way out?

Also, does anyone know what the capacitor at C22 is used for? Would that potentially cure the slight picture issue to the left side of the screen?

The main thing is the game is completely playable with the screen currently as it is, and want to thank everyone for their input which has helped me get this going Much appreciated folks

 

[gunblade]

need to get a grid test pattern on that as it looks like convergence issue
slight wobble can be caused by failing mains filter cap or leaky ptc, disconnect the degauss coil and see if it makes any difference

 

[qjuk]

I disconnected the degauss coil and it’s made no difference.

It’s funny you should mention about the main filter cap. When I got the cab the live and neutral AC wires were reversed at the inlet socket. Also, the neutral in was connected to the filter’s neutral out and vice versa. I corrected the AC wiring and ran it through my PAT tester and it passed all tests. I’ll order a replacement filter anyway - they are not that expensive, it’s worth a try.

Good shout with getting a test grid pattern hooked up. I’ll find a game board with a decent test pattern and see if I can do anything about it.

Edit to add: I’ve just looked at the neck of the monitor, looks like someone’s previously messed around with the convergence rings

 

[gunblade]

other thing to watch out for is power supply issues, it was pretty normal to link the earth and common on the switch mode psu to prevent oddball issues on screen

 

[qjuk]

Sadly, I’m still having problems with this

The chassis takes a couple of minutes to warm up. It starts of very blurry, low brightness, just blue and red, then green slowly comes to life. Once the picture has warmed up and the colour/picture comes into focus, it has now started arcing from somewhere on/near the chassis. Every time it arcs, the screen blinks with white horizontal lines.

The slight waviness in the picture is still there.

I also notice that the large white 30w resistor gets very hot.

From doing some research, I have a feeling that I might actually have the wrong LOPT fitted on my chassis.
My board is the BZ revision (which I now understand is the later version, not an earlier version that I first thought). It’s got a 7025 flyback fitted which I now believe should only be used for the MZ boards. It looks like the LOPT should be the 7107 (which is what you guys have said earlier!)

Would an incorrect LOPT cause the issues I have described above?

To recap (pun intended), this is what I’ve done so far to the chassis:-

1. Re-capped all the electrolytic caps (including the C22 and C53 filter cap).
2. Replaced CRT neck socket (which has cured the blurry psychedelic colour issue).
3. Replaced R126 because it was very brown and cracked (but still read in tolerance).
4. Reflowed any solder joints that might look suspect.
5. Replaced the main filter to the machine with a brand new unit (it made no difference to the waviness).
6. Checked the earth connection on the switch mode PSU to ground (like most modern PSU’s it’s already connected internally so no link wire between Earth and GND is needed - but I tried it anyway - it made no difference).

 

[gunblade]

only things that will cause arcing is flyback or bad solder joint or insulation sheet on HOT
7025 or 7107 both fine on this version although i would suggest checking the eht level
first thing to do is monitor the b+ which should be 130v or close