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Brisbane CRT issues, please help!


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Hi all, looking for any advice or assistance please.

 

I have an MAME arcade unit with a 29” CRT Pentranic 1125 (CH288 chassis) connecting to an IPAC board. There was an intermittent issue for a number of years where the red colour on-screen screen flicked on and off, usually only after it had warmed up.

 

Then, once fateful day the red stopped working altogether. Did a bit of research, checked all cables, then removed and replaced all caps on chassis board with no success. No worries I thought and bought a replacement chassis from the US and on arrival this had a vertical collapse *groan* So, sent both of these Pentranic 1125’s to JOMAC who did a great job of repairing them.

 

When I got these back from repair and put either chassis into the arcade, fires up great except still no red colour… at this point I have no hair left to pull out! :(

 

Contacted JOMAC and they suggested the boards are fine so the tube may have expired and to post in this forum to see if anyone can help.

 

Essentially, I’m stuck… I don’t have the knowledge or tools to attempt a tube rejuvenation or repair. Ideally, I’m looking for someone in the Brisbane area with CRT repair experience who could visit me in Toowong and repair. I’d be happy to pay for your time or arrange a swop for my spare Pentranic 1125 if you need one.

 

If not, can anyone suggest how to best go from here to fix the tube? Are there replacement red tubes available, is that easy to do with basic soldering experience? …or perhaps a 4:3 LCD screen which could size match the 29” bad boy I have in there at the moment??

 

Any thoughts/advice/suggestions would be greatly appreciated. Fingers crossed somewhere out there can assist!

 

Cheers

 

 

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If Joey says the chassis are working, then they will be. Homepin was merely commenting :)

 

Hmmm, I don't know that chassis in particular, but for general advice...While the monitor is running you can try grounding out the neckboard transistors one by one. Remembering to be sensible around dangerous voltages, connect one end of a lead to chassis ground, then touch the other end to the metal back of the tab-transistors, one transistor at a time. Each should flood the tube with that colour. I doubt this is good for anything, so do it briefly. If you get nothing on red, the red filament is probably open. Or the pin isn't making contact in the socket, so check that just in case. After that it's probably time for a new tube.

 

You could probably do the same thing just by testing the pins with a multimeter, I guess? You'd need to know which pins, of course.

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If Joey says the chassis are working, then they will be. Homepin was merely commenting :)

 

Hmmm, I don't know that chassis in particular, but for general advice...While the monitor is running you can try grounding out the neckboard transistors one by one. Remembering to be sensible around dangerous voltages, connect one end of a lead to chassis ground, then touch the other end to the metal back of the tab-transistors, one transistor at a time. Each should flood the tube with that colour. I doubt this is good for anything, so do it briefly. If you get nothing on red, the red filament is probably open. Or the pin isn't making contact in the socket, so check that just in case. After that it's probably time for a new tube.

 

You could probably do the same thing just by testing the pins with a multimeter, I guess? You'd need to know which pins, of course.

Thanks heaps for your detailed suggestion Buttersoft! If I can't find anyone that can help with this, I'll definitely give it a go... just a bit scared of combining high voltage and my technical ineptitude in the same room! ;)

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If you get the tube to me I can test the tube in shop, I am at Springwood

Hey GameDude, wow that would be amazing! I'll get the tube to you even if I've got to use a can-opener to get the darn thing out! When are you free for a visit??

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If you're near gamedude I'd take him up on his offer :) TBH if the cassis are working, and the tube is getting no red at all even when you turn up the gain, then it's going to be the tube that's faulty. Be careful around those voltages either way. You'll need to discharge the tube to get it to gamedude.
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If you're near gamedude I'd take him up on his offer :) TBH if the cassis are working, and the tube is getting no red at all even when you turn up the gain, then it's going to be the tube that's faulty. Be careful around those voltages either way. You'll need to discharge the tube to get it to gamedude.

Yep, previously cranked up the red gain fully to no avail, so 99% certain it's the tube that's the problem child. I've got fingers, toes and eyes crossed GameDude can sort it. I'll be sure to discharge the tube before attempting any removals, your comments are very much appreciated.

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He probably won't be able to do anything. If the filament were shorted internally you'd more likely get a red flood. Most likely the filament is dead which means the tube is finished. Still, it could be a G1 short or something? Let the man with the meter figure that out :)
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He probably won't be able to do anything. If the filament were shorted internally you'd more likely get a red flood. Most likely the filament is dead which means the tube is finished. Still, it could be a G1 short or something? Let the man with the meter figure that out :)

Haha, I'm more than happy to leave it to the experts! :) Kind of already resigned myself to the fact I'll probably be looking at a replacement tube or dare I say it... LCD?!? *shudder*

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I have had two different CRTs that were missing one colour, both times it ended up being a broken or cracked trace on the neckboard (one of them was a brand new chassis and neckboard that came with a borked trace from the factory, shit happens) fixed by jumpering the break by soldering in a wire.

 

Hopefully someone can come along and explain how you can do a continuity test to check if this is your problem? (Sorry I don't have the time ATM and besides I know others with more experience would be able to explain it better)

 

- - - Updated - - -

 

Haha, I'm more than happy to leave it to the experts! :) Kind of already resigned myself to the fact I'll probably be looking at a replacement tube or dare I say it... LCD?!? *shudder*

 

 

There are plenty of things that people here can help you check before you chuck out a potentially good CRT and replace it with a dreaded LCD which should be your last resort. Remember YouTube can be helpful.

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Thanks for the info Rat and sounds like you had a bad run of luck with your CRTs! :(

 

In my head i've (temporarily) ruled out chassis/neckboard issues as Joe from Jomac has fixed two for me and they both show the same loss of red. From what i read he really knows his stuff so I'm now thinking it's the tube itself that has got to be the likely culprit.

 

YouTube is a great option, i'm a big fan. I watched one fellow arcadian with a tester/rejuvenator that fixed his colour problems in a few minutes. Wish i had one of those right about now!

 

100% agree with you, LCD would be very much a last resort. It'd totally spoil that authentic arcade feel. Plus 'Defender' would never look right, ever again...

 

Sent from my SM-G925I using Aussie Arcade mobile app

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If you're near gamedude I'd take him up on his offer :) TBH if the cassis are working, and the tube is getting no red at all even when you turn up the gain, then it's going to be the tube that's faulty. Be careful around those voltages either way. You'll need to discharge the tube to get it to gamedude.

 

No problem :D

Pretty much if anyone wants their tube evaluated and can get it to me I will check it out for them, sorry I dont get on the forums much these days so I dont always see the messages but I am at work pretty much every day Monday to Saturday all open hours...

 

I am also happy to provide advise or evaluate old arcade machines if anyone wants that.... no charge but you have to get whatever it is to my shop....

 

http://www.gamedude.com.au

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