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Jomac

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  1. I have highlighted the a little daughter PCB on the chassis , try spraying this little PCB while it running with some Freeze Spray , if the picture comes good you will know where the issue is. There are a several other things that cause these sort of faults on that model, it could do with a good service anyway it looks like it hasn't been touched , so around 30 + years of operation.
  2. I have a couple left atm and quite a few used spares for 25" tubes. Those tubes that @Autosteve has would be gold, Toshiba only made "A" tubes and I have only ever seen a couple of the ones Steve is talking about from AMF, the chassis they come out with as he mentioned were terrible things so most of the tubes left over were still like brand new.
  3. The firmware update disk has Version 4.01 , all the disks always come with the security chip , the same chip come with upgrade disks for Naomi, Chihiro and TriForce but as the Chip is locked there is no way to read it, the Zero Pic doesn't work.
  4. Try to re-initialize the pots, While holding the test switch push the service button which should bring up an initialize screen. When you start don't touch the bike or controls because initialize also centers the bike left /right pot , when you are in that new screen it will ask you to move the controls to find the pot lower and upper limits.
  5. A lot of people ask me this, It's used as an over voltage clamp, an add on we did here in Australia for any chassis that used the STR-S5741 after there were a stack of failures caused by the B+ going way to high. When C610 ( 10uf 160v ) and C609 ( 33uf 200v ) start to fail it causes the output frequency of the chopper circuit primary winding ( for the switch mode transformer ) to increase meaning the output voltage would increase proportionately and could go up as high as 180vdc. Pin 8 is an unused "ref" pin so we put a 120K resistor from here to the positive side of C610 Pin2 , this monitors the frequency and stops it exceeding 130vdc. Obviously when the caps are new there is no problem for a little while but this even changed as the operating temperature changed, so that one little resistor saved a huge amount of these being destroyed.
  6. Awesome work Trav, I know how much effort you have put into this for the benefit of many ! Not to forgot Shane either, always awesome! ( he definitely needs the default white background or he thinks the monitor is in standby 🙂 )
  7. I should have replied to this sooner, That is a TV tube not an arcade tube, Horizontal Yoke with this value 1.9 ohm & 1.118 mH is designed specifically for CGA ( 15.75Khz ) use, it can be used with certain chassis modification to operated on 25K EGA but it can't be used for VGA at all, if you try a VGA on this tube is will burn out the horizontal deflection circuit in most cases instantly. Thomson tubes like this are quite often mistaken for the Thomson tube used in arcade machines with Wells Gardner 27D9200 or 27D9400 chassis which are CGA, EGA, VGA and EVGA (15~38K ) . These tubes and chassis are failing or have already failed at an alarming rate, the D9200 was a disaster from the start, the D9400 Pure Flat screen version was a nice looking monitor when they were released but 9 out of 10 now are way past their design life and beyond repair.
  8. Some good points there Steve and valuable feedback. Shane gets to see what comes in everyday, all sorts of 5v power supplies with adjustments turned up to the maximum, plenty with broken pots because they couldn't be turned up any higher and then the resulting damage to boards. Not saying you or people in the know are going to over voltage things but trust me if there is an adjustment people can play with they will play it long before pulling out the multimeter. The original LM323K has always been a problem but so much worse now due to there being so many fake ones on eBay etc, just like the LM338K they are rebadged T03 packages with 7805 regulators soldered internally, Shane has some pictures of packages we opened up because they failed way under maximum current specs.( The LM338K rated at 5 amps all failed at maximum 2.4 amps ) We talked tonight about having an adjustment up to 5.2v but the most important thing is making this bullet proof so it's going to be tested in every way possible and work all day at quoted specs not just for short bursts at maximum claimed specs.
  9. Sorry mate I didn't notice you had responded to this, if your boards were repaired by me there will be a Jomac sticker on them with a serial number, we do that to keep track of what was done and who for because for some reason people often claim someone has sent something to us on their behalf when they never did at all. Not saying Norman would do this but from memory there were some boards that sat for months after being repaired. If it turns out these are the ones and you are still having problems I will take care of them under warranty for you.
  10. Now that is next level restoration, amazing mate you should be proud of that effort!
  11. Sega Rally doesn't have voice, the voice data is part of the music data EG: at the start or end of music. You can call in anytime if you want to test ROMs or need new ones for anything.
  12. There is a guy over there I know well and does a great job rick@niemandisplays.com , while he doesn't do everything we do he does specialise in monitor repair.
  13. I haven't seen any ManxTT boards for a couple of months, are you sure they were sent to Jomac ? @Andyj965 , He is talking about whoever he had look at the machine from how I read it. Yes this is totally off topic and should be posted in the technical section.
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