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Thread: Focus adjust failing on flyback G3. Hope it's not termial.

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    Focus adjust failing on flyback G3. Hope it's not termial.

    UPDATE: Save your time and money. The Kaga Denshi or Nanao KZ-20EN does not have a replacement flyback MSH1FAC02. No one is making them! The MSH1FAC13A wont do. The MSH1FAC11A won't do. Until someone makes a MSH1FAC02 the chassis is out of order! There's some interesting stuff in here but dont waste you time and money trying anything eles. Read on and be amused and confused if you like. Now on with the thread.....

    Hi Joey,

    I think myflyback is on the way out?
    NANAO KZ-20EN
    I get the tube in focus but the little spark gap glass tube on the back of the neck board begins to tick.

    I think it's getting worse. I have to keep rolling back the focus a little every couple of hours of game play. Getting more and more out of focus. Aaaah.

    I think flyback is on the way out?

    Prognosis negative?

    The voltage at the 800mA fuse is 110V. Schematic says should be 105V. But I doubt that's is issue.
    The monitor is operating nicely otherwise. Sigh.
    Cheers Ro
    Last edited by taito; 9th August 2017 at 08:40 PM. Reason: To save every body the pain and suffering

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    You might be lucky with this one , quite often it's corrosion inside the socket but it's hard to see without breaking it open , best to just replace it and resolder the focus lead back into the neck board.

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    Quote Originally Posted by Jomac View Post
    You might be lucky with this one , quite often it's corrosion inside the socket but it's hard to see without breaking it open , best to just replace it and resolder the focus lead back into the neck board.
    Thanks Joey,

    Ive been all over the neck board and the neck pin sockets are all clean as a whistle. Plus checked resitors and cleaned up the back. Only to get a very dissapoint result. No change.

    The G3 (focus) pin 1, starts around 400V at power on, but rises a volt every 5-10 seconds up to 429 where SP-6 starts sparking.

    Something's causing the voltage to rise and that could be a symptom to another problem. See below.

    Joey, what's the expected voltge range of the flyback focus output, G3? If this voltage rise is normal as part of the warmup the fault could be elsewhere, -a case of G3 being set too high by the user because the chassis is not opperating properly properly because of something else is not right.
    I sadly suspect the flyback, but another type of fault could be causing the voltage to ramp.

    Here's hoping...

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    The focus does drift as the tube warms up, you will notice the screen voltage doing the same but not as much.
    These chassis are plagued with leaky diodes and can cause the strangest faults, really if you want any stable results best to replace all the glass diodes all over the chassis and the silicon diode beside the flyback, you need to keep in mind that 1volt variation on the flyback primary is multiplied many times on the output side.

    The focus and screen control pots are another problem these flybacks have if they have been near moisture or even worse ( cleaned with water ) , so tip the chassis up so you can get some isopropyl into the front of the flyback around the focus control and turn it full scale both ways a few times , you will feel the wiper starting to contact better , then let it dry for a while before switching on because if it's still wet and arcing you will get flames!!
    If this makes no change and the voltage is still rising as it warms up you can easily isolate it by spaying the front of the flyback with some freeze spay and see if it changes the voltage / focus , if no change then something else is leaking or drifting in value.
    These pots on the front of the flybacks while troublesome aren't where they normally let go , it's the internal windings that arc and short together

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    Quote Originally Posted by Jomac View Post
    The focus does drift as the tube warms up, you will notice the screen voltage doing the same but not as much.
    These chassis are plagued with leaky diodes and can cause the strangest faults, really if you want ...

    Thanks Joey! That's very helpful. Cheers.

    Ill give these suggestions a go, probably starting with the diodes. I really appreciate your response. Thanks mate.

    In the meantime I've dropped screen voltage considerably, put the brightness to full and turned up the RGB cut off on the neckboard. Ive got a decent picture, sharp, and SP-6 hadn't complained once. So I can play! Edit; Few hours play but sp-6 started ticking again.

    I'll have to see how I go with those suggestions.
    Last edited by taito; 28th June 2017 at 03:12 PM.

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    Hi Joey,

    Can I put a MSH1FAC13A
    into my KZ-20EN-F?

    In another post you said the following.

    Quote
    The real model number of this chassis is a Kaga KZ-20EN , it is a 12 pin tube only and uses the MSH1FACO2 Flyback)
    End quote.

    The current flyback back in the chassis that ticksof has a different part number than you decribe. Plus it has solder flux so its not factory. It reads MHF028- xxx can't read that last bit. Obscured by the cage.

    Question :

    Could this be the wrong flyback in there, hacked in, and maybe causing the problem?

    And can I put a MSH1FAC13A into my
    KB240331C? (Kaga Denshi KZ-20EN-F)
    Thanks.

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    I'm pretty sure that flyback was hacked in. It explains the cut high tension lead too. So this sick puppy was never going to work right as it stands.

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    Quote Originally Posted by taito View Post
    Hi Joey,

    Can I put a MSH1FAC13A
    into my KZ-20EN-F?

    In another post you said the following.

    Quote
    The real model number of this chassis is a Kaga KZ-20EN , it is a 12 pin tube only and uses the MSH1FACO2 Flyback)
    End quote.
    The flybacks are the major difference between the 2 models , the MSH1FAC13A is for the 10 pin version KZ-20ES which needs a higher focus voltage, pretty much what you are experiencing now with the hacked flyback in there.

    Question :

    Could this be the wrong flyback in there, hacked in, and maybe causing the problem?

    And can I put a MSH1FAC13A into my
    KB240331C? (Kaga Denshi KZ-20EN-F)
    Thanks.
    MHF028- xxx No Idea what this flyback is , would be curious to know full part number.

    Yes the MSH1FAC13A physically fits, is the same pinout and will give you a picture but if it is a genuine original then you won't be able to get it focused because the focus voltage is to high even at minimum setting.
    If you are talking the after market MSH1FAC13A seen selling recently there has been a modification made internally that brings it much closer , with some tubes it is perfectly acceptable but a minor issue is that the mod has effected the flyback when used in the chassis it was intended for, it causes slightly lower vertical deflection and a slight pin cushion distortion.
    It's not really possible to make one flyback to perfectly suit both models hence why there are 2 different flybacks, the after market one is about as close as you can get.

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    Quote Originally Posted by Jomac View Post
    The flybacks are the major difference between the 2 models , the MSH1FAC13A is for the 10 pin version KZ-20ES which needs a higher focus voltage, pretty much what you are experiencing now with the hacked flyback in there.



    MHF028- xxx No Idea what this flyback is , would be curious to know full part number.

    Yes the MSH1FAC13A physically fits, is the same pinout and will give you a picture but if it is a genuine original then you won't be able to get it focused because the focus voltage is to high even at minimum setting.
    If you are talking the after market MSH1FAC13A seen selling recently there has been a modification made internally that brings it much closer , with some tubes it is perfectly acceptable but a minor issue is that the mod has effected the flyback when used in the chassis it was intended for, it causes slightly lower vertical deflection and a slight pin cushion distortion.
    It's not really possible to make one flyback to perfectly suit both models hence why there are 2 different flybacks, the after market one is about as close as you can get.

    Thanks Joey. When you talk about the after market MSH1FAC13A you mention there's an issue when used with the chassis it was intended. Do you mean the KZ-20ES? You're saying... putting one of these modified MSF1FAC13A into a KZ-20ES chassis doesn't work properly because of the the modification?

    I have the lower voltage focus chassis, KZ-20EN, with the original tube, 510UKB22, so the modified after market one may just work for me.

    That's what I got from what you said above. It may be perfectly acceptable? If indeed it is the modified MFS1FAC13A you speak of? If it's not, then I'll never get it into focus.

    BTW I found this in another post...http://www.aussiearcade.com/showthre...ega-MC-2600-SC

    The sticker on the flyback:
    MSH1FAC11
    GF13053A1

    Stamp on the flyback:
    MHF-028-21
    7402

    Hey so it was the right uht after all. Just the stamp I was reading.

    UPDATE: l found a resistor near the flyback that looked slightly damaged but it tested OK. 5 ohms R525.

    Replaced it and the sp-6 stopped sparking.

    That was a bit of an anxious wait.

    An hour or so in and still good. Left it running for another half hour and when I returned could smell that faint but distinct smell of burnt semiconductor. And there's a small regular tick coming fron the flyback area. Sigh.

    Out of one frying pan into another frying pan.
    - The Young Ones

    So I still need another flyback before the whole thing goes up and makes my whole place stink!

    Still we're enjoying the game. Good game play, so addictive, can easily see why it became the best earner of its era. So glad I persevered with that game pcb. Ill be the first to admit I almost lost my mind, still searching for parts of it.

    Cheers all.
    Last edited by taito; 30th June 2017 at 07:27 PM.

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    What more....

    Yes I did a search for the manual on arcade museum and made headway with my findings. ...


    This was lifted from another I started out of frustration.....
    http://www.aussiearcade.com/showthre...20EN-schematic


    Thanks mate I only wish Id asked sooner.

    Just after I posted this I did a search on arcade museum and found the sega MC-2000-S manual almost immediately. Which is what sega called the KZ-20EN.

    Yey! Beautiful numbers I can read and part numbers!

    It would have made life so much easier.

    Also learning to set srcreen voltage was the big win for me. I had mine up way too high.

    No wonder I could smell semiconductor burning.

    Well had a stack of stress free games.

    The screens not as bright as I'd like but hey...

    Im hoping this is the last I say about it.

    Been on for hours.

    Theres no spark at sp-6.
    There's not ticking sound.
    And the screen voltage is stable.

    I hope it says that way....

    The proof will be when it gets hot. I don't see it holding out long on a 30 degree day. Thank goodness it winter!
    Last edited by taito; 30th June 2017 at 11:02 PM.


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