Auteur Sujet: Sega G-loc deluxe motor power supply  (Lu 10915 fois)

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« Réponse #80 le: Lundi 25 Février 2019, 10:15:12 am »
  • Hey that's a nice game room !


    Hi

    Thanks  :D I am also proud of my room  :D but i need more space.

    Super to follow your repair  ^-- I hope that the L2 transformers arrive soon.

    Your IC 9-10-11-12 (78L05 / 5 volt regulators) might also be dead and give over 5V
    I have learned if they put out over 5V then the PC910 might also be fried, and need to be replaced.

    Also remember to test the big diodes, the Q19 and Q22 seems always to be the one who go bad first.

    Kind regards
    Per

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    « Réponse #81 le: Lundi 25 Février 2019, 10:16:57 am »
  • Hi,

    Wow !! Your gameroom is fantastic Per !!  :o

    Pinballs, dedicated cabs, including sitdown race cabs, a cocktail table, a pool table, pachislots, etc !

    It's so varied and so well arranged ! Your bar corner and its jukebox is awesome too ! ^-^

    You must be very proud and vey happy with such a nice gameroom : a complete success !  :-)=

    Thanks  ^-^
    Kind regards
    Per

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    « Réponse #82 le: Lundi 25 Février 2019, 12:40:23 pm »
  • Yes. Quite right about other devices failing which might be unrelated. I found IC2 was dead, and it's not directly part of the low voltage power supply using L2. I tested IC2 with the OP-AMP tester I built for another repair project (vintage drum synthesizer) which had dozens of OP-AMPS:


    For now, I put the G-Loc project aside, awaiting your L2 transformers  =:))
    When I install the new transformer, I'll have to check EVERYTHING very carefully before I turn it on.

    Cheers for now!


    Pinball:
    Black Knight by Williams (2 off) 1980
    High Flyer by Bally 1977 (Electromechanical bingo machine)
    Video:
    Space War by Vectorbeam 1977

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    « Réponse #83 le: Samedi 02 Mars 2019, 14:05:02 pm »
  • Hi all.

    Thanks to Per and his very fast shipping, I have received 3 beautiful new L2 transformers ^-^


    After testing EVERYTHING else, I installed the new L2 and tested.... No smoke or burning  :D
    The main 12v supply is perfect  ^-
    The 15v "delay" supply is perfect   ^-
    It seems though, that the other 15v windings are still not enough. In theory, as they use a 78L15, we need at least about 17v on the cathode of the rectifying diode (eg. D11). The 78L15 has about a 2v dropout voltage (depending on the manufacturer), so we need 15+2=17v.
    I adjusted trim pot (marked "VR2 +5v") on the 12v rail up to 12.6v, as it's the reference, and I can now get 15.1v on the cathode of D11 which is still not really enough to supply the 78L15  :(

    The 78L15 gives out about 14.5v  :(
    I've not tested anything else.

    Where to from here....?    :'(
    Maybe find a low dropout 15v regulator as a replacement for the 78L15 ??
    Does anyone have any ideas ?

    Cheers for now.


    Pinball:
    Black Knight by Williams (2 off) 1980
    High Flyer by Bally 1977 (Electromechanical bingo machine)
    Video:
    Space War by Vectorbeam 1977

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    « Réponse #84 le: Samedi 02 Mars 2019, 14:33:14 pm »
  • Hi

    Super that they made it to you, and also relativly fast  ^-^
    I hope that someone have a solution for the low volts issue.
    Love to follow your repair  ^-


    Kind regards
    Per

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    « Réponse #85 le: Samedi 02 Mars 2019, 14:43:03 pm »
  • Hi Per.

    Thank you for the transformers  ^-^
    You are so kind to send them so quickly !

    You mentioned that the first batch of transformers had low 15v. So you had another batch made.
    I have a copy of the "Specification for approval" for the first batch.
    What exactly was made different in the second batch of transformers ?

    Cheers.
    Pinball:
    Black Knight by Williams (2 off) 1980
    High Flyer by Bally 1977 (Electromechanical bingo machine)
    Video:
    Space War by Vectorbeam 1977

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    « Réponse #86 le: Samedi 02 Mars 2019, 14:49:45 pm »
  • Hi

    I told them that the 15v where low, but i do not know what they have changed, I also asked them for the datasheet for the new ones but i newer got it.

    They wrote that they have changed the number of windings on the 15v side.
    Kind regards
    Per

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    « Réponse #87 le: Samedi 02 Mars 2019, 15:01:31 pm »
  • Si vous avez 15 volts alternatif en sortie du transformateur ca doit faire env 17 volts une fois redressé non?
    « Modifié: Samedi 02 Mars 2019, 19:00:42 pm par lencouet »

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    « Réponse #88 le: Dimanche 03 Mars 2019, 12:09:07 pm »
  • Hi all.

    Yes, ordinarily we might get 17Vdc from 15Vac, but we have half-wave rectification, and not a sine wave. Plus it also depends on the load...... But you will see below it's all much simpler....

    Per, I was thinking about the 15V windings on your transformers. In theory, all 15V supply windings should be the same, right?  So why does the 15V-delay supply provide about 18Vdc before the zener-transistor regulator... :? This is what I want from the other 15V supply windings after rectification, so the 78L15 regulators (IC5 and IC6) can function correctly.
    What's different ?

    If I measure, with the multi-meter, the cathode of one of the (low) 15V supplies, I get 15.1Vdc (as my last post shows).
    BUT now looking at the waveform with the Oscilloscope shows something quite wrong:

    ...there's about 8V of ripple  >:(
    The 15V-delay supply has a 470uF capacitor. So I temporarily connected a 470uF capacitor across C30 in the low 15V supply. It gave 18V  ^-
    Now I begin to wonder about the original capacitor, C30   ):)
    I took out C30 which was supposed to be 47uF but it measures a few hundred pF  >:D

    It's almost as if there is no capacitor !!!!
    No wonder there is so much ripple !
    (I tested at 10KHz, as the supply is switching at about 90KHz, but the tester does not go higher in frequency. A new capacitor measures correctly at 10KHz)

    I replace C30 with originally specified 47uF low ESR and get very little ripple:

    As you can see, there is about 250mV ripple, which is acceptable  ^-

    More importantly, I get almost 18V before the 78L15:

    Of course the 78L15 regulator IC6 is now giving 15V as expected  ^-

    I did the same on the other 15V supply, and checked C28. It was also a few hundred pF   >:D
    I replaced C28 and everything is good  :-)=

    In summary, it seems that the L2 transformers from Per are good  ^-^
    Thank you again, Per, for getting the transformers made and sending some to me. I can't thank you enough  8)

    The golden rule is to check the filter capacitors, or just replace them if there is any doubt. I found out the hard way, and spent a lot of time looking for a problem which turned out to be quite simple  :-[

    It might be worth checking or replacing all of your small electrolytic capacitors (eg. C13, C28, C30, C25, C26, C27, C19, C20, C21, C36, C18), it might solve (or prevent) all sorts of strange problems  :D

    Next step is to put the triac back in, as well as the OP-AMP and 5V regulator for the logic circuits.

    Cheers for now.
    Pinball:
    Black Knight by Williams (2 off) 1980
    High Flyer by Bally 1977 (Electromechanical bingo machine)
    Video:
    Space War by Vectorbeam 1977

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    « Réponse #89 le: Dimanche 03 Mars 2019, 12:24:37 pm »
  • bravo
    c'est un peut a ça que je pensé et c'est vrais qu'il vaut mieux travailler avec l oscilloscope que le multimètre

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    « Réponse #90 le: Lundi 04 Mars 2019, 23:40:26 pm »

  • In summary, it seems that the L2 transformers from Per are good  ^-^
    Thank you again, Per, for getting the transformers made and sending some to me. I can't thank you enough  8)

    The golden rule is to check the filter capacitors, or just replace them if there is any doubt. I found out the hard way, and spent a lot of time looking for a problem which turned out to be quite simple  :-[

    It might be worth checking or replacing all of your small electrolytic capacitors (eg. C13, C28, C30, C25, C26, C27, C19, C20, C21, C36, C18), it might solve (or prevent) all sorts of strange problems  :D

    Next step is to put the triac back in, as well as the OP-AMP and 5V regulator for the logic circuits.

    Cheers for now.


    Hi

    Whau - nice job  ^-^ and I am happy that my L2 transformers are working  :-)=

    I have just looked in my excel sheet from when I tried to use one of my L2 transformers, an ran into the problem with low 15V.
    As i can see I had changed C28 and C30  them to new 47uf... but I need to check visual at my two "spare" power supplys, if I have mounted 4.7UF... I can be... 

    Nice work restoring! - also all your super discovery If just I know how to use an Oscilloscope  :D
    Kind regards
    Per

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    « Réponse #91 le: Mercredi 20 Mars 2019, 10:48:58 am »
  • Hi corner-tech

    Some new status?   :D
    Are the g loc up and running ?
    Kind regards
    Per