Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Old March 29th 16, 06:24 PM posted to sci.electronics.repair
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Default Flyback replacement on a historical arcade machine.

I didn't mean those, I meant the later ones with the kamikazi power supply using I think the 2SC4834s.

If I am not mistaken, those 2SG613s mostly blew because of a drive fault. Lose the negative pulse to the gate and it stays on too long and boom.

In the earlier ones, I think the SRC (sine resonance choke) saved alot of flybacks from overload. The SRC was there to increase the efficiency of the HV rectifiers.

Talk of these Sonys brings back a memory. I was working on a stock 26" console. (you know a toilet seart manufacturer made those cabinets, the only one could meet the specs, and like three guys could sit on top of one and you can still roll it across a thickly carpeted floor) I was pulling the control unit from the front and somehow caught the CRT board and broke the neck.

I thought ih ****, there goes a couple hundred bucks, but that ain't how it is. Under warranty all you sent back was the neck of the CRT. They said to write it up as "unable to get good convergence". I almost had to laugh, with the neck broken like that, damn right I can't get good convergence. They even paid me to change it ! Well after all Sony paid them.

Really, it was dishonest but things like that happened VERY rarely.

And now I work for factory service for RSQ, which is a marketer of Karaoke machines. They are cheap Chinese or Korean built, but what isn't anymore ? They are actually modified DVD players. In the same building is a retail outlet for them and a few other things. It's like I got two jobs in one. But anyway, they do not record the serial numbers or anything. If I fix something and it breaks again nobody has any way of knowing. Also, as I pointed out to them, the customers could rob us blind if they knew.

Good old American business, but the money spends just fine.

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Old March 29th 16, 08:14 PM posted to sci.electronics.repair
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Default Flyback replacement on a historical arcade machine.

On 03/24/2016 1:44 AM, Top Cat wrote:

...
I hope someone can help me.

I have an extremely old CRT attached to a Space Invaders B&W arcade cabinet.
There is no available schematic, that I can find. The flyback has died but
there is no modern replacement, mainly because the documentation for the
historical model is non existent. So I dont know the input or output
voltages, I have no circuit diagram, and I cannot find anything to determine
what its input/output parameters can be. I do have the old flyback, I know
the monitor size, and I have the actual circuit.

The model is marked as "Toei GM-140 TV MONITOR". It was produced around
1979; or from 1976 onwards.

My question is this: Can one retro/reverse engineer or somehow determine
what modern equivalent could replace a flyback in this circumstance. Is
this possible?



YOu may want the game to stay as it is, but if you just want to play the
game, you may want to look at some of the converter boards made that will
let you use a VGA type of display, either CRT or the newer LED types.



I have Taito B&W monitor schematics that I am trying to scan, they are
old blueprints and they have turned VERY blue, so my colour scanner is
having a bit of trouble.

Email me and I will send you what I have...

John :-#)#

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Hi John, if I could look at what you have that might be the answer to my prayers. I can't find your e-mail though. Am I being dense? Is it glaring at me somewhere? Cheers.


Hi Chris,

I have now scanned my files and they are legible. Is there any marking
on your monitor? Letter and number codes? Failing that, what is the
number on the picture tube?

I scanned these as TIFs and they are huge (100mb) because they are
blueprints. If anyone can convert scanned blueprints to straight B&W I
would be happy to share these via dropbox.

My return email is valid! Or replace spam with jrr if you prefer.

John :-#)#

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Old March 30th 16, 01:09 AM posted to sci.electronics.repair
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Default Flyback replacement on a historical arcade machine.

"I scanned these as TIFs and they are huge (100mb) because they are
blueprints. If anyone can convert scanned blueprints to straight B&W I
would be happy to share these via dropbox. "


Pretty sure I can do that in PSP, and save them in JPG format so they aren't so huge.
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Old June 11th 16, 03:43 PM posted to sci.electronics.repair
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Default Flyback replacement on a historical arcade machine.

Thanks for all the chat. The flyback had smoke emanating from the point where the cable comes out. I switched it off and am trying to find information on what I should and shouldn't be doing to repaid the chassis pcb.


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Old June 11th 16, 05:19 PM posted to sci.electronics.repair
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Default Flyback replacement on a historical arcade machine.

On Thursday, March 24, 2016 at 8:41:39 PM UTC, wrote:
"I think you've hit the nail on the head, in terms of wanting to keep it as original as possible. I realise that may not be possible eventually, but I so want to try. I have bought a converter ready, and tested it but could not for the life of me get an image to show."


I think most of those convertors are designed for NTSC input, and this might not be NTSC. It could be anything.

If you have to retrofit a different fly in there that can be hairy, even scary. The first thing to know is how many pins are used. It may have eight or ten pins, but the less of them used the better. Also look se if there is a focus output, if monochrome it might be automatic focus which gets you off the hook there.

Ideally, there would only be three pins on the bottom connected. If so you got to balance three parameters. One is the pulse width and amplitude for the yoke. Then you have to get the right HV level at the same time. It may require compromises.

If there are scan derived sources off of it the plot thickens. Best to just figure on replacing those sources somehow.

Now, if you get a flyback for it with an open core you can put some windings on it. Either bucking or boosting, or maybe for a supply. I had to put a bucking winding on one a long time ago to match a yoke on a replacement CRT because the yoke native to the chassis would not converge properly. But that was then.

Scan derived sources are not as common in stuff like this as they were in TVs. You might get lucky.

Retrofitting the wrong fly in there can be tricky. You will need a variac.. Also probably a selection of capacitors. And then you might have to install a regulator to get the HV where it needs to be.

In this case, since it is probably reactive scanning, the vertical sweep will tell you when you got it right. You are playing with the horizontal so you can't count on that.

This can be done, it is just a matter of how much time and trouble it will take.


That's super advice and well advanced. I am clearly in over my head. I will start reading and learning more on the subject, before I attempt to fix it. I really do want to keep it original for the sake of preservation. I'm not trying to make a buck or just to play the game. I'm exited to bring it back to life. ...One day.
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Old June 12th 16, 03:38 AM posted to sci.electronics.repair
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Default Flyback replacement on a historical arcade machine.

On 11/06/2016 23:43, Top Cat wrote:
Thanks for all the chat. The flyback had smoke emanating from the point where the cable comes out.


I switched it off and am trying to find information on what I should and
shouldn't be doing to repaid the chassis pcb.

Look Here?

http://www.hrdiemen.com/reparation/flyback/index

Colin

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Old June 12th 16, 09:40 PM posted to sci.electronics.repair
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Default Flyback replacement on a historical arcade machine.

On 06/11/2016 8:19 AM, Top Cat wrote:
On Thursday, March 24, 2016 at 8:41:39 PM UTC, wrote:
"I think you've hit the nail on the head, in terms of wanting to keep it as original as possible. I realise that may not be possible eventually, but I so want to try. I have bought a converter ready, and tested it but could not for the life of me get an image to show."


I think most of those convertors are designed for NTSC input, and this might not be NTSC. It could be anything.

If you have to retrofit a different fly in there that can be hairy, even scary. The first thing to know is how many pins are used. It may have eight or ten pins, but the less of them used the better. Also look se if there is a focus output, if monochrome it might be automatic focus which gets you off the hook there.

Ideally, there would only be three pins on the bottom connected. If so you got to balance three parameters. One is the pulse width and amplitude for the yoke. Then you have to get the right HV level at the same time. It may require compromises.

If there are scan derived sources off of it the plot thickens. Best to just figure on replacing those sources somehow.

Now, if you get a flyback for it with an open core you can put some windings on it. Either bucking or boosting, or maybe for a supply. I had to put a bucking winding on one a long time ago to match a yoke on a replacement CRT because the yoke native to the chassis would not converge properly. But that was then.

Scan derived sources are not as common in stuff like this as they were in TVs. You might get lucky.

Retrofitting the wrong fly in there can be tricky. You will need a variac.. Also probably a selection of capacitors. And then you might have to install a regulator to get the HV where it needs to be.

In this case, since it is probably reactive scanning, the vertical sweep will tell you when you got it right. You are playing with the horizontal so you can't count on that.

This can be done, it is just a matter of how much time and trouble it will take.


That's super advice and well advanced. I am clearly in over my head. I will start reading and learning more on the subject, before I attempt to fix it. I really do want to keep it original for the sake of preservation. I'm not trying to make a buck or just to play the game. I'm exited to bring it back to life. ...One day.


For a converter you want to get the Composite Video style, not the RGB.
Your game (SI) puts out B&W composite video...

Something like this:

http://www.ebay.com/itm/Tv-Rca-Compo...-/321366580263

John :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."


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