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Author Topic: NeoTec NT-27E (San Francisco Rush) Need Help  (Read 136 times)

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grifter2

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NeoTec NT-27E (San Francisco Rush) Need Help
« on: September 12, 2019, 09:07:14 pm »
I recently bought a pair of San Francisco Rush games that needed a little love.

Both machines have the factory NT-27E Lian monitors from 1997, both monitors were really dim (cracked flybacks), wouldn't resize horizontally and also would jitter if left alone.

I bought new cap kits and flyback (MRCFT-923A) from Bob Roberts. I though the flybacks were correct, upon installing one i realized that while it was for a NeoTec it must not be for mine. Unfortunately i powered on the monitor with the wrong flyback.... no noise or smoke, just no picture. But i think this is what caused my problem.

I then did some more research and found the right flybacks  (MRCFT-216). After a cap kit and a new flyback the second board works great. However the first board (that had the wrong flyback in it for 5 minutes of operation is still having issues even after the cap kit and the proper flyback was installed.

The monitor has 3 board (the neck board, a horizontal sizing board, and the main board). I know the problem is with the main board because if i use the neck board, controls and horizontal sizing board in my working monitor it still works great. I also tried using the other picture tube that i know works with the exact same results. So the problem has to be somewhere on the main monitor board.

The symptoms. (I have attached photos). The monitor is able to reproduce red green and blue but the image is very dim. The flyback can be adjusted to make the screen wash out which a bright white light but the picture obviously washes out and then the horizontal lines start to show up. So in short its like the red/green/blue guns are WAY to dim.

I guess its possible i got a bad new flyback but i think its more likely that i blew something on the main board when installing the wrong flyback.

I should also mention that on the broken monitor i installed the cap kit before installing the wrong flyback, so its possible I now have a bad cap somewhere.

and i think i found the manual (with schematics) here.
https://www.arcade-museum.com/manuals-monitors/Neotec%20NT-27E.pdf

Thoughts on what i can check/replace?
« Last Edit: September 12, 2019, 09:35:23 pm by grifter2 »

grantspain

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Re: NeoTec NT-27E (San Francisco Rush) Need Help
« Reply #1 on: September 13, 2019, 06:27:42 am »
does the contrast pot work at all?

grifter2

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Re: NeoTec NT-27E (San Francisco Rush) Need Help
« Reply #2 on: September 13, 2019, 08:38:08 am »
yes the contrast pot changes the contrast, in fact every pot does make the proper change to the image,

unfortunately none of them will adjust enough to bring the colors back brighter.

grantspain

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Re: NeoTec NT-27E (San Francisco Rush) Need Help
« Reply #3 on: September 13, 2019, 11:26:30 am »
maybe a safety resistor has gone open, do you have the schems?

grifter2

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Re: NeoTec NT-27E (San Francisco Rush) Need Help
« Reply #4 on: September 13, 2019, 01:12:16 pm »
Here are the schematics

https://www.arcade-museum.com/manuals-monitors/Neotec%20NT-27E.pdf

I am unfamiliar with the term safety resistor.  What am I looking for?

grantspain

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Re: NeoTec NT-27E (San Francisco Rush) Need Help
« Reply #5 on: September 13, 2019, 02:19:02 pm »
so you proved the neck card and tube so issue must be on main chassis
check values of R429,R430, R524 and R526

grifter2

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Re: NeoTec NT-27E (San Francisco Rush) Need Help
« Reply #6 on: September 13, 2019, 06:30:42 pm »
Great, thanks, i am heading home from work now and will report back soon.

grifter2

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Re: NeoTec NT-27E (San Francisco Rush) Need Help
« Reply #7 on: September 13, 2019, 11:59:52 pm »
so you proved the neck card and tube so issue must be on main chassis
check values of R429,R430, R524 and R526

GRANTSPAIN you are my new HERO!!!!!

R526 was the ticket, pulled it out, showed 0 ohms, replaced with a new 1/2 watt 2.2 ohm resistor and the monitor works perfectly now!

I never even got to R429, its under the flyback so i figured i would try the easy 3 first.  R430 and R524 tested ok when compared to the values in the manual.


Thanks everyone for your help. the monitor lives again!!!!

grantspain

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Re: NeoTec NT-27E (San Francisco Rush) Need Help
« Reply #8 on: Yesterday at 03:55:36 am »
excellent, what about some photos of the game running

grifter2

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Re: NeoTec NT-27E (San Francisco Rush) Need Help
« Reply #9 on: Today at 08:03:58 am »
Pictures or it never happened :-)

Works great. Got the monitor back in last night and raced my wife for a while. Never got the whole unit together. To distracted now that they both work. :-)

It did have one other problem with a bad solder joint on the neck board that would cause blue to drop every once and a while. Found that pretty quick and fixed it with a short jumper wire.

Sorry posting these from my phone while waiting for my plane to take off and I cant figure out why my phone shows them rotated properly but the forum flips them.

Thanks again for your help!
« Last Edit: Today at 08:05:44 am by grifter2 »