Astro City sync issues?

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nikolash
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Astro City sync issues?

Post by nikolash »

Hello,

On a ms9-29 with 15khz pcb i have this :
Image
The chassis is set on "low res" (15khz), i try to ajust H.H.15 pot but problem still there.

Any idea?
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DaveyD
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Re: Astro City sync issues?

Post by DaveyD »

Do you have more than 1 pcb to try in the cabinet? If so do they all act the same?
nikolash
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Re: Astro City sync issues?

Post by nikolash »

Yes, i try with a mvs slot and parodius pcb.
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Asayuki
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Re: Astro City sync issues?

Post by Asayuki »

Is video ground properly and actually connected?
My 15kHz cabinet Peplos will never power up, with any item, and I am quite proud of that.
nikolash
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Re: Astro City sync issues?

Post by nikolash »

You're right, it could be a ground problem, what can i check? Because with another chassis no problem.
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Asayuki
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Re: Astro City sync issues?

Post by Asayuki »

Look at the jamma pinout around on google. Near the sync pin there should be video ground. Try beeping from the chassis ground to the jamma board ground and see if there is connection. Some boards and some harnesses don't have connection there so you might want to check the obvious first.
My 15kHz cabinet Peplos will never power up, with any item, and I am quite proud of that.
nikolash
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Re: Astro City sync issues?

Post by nikolash »

I have continuity between ground on chassis and video ground on jamma.
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grantspain
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Re: Astro City sync issues?

Post by grantspain »

does the h.h 15k have any affect?
nikolash
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Re: Astro City sync issues?

Post by nikolash »

Yes but i can't stabilize picture.
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grantspain
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Re: Astro City sync issues?

Post by grantspain »

i am not sure if i have seen that fault on that chassis before but the issue is with the horizontal hold circuit -pretty sure its not sync related
what is the history of the chassis?
nikolash
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Re: Astro City sync issues?

Post by nikolash »

I bought it to a friend for spare, turn off directly after power on.
A capkit was done but 6 caps didn't have good values. I change bad caps, la7837 and la7853 and now it starts with this sync problem.
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Re: Astro City sync issues?

Post by nikolash »

So what can i check? You think it could be a ground fault?
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grantspain
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Re: Astro City sync issues?

Post by grantspain »

i really can't tell you what the problem is without having it infront of me
sometimes you have to admit something is beyond your skills
nikolash
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Re: Astro City sync issues?

Post by nikolash »

I'm know but i'm obstinate...Sometimes I can stabilize the picture but it's not good:
Image
Also vertical size don't work (chassis and remote).
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Eddhorse
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Re: Astro City sync issues?

Post by Eddhorse »

If you arent gonna send it for repair, at least put up some pictures of the chassis.

I had a similar issue recently, grant had it fixed and back to me in a week. He is the expert.

The other thing is that i found was that my time is worth money, so spending 2 weeks looking at an issue, head scratching and reading page after page on the internet didn't solve my problem. It was beyond my skills and i was wasting my time.

My 2c

Ed
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zak
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Re: Astro City sync issues?

Post by zak »

Eddhorse wrote: grant had it fixed and back to me in a week. He is the expert.
What he said :thumbup: Grant is a level 11 wizard! :awe:
nik2000
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Re: Astro City sync issues?

Post by nik2000 »

nikolash wrote: April 18th, 2016, 7:52 pm I'm know but i'm obstinate...Sometimes I can stabilize the picture but it's not good:
Image
Also vertical size don't work (chassis and remote).

hey, did you ever identify what the exact issue was? / how to fix?

my monitor has exactly the same problem

(sorry for bringing up an old thread)
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copados33
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Re: Astro City sync issues?

Post by copados33 »

Check C452, its a plastic cap which is located on the solder side of the chassis pcb, it shoud read 1.0nF, if its bad you don't need to remove it, just place a good one over it, there are even actual solder holes/points on the parts side to place a ceramic cap in there, a bad C452 can cause v.sync issues when its on its last legs, but if you remove it or is completely burnt it will give you all sorts of problems.
nik2000
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Re: Astro City sync issues?

Post by nik2000 »

copados33 wrote: October 8th, 2020, 12:54 pm Check C452, its a plastic cap which is located on the solder side of the chassis pcb, it shoud read 1.0nF, if its bad you don't need to remove it, just place a good one over it, there are even actual solder holes/points on the parts side to place a ceramic cap in there, a bad C452 can cause v.sync issues when its on its last legs, but if you remove it or is completely burnt it will give you all sorts of problems.
thank you, will take a look!
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