MS9-29 SU (Nanao Chassis 05A00585D1) problem

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dingsbums
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MS9-29 SU (Nanao Chassis 05A00585D1) problem

Post by dingsbums »

So I got a New Astro City :D - the screen was not working :(
Screen is a Toshiba Tube (labeled MS9-29 SU) , Chassis is also a MS9-29 SU (with a Nanao 05A00585D1 printing on it)

I decided to start with recapping the chassis :awe: - put it back together, screen was working perfectly. Sadly just for a few weeks :(
Since it's a vertical problem I reflowed the complete neckboard, the vertical deflection IC and the complete vertical IC area => but still the same problem :( .

So I'm out of ideas & stuck & I need somebody who is smarter than me when it comes to screens :awe: ( where are you @grantspain )

Here is the problem:

Picture after start of the cab:
Image

Picture after ca. 30 seconds:
Title screen
Image
In game
Image

Picture after ca. 1-2 minutes:
Image

Picture after ca. 5 minutes (perfect - as it should be from the start :awe: ) :
Image

When it is perfect like in the last picture and I turn the cab off to switch out a PCB (1-5 minutes) and turn the cab back on it is perfect again 8-) .
When I turn the cab off for longer than 1 hour and turn it back on the problem starts from the beginning :think: .

I need help please 8-) .
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RMRM
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Re: MS9-29 SU (Nanao Chassis 05A00585D1) problem

Post by RMRM »

Until Grant the guru arrives to save the day :awe: you could check the b+ voltage, i had a chassis that had a very similar effect before the b+ was adjusted.

It never hurts to check.
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grantspain
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Re: MS9-29 SU (Nanao Chassis 05A00585D1) problem

Post by grantspain »

it could be either the LA7837 or the LA7853, if it is vertical roll then it will be the latter
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dingsbums
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Re: MS9-29 SU (Nanao Chassis 05A00585D1) problem

Post by dingsbums »

RMRM wrote:Until Grant the guru arrives to save the day :awe: you could check the b+ voltage, i had a chassis that had a very similar effect before the b+ was adjusted.

It never hurts to check.
I have never measured the b+ voltage, so please let me know how / where to measure it :oops: . And how much voltage it's supposed to have, please.

I reflowed the 2 vertical pots on the chassis, the LA7837 & LA7853, the complete areas around the 2 LA chips, the connector to the remote on the chassis, the complete neckboard & the complete remote.
The problem is still the same :( .
grantspain wrote:it could be either the LA7837 or the LA7853, if it is vertical roll then it will be the latter
Thanks for pointing me in the right direction, mate :thumbup: :thumbup: :thumbup: . It doesn't roll, it's more like the picture is divided in two parts in the beginning and after ca. 30 seconds it does fold/roll together to one picture :think: .
With the top part of the picture looking liks it's folded over the top edge and this decreases slowly in about 5 minutes until the picture is perfect.

So you think the LA7837 and/or the LA7853 are bad ? Time to do some ordering :awe: .

Just to be sure, are these the correct replacements ?

LA7837
http://www.ebay.de/itm/1-x-LA7837-Verti ... Sw8axaLqml

LA7853
http://www.ebay.de/itm/LA7853-Integrier ... hhoQ15KmNw
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grantspain
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Re: MS9-29 SU (Nanao Chassis 05A00585D1) problem

Post by grantspain »

correct ic, be careful of the tracks -use good quality solder mop
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dingsbums
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Re: MS9-29 SU (Nanao Chassis 05A00585D1) problem

Post by dingsbums »

Today arrived the LA7837.
Changed it.
The problem at the top which slowly decreased in about 5 minutes is completly gone :thumbup: .
However the devided picture at startup merging together to one after 30 - 60 seconds is still there => guess that is the LA7853 :awe: (which is not here yet :cry: ).
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dingsbums
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Re: MS9-29 SU (Nanao Chassis 05A00585D1) problem

Post by dingsbums »

This week the LA7853 arrived finally.
Soldered it in today => all problems are gone, nice, complete & stable picture at start up of the cab :thumbup: :thumbup: :thumbup: .
Thanks in particular @Grantspain :thumbup: .
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