Re: odd fault..

 I have a Wico XY pattern generator on pattern 6, just a straight grid.. its
a tried and tested setup, the CRT/hv/harness is all fine, its definately
_on_ the defelction pcb

 The almost pincushion-looking distortion is more worrying and bizarre, the
grid is distorted from how it should be - dead straight horiz and vertical.
Its not over deflecting...

 How to explain - hmm.. in the middle range of the deflection on a scope
image of the drive transistors where normally you see nice lines showing the
beam deflection path, it just turns into a cloud-haze. Q606/Q607 Q706/Q707
all measure in-circuit as perfectly fine. It feels like something is
affecting the +v supply, i went and checked the Z amplifer Q500/Q501/Q502 as
this uses the +v supply as well, but they all check out fine. The problem
affects both amplifiers..

 This is a bit like the Amplifone fault i had the other week, i'm sure its
going to be something completely unexpeced i'm sure.

--
Andrew Welburn
http://www.andys-arcade.com
----- Original Message ----- 
From: "John Robertson" <pinball@telus.net>
To: <vectorlist@vectorlist.org>
Sent: Tuesday, May 31, 2011 5:14 PM
Subject: Re: VECTOR: odd fault..
> Andrew Welburn wrote:
>> http://www.andysarcade.net/pix/DSC_1885.JPG
>>
>> Has anyone seen this before? its an LV2000
>>
>> CRT good, HV good, Loom good, PSU good (basically a good deflection works 
>> fine in the setup).
>>
>> Its very hard to explain whats going on with this as seen on my scope, 
>> and even harder to find whats actually wrong with it! all side by side 
>> comparisons i've done so far with a working deflection showup no 
>> differences. the only commnality i can see i think is that there is a lot 
>> of noise on the +ve supply. i think, anyway.
>>
>> I'm just throwing it out there in case anyone has seen this before...
>>
>> -- 
>> Andrew Welburn
>> http://www.andys-arcade.com
> Hi Andy,
>
> Well, it appears to be a problem causing the deflection to fade as the 
> display gets into the more positive range. The (-1,-1) bottom left corner 
> starts out OK and fades off as the values get close to (0,0).
>
> What are you driving this with? A board or a monitor signal generator? Bad 
> edge connections are always suspect but pretty sure you will have checked 
> those carefully
>
> John :-#)#
---------------------------------------------------------------------------
** Unsubscribe, subscribe, or view the archives at http://www.vectorlist.org
** Please direct other questions, comments, or problems to chris@westnet.com