Re: Amplifone problem

Thanks guys. I've tried a bunch (hopefully all) of the things you suggested. It's definitely not the PCB since I tried swapping it out with another. I tested everything on J103 for continuity and re-reflowed the solder just in case I screwed something up the first time. 

When I got down to checking the pins on the neck for continuity I ran into a little confusion with how they are numbered so I made a picture to reference instead.  It can be found here: http://i55.tinypic.com/28wj95l.jpg

The first pin on the left of the pic (not sure what # it's called but I believe it's ground) gets continuity with both of the ones indicated (the brown heater pins I believe they are).  Which I think you said is not a good thing right?

--- On Wed, 7/13/11, William Boucher <wboucher6@cogeco.ca> wrote:

From: William Boucher <wboucher6@cogeco.ca>
Subject: Re: VECTOR: Amplifone problem
To: vectorlist@vectorlist.org
Date: Wednesday, July 13, 2011, 6:16 PM

 The spot killer doesn't come on at all during normal operation, otherwise you would see the spot killer LED flickering all the time.  There's is a slight delay (due to filter circuit) between the time that X/Y deflection current goes to zero and when the spot killer activates.  The intention of the SK is to shut the beam off completely, even during what would be normal vector drawing, in the event of a total failure of deflection regardless of the cause.  What shuts the beam off in between vectors is the Z signal.   The Z signal in the case of a color monitor is actually 3 signals, R, G, & B.  I doubt that all three of the Z-amps have failed so look for something that is common to them all.  Maybe a missing ground lead from the neck board.  Sometimes it breaks off.  Refer to page 38 in the manual and note that J103 outputs the RGB signals along with a ground on pins 1 thru 4 respectively.   Also be aware that a short inside the tube can cause your problem such as heater to something.  Sometimes a heater isolation transformer can cure help this.  Other shorts might be dealt with in other ways.  Maybe you could power everything down, discharge the crt, remove the neck board, and use an ohmmeter to check for shorts from the heater pins to other pins.     William Boucher
http://www.biltronix.com ----- Original Message ----- From: Jess Askey To: vectorlist_at_vectorlist.org Sent: Wednesday, July 13, 2011 7:53 PM Subject: Re: VECTOR: Amplifone problem
that is is purpose of the spot killer circuit, to turn off the beam when it is at rest in the center of the screen between vector routines.... so, I would start to look at the circuit that senses the X/Y levels and affects the brightness of the beam... much like a 'blanking' signal.

See page 8 on the manual...

http://arcarc.xmission.com/PDF_Monitors/Atari%20Monitor%20TM-239%201st%20Printing%20Amplifone%2019in%20and%2025in%20Color%20XY.pdf

jess

On 7/12/2011 10:15 PM, John Huie wrote: What is the Z-signal and where would I find it to check the connection?  Is it carried on one of the pins on the wiring harness?

Turning the brightness down and then adjusting the colors up doesn't seem to help

Thanks guys.

--- On Tue, 7/12/11, Matt Quirk <quirk.matt@gmail.com> wrote:

From: Matt Quirk <quirk.matt@gmail.com>
Subject: Re: VECTOR: Amplifone problem
To: vectorlist@vectorlist.org
Date: Tuesday, July 12, 2011, 6:42 PM

> Yes, I've done that. But if I turn it down enough to kill the spot then I can't see any of the other graphics.
>
> --- On Tue, 7/12/11, Andre Sinclair <livnfree_can@yahoo.com> wrote:
>
> From: Andre Sinclair <livnfree_can@yahoo.com>
> Subject: Re: VECTOR: Amplifone problem
> To: vectorlist@vectorlist.org
> Date: Tuesday, July 12, 2011, 6:16 PM
>
> Turn the brightness down on the flyback.
>
> Sent from my Samsung Captivate(tm) on Rogers
>
> John Huie <jehuie@sbcglobal.net> wrote:
>
>>Hey guys,
>>
>>I'm new to Amplifone monitors and not all that technical anyway but I ordered most of the parts from Bob Roberts and rebuilt one that was completely dead.Β  Now it's working....mostly.
>>
>>The problem is that it has a bright spot right in the middle at all times.Β  I don't dare turn the brightness up because I don't want to burn the screen.Β  But the rest of the graphics are there and working fine.Β  I've just got that blasted extra bright dot in the middle.
>>
>>I set the voltage using a HV probe early on and I don't think it's changed.Β  I'll have to borrow a probe to check that.Β  But the B+ is hovering at +185.Β  I tried adjusting the color drive pots and it didn't affect the bright spot at all.
>>
>>Any more ideas or tips?Β  Thanks!
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Received on Fri Jul 15 15:08:15 2011