----- HDTV Magazine Tips List -----
Richard,
Agree that direct view with two speakers on the side would be more suitable to that problem because
the magnets of the speakers would be closer to the CRT gun compared to an RPTV which have the 3 CRTs
in the center of a large cabinet, therefore giving at least one foot to either side to reach the end
of the TV cabinet, so even if you have the speakers edging with the TV cabinet, shielded speakers
should not be a problem.
However, some old speakers with large woofers and magnets that are not shielded could create enough
field to exceed a couple of feet, one case was the Allison Ones (a hi-end speaker made by the one
and only Roy Allison that I use to have), a magnetometer allowed me to verify that the two 10 inch
woofers of each speaker column were creating a heavy magnetic field, the field was dropping its
energy after two feet from the cabinets, which was not a problem for my particular installation and
the way those speakers should be installed (away from any lateral surface), but some people like to
use their large old stereo speakers edging the TV cabinet as part of their surround system, and in
such case that could affect the CRTs, not to mention using those as center in the floor right in
front of the CRT guns.
I agree with you that the strength of such field would not change in a way to produce different
effects of convergence, unless changing the location of the speakers relative to the TV. Also,
having the speakers playing or not does not typically affect the field strength, so the fact that
the surround system is active or not should not be a reason for a different magnetic field, so I
would cross that out of the behavior list Hal needs to take note to debug this problem, it should
not be produced by the surround system being on or off.
Ironically, using a magnetometer I was able to verify that the small speakers that are usually
included with RPTVs, even when they are a pitiful piece of ..., do generally create a field over the
CRTs position in the TV cabinet that is similar to the strength that shielded L/R columns create
from one and half feet away, however, unshielded speakers with oversized magnets (like the old 15"
Klipsch woofers) should be expected to create stronger fields and should be positioned as far away
as possible.
Regarding subs, some people put them right at front close to the RPTV CRTs, and keep changing their
position while testing where they sound more appropriate to the room, if that was the case of Hal I
do not know, we are all debugging a problem thinking in alternatives from the long distance of the
internet, I hope that with more suggestions he would not have to pay for a service call.
Best Regards,
Rodolfo La Maestra
-----Original Message-----
From: HDTV Magazine On Behalf Of
Richard
Sent: Thursday, September 22, 2005 2:26 PM
To: HDTV Magazine
Subject: Re: Convergence still impermanent
----- HDTV Magazine Tips List -----
> Do you have any source of strong magnetism close to the CRT tubes?
L/R large speakers which low
> frequency woofers (typically located low in cabinets) might not be
properly shielded for example?
>
> Do you have unshielded center speaker/s close to the CRTs down below
or down in front of the TV
> cabinet? About any subs in the vicinity? Any tactile transducers?
I have never seen this cause a convergence problem as described. The
only problem this would create is you having set the convergence
correctly and then move the TV or the speakers which would definitely
change the response.
Direct view CRT is a different story...
http://www.hdtvmagazine.com/forum/viewtopic.php?t=4809
Richard Fisher
www.HDLibrary.com Published by Tech Services
A division of Mastertech Repair Corporation
Rodolfo La Maestra wrote:
> ----- HDTV Magazine Tips List -----
>
> Hal,
>
> I believe you were already recommended to perform convergence only after the set has properly
warmed
> up; since I believe you did not mention that you actually did that on your further emails, I hope
> you did (or do on your next adjustments).
>
> Do you have any source of strong magnetism close to the CRT tubes? L/R large speakers which low
> frequency woofers (typically located low in cabinets) might not be properly shielded for example?
>
> Do you have unshielded center speaker/s close to the CRTs down below or down in front of the TV
> cabinet? About any subs in the vicinity? Any tactile transducers?
>
> You can get a magnetometer and measure the magnetic force if you like to make 100% sure.
>
> Having the convergence as bad as you describe on a daily basis, assuming you have performed and
> saved the changes correctly, is not normal. Is it consistently happening every time or there are
> periods when the convergence holds its adjustments? Any particular pattern of events? Is it
always
> off equally to the last convergence time, or it varies?
>
> Are you making the convergence adjustments in the user memory or the service mode memory?
>
> If the set is still in warranty I would recommend to place a service call before it runs out.
>
> Best Regards,
>
> Rodolfo La Maestra
>
>
>
>
>
>
>
>
>
>
> -----Original Message-----
> From: HDTV Magazine On Behalf Of
> Hal Turner
> Sent: Wednesday, September 21, 2005 10:10 PM
> To: HDTV Magazine
> Subject: Convergence still impermanent
>
>
> ----- HDTV Magazine Tips List -----
>
> Can anyone out there offer some advice for my convergence problem?
>
> Every morning the TV's convergence is bad, and it's NOT the same as the day before (which
> indicates to me that the problem is not an issue with saving my daily changes).
>
> Any techs out there have any ideas?
>
> Thanks!
> Hal
>
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