I have a Magnavox 20" TV that has the built in DBX speakers. Model: RH4350 WA01 and the chassis number: 20C9-01

And this set needs some convergence adjustment, especially at the top right corner and a little bit everywhere else. I'm going to be getting a physical copy of the service manual, but for now I got a PDF form to get me by.

This isn't something I've done before, so I feel a bit clueless when it comes to adjusting the yoke for the screen edges.

Here's a picture.
http://reeseriverson.com/rriverson/pics/IMAG0034-364pxw.jpg (http://reeseriverson.com/rriverson/pics/IMAG0034-1500pxw.jpg)
(Click for larger version.)

Also, there's two other things, and one I feel needs to be addressed before I even touch the convergence. Ever since I got this set, I never once heard the degaussing coil kick in, I thought it didn't have one until I pulled the back cover off earlier.

I always can hear these things kick in on computer monitors and other CRT sets, but certainly not this one. So looking at some of the schematics, I probed around and I'm not getting anything out of the thermistor. 120 volts is going into it but hardly a fraction of one volt's coming out of it. Anyone have any ideas? Most I've gathered is the SM says it's a 10.1 cold PTC.

Here's the thermistor.
http://reeseriverson.com/rriverson/pics/IMAG0052-364pxw.jpg (http://reeseriverson.com/rriverson/pics/IMAG0052-1500pxw.jpg)
(Click for larger version.)

Then lastly, I find the composite in to be touchy... like when I first power it up and run a game console or DVD player, the signal acts like it's not going through well or something, I have to unplug the cable from the DVD player or console and plug it back in. I don't have to touch the cable on the TV's input jack itself.

Plus if there isn't a clean RF signal being injected into the TV, I noticed the composite being effected a tiny bit.

I'm wondering if something may be up in the aux video amp circuit or something. I am thinking of checking things out there as well.


But other than that, the TV works wonderfully. :yes:

20 Inchers should normally look a little better, but not sure If you'll get it all better
than that.... If you have not done it before, be ready to do it several times to get it
right.....

Before you begin, look at those parts and see if the white glue has not dried
and cracked and let those parts move a little.... You may just be able to move them
back and reglue and be done with it....

Moving the yoke is pretty much for purity, If you don't have a purity problem, then
best leave it alone....

On the other hand, I did a Sanyo DS25250 or something like that, 25" it was horrible
when I got it, the glue cracked, and the entire assembly moved, no clamp.
When I was done, it was almost perfect, I thought my sister was going to take it
back, but she didn't we use it now full time, and it's really got a great picture...

Doing it is a little different than the delta gun set, but you can definitely get these
tubes much better looking....

Don't forget some of these tubes have little magnets actually taped to the tubes to
do fine conv. touchup.... Not sure if you have to remove them or not....

Good luck, please post your results.... !

I wish I would have documented that Sanyo, it's really a great performer and looks
great now..... Although not perfect in one corner, not that it matters it's really on the
edge....

.

The degauser "DGS" on most NAP sets works at turn off
not turn on like most. Also this one uses a triac instead of
the usual relay so no click. If the DGS were not working
you would soon have totally messed up purity.

73 Zeno:smoke:

The degauser "DGS" on most NAP sets works at turn off
not turn on like most. Also this one uses a triac instead of
the usual relay so no click. If the DGS were not working
you would soon have totally messed up purity.

73 Zeno:smoke:

The power stops flowing to the thermistor when I power the set off. I don't see any power going to the coil upon power on or off either.


20 Inchers should normally look a little better, but not sure If you'll get it all better
than that.... If you have not done it before, be ready to do it several times to get it
right.....
At least it'll be a learning experience. :yes:


Before you begin, look at those parts and see if the white glue has not dried
and cracked and let those parts move a little.... You may just be able to move them
back and reglue and be done with it....
No white glue, but it appears to be like a brownsish type of adhesive on the three wedges around between the yoke and the CRT tube. The yoke is fastened by a clamp.


Moving the yoke is pretty much for purity, If you don't have a purity problem, then
best leave it alone....


That's what I thought too, but it claims you do it for the edge convergence. :scratch2:

http://reeseriverson.com/rriverson/pics/convergence.jpg


On the other hand, I did a Sanyo DS25250 or something like that, 25" it was horrible
when I got it, the glue cracked, and the entire assembly moved, no clamp.
When I was done, it was almost perfect, I thought my sister was going to take it
back, but she didn't we use it now full time, and it's really got a great picture...
Awesome, I would simply like to get this Magnavox in that same condition. :thmbsp:


Doing it is a little different than the delta gun set, but you can definitely get these
tubes much better looking....
Ah, so that's what this type is, a delta gun?


Don't forget some of these tubes have little magnets actually taped to the tubes to
do fine conv. touchup.... Not sure if you have to remove them or not....

Good luck, please post your results.... !
Hmm, this one doesn't seem to have any. However, could I add any to help fine tune on this set?

Thanks, I likely will!

I wish I would have documented that Sanyo, it's really a great performer and looks
great now..... Although not perfect in one corner, not that it matters it's really on the
edge....

.

Documentation does help, so I hope this one can be one to be helpful. :D

It ain't a delta gun it is an inline gun. Delta guns were being phased out in the mid-70's and I'd be surprised in any new deltagun sets were sold after 1982.

Delta gun color CRT's are the first built. Delta comes from
the Greek letter delta which is a triangle. The three guns
are placed 120 degrees apart, usually blue on top. As tom said
the went away by the early 80's.
In line like yours all guns are in a strait line. Look at the neck
when its running you can see it.
In the end deltas will probably live longer. Some are 60 yrs old
& still going. Probably due to larger parts & the quality they
were made at.

On edge convergence leave everything tight. Remove the wedge
on the side its off. Bend the edge of yoke lightly & you will
see it change. If the yoke needs to be closer to the CRT
you may have to move the yoke forward to wedge it & also
may need to touch up the other side.

73 Zeno:smoke:

Yeah, the guns are in a straight line on this set.


On edge convergence leave everything tight. Remove the wedge
on the side its off. Bend the edge of yoke lightly & you will
see it change. If the yoke needs to be closer to the CRT
you may have to move the yoke forward to wedge it & also
may need to touch up the other side.

73 Zeno:smoke:

Okay, this is getting really helpful already, since I had no clue what to do with the yoke. lol

Now do I have to be careful when handling any part of the yoke? I know to watch out for where the flyback hooks into, I just don't know the voltages that could pass through the yoke.

Also, I think I may go take a picture of the yoke when I get home and post. To help verify what I need to do with what.

Any recommendations on what adhesive to use to reglue the wedge in place?

There are 1000 volt spikes on the hoz winding of the yoke.
Wont kill a health person but it will sure make you jump !
The windings are well insulated & I never got a shock there.
Just try to keep your fingers on the plastic.
BTW package in the mail

73 Zeno:smoke:


Yeah, the guns are in a straight line on this set.
Okay, this is getting really helpful already, since I had no clue what to do with the yoke. lol
Now do I have to be careful when handling any part of the yoke? I know to watch out for where the flyback hooks into, I just don't know the voltages that could pass through the yoke.
Also, I think I may go take a picture of the yoke when I get home and post. To help verify what I need to do with what.
Any recommendations on what adhesive to use to reglue the wedge in place?

Well, I haven't touched that yet, but I did some testing around with the degaussing coil.

I removed the thermistor from the circuit and tested it. Under normal room temperature, 12 ohms. Under ice it went down to 9.5. Then heat from my partially cooled off solder iron it went up to 20, so that seems to be doing its job.

The degaussing coil itself measures a 2 ohm resistance. Left unplugged upon first power up its pins are receiving a full 120 voltage.

Though when plugged in, it stays at 120 for a split second and drops down to 0.2 volts.

I thought degaussing coils get a steady voltage drop through the thermistor?

The degaussing coils are only powered for a very short time. You may only see a little
spike if you watched it on an analog meter.... Or you would see it on a oscilloscope.
Basically, if you watch the tv, turn it off, move it to a 90 degree angle turn it on hours
later, watch it, turn it off then turn it some other way do the same - again, and if you don't
see color splotches beginning to show up on the screen during a solid color advertisement
or something like that, then the degaussing system is working.....

Your tv is an in-line gun tv. The delta gun sets are easy to spot, they have three
opposing electromagnets on the neck of the tube in place of the multi-pole convergence
magnets on your tv.....

You should follow the instructions you have, that is the way I did mine, and it turned out
great !

But a good idea is to kinda push on the yoke corners gently as suggested but possibly
not remove the glue, or wedges unless you see some improvement. In my case, it
all was already all loose, so I was doing a setup kinda like at the factory....

When your done with this, it will have a much sharper and more perfect picture
than any delta 120 degree gun tv with the same size screen....

Reading the instructions you posted, you might just want to focus on the yoke
tilt. The center of your screen looks really good...... I'm going to have to
re-read the instructions I had for my Sanyo, it's the last inline set I did,
and I don't remember doing anything to the yoke.... I think it was still
fully fixed, and all I did was add more glue....

I used quality GE Clear Silicone on my set several years ago now....
I did not gob it on, just a little spot to keep it from moving.....
You ever try & move that dab that comes on the package....?
Pretty tough stuff....

I put the glue on top of stuff, not under things, so it could be easily removed
and would not "glue" anything together, just keep it from moving....

It's not like your going to go skydiving with the thing when yer done....

.