Donor Tubes looking for Chassis

plgDavid

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Hi

Typically people look for TV Tubes whose impedance match a chassis they already own, but in my case two TVs I found on the curve around xmas time (typical), had impedance readings far off anything on the list of typical Arcade Chassis readings from http://www.junknet.net/donor-tvs

my two tvs have the following specs

Maker: Model : Tube: Vert : Horz
Panasonic: CT-20D11DE : A51KQN011X : 11.8 : 4.1
Digistar (Prima?): (forgot) : A51QDX993X001 : 11 : 4.9

So both have very close V/H readings, would just make sense for me to get one or two chassis that are either generic, or used on ebay that closely match those readings, but the list on junknet is slim. Are there any other sites with H/V readings of chassis?
Thanks!

EDIT: these are CR-23's of course
 
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Worst case, you could always swap yokes. I know I've got boxes of yokes (G07's, 4600's, etc). I can't be the only one. I know Bob Roberts also sells used yokes.

Edward
 
Worst case, you could always swap yokes. I know I've got boxes of yokes (G07's, 4600's, etc). I can't be the only one. I know Bob Roberts also sells used yokes.
Edward

Or so I've read indeed. However I would prefer keeping the convergence as is for these Tubes.

Funny thing is I wonder if I should just try and hack the TV's chassis to support RGB directly. As in:
http://133fsb.wordpress.com/2010/05/22/adding-an-rgb-input-to-a-cheap-generic-ntsc-tv/
(found the service manual for the panasonic, and indeed RGB is used for OSD, so might be a fun experiment)

Wonder if anyone tried for fun to actually put a TV chassis in a cabinet, once hacked, but i know its a completely different subject.
 
Funny thing is I wonder if I should just try and hack the TV's chassis to support RGB directly.

I've done it. All TV's have a separate R, G, and B stage somewhere. Just a matter of disconnecting right before the video amplifiers. Then find a suitable location to patch in the sync. If the set has a composite video input, you can usually just give it sync there, and the RGB signal over at the video amps.

The problem is that TV sets have a lot less flexibility when it comes to the range of acceptable sync frequencies, and the ability to adjust the picture to fit on the screen. It winds up being rather a lot of work to modify and tweak the circuit to make it all work right, and the end product isn't as robust or flexible as a normal arcade monitor.

But, it's good fun, and sometimes you can get pretty good results.

-Ian
 
But, it's good fun, and sometimes you can get pretty good results.
-Ian

Thanks a lot for this pep talk! I think I'll try it out. I only have two cabs (G07 and EZ20) which currently have OK monitor/chassis. So i'll probably leave them alone for now.
I'm really hoarding tubes while I can and think about the future when replacement are going to be rare, i just dont like playing a classic game on an LCD.

I might just make a nice big JAMMA test rig with such a hacked RGB TV. I already have a RGB->SVIDEO board, but as you've guessed I'm unimpressed with the quality it gives. I also use Commodore 1084 monitors, but 13/14 inch is just not enough.

Cheers
 
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FYI - those tubes are 20" tubes (A51), not 19's, so they won't fit in a normal arcade monitor frame. They're close and chances are they'll work with a chassis but the mounting tabs are prob an inch or so too wide in each direction.

PS - I added the panasonic you listed above to the "do not buy" section for the fact that it has a 20" tube. Again you can try but they're usually not worth it. I am however wondering if anyone's ever used one to replace a Sanyo tube.
 
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Or so I've read indeed. However I would prefer keeping the convergence as is for these Tubes.
http://


Convergence is (usually) not a big deal when doing a tube swap.

Take the bad tube and remove the convergence rings and the yoke (I also remove the dag and the degaussing loop).

Take your new donor tube and mark exactly where it's convergence rings are place (their depth and their right-left placement). Since these rings were already converged for this tube, we're re-using them in our swap....thus, not having to re-converge.

Now remove the convergence rings, the yoke, the dag, and the degaussing loop from the donor tube.

Install the old tubes dag and degaussing loop onto the donor tube.

Mount the donor tube to the monitor's metal frame.

Install the old yoke onto the donor tube.

Install the donor tubes original convergence rings back onto the tube, carefully placing them in the exact location you removed them from.

Hook up chassis and fire it up

Adjust yoke and convergence rings, if needed.

My experience, I never have to mess with the convergence when doing it this way (that is, unless someone has already messed with the rings prior to this).

Edward
 
orion3311: yes i am aware of 51 vs 48 sizes. Seems easier for me to eventually hack a frame with scrap metal than finding a good chassis match :)

And Thanks ELutz for the steps for yoke replacement, might try few things.
 
Orion:

got another TV off the curb, this one is near identical to one in your list:

19" RCA F19281 (manuf 1999), tube: A48AAB13X02, chassis CTC185B4

Same
Horiz 3.8ohm
Vert 11.7ohm
reading as your CTC15xxx (XL-100).

NOTE1: the entry CTC15xxx in your list is not a TV model its more the chassis model.

NOTE2: Anyone has a spare K4600 to sell? (this wont fit on my G07 CB0).

NOTE3: What happens if you add a 40ohm resistor in series with one end of the Vert with a CB0?
 
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