What's my chassis?

p1001

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I have at least 2 of these new chassis. Can you ID what monitor they came from?

Hans O

P1010097.jpg
 
monitor chassis

I believe it is a Wei-ya 814sr model.
 
monitor chassis

Now what game would it be used in is a different story. Generic after market monitor probably seen more on the west coast probably or even east coast, this monitor could be put into anything that has a standard resolution.
 
It's a Rodo Tron. Note the CH-203 printed at the corner.....that's a Rodo Tron model number.

Rodo Tron made "generic" replacement chassis....as well as other companies "re-branding" them, as mentioned Pentranic.....and also Eygo, Promax, and a slew of other here today-gone tomorrow companies.

Edward
 
No, two yoke connectors were usually fitted on these replacement chassis to allow the user to flip the image without having to break apart their yoke connector. Pick the connector that works best for your game application.
 
It's a Rodo Tron. Note the "CH-203" printed at the corner by the flyback.....that's a Rodo Tron model number.

Rodo Tron made "generic" replacement chassis....as well as other companies "re-branding" them, as mentioned Pentranic.....and also Eygo, Promax, and a slew of other here today-gone tomorrow companies.

Edward

http://www.rodotron.com.tw/
 
OK, it's a generic replacement chassis of some sort. Used by an unknown number of fringe monitor manufacturers. Next step is figuring out how to use it on a monitor; Is there a way of determining the output impedance to match it up with a yoke or should I just hook it up and watch for smoke?
 
Here's a link to the schematic:

http://elektrotanya.com/pentranic-rodotron_ch688_ch-203h_203c_sch.pdf/download.html

Be sure to turn off adblock then wait about 60 seconds for the page to say "Get Manual" then click on get manual.

Rick Nieman can tell you if it is a high impedance or low impedance chassis. Here is a posting from another forum in which he talks about the CH-203:

If you need a Schematic I can help you with that, need it repaired also can help.

Rick Nieman
[email protected]
_________________
Rick Nieman
President
Nieman Video Displays
1023 Rife Rd Un 10, Cambridge N1R5S3
519-621-1722
 
OK, it's a generic replacement chassis of some sort. Used by an unknown number of fringe monitor manufacturers. Next step is figuring out how to use it on a monitor; Is there a way of determining the output impedance to match it up with a yoke or should I just hook it up and watch for smoke?

Sorry Hans, I have no experience with the CH-203 model.
Here's a schematic......looks like Pentranic uses it.
http://arcarc.xmission.com/PDF_Monitors/Pentranic_Rodotron_Models_CH688_&_CH203_Schematics.pdf

Edward
 
OK, boys...I dug thru my piles of crap and pulled out a new Happ 1901MG that doesn't work. I hooked her up to the chassis and fired it up. I get a gorgeous picture (man I miss new crt monitors) but the picture is too short. Max vertical height only fills about 2/3 of the screen. Has to do with yoke impedance, I'm sure. Any ideas on how to fix this? The flash doesn't do the picture justice but here's what I got............

P1010218_zps85e2c8e3.jpg
 
OK, boys...I dug thru my piles of crap and pulled out a new Happ 1901MG that doesn't work. I hooked her up to the chassis and fired it up. I get a gorgeous picture (man I miss new crt monitors) but the picture is too short. Max vertical height only fills about 2/3 of the screen. Has to do with yoke impedance, I'm sure. Any ideas on how to fix this? The flash doesn't do the picture justice but here's what I got............

Out of interest, if you measure the resistance on the Vertical yoke, what's the reading come out at ? My notes say the MTG-1901 measured 14 ohm vertical with the stock yoke.

- James
 
Out of interest, if you measure the resistance on the Vertical yoke, what's the reading come out at ? My notes say the MTG-1901 measured 14 ohm vertical with the stock yoke.

- James

I measured 15 ohms resistance.

Let's say the chassis has a higher output "impedance" of 50 ohms. I mate it to a low "impedance" 15 ohm yoke. The chassis cannot put out enough current to match the yoke and creates something of a brownout. The result is not enough current going through the yoke and therefore not enough vertical deflection. Is this thinking sound?
 
Let's say the chassis has a higher output "impedance" of 50 ohms. I mate it to a low "impedance" 15 ohm yoke. The chassis cannot put out enough current to match the yoke and creates something of a brownout. The result is not enough current going through the yoke and therefore not enough vertical deflection. Is this thinking sound?

Also the inductance of the vertical yoke also comes into play. But basically the impedance and inductance of the yoke need to be close enough for the vertical drive to end up with enough current in the yoke.

Both the impedance and inductance of the yoke effect the voltage across the yoke from the vertical drive, which has a fixed supply voltage. This will have been designed to produce a peak current in the yoke for the maximum deflection. If either is way off the calculation fails and yoke doesn't get enough current for complete/correct deflection. Adjusting the vertical drive supply and feedback for the vertical amp ultimately effect the current in the yoke and the deflection that's possible. I think I'm saying that correctly. I'm sure someone will correct me if not :)

There were/are some application notes from Philips in the 90's detailing the calculations for their TV semi's and how resistance, inductance, voltage and current all factored in to the design for a given yoke.

- James
 
I have the exact chassis sitting in an old Go7 frame and tube..
That should give you a good idea on what yoke to use :)

Funny, same here.
I pulled the tube as it had bad PAC Burn and dropped in another tube from a Sharp Image monitor. Works great. Same resistance as the G07 yoke BTW, just can't remember the numbers off the top of my head.
 
It's been over 30 years since I went to college and this is very dim for me. I can see inductance also coming into play. My original thought was that since the yoke on any standard res monitor is subject to the same frequency (unlike a vector monitor) inductance isn't a factor. After some more pondering I'm thinking frequency, although a constant in a raster monitor, is still a component in calculating the inductance and therefore would play a part in grand scheme. No?

To get true compatibility between yokes we'd need to measure the impedance at the proper, fixed frequency like 15.75kHz for horizontal and (15.75kHz/200?) for vertical......


Also the inductance of the vertical yoke also comes into play. But basically the impedance and inductance of the yoke need to be close enough for the vertical drive to end up with enough current in the yoke.

Both the impedance and inductance of the yoke effect the voltage across the yoke from the vertical drive, which has a fixed supply voltage. This will have been designed to produce a peak current in the yoke for the maximum deflection. If either is way off the calculation fails and yoke doesn't get enough current for complete/correct deflection. Adjusting the vertical drive supply and feedback for the vertical amp ultimately effect the current in the yoke and the deflection that's possible. I think I'm saying that correctly. I'm sure someone will correct me if not :)

There were/are some application notes from Philips in the 90's detailing the calculations for their TV semi's and how resistance, inductance, voltage and current all factored in to the design for a given yoke.

- James
 
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