Build Your Own Arcade Controls Forum
Main => Monitor/Video Forum => Topic started by: MonitorGuru on March 04, 2005, 09:47:00 am
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Hey, another post for Ken :)
Long story short: 1991 Magnavox 25" TV set that suffered vertical collapse around 2001. Over course of a week shrunk down to 3" wide band, then sat unused and shrunk to a couple pixel band. Replaced the caps in the vertical circuit but didn't affect things. Model RR2540 A101
Thought I would gut it and use the tube for a 25" arcade display with one of the replacement chassis. Cracked it open this morning and found the tube was a Philips, 10 pin. H20X MVA63AEH20X
Then I attempted to read the DC resistance of the yoke. Rather than a single connector, it split the yoke into two connectors, one attached next to the flyback (Horizontal) and the other pair connected in the middle, sorta next to the coax input (vertical).
The Vertical (Yellow/Green) read: 3.3 Ohms The Horizontal (Red/Blue) read: .7 Ohms. (Once it read .3 but that may have been my fingers "helping the measurement" pressing against the leads trying to get a clean connection in the socket).
Obviously that is HUGELY off from standard 25" let alone 19" tubes of around 2 horizontal and 8 + vertical. I would suspect there is no arcade chassis that could possibly drive this, correct?
Also--would it be possible something on the yoke itself is fried (windings shorted?) and that is the cause of the vertical collapse? Or did they implement resistors/coils to increase the resistance/impedence of the yoke on theri boards and thus why replacing the caps didn't help one bit?
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Magnavox (or as it's known on the Simpsons, "Magnet Box") is well known for shorted yoke problems causing collapse. Give the yoke a good sniff and see if there's any burnt smell. Those readings you got are awfully low as if the yoke were indeed shorted. You could save the tube itself for a tube swap project though.