Main > Monitor/Video Forum
Wells Gardner D9200 - Horizontal Collapse?
grantspain:
i take back the readings on q428 should be about 0.640 on those junctions
princess prin prin:
--- Quote from: Rocketeer2001 on February 10, 2024, 09:25:44 pm ---I tested the resistance of the coils and got 0.2 ohms for the horizontal and 2.3 ohms for the vertical. These numbers seem low, right? Then again, I don't know what the resistance should be on a D9200.
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Low resistance (and inductance) is what you find on the horizontal coil of monitors that can do 31KHz so 0.2 ohm is fine to me. If you have an LCR meter measure the inductance, it should be in the 0.2-0.3 mH range.
--- Quote from: Rocketeer2001 on February 10, 2024, 09:25:44 pm ---I then removed transistor Q418 to check it again. Q418 was identified as a "resistor", which seems odd to me (see pic). I did a diode test afterwards with my multimeter and I got 0.262V between center and one leg, and 0.334V between center and the other leg, which is what I think are normal, so Idunno.
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Q418 is an NPN transistor so it tests like any other NPN, with Base-Collector being one P-N junction and Base-Emitter being the other one. This means that you'll have voltage drop readings only on those (with red probe on Base). You should have about 0.45V on B-C and 0.50V on B-E (all 2SC5144, all test similarly):
Rocketeer2001:
The one wire on the yoke connector does look like it's been getting hot, but the actual pin inside is still clean and makes a good connection.
I can probably use the LCR meter to test inductance of the yoke. I've never tried, but it's a feature-packed little device, so I'll give it a go.
I did notice that C456 on the schematic is 0.24uf, but the actual part has a '304' on it (see pics), so you're probably right that the components used don't match the schematic and I should just check the labels on the parts instead. It just means I have to split that glue to get them apart. I hope the labels don't get ruined by this and become illegible.
If Q418 is just a big NPN transistor, then I would expect the LCR meter to identify it as so. It identifies all functioning NPN transistors, so I'm leaning towards this being the culprit. I kind of tested it backwards in diode mode with the negative probe on the base.
Lets see if the pics will upload this time...
...nope, still get this error that says "your attachment has failed security checks and cannot be uploaded". Not sure what security check it's failing. It's under the size limit and it's just a jpeg, like the other photos I posted. Is there a limit to how many photos can be posted in 24hrs or something?
grantspain:
i thought it was q428 that was reading bad, its a 2sc945c and is part of the frequency circuit and would certainly explain your issue as the chassis would not be able to find the right frequency
q418 is the horizontal output transistor, 2sc5144 and should read exactly as princess prin prin has shown
PL1:
--- Quote from: Rocketeer2001 on February 11, 2024, 11:49:08 am ---Lets see if the pics will upload this time...
...nope, still get this error that says "your attachment has failed security checks and cannot be uploaded". Not sure what security check it's failing. It's under the size limit and it's just a jpeg, like the other photos I posted. Is there a limit to how many photos can be posted in 24hrs or something?
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Unfortunately, the forum software sometimes throws false positives during the security checks. :banghead:
https://forum.arcadecontrols.com/index.php/topic,164181.0.html
The best known workaround is to either crop or resize the image by about 3-5% and try uploading it again.
Scott