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Wells Gardner D9200 - Horizontal Collapse?
Rocketeer2001:
I hooked the LCR meter up to the yoke and got:
2.8 ohms, 0.23mH for the Horizontal and
9.3 ohms, 5.71mH for the Vertical
Those readings look much better than what my multimeter spat out, and is close to that 0.2mH range you mentioned, so it looks like the yoke is good! (whew).
I hadn't actually looked up the spec sheet for Q428 because it didn't look vastly abnormal at a glance. Is the hFE or Uf no good? Is that the 0.64 you were talking about?
Makes me second guess if any of the transistors I tested were actually good. If the LCR meter didin't show a fault or incorrectly identified it, I assumed it was good.
The Q418 transistor definetly doesn't read 0.5v, so maybe it is kaput.
I broke apart the group of poly caps so I could read their labels and only got a 75% success rate. That white paint or epoxy or whatever it is absorbed the ink from the label, so when I scraped that off the ink went with it. I have no idea what C455 is supposed to say, which is of course the only one I really wanted to know, but all the other ones matched the schematics. Well, mostly; the other 3 said they were 440V MMP on paper, but the actual parts are 400V MPA. Not sure if that's a big deal.
So do I trust the schematics that C455 is supposed to be 0.15uf? Mine reads 0.319uf, which would be wrong.
C456 reads 0.30uf when it should be 0.24uf. Big enough of a variance to warrant replacing?
Do Q418 (and maybe Q428) seem sketchy? Should I just replace all those parts and see what happens?
princess prin prin:
The HOT is definitely at fault (leaky) as you should have OL with the probes connected like that (or whatever your meter displays when the probes are disconnected).
Your 2.8 ohm reading isn't correct for the horizontal yoke (looks like your meter was doing a better job here).
Rocketeer2001:
Prin prin, I took out the Q418 again and hooked it up to my multimeter in the same configuration you did. It said 0.32v and 0.08v. I think we can confidently say that its broken. I'll get a new one of those.
What would cause that to fail? Or is being 21 years old reason enough?
Should I replace C455 as well? I mean, it must be a cheap part. I might as well just get one and hope the schematics are accurate and it's a 0.15uf, 250V.
Anything else I should be ordering just to be safe?
Scott, thanks for the suggestion about cropping the photos! It's a bit inconvenient, but it does work.
grantspain:
don't get a 2as5144 to replace q418, get one of these
https://www.mouser.com/ProductDetail/onsemi-Fairchild/FJL6920TU?qs=CR8BwU6haLdFGBuY0BHhSA%3D%3D
i would also replace q428, 2sc945c and c455
Rocketeer2001:
Hey Grant, I did discover before your reply that the stock Q418 part number of Toshiba 2SC5144 was hard to find, and the ones I did find were questionable. I did find the alternative part number for the Fuji FJL6920TU, so I'll go with that.
I'm thinking I'll remove these transistors and check them again with the LCR meter, since I'm clearly a novice at determining which are good and bad. Some of them are similar to Q428 so might be failing too:
Q412 - C945C-Y
Q413 - IRF644
Q414 - 2N7000
Q415 - IRFS640A
Q423 - C945C-Y
Q424 - A733C-Y
Q425 - C4770
Q426 - IRF630A
Q427 - IRF630A
Q428 - C945C-Y (this is the CS2)
Q430 - C102M (this is the CS1)
I don't have a CS3 so there is no Q429 or Q416 on my board.
See anything else worth checking? Just want to make sure I order all the parts I need at the same time.