Sharp 3" mdl 3LS36 Vertical Problem

[Eric H]

Originally Posted by kx250rider

I think that set has one of those inline IC chips for the vertical outputs, and I've seen those go intermittent a lot, but they act more like a cracked solder connection (popping in & out of full sweep) ; not so much just gradually shrinking or slowly changing as the set warms up. But they're cheap, so it might be a good shot to try it. I don't remember which version it would be, but it might be LA7838, or if not, LA78(and two more digits) .

Charles

I thought the Vertical chips for these were unobtainable?

[kx250rider]

Originally Posted by Eric H

I thought the Vertical chips for these were unobtainable?

I don't remember it being hard-to-get... But maybe time has gotten away from me, since now I can't remember the last time I repaired one. Probably the mid-90s . But I think those output ICs are still out there. Mitsubishi used a funny one (AN5553 or something like that odd number), which was a tough one to get in the early 2000s. But I blamed it on so many of them blowing, and the demand. The nice thing is that the most expensive one I remember, was about $3 from the traveling salesman. Most (like LA7838 and AN5521), were about $1.25.

I've seen them cause a vertical hop or jump, which can look like a roll. It's not a loss of v-sync, as if the oscillator is acting up. It's a feedback from the output that kicks the oscillator out of whack as it tries to correct the hop.

Charles