1. Home
  2. Electronics Repair
  3. Samsung Projection HDTV Convergence Problems

Samsung Projection HDTV Convergence Problems

This Samsumg set is clearly not going to be an easy fix. It came in with severe convergence problems - no two colors converged properly at any point on the screen. I started by checking the two large convergence IC's (STK392-010); both had the correct supply voltages, but two of the three sections on one IC were not functioning at all (input present but no output) so I assumed the IC was bad. For good measure, I replaced both IC's. Once powered up, the picture was still severely distorted but this time, ICZ103 (which was formerly bad) now overheats severely. So I tried disconnecting the output leads from that IC, and it now runs cold - but of course the picture is still distorted. At this point I suspect an underlying fault somewhere else, putting an excessive load on the IC and causing it to fail. I checked the three yokes and all measure the exact same impedance, ruling out the possibility of a shorted yoke. Because of the complexity of this set, it would be pointless to venture any deeper without the aid of a service manual, or at least some advice as to what the problem might be. Thanks for any advice.

Reply to
Chris F.
Loading thread data ...

May I ask a stupid question? Is there any possibility the "display elements" (tubes, LCD panels, whatever) are themselves misaligned? I assume they would be mounted and locked into a rigid frame, but... Is there any chance the owner is a screwdriver mechanic, and that a minor convergence problem tempted him into going where h*mo vulgaris is not supposed to tread?

Reply to
William Sommerwerck

Check the static alignment and check around the STK devices for open low value, low wattage resistors (10 ohm 1/10 watt). Samsung were notorious for chewing up convergence amps and surrounding components.

The convergence amps didn't need a special reason to fail other than after time not being sufficiently torqued to the heatsink.

Reply to
Meat Plow

There's no evidence that the static alignment was tampered with, or that the set was ever dropped etc. I will do some more checking and let you know.

Reply to
Chris F.

Disconnecting the output leads (presuming you mean the leads to the yokes) should not make the ICs run cold. Running them unloaded will usually cause overheating in the output resistors in the circuit. You may have disconnected the supply to the ICs.

If you are getting correction from the DCU to the inputs of the output ICs, you probably missed something like an open resistor on the output stage. You may have blown a chip or a supply fuse.

Leonard

Reply to
Leonard Caillouet

Still could have problems in the convergence that would mimic a pincusion amp problem.

Reply to
Meat Plow

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.