Barry L. Kline wrote: Even with the horizontal output also shrinking by about 60%? Otherwise yep, that would have been my suspicion too - just seems odd the way vertical dies completely and horizontal is also significantly affected. I hate trying to fix displays :-) cheers J.

On Monday 10 July 2006 01:48 pm, Barry L. Kline wrote: Yeah... I had a tv repair business in 1974, and also worked on them at later points in time. Not something I'd particularly care to go back to any time soon, either. :-) It would be unlikely to be the transistor if it was opening up, but if it was shorting it may be loading down the supply to the extent that it would shrink the horizontal some. Or the supply for the vertical may be flyback-derived, which would mean that a short there (whether it's a transistor or a bad electrolytic) would load down the flyback a bit more. But yeah, that's where I'd start looking too. -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, a critter that can be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin

Tony Duell wrote: :-) It's one of these Superbrain ones - single fixed frequency, mono, TDA1170 for the vertical - and from the looks of it, supply for the vertical is taken directly from the system's PSU rather than being generated within the monitor. (I've got Intertec's official released schematics - but they're so shrunk on A3 paper as to be next to useless as hardly any component details / part numbers can be made out) Sure - just wondered if ot was one of those symptoms where the answer is foobar xyz in 99% of cases; I'm happy to be poking around looking for specific problems in the meantime, though. Seems strange to lose vertical completely though, surely? It's entirely separate for this display it seems - the TDA1170 takes the vertical sync pulses and drives the vertical deflection directly, without any connection to the horizontal part, EHT etc. (except the ground and power lines!) Indeed there is, and luckily I do have some of those spare if that's what this turns out to be (I've certainly had those die in displays before, but I would have thought it more likely to be a dead cap somewhere that's causing the trouble) True. At least it's a single +12V supply to the display, so I can stick the ammeter on it and see if it does anything odd at the point where it breaks. cheers Jules

The next thing I'd do is get the TDA1170 data sheet (it should be on the web somewhere). 99% of designs using that chip follow the same schematic, at least for the output stage, so you should be able to match things up. Then suspect the electrolytics associated with the output stage. One of them might well be shorting... My thought was a fault in the vertical section that (a) completely killed the vertical deflections and (b) loaded the supply to the the vertical section, (from the flyback transformer), enough to much up the horizontal side too. Anothre thought was that the vertical fault caused a heavy current to flow in the deflection coils -- heavy enough to saturate the core and thus change the inductance of the horizontal coils enough to mess up the operation of that side of things. But it's not that either -- if it was, the beam would surely be deflected well off-screen, it wouldn't be in the centre. -tony