DT-40 Pot Assignments

[DZ]

Ok, problem resolved. Took a bit of digging and going down alot of wrong roads. It ended up being a fuse, well, I suspect its a fuse anyway. On the board the component is labeled FU, and I suspect the SE was just dropped. I have not been able to find any details about it online, here is a photo of it. Maybe someone out there has some more info about it. Its a dead short, however when the problem occurs it seems to develope a high resistance yet doesn't completely open. With the component removed and a bare wire in its place, its worked fine with that abstract for 10 minutes straight.

Adam, are you still using the original DT-40's? Might want to try shorting this component and see if it solves the problem you were having. I'm going to leave it in place on the Y amp and see if it will eventually fail.

[dave]

That would be a polyswitch. Its much like a self resetting fuse.. Goes open when too much current is drawn, but then self resets..

Sounds like the abstract is a bit too taxing for this particular scanner...

[DZ]

That would be a polyswitch. Its much like a self resetting fuse.. Goes open when too much current is drawn, but then self resets..

Sounds like the abstract is a bit too taxing for this particular scanner...

Thanks Dave! Would you happen to know what the specs are for this component? I'd like to test it and see if its out of tolerance. If it is, then problem solved. If not, then maybe I have more issues to deal with. With it out, the head runs fine, ilda test pattern at 30K is as good as it gets.

[buffo]

I had a feeling it was some sort of overload protection. Would be interesting to see if it really is out of spec, or if the pattern is just too much for the scanners. (Would hate to short it out and then blow the galvos!)

Adam

[dave]

Thanks Dave! Would you happen to know what the specs are for this component? I'd like to test it and see if its out of tolerance. If it is, then problem solved. If not, then maybe I have more issues to deal with. With it out, the head runs fine, ilda test pattern at 30K is as good as it gets.

You could always swap the polyswitches between scanamps and see if the problem moves or stays with the same amp.. I guess that would quickly tell you if the polyswitch is the issue..

[DZ]

Thats not a bad idea! I may give that a try. I also found the specs for that polyswitch: http://www.littelfuse.com/data/en/Da...elfuse_30R.pdf So now I know what it should be capable of. I'm still betting its out of tolerance, since when the abstract is being displayed, its taxing the Y amp just as much as the X amp. Unless of course the Y amp polyswitch is over-tolerance!