Problem with Beseler Universal VC head

[Duolab123]

Google found me these guys: https://www.controlrepair.com/produc...ntroller/29485

but am going to call $500 "uneconomical", at least without some significant cost-sharing from the seller (and the listing is for the color controller, not the VC, although I'd bet the electronics are pretty similar).

Are you keeping the unit?

[Drew Wiley]

Could be the control panel or the power supply. I had a green channel overheat today. I've got spares of both the power supply and control box, and will just make a temporary switch until I diagnose the problem. I have some replacement triacs on hand - cost me around $5 apiece. After 20 yrs of hard use, a bit of maintenance is to be expected.

[Drew Wiley]

Well, I cannot induce the same problem today, so will not even bother to switch out anything unless it happens repetitively. But I will offer a hypothesis which might be analogous to the problems others sometimes encounter. We're starting to enter our "red flag" high fire risk season here. The utility company has, without advance warning, been cutting power to huge swaths of inland areas not too far away where dry high wind conditions are anticipated and could topple power lines and start fires. That kind of sudden big-scale utility intervention induces brief surges or fluctuations which can easily induce EMI fritzes in this kind of equipment. Ordinarily, the power is very predictable here. But if a major transformer pops, or a sudden power disruption, the control unit seems to get the jitters for awhile. It settles down; but I'm not an electronics tech, so won't try to define the specifics beyond generic EMI itself. A similar situation can happen if you're in an industrial building with internal 115 step-down voltage from a much higher input; fluctuations in those settings tend to be higher than acceptable for sensitive electronics. I wouldn't worry about basic household 220V single-phase present in the same bldg.

[Duolab123]

AC lines are so noisy these days. Try to use an AM radio it's nearly impossible. I've noticed driving down the highway, buses and trucks emit all kinds of weird static I pick up on my AM radio. SW radio guys are really having a tough time,,probably the same with any older delicate electronics.

[MrFujicaman]

Drew-

A thought-would plugging the head into a UPS like is used with computers help?

[Drew Wiley]

Thanks, but that doesn't work. For one thing, this is high-wattage equip. I have serial banks of these controllers, in one instance, handling 1500W of halogen. But even individually, EMI can occur even in the vicinity, and is not necessarily a line issue per se. My building is pretty well shielded from outside problems of this nature, but not totally immune. One could spend ten thousand bucks on a line shape tamer and really do no better than ordinary line voltage under routine circumstances. I carefully tested all that in advance, of course. When there is an incident, something internal either gets magnetized or overheated in such a manner it takes awhile to neutralize. It's a pretty rare problem for me; but I do keep backups, and also have the option of using the Durst 10x10 subtractive head instead, or in the case of b&w prints, an 8x10 cold light. My smaller additive enlarger is necessary for critical color work like color dupes and internegs, and is the most convenient enlarger I have for 4x5 and smaller negs. The other additive machine is a monster, and dedicated to 30x40 inch color prints. Speaking of EMI, after the continuous spectrum massive IBM spectrophotometers which used pre-aged bulbs, industrial spectrophotometers started using intense flash bursts of xenon, then dividing this into discrete spectral points of measurement. The more the readings, the more accurate the result; but in turn, the more power it needed. So it would store up a massive burst of energy in a capacitor. One of my early ones blew its capacitor. Even though there were three industrial line tamers on that circuit, acting like dams preventing any backlash in case of such an incident, it overwhelmed every one of them and generated an EMI field or backlash echo so intense that it also blew out every office computer in use on that 6,000 sq ft building floor, at least a dozen of them - outright ruined them. Those were on fully independent circuitry. The EMI was in the air. Ironically, it doesn't seem to bother people unless static is involved. But these Beseler U controllers are sensitive to even minor EMI in the vicinity, which is why I expressly mentioned solid state lighting ballasts, or really, anything solid state. And it makes me wonder if their new LED system is itself immune, or if it has just re-adapted the previous control model, and basically decreased heat issues without thinking out other issues completely. Time will tell.