I've got an answer from Perkins-Elmer about the Vactrol's specs
I just got an answer from Perkins-Elmer about the VTL9B8 Vactrol. They sent me data sheets for the VTL9 series and another sheet of the newer replacement Vactrol specs.
The Vactrol you have is a neon type, meaning it has a small neon bulb on the AC side of your circuit, your on-off switch... and a photocell on the lower voltage DC side, your lamp regulator circuit. It's main function is to isolate the AC side form the DC side via a light beam on the photocell. When the neon light is "on" the photocell conducts and turns the lamp circuit on. This Vactrol's input is 80Volts AC or 85Volts DC. The newer LED style Vactrols run on 3Volts DC. I have a feeling Beseler used this Vactrol in a 115VAC circuit thus the reason they burn out in such a short time.
There are 2 solutions...
ONE.... Install a really. A really is nothing more than an elecro/mechanical switch. When you turn on your enlarger, the relay's magnet (this would be the AC neon bulb side) pulls a switch closed (where the photocell was in the Vactrol) causing it to conduct, turning on the DC enlarger lamp circuit. This can be soldered directly in place maybe using wire to adapt it to the solder pads of the Vactrol.
TWO... Another more difficult modification would be to use a newer LED style Vactrol. Since they operate on 3volts DC. You'd have to drop the voltage 112volts AC @40ma using a resistor then converting the AC to DC using a voltage regulator circuit. It's not difficult and can be done but... do you want to go to all the trouble?
If you have any questions, e-mail me at email@example.com maybe I can explain it better.
Seems to me a third solution would be to tape a neon bulb to a CDS cell of the right value with black electrical tape and solder it in. It would be pretty much the same thing.
If it were mine I would open the little can and replace the neon bulb. How many people will do that? I suspect most just want to purchase a replacement part. It sucks that Beseler wouldn't repair it with some retro fit part knowing this is a problem.
The relay would be the cheapest way to go. I did see an article about a way to make your own Vactrols but they were LED style.
Do you have this same enlarger? Can you measure the voltage at the vactrol's neon lamp? Is it AC or DC?... Does the voltage keep the neon hot all the time and peaks at breakdown voltage? If you can get me some more info I can look up neon bulbs as a way to replace the burnt out one.
Hello Paul and thanks for all the time and effort you have put into this issue.
I have the Dual Dichro 'S' head and will open it up and take the voltage measures
for you. Right now it is packed away and not being used so it may take a few days
to get around to it. I did take a dremel to the failed part and open it up. The idea
of replacing only the neon bulb looks feasible. If I recall, the halogen lamp in this
enlarger is 82 volts, so they have to step down from 115 somewhere in there.
I'll post back here when I get it out and take the measures. Thanks again! Gary
What to measure...
If you are going to measure the voltages, what is important is the voltage accross the neon bulb when the box is idle and in the turned on mode. I assume the timer turns this on and off but the voltage stabilizer is on the entire time.
Then measure the voltage on the photo cell side to see if it has an idle and on state voltage. If there is an idle state which keeps the circuit hot at a standby voltage it will have to be shunted in, the realy will just have to add the difference to bring it up to working voltage.
It is a shame these units will become trash if there is no easy fix. Perhaps I may be able to get buy one broken for $50 now?
I wonder what ever happened to the other person that got a part? That part has an LED adn will cook as soon as it is turned on.
Let me know when you have the measurements?... e-mail em to me at firstname.lastname@example.org
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We may be on to something... I spoke to Beseler today.
I called Beseler a couple days ago and guess what?.... I got a call today from Steve, a Beseler representative.
Steve has been following our discussions here on APUG, also spoke to Phoebe. He is very familiar with the problem as it seems this isn't the only time this has come up. It's been even more of a concern since the company that made the Vactrol doesn't make them nor a replacement for this part. Beseler has moved it's operation to a new location and they don't have a repair department anymore, but they are willing to help us search for a replacement part.
Steve told me he was consulting an engineer to look at the schematic to answer our voltage concerns and possably come up with a replacement solution. He is also sending me a copy of the schematic so I can asses the voltages to find a part that can be retrofitted instead of a Vactrol which is nothing more than a fancy electronic switch. I feel a simple relay will do teh job just fine but we have to see if there is a reason Beseler chose the neon Vactrol. Maybe there is an idle voltage to keep a circuit hot till it is triggered by a rise in voltage which will trigger another circuit?... I won't know till I see the diagrams.
Once we do find a part, perhaps someone can post some pix of the actual PC board so I can see the solder pads, also see how much room we have in the case to house the replacement part?
Steve, if you are reading this... my hat is off to you and Beseler for a fast responce and your dedicated efforts. Thanks!
Hello Paul, I was just getting ready to email you on this when I came here and found
your update. I also emailed Stephen at Beseler to see if I could get specs on the part.
Beseler is also mailing me a complete copy of the schematics (just emailed me this morning) I have not gotten a chance to dig my Dichro 'S' out of storage yet. I will
get around to this soon and get some info on the measures (physical and electrical)
but was hoping the schematics would provide the more useful information. Yes, once
again Beseler Tech support comes through!
Steve is a nice guy, trying to help as much as he can. Too bad about Beseler not repairing their products, maybe they'll farm it out to independants?
It would be nice to see the PC board, if you can post some pix of it?... I'd be more familiar with the layout and should be able to see exactly where the leads will have to get soldered in.
I have the schematic
Beseler sent me the schematic diagram of the electronics. I see the part you are having trouble with. I have a couple possable solutions which I need some help with before implementing. I need someone to measure voltages to confirm my calculations and also check to see if your board is a revised one or not. It seems there may be a modification the manufacturer made later that may have been done to avoid just this type of failure.
E-mail me at AUTOMAX1@JUNO.COM ???
Beseler Dichro delay problems
Just a note to the list to let you know that I still have my unit in the shop. However, Paul Ron has kindly send me the schematics he received from Stephen at Beseler. Hopefully, my electronics person will be able to find a fix now. I will keep you updated.
Also, once I have the schematics back I would be happy to make a copy for anyone who needs one.
I have only one extra vactrol so I haven't decided whether I'll keep it or pass it on. Will let you know when all is working.