Need troubleshooting help: Aristo 810

[jbenedict]

Hi:

A couple of years ago, I received a call from a real estate agent. Seems she was in the process of helping an older woman get her house ready for sale. The owner was in her middle 80s and her husband had passed away about 10 years earlier. He had been an active amateur photographer and she had sold his cameras at the time of his death but the darkroom remained. I was teaching photographer at a HS at the time and I was given free reign to come up and take whatever I wanted. There was a lot of hardware- enlarging less, trays, print washer, etc.- that was very useful. I already had three donated enlargers I had no room to use so left the enlarger behind.

Anyhow, one of the items was an Aristo 810 cold light head. I just looked at it and said, "Wow. Someday a big enlarger for me!" and put it in a cabinet and kind of forgot about it. This was maybe five years ago. A couple of months ago, I bought a B&J 8x10 flatbed. I wanted the extension rail and the sliding block and the 5x7 reduction back for the B&J 8x10 I already had so the rest was extra. Good bellows, the rail needed a little gluing but a good place to start. I already had the column and baseboard from a Polaroid MP4 copy camera, an 8x10 negative holder and a 240mm process lens so I figured I had all the stuff for an 8x10/5x7 enlarger 'kit' and decided to get going on it.

There is some kind of problem with the 810 cold light head. I plugged in the thermo cord and it was fine. I plugged in the light cord and the cold light lit up but a buzzing came out that sounded like the alarm on a GraLab developing timer. Unpluggged it quickly. You never know when something might explode. I opened up the bottom and I didn't see anything burned or fried. I plugged it in again and the buzzing remained and I did not see any sort of arcing inside the case. Put the bottom back on and turned it over to the light side. I took the frame and diffusing plastic off and the tube looked normal. No burned spots or cracks or obvious problems. Plugged it in. The buzzing started and the tube lit up. I left it on for about five minutes and the light was constant, did not flicker and seemed pretty bright (I have an Aristo head for a Beseler 45 so I have a little bit of an idea of what it should be). One thing I noticed was that the "on/off" switch did nothing. I didn't need to turn it "on" for the lamp to light and, when I turned it "off", the lamp stayed on. I did not see any wires which were not connected inside so I'm kind of at a loss. There was also another item in the circuit that looked something like a relay and it had a screw on the top of it as if it was a control for the brightness. That's a guess but... I tried turning the screw and it did not move easily so I stopped.

I found the website of the new owners of the Aristo trademark and products: http://www.light-sources.com/special...aristo-archive The 810 was listed but the information they had was just the outside dimensions of the unit and voltage needs but no manual or schematic of the unit.

Does anyone here have any idea of what direction I should go with this? By a process of elimination, it would seem that the 'relay/brightness control' has a problem. Like I said, at least from what observation I could do, the tube seems fine.

Thanks.

Jeff

[ic-racer]

Pictures? Is the lamps power transformer in the lamp housing or separate? What is making the buzzing?

[jbenedict]

Here's a shot of the inside of the 810:

1. The power transformer is in the middle. The leads coming from one power cord are connected to the two white leads coming out of the transformer. The two black leads coming out of the transformer are connected to each end of the tube.

2. The power switch is at the top of the box. The black side of the second power cord is connected to the switch w/110. The other side of the switch is connected to what might be some sort of rheostat to the left of the power transformer.

3. The two gold objects at the top right and the bottom left appear to be resistors. These could be the heat generators to stabilize the cold light tube. One end of each resistor is connected to the rheostat and the other end is connected to the white side of the power cord.

4. There is a capacitor across the two terminals of the rheostat.

5. The tube lights up and does not flicker and seems to be bright.

When I plug in the first power cord (connected to the transformer) I immediately get a loud buzz like a Gralab timer going off. The power switch doesn't turn anything on or off at this point.
When I plug in the second power cord (connected to the power switch and the resistors) by itselfI get no buzzing. I felt the case and it did not seem to be getting warm after being plugged in for about 5 min.
When both cords are plugged in, I get buzzing.

I'm guessing that the buzzing is coming from the circuit connected to the transformer and the cold light tube.

I hope the additional information and the picture helps. Any ideas?

Jeff

[Luis-F-S]

Have spoken to the LCD Lighting folks? Did they have any suggestions?

[ic-racer]

Yes, the power switch is just for the heater.

"There was also another item in the circuit that looked something like a relay and it had a screw on the top of it" Is this item in the picture?

[DennisD]

Hi jbenedict,

From your description it sounds as though the power transformer is causing the buzz. Transformers generally hum. When they get old, the laminations sometimes separate or loosen. What used to be a mild or even unnoticeable hum can turn into a loud clatter due to vibration of the lamination cores. The transformer will work despite the noise.

If you touch the top of the transformer with an insulated object, (just to be safe) you will feel the vibration.

Probably best to find a replacement transformer if that's the case.

Note: the power switch is for the heater which should provide a detectable amount of warmth within a few minutes. If you're not feeling some heat, the heating element may be defective. (Unrelated to the buzz.)

The item with a screw adjustment is probably a thermostat to regulate heating element temperature. A defective or incorrectly set thermostat might also prevent the heating element from warming up.

The lamp circuit is not switched because Aristo assumed you would plug the lamp power cord into a foot switch (or other remote control device).

Dennis

[jbenedict]

Yes, the power switch is just for the heater.

"There was also another item in the circuit that looked something like a relay and it had a screw on the top of it" Is this item in the picture?

Yes. It is to the left of the transformer on the bottom of the box.

[jbenedict]

Hi jbenedict,

From your description it sounds as though the power transformer is causing the buzz. Transformers generally hum. When they get old, the laminations sometimes separate or loosen. What used to be a mild or even unnoticeable hum can turn into a loud clatter due to vibration of the lamination cores. The transformer will work despite the noise.
If you touch the top of the transformer with an insulated object, (just to be safe) you will feel the vibration.
Probably best to find a replacement transformer if that's the case.

I guess I'll have to take out the transformer and see if there are any specs. on it. Contacting LCD might be an idea, too. If not to get a transformer then to get the specs. I understand the woman who handles Aristo questions is named Louise. The 'information' about the 810 on their site is just the outside dimensions and the voltage. No schematics, etc.

Note: the power switch is for the heater which should provide a detectable amount of warmth within a few minutes. If you're not feeling some heat, the heating element may be defective. (Unrelated to the buzz.)
The item with a screw adjustment is probably a thermostat to regulate heating element temperature. A defective or incorrectly set thermostat might also prevent the heating element from warming up.
The lamp circuit is not switched because Aristo assumed you would plug the lamp power cord into a foot switch (or other remote control device).

That all makes perfect sense. Thanks for the information and hints. Sure would be nice to make some enlargements from 5x7 and 8x10 negs. Not huge ones but an 11x14 from a 5x7 would be nice. Cropped photos from each size also.

Thank you, Dennis!

Jeff Benedict

[DennisD]

Hi Jeff,

Regarding the transformer, the LCD people should be able to help with a replacement, or at minimum, specs.

This may be a long shot, but if LCD does not have parts, once you get the specs you might look into neon sign transformers. I have no idea about voltages, or the requirements for the specific lamp in your coldlite, but the aristo lamps are similar to neon sign lighting. A neon type transformer might provide what you need.

Again, don't try anything until you are certain of the lamp and transformer requirements.

Obviously, your best bet is the current manufacturer. They should provide the necessary support.

Please post your findings in the thread once you have answers. It may help others. Good luck in your effort.

Dennis

[jbenedict]

Hi Dennis and all:

I did exchange e-mail with Louise Kessler at LCD. She is the person that has all the Aristo questions put on her desk. Here's a piece of the exchange:

"I remember there most of the Aristo products used magnetic ballasts that
custom. Magnetic ballasts as they age do loosen and make buzzing noises- which
even though buzzing they can last for decades. The other caveat to remember
is that these kinds of lamps do not like to work on electronic ballasts.

I'm not sure if there is anything you can do with a buzzing ballast. I
had one on a heater at home that buzzed and my husband put small pcs of
cardboard in-between the coils to tighten things and that cut down the
noise. I don't know if that's applicable to your ballast.

I also remember there being numbers on the ballast but I have no info as
to which manufacture they would have come from.
As a guess - I would assume the ballast mfg company - Imag out of
Arizona."

She did not have any list of specs and the ballast just has a Aristo part number on it.

I am going to take the ballast out of the metal case and see if any of the ballast windings are loose.

I may take the whole schemer to a neon sign shop and see if they could help.

So that's it. I will keep the group apprised with what I find. I have some ideas about using CFLs or LEDs for a light source but I am going to exhaust the possibilities of the Aristo setup first.

Jeff