Buzzing Aristo D2-HI lamp

**radu_c** · 13-Jul-2018, 07:31

I recently got a cold light for my D2 enlarger, it's an Aristo D2-HI. I tried it the other day, and I noticed it has a buzzing sound to it. Does anyone experience this? Is it a sign that the lamp it's on its last leg?

BTW: can I attach an audio file here? I could do a short recording to hear the sound I'm talking about.

**Drew Wiley** · 13-Jul-2018, 12:41

It's the ballast. Kinda like the Engine light on a car dashboard. Might mean something bad, might not. In cold weather it could mean the ballast is struggling and that the ambient air temp needs to be warmer. Cold lights were often equipped with a separate warming device for this reason, intended to be turned on
in advance of a printing session. But things could be struggling because the tube itself is going bad, just like any fluorescent light.

**RichardRitter** · 13-Jul-2018, 13:47

It is the transformer.

The transformer generally goes before the bulb.

Cold light do not have ballast.

**AJ Edmondson** · 13-Jul-2018, 14:43

Had a similar problem years ago and the person I spoke with at Aristo suggested I reverse the two-pronged ac line plug and it did help (he had stated that "it may help" and it did though it didn't eliminate it. I can no longer recall whether the two-prong plug was the heater or the transformer.
Joel

**Robert Bowring** · 14-Jul-2018, 05:31

My aristo cold light head for bseseler 23c also makes a buzzing sound when it is turned on. It always has. I always thought that was normal. It has been working for about 30 years so I think it is ok.

**Drew Wiley** · 15-Jul-2018, 14:03

Thanks for the clarification, Richard. But in that case, the transformer is analogous to a lighting ballast because it gets fussy in cool humid conditions. There are times the onboard heater doesn't solve this. The ambient room temp and humidity need to be kept in bounds first. My darkroom uses passive electric heat and not forced air, so I might have to run the exhaust air fan on low for awhile in conjunction. The shop fluorescent bulb acts up too, under the same conditions. And I can't use electronic ballasts because they produce EMI that messes with any solid state darkroom controls in use. Only happens to me a few days a year; but those days predictable. In one instance I didn't want to wait for things to stabilize, so did my black and and white printing with a different enlarger equipped with an 8x10 colorhead instead of a cold light.

**radu_c** · 16-Jul-2018, 06:51

Thanks all for the input. As AJ suggested, first I tried reversing the power cord. Unfortunately it didn't help.
The warmer definitely does work because after an hour or so the housing does get warmer (with the lamp off).
So it's probably the transformer... although it can be a number of other things. This week I'll bring it to work and put it on the oscilloscope to see how the signal looks like. Judging by the noise, the transformer core is "leaking" but we'll see soon enough.
I thought I should ask first to see if it's something they normally do, or I just have one that's not doing so hot.

I'm listening to other suggestions if anyone had experienced this.