Ilford 500 H Issue with green dichoic filter light

[dacheste]

I have been trying to figure out this strange light issue I have been experiencing on my Ilford 500H head on my Durst 138 Enlarger. The Enlarger and head was left sitting for about 6 months, after which I purchased it from a friend. The enlarger appeared to work for our test before the purchase, but since has had issues. The first time the bulbs blew, I was raising the enlarger while the focus light was one, and the power cable from the head to the power supply had slight strain put on it, which caused both bulbs to blow. I replaced both bulbs and the enlarger was then working again for approximately 3 prints. The bulb with the green dichroic filter blew, while the bulb under the blue dichroic filter was still in tact. I again replaced just the one blow bulb and this time was able to get through 24 contact sheet prints before the same bulb blew. I again replaced the bulb, and was able to print another 13 prints before the green dichroic bulb again blew.

Having posted to the forum and heard people's suggestions that perhaps the light chassis were corroded, I went ahead and replaced both halogen chassis. Today when I returned to the darkroom to reaffix the head with the new chassis, I placed two brand new halogens into the chassis and turned on the power supply to find that only the bulb in the blue dichroic filter chassis worked. Both bulb were in tact, and when I switched the bulbs to the opposing chassis, the same thing occurred where the bulb in the chassis with the blue dichoic filter lit while the bulb in the chassis with the green dichoic filter did not turn on.

I am completely perplexed. To add to this I have noticed that on the Power Supply for the Ilford 500H, the light in the power button has blown out in the past few weeks along the same timeline as these issues. I am wondering if there may be an issue with the power supply that is causing this strange problem.

Thanks,
Diana

 

[dacheste]

are you using chinese bulbs?

I am using WIKO Japanese bulbs

 

[George Nova Scotia]

The light on the power supply switch is a neon bulb. They die with age and it is now very old indeed. They usually flicker for a while before they die. It should not be related to your problems.

It sounds like the green lamp has never worked since you changed the the sockets, if so start with checking your connections. Did you just change the lamp socket or did you get the complete assembly with the filters and sockets? A slight strain on the cable would not normally cause a problem, but it worries me a bit. The power supply does have electronics that control the lights but it's pretty basic. Also double check you are not set for grade 5 it will only turn on the blue lamp.

 

[George Nova Scotia]

How are you making out? I noticed something today on my unit. When I tried it after having the cover open the green light didn't work. Seems the interlock switch has two stages/sets of contacts. The first connects the blue the second the green. If I used a pencil to push in the switch there are two distinct clicks, one for each light. If the cover wasn't closed completely the green light didn't work.The early models with all flat pins on the connector may not have this switch.

 

[dacheste]

George I have as far as I can tell resolved the problem. I did chafe out the halogen chassis and you re correct about the interlock switch issue. I think this is probably one of the least robust components on the 500 head. The interlock for the heat sensor and blue bulb (the bottom two) were clicking in, while the interlock for the green bulb (the one on the top) was not. Thanks for checking in. Now I am finding that I need to recalibrate the enlarger. After all of the messing around I did my prints are coming out grey. Thanks for checking in.

D