Ilford Multigrade 500 problem

[Danby Mike]

I hope someone can help with this. Having worked faultlessly for the past nine months my Multigrade 500 set-up has started to be unreliable with exposure times.
I can make test strips of say 9, 10 11, 12 seconds and all is fine. I then make the print at 11secs and it comes out light, looking more like 10secs. Another test strip at 13 secs will match the previous 11 sec strip. So, very frustrating.
I have tested the 500c control unit against a stopwatch and it appears accurate. Both bulbs are working. Could the 500s power supply have become faulty? Could it's output voltage be decreasing as it gets warmer?
All thoughts appreciated.........

 

[MARTIE]

Could it be that one or both of the lamps are on their way out?

 

[Danby Mike]

Thanks Martie. Both were renewed about nine months back albeit with "new" old stock. The new spare that I had turned out to not work at all so their reliability is certainly iffy.
Could their output decrease with age/heat?
I will get replacements (not that easy to find). Great if the problem is simply bulbs. I dread a power supply failure!

 

[MattKing]

IIRC, the Multigrade 500 bulb sockets tend to require replacement from time to time, so it would be worthwhile to consider them as well.

 

[Danby Mike]

Thanks Matt, I will look into this.

Mike

 

[AgX]

Could it be that one or both of the lamps are on their way out?

Could their output decrease with age/heat?

Plain incandescent lamps indeed age. Metal vapours condense at the bulb, reducing light output. Also the colour temperature falls a bit.

However the Multigrade 500 head has got halogen incandeecent lamps. They pracically have a consistent light output to their last minute.

But Matt made a good remark. Contacts can become an issue, typically due to the heat involved. One might clean the contacts of the lamp and even exchange the socket.
The Multigrade 500 though even had ventilated lamps. On the other hand , such head typically was used commercially in its former life and thus had seen by magnitudes more working hours than in an amateur darkroom.

 

[Danby Mike]

Thanks AgX. I had a few minutes spare today and dismantled the left bulb assembly and cleaned the two glass pieces and the filter glass. The lamp socket is riveted on and made in USA. Are these available in the UK? At the very least I will clean the contacts thoroughly as advised by Matt and yourself.
I bought my multigrade set-up and Durst Laboritor enlarger about 14 years ago from a professional printer who was emigrating so it has certainly had plenty of commercial use .

 

[esearing]

With those short times are you sure you are not getting light bouncing off nearby wall or something that makes 11 seconds no different than 10 seconds? I find if I use times around 30-40 seconds it takes a great deal more effort to underexpose or overexpose, and is very dark due to lens being stopped down more. Also is you time in developer consistent?

 

[Danby Mike]

Thanks Eric,
Your point re longer exposure times is interesting and I will try this out.

 

[Lachlan Young]

@Danby Mike - you might want to check that the head plug is not getting worked out of its socket at the transformer end - and if you need lamp sockets, contact Odyssey Sales/ De Vere - be warned, it is a slightly fiddly job to replace them. Hopefully it isn't a problem in the controller unit. Do also consider that you may be discovering that short tests and longer final exposures are not going to be consistent, unless you take steps to compensate for the time taken for start-up/ switch-off of the bulbs.

 

[Danby Mike]

Multigrade head now working as it should so all is well. The power unit was checked over by an electronics expert friend and found to be in good order. Bulb sockets replaced and new bulbs fitted. All connections scrupulously cleaned and I'm printing happily again! Thanks to all who helped.
Mike

 

[Andrew O'Neill]

That's good to hear, Mike. I had same unit over in Japan in the 90's. It was loaned to me by Ilford Japan. I had it for almost a year. Loved it until the the fan started vibrating! Great system, though.

 

[esearing]

Fire it up once every week or so for a few minutes to keep it running at peak performance. Dust is the killer of the power source. The light source doesn't seem to need the cycling or use. I clean the contacts into the power unit every 6 months or so.

 

[John Wiegerink]

I had this same head and all the goodies years ago on a Beseler V-xl, but sold it. Kind of kicked myself later for doing so, but life goes on. Now I have two of the older Ilford 400 units, one on my Leica Ic Focomat and one on my old trusty Omega D6 enlarger. I actually think I get along better with the 400H and 400L better than I did with the fancy 500H. Of course my printing has changed since the 500H. When I had the 500H I printed on graded paper almost exclusively and now it's almost exclusively VC paper. I bought up all the spare parts I could for the 400 units just in case???? JohnW

 

[Dwayne Martin]

Another thing to check out would be all of your electrical connections in the outlet that the unit is plugged into and your breaker panel. Obviously you should have an electrician do this work. I would check the neutral connections particularly. For some unknown reason they tend to get loose after some years and can cause flickering lights in your house if I’m not mistaken.