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Old 11th September 2013, 04:45 PM
Tom Kershaw Tom Kershaw is offline
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Default ILFORD MG500 / Stop Clock 500 - blue lamp not working

Has anyone here experienced one of the lamps on their MG500 systems not working? Last week I was in the middle of a printing session when I noticed the blue lamp wasn't firing and changed the lamp to no effect. I'm using the RH Designs timer which fires the green and then blue lamps separately. As I have another older MG500 system connected to a De Vere 203 I tried the timer on that and the blue lamp worked fine, so the RH Designs product is not at fault.

Unfortunately, as many of us have become more aware in recent years when sourcing spares, the two MG500 systems are not directly compatible so I cannot simply swap over the power supply from the older system and continue working. I have both the 500C and 500CPM controller but as I'm unable to find the cable for the 500CPM I connected up the 500C to the 504 and found the same result, i.e. green exposure and focusing fine, no blue exposure.

These problems seem to suggest the power supply is at fault and I'm aware the 500S supply had been sent off for repair some years ago by the previous owner, although I'm unaware of the nature of the defect at that time. Assuming I can swap over the conversion plates of the two MG500 systems I may try attaching the older MG500 to the De Vere 504 but I'd prefer the current set-up to work; it would certainly be more reassuring.

any ideas?

Tom
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Old 11th September 2013, 05:47 PM
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vanannan vanannan is offline
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Quote:
Originally Posted by Tom Kershaw View Post
Has anyone here experienced one of the lamps on their MG500 systems not working? Last week I was in the middle of a printing session when I noticed the blue lamp wasn't firing and changed the lamp to no effect. I'm using the RH Designs timer which fires the green and then blue lamps separately. As I have another older MG500 system connected to a De Vere 203 I tried the timer on that and the blue lamp worked fine, so the RH Designs product is not at fault.

Unfortunately, as many of us have become more aware in recent years when sourcing spares, the two MG500 systems are not directly compatible so I cannot simply swap over the power supply from the older system and continue working. I have both the 500C and 500CPM controller but as I'm unable to find the cable for the 500CPM I connected up the 500C to the 504 and found the same result, i.e. green exposure and focusing fine, no blue exposure.

These problems seem to suggest the power supply is at fault and I'm aware the 500S supply had been sent off for repair some years ago by the previous owner, although I'm unaware of the nature of the defect at that time. Assuming I can swap over the conversion plates of the two MG500 systems I may try attaching the older MG500 to the De Vere 504 but I'd prefer the current set-up to work; it would certainly be more reassuring.

any ideas?

Tom
Hi Tom
I'm afraid I am unable to help with your problem, could you please tell me more about the two different MG500 systems as I have recently acquired a second MG500 thinking that the controllers would be interchangeable, I have not tried to swap them yet so I need to know of any issues.

Thanks
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Old 11th September 2013, 06:01 PM
Tom Kershaw Tom Kershaw is offline
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The controllers do seem to be interchangeable (or at least the 500C is compatible with the newer system), although the power supplies are different.

Tom
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Old 11th September 2013, 07:32 PM
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dsallen dsallen is offline
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Originally Posted by Tom Kershaw View Post
The controllers do seem to be interchangeable (or at least the 500C is compatible with the newer system), although the power supplies are different.

Tom
The control pads are completely interchangeable but you are using a RH Designs timer so you need to talk to them.

Bests,

David
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Old 11th September 2013, 08:11 PM
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If the other system's blue lamp works with our Timer then it's not the Timer that's the problem. There are indeed two different power supplies with different plug connections to the head, but the controllers work with both. Hence there is only one variety of StopClock 500 / Analyser 500.
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  #6  
Old 11th September 2013, 10:56 PM
George R George R is offline
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As mentioned the control pads are interchangeable. Starting at the controller the is one lead that controls the blue and another for the green. The first point of failure after the controller could be the cable to the power supply. The circuit in the power supply is very simple for the lamp control. An interface transistor for each lamp controlling a triac for each lamp. The newer power supplies (round pin) add an optical-isolator in the middle. From the power supply to the head are separate control leads from the triacs to the lamps. The both share a common 120VAC from the power transformer.

Another point of failure could be the lamp socket - these can get corroded and fail. If you or a friend has the right tools and are not afraid of schematics I do have copies. A little while ago I was able to find current listings for the transistor and the triacs - not sure about the isolator but I 80% sure something could be found.

George
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Old 11th September 2013, 11:11 PM
Tom Kershaw Tom Kershaw is offline
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Quote:
Originally Posted by George R View Post
As mentioned the control pads are interchangeable. Starting at the controller the is one lead that controls the blue and another for the green. The first point of failure after the controller could be the cable to the power supply. The circuit in the power supply is very simple for the lamp control. An interface transistor for each lamp controlling a triac for each lamp. The newer power supplies (round pin) add an optical-isolator in the middle. From the power supply to the head are separate control leads from the triacs to the lamps. The both share a common 120VAC from the power transformer.

Another point of failure could be the lamp socket - these can get corroded and fail. If you or a friend has the right tools and are not afraid of schematics I do have copies. A little while ago I was able to find current listings for the transistor and the triacs - not sure about the isolator but I 80% sure something could be found.

George
A useful post George, I wasn't aware of any light flickering or smoke though when the "blue" lamp stopped working. Could corrosion go to the point of an on-off response; although I suppose that could go in hand with a lamp blowing and the new lamp not making good contact - It worked one moment and not the next.

Tom
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Old 14th September 2013, 08:54 AM
youngrichard youngrichard is offline
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I had the same problem a couple of weeks ago. I also have 2 MG500s on separate enlargers, and an RH Designs Analyser 500. A bulb blew , the replacement came on briefly then died. I tore my hair out trying to isolate where the problem was, swapping bulbs and power supplies and the controller. Cut a long story short, I wasn't pushing the bulb fully home into the socket. Probably there is some corrosion in that particular socket. Finally I gave the base of the bulb a good push, felt something "give" as the pins slid home, and bingo, back in business.
Richard
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