ilford 500 heads

wager123 said:

hi marco
the manual with the diagrams is the service manual i have. so its for the newer unit with a cpm controler. i wanterd to compair the two as after takeing the two different plug heads off the color wires , even tho they use the same colors, are on different pins. thanks for all the links. i just have to hope someone has one.
mitch

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Hi Mitch,

Maybe this is a little bit of use. It shows the wire connections for the controller cable to the 500C controller and the respective voltages on some of the cables. See attachment.

Marco

hi marco
thanks for the image. what i am trying to do is get a diagram of the 500 head to power supply connection .i have one head with all flat pins and one with 7 flat and 1 round. i have the wireing info for the one with the round pin but need one showing the wires of the plug with all flat pin.
thanks all
mitch

wager123 said:

hi marco
thanks for the image. what i am trying to do is get a diagram of the 500 head to power supply connection .i have one head with all flat pins and one with 7 flat and 1 round. i have the wireing info for the one with the round pin but need one showing the wires of the plug with all flat pin.
thanks all
mitch

Click to expand...

Mitch,

Essentially, both the 500S power supply and the head have changed little, at least not in any significant way.

The main differences between the circuit diagrams of the 500S power supply and head of the MG500 system with the 500CPM controller versus the ones with the 500C controller, seems to be that in the newer power supply two circuit boards are used (PCB1 & PCB2 in the circuit diagram of the power supply in the "MG500 Exposure System Service Manual") versus one in the older power supply for the 500C controller. However, the basic functioning of many of the components listed for the newer powers supplies circuit boards, are exactly the same as in the old one, and many of the IC (integrated circuits) model numbers match.

In terms of changes to the head, it seems Ilford added an additional "door interlock" switch (SW1 in the circuit diagram of the enlarger head - fig 2.1 on p15 of the "MG500 Exposure System Service Manual") to cut out the high voltage connections to the head whenever you open the heads front panel. This is just a basic extra safety measure. In my older unit, I can open the head with the lamps burning.

I don't think this last change affects the wiring schema to the head in any way, it is just an internal switch in the head itself if I am right, but you can check it in your heads.

I basically wouldn't be too surprised if no real change in the wiring to the enlarger head has taken place... The main difference is in the two types of controllers, and how they interact with the power supply to switch and modulate the light output of the lamps.

Looking from the fig 2.3, p17 diagram of the power supply in the Ilford service manual, SK2 denotes the socket of the enlarger head. Pins 5 & 6 are for the high voltage connections to the two lamps, allowing them to be switched. 1 (the rounded pin on the new units) is the ground. Pin 7 & 8 should be 120V AC, pin 2 30V AC, 4 is connected to the 0V and switches the cooling fan in the head by means of relay RL2/1. Relay RL1/1 switches the safe light. Both of these you can actually "hear" switching with a small tick if you listen carefully. Pin 3 seems unused...

Marco thanks for the very detailed info. I have noticed that the fan in my head doesn't turn off but runs all the time . i would guess that the relay must be bad. do you think that the fact the fan runs all the time would cause a problem that must be fixed? if so how hard would this be? again thaks to everyone. this is the best site i have found and this kind of help from all is why i subscribe
mitch

wager123 said:

Marco thanks for the very detailed info. I have noticed that the fan in my head doesn't turn off but runs all the time . i would guess that the relay must be bad. do you think that the fact the fan runs all the time would cause a problem that must be fixed?

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I am not an electronics expert or so, but to me, the fan not turning off seems to be a negligible issue. The only reason I can think of that you might not wish to have it run all the time is the noise and possible diminished life time of the fan. But looking at computer fans, I guess the fan will keep running almost eternally...

However, if it would break, you might have some trouble finding a replacement for this specific type of fan.

By the way, much to my own surprise, in terms of real electronics repairs, it turns out that most of the components, even though designed and manufactured for the first time at the end of the '70s, are still being manufactured and can be bought through good electronics shops.

I was actually astonished to learn this from a very helpful Dutch APUG member with good electronics knowledge, but it turns out these components are so generic, they still have use today and have probably had wide spread application in industrial equipment needing servicing for decades, hence they are still available to be bought new.

This means that a true repair of even the more complicated (IC) components in the power supply or controller may be viable, if really necessary.

But be careful before calling something "broken". I had issues with the start up of the controller and it going bezerk. Besides an easily fixed issue with the cable connecting it to the power supply, it also turned out the unit had issues with dampness. My bathroom doubles as darkroom, and even though I ventilated it well, the controller gave issues. Turns out that switching the MG500 including the controller on during showering each day, solves the issues completely!!! I guess, since the controller and power supply warm up during use and being on, no longer any tiny water film or dampness can form, allowing the unit to start up properly as it should.

WoW, Marco,
it looks like you have PhD in Ilford 500 Heads!!
Thank you!
Goran

gorbas said:

WoW, Marco,
it looks like you have PhD in Ilford 500 Heads!!
Thank you!
Goran

Click to expand...

Well, actually, all honour goes to that Dutch member of APUG that helped me out on a repair of the unit that I referred to earlier in the thread, and gave me a quick course in electronics in the process!

In addition, some of the stuff I wrote may not be correct. Wager123 now managed to dig up the circuit diagrams of the power supply and enlarger head for the older units with 8 flat pin connectors, and started a new thread about that, read that for the latest info:

(there was a url link here which no longer exists)

Marco

Marco B said:

But looking at computer fans, I guess the fan will keep running almost eternally...
However, if it would break, you might have some trouble finding a replacement for this specific type of fan.

Click to expand...

The fan in my 500CPM version runs continuously also. I think it's meant to.

This style of fan (called a "muffin" fan) is readily available and manufactured in standard sizes. I don't expect it would be difficult to find a replacement.

Marco B said:

By the way, much to my own surprise, in terms of real electronics repairs, it turns out that most of the components, even though designed and manufactured for the first time at the end of the '70s, are still being manufactured and can be bought through good electronics shops.
I was actually astonished to learn this from a very helpful Dutch APUG member with good electronics knowledge, but it turns out these components are so generic, they still have use today and have probably had wide spread application in industrial equipment needing servicing for decades, hence they are still available to be bought new.

Click to expand...

In reviewing the parts list and schematics in the manual, virtually all components should be readily available. The only exception would be the power transformer, which is unique to the product.

The weak link in the power supply chain (and in all such products universally) is the electrolytic capacitors. These have by far the highest failure rate of any component. Fortunately, they're easy to replace, and exact replacements should be easy to find.

- Leigh

Leigh B said:

The fan in my 500CPM version runs continuously also. I think it's meant to.

This style of fan (called a "muffin" fan) is readily available and manufactured in standard sizes. I don't expect it would be difficult to find a replacement.

Click to expand...

Good to hear this Leigh, comforting to know replacements are available.

Leigh B said:

The fan in my 500CPM version runs continuously also. I think it's meant to.

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The fan in my 500C controller controlled head, certainly doesn't run continuously. It shuts down after about 2 minutes, which is actually quite convenient as a means to tell me it's about time to pull the print from the developer

Leigh B said:

In reviewing the parts list and schematics in the manual, virtually all components should be readily available. The only exception would be the power transformer, which is unique to the product.

Click to expand...

Since the term "power transformer" is a bit ambiguous in view of having the 500S power supply unit, do you mean with non replaceable "power transformer" the actual copper coils and iron bars that form the actual heart of the power supply by transforming mains voltage to the appropriate output voltages for the rest of the power supply circuitry?