Ilford 500C controller electronic circuit diagram

Hi all,

Does anyone happen to have the electronic circuit diagram of the Ilford 500C controller, whether in paper or digital form?

Please note, I am NOT(!) looking for the circuit diagram of the later 500CPM controller, which is a different version, and for which the circuit diagram can be downloaded from Ilford's website (here: http://www.ilfordphoto.com/products/page.asp?n=161)

I have contacted Ilford / Harman Technology directly about this via e-mail, stating there are different versions of the 500 multigrade system, and asked them if they were able to make available all manuals and electronic diagrams of all versions for repair purposes. However, as it stands now, they probably aren't based on their answer. They just don't seem to have it any more. If they come across something accidentally though, they may update the list of available documentation.

But that doesn't help me. Is there possibly someone who in the past has received such a circuit diagram of the 500H multigrade system with the 500C controller from Ilford??

Marco

Hi all,

Well, far from a true circuit diagram, but after some Photoshop work, I managed to superimpose the circuit of the lower site of the electronics board on top of the upper site of the board. The image does give some idea of the complexity and layout of the electrical wiring:

Improvised circuit diagram in PDF format

Actually, it is quite interesting to see the "guts" of this thing, you probably never had a look in there too!

Essentially, contrary to some posting I saw on another discussionforum that stated that the controller was "pre-microchip-era", this statement turns out to be utterly untrue!

The controller, despite being from 1983 and many of the components from the 70's (note the '74 and '77 depicted on some components), is essentially almost completely computerized! It uses multiple integrated circuits (IC's - these are the big black square things with the many legs / connectors to the board). It even includes a programmable(!) EPROM, that is the flat object on the lower left site with the white Ilford sticker on it, that is fixed on the board like a true computer microprocessor fitted into a "CPU-style-socket".

Now, even more surprising (well, at least to people like myself that do not know much about electronics), many of these components, including the IC's, are actually completely generic, and hence, can STILL BE BOUGHT!!! And that 35(!) years after their original production... who would have thought that in an era where perfectly functioning computers are being replaced within one or two years or so, because they are "not-fast-enough" and superseded by a "new" model...

Yes, many or all of the complex IC components are obsolete by now, but there are still companies selling these things, and they have been produced new, for the repair market. Of course, since Ilford used generic components, these components must have been used in literally hundreds or thousands of different (industrial) machines and control equipment, and likely produced in the millions.

But replacement IC's, at least most of them, just cost a few dollars nowadays...

Since these things can still be had, this essentially means these units are, at least theoretically, repairable. The only thing that is non-replaceable, and thus non-repairable, is the programmable EPROM, because that needs the Ilford written control software. Since that is undoubtedly impossible to obtain, it can not be replaced.

Marco

On the other hand Marco, EPROMs can easily be copied, all that you would need would be another controller to copy from. If the EPROM is socketed it should be easy to copy without damage. There is probably a reasonable chance that Ilford would give you permission to do it too, under the circumstances.

Given that the EPROM (the chip with the paper label) is socketed, I wouldn't mind betting that some "dead" controllers could be revived by removing the EPROM, cleaning the pins, and replacing in the socket. IC sockets are notoriously unreliable when they get to be a few years old. As are any plugs and sockets that are not occasionally unmated come to that - the action of separating and reconnecting them cleans the contacts to some extent.

Marco, if I can be of any help let me know. Have you seen this thread? there was a url link here which no longer exists)

I have repaired on of my Omega controllers by swapping out integrated circuits (those circuit boards were made with all the ICs in sockets). One good thing about the Omega components in the USA is that they are plentiful. I have never had to completely rebuild a controller, because I have been able to collect 4 of them without too much trouble.

paul ewins said:

On the other hand Marco, EPROMs can easily be copied, all that you would need would be another controller to copy from. If the EPROM is socketed it should be easy to copy without damage. There is probably a reasonable chance that Ilford would give you permission to do it too, under the circumstances.

Click to expand...

I realize this may be possible, but IF the EPROM is copyable, it probably is fully functional and doesn't need replacement. If on the other hand the EPROM is damaged, and needs replacement, it probably is uncopyable, or is this latter assumption wrong?... well, probably depends on the kind of damage.

ic-racer said:

Marco, if I can be of any help let me know.

Click to expand...

Thanks for the offer, but actually, I already have help. Theo Kints, a Dutch member of APUG, who knows an awful lot about electronics, offered to help me out. I am in no way capable of doing this myself, since, although I have a very small bit of knowledge about electronics, I have no experience at all with soldering circuit boards and IC's. Theo is actually the one going to do a possible repair, and I have now send the controller to him for inspection and any follow up measures. He's really knowledgeable in this area, and in fact about everything I wrote up to now is based on his preliminary observations and judgements.

ic-racer said:

One good thing about the Omega components in the USA is that they are plentiful. I have never had to completely rebuild a controller, because I have been able to collect 4 of them without too much trouble.

Click to expand...

As I wrote, and based on Theo's and my own observation searching the internet, Ilford didn't use any specific "Ilford" components, but just generic ones, that is the reason they can still be had through specialized electronics traders and shops. So no need to hunt down "Ilford" branded parts...

RH Designs said:

Given that the EPROM (the chip with the paper label) is socketed, I wouldn't mind betting that some "dead" controllers could be revived by removing the EPROM, cleaning the pins, and replacing in the socket. IC sockets are notoriously unreliable when they get to be a few years old.

Click to expand...

Thanks for the tip and I will forward this to Theo, although I am pretty sure he has already thought about this himself and done this check.

Marco

ic-racer said:

Marco, if I can be of any help let me know. Have you seen this thread? there was a url link here which no longer exists)

I have repaired on of my Omega controllers by swapping out integrated circuits (those circuit boards were made with all the ICs in sockets).

Click to expand...

No, I had missed that. Interesting read ic-racer and great what you managed to do with these boards. I definitely wouldn't be able to do this, but Theo can.

I also noticed you wrote somewhere that SMD type circuit boards are about impossible to repair. While this is probably close to reality for most boards, here is a website that actually describes how to deal with SMD and soldering on these boards:

http://poeth.com/smtmfg.htm

But you probably already know this link...

Marco

Marco B said:

here is a website that actually describes how to deal with SMD

Click to expand...

If you have the tools, SMD boards are much easier to repair than through-hole boards.

Even without specialist tools, using only low temperature alloy,solder braid, an extra fine tip and some flux they are no harder to work on

Ilford 500C controller repaired

Ok guys,

Yes, we managed to solve the issues. Thanks to Theo van Kints, a Dutch member of APUG, I know have a working controller again.

But... the story has gone different than we thought...

What happened: I send the controller of to Theo, who is quite an expert in electronics.

Theo improvised a power supply, based on the electronic circuit schema's available from the Ilford website, that could supply all the voltages needed to power the 500C controller (5,-5,12V DC, and 12V AC). Actually, not much has changed in the 500S power supply, when Ilford introduced the newer 500CPM controller. The circuit diagrams of the 500C controller and 500CPM, do differ quite significantly though, especially some IC's have been replaced.

However... in the end it turned out we had a malfunctioning flatcable!

Now how could we have missed it? Well, first of, the flatcable (like the ones in computers) was inside the controller, and not the first obvious candidate for cable trouble. At least, the external cable that I replaced and resoldered, was a far more likely candidate for cable failure due to all the flexing and possible damage because of that.
The internal flatcable on the contrary, was fixed onto the housing and circuit board of the controller, allowing little if any movement.
Checking the electrical connections using a multi-meter, actually showed a working electrical connection on the internal flatcable, so Theo and I initially assumed this was not the source of the error.

Wrong of course... While Theo initially contemplated the replacement of the IC's, Theo did decide to give the connections a further check, especially since, although it is possible to buy the necessary IC's, it would be a major job, since the soldering is completely through the circuit board.
When he removed the rubber covering up the ends of the flatcable, where they connected to a small "circuitboard" that also held the external cable, he discovered that one of the split up thin flatcables, consisting of a core with at least 6 individual wires, had all broken wires, except 1!...

This meant that the initial check for electrical connectivity was OK, but all of the energy / Wattage needed to power the controller, also needed to be funnelled through this single tiny wire... Since it needed to power multiple IC's, this just wasn't enough and causing the controller to go haywire, while at the same time not being completely disfunctional, in the sense of completely dead.

In the process, Theo also discovered some of the other cables in the flatcable had broken wires. Shortening and resoldering the cables, Theo switched on the unit afterwards... And yes, there was life! No more haywire behaviour.

Theo now suspects, based on some other observations of the circuit board as well, that the unit may have seen a repair before (not unlikely considering it's 25 years old), and that in the process, the vulnerable ends of the flatcable, may have been damaged.

So what did we learn from all this?:

- Well, if you have a malfunctioning Ilford 500C or 500CPM controller, check all (flat-)cables first, including checking the integrity of the cable wires itself, not just relying on connectivity.
- Replacement IC's, if necessary, can STILL be bought! I am amazed that this is still possible, 35 years after the original production of some. They are obsolete though, and it may become harder to get them, but there are companies specializing in it.
- The circuit diagrams of the 500S power supply and 500C/500CPM controllers, do show differences, but they are insignificant in as much the 500S power supply is concerned, and the Ilford circuit diagrams for that unit in combination with the more modern 500CPM controller, are also perfectly usable for the older 500C unit combination. Basic circuit layout of the 500C and 500CPM units is different, but still readable in some extent, and the Photoshop figure I made may be of help to some who may need to make more drastic modifications, like truly replacing an IC.
- There are also circuit diagrams / schema available for the individual IC's on the net, and I have collected all of them and attached them here, for anyone needing it. PLEASE NOTE THE ATTACHED SCHEMAS ARE FOR THE 500C(!) UNIT, NOT THE 500CPM, which has different IC's.

Marco

Thanks for posting your experiences with our controller. Good to see it up and running again!

ic-racer said:

Thanks for posting your experiences with our controller. Good to see it up and running again!

Click to expand...

Yes, I am glad too it's up and running again, can finally do some LF printing again (I have a second 35 mm enlarger, Durst 670BW).

This minor problem, does make me wonder though, how many of these control units have ended up in the garbage bin because of similar problems... I have seen a few other discussion threads with people describing similar issues. Although there is no guarantee that they had the same problem, it might well have been a malfunctioning flatcable too.

Anyway, I think quite a large portion of electronics stuff ending up in waste dumps, could in fact have been repaired.

Marco

Marco B said:

Anyway, I think quite a large portion of electronics stuff ending up in waste dumps, could in fact have been repaired.

Marco

Click to expand...

When I see stuff, even possibly broken, I had picked it up (if price was reasonable). Over the years I have stocked up on 3 working heads, 1 parts head, 3 working controllers, and 1 parts controller.

Any electronic techs out there are probably nodding their heads over your experience. Most likely failure on any electronic item is a bad connection. Second most likely failure is the power supply.

Most techs troubleshoot this in reverse order. Check power first. Look for bad connections next. Check intermittent connections last.

Dave Pritchard said:

Check power first. Look for bad connections next. Check intermittent connections last.

Click to expand...

Theo did all that and in the order you described, but since we are not living close by, he had me check out from a distance, via phone calls, the 500S power supply first, before he asked me to send out the 500C controller to him, just to make sure I wasn't going to send him a perfectly working controller, while the real problem might have been the power supply...

He than checked the major electrical connections first when he received the 500C, but as I wrote, because the cable wire WAS giving a "healthy" signal, he did contemplate other options too.

It was only after he decided to check out the flatcable a second time, and removing the rubber covering up the ends, that he discovered the real problem.

And of course I should have done that too in hindsight

Marco