Rebuilding a Jobo….

My old Jobo (CPE2 the old type) is gone… or the motor is. There for I’m rebuilding/upgrading it. Putting in a microchip controlled stepmotor and temperature control together with a water pump.
With the temperature controller and a extra heating element I should be able to control the temp. to 0.1 degree C.
I have to hardcode the controller for the step motor with different rotations speeds but witch? And how often should it change direction ? I’m using the 1500 drums for film (B&W) and rarely the 2800 series for print.

Jesper

I've just checked mine, and the motor reverses every 2 sec on the higher speed.
Jobo advise not to use the low speed, but in case you need it, it reverses every 4 sec.
It does 2 revs each way, regardless of speed.

You might have these already, but I thought you might find them useful if not:
http://www.tech-diy.com/jobo.htm
http://www.ludens.cl/photo/processor/processor.html
http://www.ludens.cl/Electron/photoproc/photoprc.html

Dear Jesper,

The high speed is around 75rpm.

Neal Wydra

On mine: 75 rpm, and 4 second intervals.

I have had the 'CPE-2', and now have the later 'CPE-2 Plus'. The 'Plus', paradoxically, only has a single speed setting, marked '75'. The earlier one had two speed settings '1' and '2'. I vaguely remember reading somewhere that the motor didn't like one of the speed settings and tended to go kaput; I guess that's what yours has done.

Personally, given the price you can pick them up for second hand, I would just look for another on the auction site. Preferably with the lift. Might save a lot of hassle.

I use the 75 RPM for everything except for my 12x20 film. For the large film I use 25rpm and add more developer. It keeps me from getting streaks.

I am interested in your plans for doing this yourself. Would you care to expand on your plans?

Thanks,

I'll put all my part's lists cirkuts photo online as the projekt goes on.
The reason for rebuilding instead of buying another used is tha it's old machinery, and I'll like to control the temp more precise. I got no use of a lift with my drums so..
And for the fun of it..

Jesper

Don't know what microcontroller you are using but the Arduino (Atmel chip) has an open source PID implemenation now. Much easier than writing your own.

One nice thing about having a darkroom is it is easy to make ones own PCBoards

CCOS said:

My old Jobo (CPE2 the old type) is gone… or the motor is. There for I’m rebuilding/upgrading it. Putting in a microchip controlled stepmotor and temperature control together with a water pump.
With the temperature controller and a extra heating element I should be able to control the temp. to 0.1 degree C.
I have to hardcode the controller for the step motor with different rotations speeds but witch? And how often should it change direction ? I’m using the 1500 drums for film (B&W) and rarely the 2800 series for print.

Jesper

Click to expand...

What you are doing could provide valuable information to those of who may face the same problem with these processors. I hope you will share your expertise. For the moment my processors are still working; I just purchased a back-up in case my my now 20year old one dies.

Robert Hall said:

One nice thing about having a darkroom is it is easy to make ones own PCBoards

Click to expand...

I have to make up six boards for an amp I am making. I was going to use the 'xerox-paper-heat-transfer' method. Do you have a good link to doing it photographically in the darkroom.

I use both methods. I have just gotten down the secrets of doing it with toner transfer. I needed a harder surface and more heat. I tried doing it in my press but it wasn't near enough pressure. I use an iron on a piece of non-corrugated cardboard with a quite hot iron for about a minute and a half. I use a piece of release paper to keep the iron slippery on the surface so I can move it back and forth with a lot of pressure on it. I have used the Pulsar stuff and that work well too doing the same thing. I then soak it in water after it has cooled and it comes off quite nicely. I make sure I rough up the board with 600 grit wet/dry paper first to make sure it has a tooth and is clean. I etch with either HCL and 40 strength hydrogen peroxide or ferric chloride and hydrogen peroxide. (this releases chlorine gas so do it under a fume hood -- nasty stuff) and it cleans to perfection in 3 minutes.

Doing your board above with a transparency would be a piece of cake as well. You will be fine doing it either way. One can get very fine lines doing it with the coating and a good print frame and uv light. I have my own UV source, I can't remember if you do as well, it really helps.

One can get some very fine lines with doing it in the darkroom but with what you have above looks just fine either way.

If you find the chems to coat the board, they have fine directions on the package. I have a spray that is nice, sorry, can't think of the name of it at the moment. I then use a positive developer mixed 1:9 (go figure lol) and let it dry, then etch. GC has the developer, I have a hard time finding the chems to coat it anymore, probably something toxic in them that people need to be protected from. (tongue firmly planted in cheek)

73's -- KE7VHF