Jobo Processor Rotary speed

gelatine · Sep 9, 2024

Hi, Folks:
I have a JOBO CPP2 from 1990. I'm trying to repair/remake a PCB board for it.
I have done most of the design except I'm not sure how's the rotary speed.
Does anyone know what's the RPM for each speed?
As far as I can remember, the dial is 0 / F / 3 / 4 / P / 6 / 7.
I need to know the RPM of each No.

Thank you very much for your help.

emeraldcity_grain · Sep 9, 2024

The speeds were different depending on the motor used. The ‘older‘’units (slotted screw on center cog) had different speeds from ‘newer‘ units (hex sccket screw on center cog).

I took these notes years ago from this site and from instruction manuals.

Old Settings
0 - Off
F - 25 r.p.m.
3 - 40 r.p.m.
4 - 50 r.p.m.
P - 75 r.p.m.
6 - 78 r.p.m.
7 - 80 r.p.m.

*New Settings
0+ 25 r.p.m.
F - 46 r.p.m.
3 - 70 r.p.m.
4 - 86 r.p.m.
P - 86 r.p.m.
6 - 86 r.p.m.
7 - 86 r.p.m.
*These speeds are approximate and variations of 10-15 r.p.m.

mshchem · Sep 9, 2024

emeraldcity_grain said:
The speeds were different depending on the motor used. The ‘older‘’units (slotted screw on center cog) had different speeds from ‘newer‘ units (hex sccket screw on center cog).

I took these notes years ago from this site and from instruction manuals.

Old Settings
0 - Off
F - 25 r.p.m.
3 - 40 r.p.m.
4 - 50 r.p.m.
P - 75 r.p.m.
6 - 78 r.p.m.
7 - 80 r.p.m.

*New Settings
0+ 25 r.p.m.
F - 46 r.p.m.
3 - 70 r.p.m.
4 - 86 r.p.m.
P - 86 r.p.m.
6 - 86 r.p.m.
7 - 86 r.p.m.
*These speeds are approximate and variations of 10-15 r.p.m.

Has anyone ever translated what the F and P stand for? It can't be film and print????

gelatine · Sep 9, 2024

Hi, yes,
F for film and P for paper.
6 - 7 is usually for wash.

emeraldcity_grain said:
The speeds were different depending on the motor used. The ‘older‘’units (slotted screw on center cog) had different speeds from ‘newer‘ units (hex sccket screw on center cog).

I took these notes years ago from this site and from instruction manuals.

Old Settings
0 - Off
F - 25 r.p.m.
3 - 40 r.p.m.
4 - 50 r.p.m.
P - 75 r.p.m.
6 - 78 r.p.m.
7 - 80 r.p.m.

*New Settings
0+ 25 r.p.m.
F - 46 r.p.m.
3 - 70 r.p.m.
4 - 86 r.p.m.
P - 86 r.p.m.
6 - 86 r.p.m.
7 - 86 r.p.m.
*These speeds are approximate and variations of 10-15 r.p.m.

OMG. THANK YOU!!!!!! This is the No. I'm looking for.
Really appreciate for your help.

Sal Santamaura · Sep 9, 2024

emeraldcity_grain said:
The speeds were different depending on the motor used. The ‘older‘’units (slotted screw on center cog) had different speeds from ‘newer‘ units (hex sccket screw on center cog).

I took these notes years ago from this site and from instruction manuals.

Old Settings
0 - Off
F - 25 r.p.m.
3 - 40 r.p.m.
4 - 50 r.p.m.
P - 75 r.p.m.
6 - 78 r.p.m.
7 - 80 r.p.m.

*New Settings
0+ 25 r.p.m.
F - 46 r.p.m.
3 - 70 r.p.m.
4 - 86 r.p.m.
P - 86 r.p.m.
6 - 86 r.p.m.
7 - 86 r.p.m.
*These speeds are approximate and variations of 10-15 r.p.m.

It's important to read those data in context. For a complete version of the old U.S. Jobo's documentation on speed settings, see this post:

Jobo Rotation Speed

Hey, all you Jobonauts. What is the effect of the speed of drum rotation on development? I am talking specifically about b&w. The recommended speed for b&w is 50 RPM. Will a slower speed (25) increase development time? Will it lower contrast? What about a higher speed (75)? The slower...

www.photrio.com

Vaughn · Sep 9, 2024

Are those speeds for a set diameter drum? The Unicolor motor base rotates my Expert Drums at 15 rpm. I can not image rotating those at 45 rpm, and at 80 rpm it seems it would become a centrifuge.

Edit to add...perhaps they are the rpm of the motor and not directly related to drum diameter?

DREW WILEY · Sep 9, 2024

Do you really want to replicate the original Jobo RPM's? In general, one of their main flaws was that even the lowest speed was too high for some processes, with too little torque.

Sal Santamaura · Sep 9, 2024

Vaughn said:
Are those speeds for a set diameter drum? The Unicolor motor base rotates my Expert Drums at 15 rpm. I can not image rotating those at 45 rpm, and at 80 rpm it seems it would become a centrifuge.

Edit to add...perhaps they are the rpm of the motor and not directly related to drum diameter?

Those are the speeds for any drum, irrespective of diameter. The only factor that slows them slightly is higher loads, i.e. at or (in violation of the specified limit) above1,000 ml.

At the slowest possible speed knob position on my CPP-2 (latest motor, just past off), drums rotate at around 25 rpm. I've found this to be sufficiently slow to avoid issues with film/developer combinations that are sensitive to excessive agitation.

gelatine · Sep 10, 2024

Yes. sir. I'm trying to replicate the original JOBO.
But NO, as I can not find the 6 step switch I need, I'm gonna make it to 10 step switch.
I then can make it to wider selection of different RPM.... hopefully. finger crossed.

Vaughn · Sep 10, 2024

I had to dis-arm the auto-reverse on the motor base...the Unicolor motor-base rotates the drums with rubber-tipped wheels (constant speed) running on the side of the drum and I was not getting a full rotation with those large diameter Expert Drums before the motor-base would auto-reverse. On that type of machine, the smaller the circumference of the drum, the faster the rpm of the drum.

Sal's 25 rpm sounds reasonable. My 15 rpm seems to do a good job, based on my negatives from the 3005 and 3006.

ic-racer · Sep 10, 2024

Realize what the "New" settings are. I got my Jobo in 2001 and it is the "New" version, essentially two speeds.
For film processing I usually use 'P' for the 1500 and 2500 drums and 'F' or lower for the large "Expert" drums.
I don't use any processes that are sensitive to over-agitation, so I cannot comment on that.

Sirius Glass · Sep 10, 2024

mshchem said:
Has anyone ever translated what the F and P stand for? It can't be film and print????

I use P for 35mm and medium format film and I use '4' for 4"x5" film.

DREW WILEY · Sep 10, 2024

Depends on the developer. Some developers get excessively oxidized at the available Jobo speed settings. Fortunately, I have a customized CPI rotary processor rather than a Jobo unit, and it's far more seriously built, including a substantially bigger gear-motor operable over a much wider RPM range (it can also handle much bigger drums). But if one is patient, they could simply roll a drum gently back and forth along the bed of their darkroom sink, or even on some other smooth surface.

mshchem · Sep 10, 2024

Sirius Glass said:
I use P for 35mm and medium format film and I use '4' for 4"x5" film.

I'm still curious if F and P are German abbreviations?

Sirius Glass · Sep 10, 2024

mshchem said:
I'm still curious if F and P are German abbreviations?

Probably

Sal Santamaura · Sep 10, 2024

mshchem said:
I'm still curious if F and P are German abbreviations?

Ja, für "Film" und "Papier."

mshchem · Sep 10, 2024

Sal Santamaura said:
Ja, für "Film" und "Papier."

You betcha

Jobo Processor Rotary speed

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