Bell & Howell 185 16mm projector speed

[Osvaldo Flores]

I'm restoring a Bell & Howell 185 16 mm sound projector, and I was testing it with a sound film..., everything was going well and after few minutes the speed change by itself to high speed.
Can anyone in the forum please help me on how to adjust the speed to the normal sound speed of 24fps ?
Thank you so much
Osvaldo

[Jim Cassedy]

The 185 and 285 are two of my favorite vintage 16mm projectors. I've owned several of each.
The motor uses a centrifugal governor which is under a cover at the "rear end" of the motor.
The governor has a set of springs and contact points - one set is for "sound speed" and one
is for "silent speed" (which cuts a resistor in & out of the circuit) The contact points on the
rotating assembly gets it's power through a set of rings and carbon brushes. One problem
that happens, is sometimes the brushes get 'stuck' in their holders and don't make good
contact. The motor will still but speed will be all over the place. Sometimes all it takes is
a disassembly and good cleaning to make sure the brushes slide freely in their holders.
If the brushes are worn down to almost nothing, and no longer able to make good contact,
then you've got a problem, because it will be probably be really hard to find replacements.

The 2nd thing that can happen is that the contact points need cleaning. This is easy to do.
But if the contact points and springs have gotten out of adjustment, this is a real pain in the
butt to deal with. The adjustment screws are usually kept from moving with a drop of some
sort of 'lock-tite" compound, but you really don't want to mess with that adjustment unless
you thing you absolutely need to, because the only way to test it after adjusting is to re-
assemble the motor, put the machine back in the case, power it up, and hope for the best.
If that doesn't work, you have to start from square one again - pulling the whole machine
apart, making an adjustment, then putting it all back together, again, and testing. In short,
for every test and adjustment, you pretty much have to disassemble and re-assemble the
machine. (In the mid 1980's I worked for a while at a B&H repair depot, and to adjust the
speed, we had a special jig that we would put a 'bad' governor on and make all the tests
and adjustments on that and then put it back into the projector. But even this was a pain
to do- -so we usually just grabbed a brand-new, calibrated governor assembly out of the
parts bin - and often we'd put in a new pair of governor brushes too, just for good measure.)

As long as you've got the projector pulled apart, I'd check the motor brushes too.

I see the F-T Warehouse doesn't have a 185 manual, but the wiring diagrams in the
manual for the 179 shows the way I remember the 185 being wired. If you look at the
schematic, you'll see the governor contact points & resistor I mention, although the
wiring color codes between machines may be different.

> Does the machine go wild on both SILENT and SOUND speeds, or only one of
them? If one speed is steady, and the other varies all over the place, first thing I'd
check is the brushes & rings in the governor assembly.

The 179 Manual is here:

http://www.film-tech.com/warehouse/manuals/BH179OS.pdf

[Osvaldo Flores]

Thank you so much Jim,
The machine go wild on both, silent and sound... I order a tachometer in order to adjust the rpm but I did not received jet. I try to adjust the contact on the sound side, but there is no change at all , I also clean with contact cleaner the 3 set of brushes and cleaning the rings, but again no change on the speed.
I'll wait for the tachometer to arrive and then I'll start all over again ...
Dear Jim, If I can not get any change on the speed by doing this adjustments, what do you think I can check next.
Thanks again for answering and help me out with my problem, I really like this machine and I remember on my younger years in the school helping the teacher projecting movies
Regards
Osvaldo

[Rich Haddard]

You don't want to go adjusting things until you figure out why this happened. There's usually a capacitor in the motor circuit and they do go bad. Take a look at that. If the governor is getting juice you should see minor arcing between the brushes and the governor rings. Inspect the points side of the governor for an open circuit. Having a spare would certainly be a plus and save a lot of time. Good luck!

[John Eickhof]

check the ballast resistor #08768 (on the terminal strip) as well as the cap also on the terminal board, If I remember correctly the resistor us a line ballast and the cap is a run cap, it is a small square mica cap and the resistor is a wire wound check for shorts or burned or open connections on the terminal strip, only attempt adj of speed once all other components are checked, if it ran at speed then suddenly started erratically, its most likely an electrical wiring or component problem and not the mechanical governor, however the governor resistors may be at fault or you have a shorted / damaged winding in the motor...in the film tech manuals there is the service instructions for the 179 series and it has the correct schematic for the 185 motor circuits too, unfortunately there is no parts list showing the values of electronic parts...the cap on the terminal board is a .05 uf 600v, and the cap in the motor speed control is a dual 5-5 uf 500v mica cap, the resistor values are unmarked. one last thing...check the silent-sound switch contacts and use de-ox-it or other cleaner to thoroughly clean the contacts.

[Osvaldo Flores]

Thanks so much to Rich Haddar and John Eickhof for the help. For sure I will look at your recommendations. I'm so glad I find so many good people in this forum willing to help me.
Thanks again to all of you
Regards
Osvaldo

[Osvaldo Flores]

After having difficulties with high speed in my B&H 185 projector, I replaced the 2 X 0.5uF 600VDC sealed capacitor
( one was shorted ) and the speed normalize, but I see arcing between the brushes and the governor rings... (I do not have an spare governor to replace). there is something else I can do about this? ( I already clean the brushes and the rings with contact cleaner)
Thanks so much for all the help.
Osvaldo

[Rich Haddard]

Some arcing is to be expected and completely normal. I mentioned it originally as a visual method to help determine if the governor was operating at all. It sounds like your machine is functioning normally now with the capacitor replacement?

[Osvaldo Flores]

Hi Rich,
the projector is running at the right speed after I replace the capacitor. Now I'll do some oiling and check everything, and hope that the arcing will be at minimum.
Thanks a lot for your response
Regards
Osvaldo

[John Eickhof]

arcing is normal, it will diminish once things wear in again! lad you got it fixed! have fun!

[Osvaldo Flores]

Well..., the projector was running good at correct speed with the new capacitor for about 30 minutes and after that, went at "wild speed again". I check the capacitor and one part of it is shorted!
I got no idea what's going on...??

[Vern Dias]

What was the voltage rating on the capacitor?

[Osvaldo Flores]

Hi Vern,
The voltage rating on the cap is 600VDC

[Sam Chavez]

Don't know what the voltage rating of the original caps. Obviously not enough and I would guess the arcing is more than the cap can absorb. You might need something with a higher Voltage rating. Car radios used to use a buffer capacitor that was rated up around 1,500 Volts to stand up to the multivibrator power supply in general use back then. Even then they would occasionally short circuit from the strain and white smoke would billow out from under the dashboard.

[Osvaldo Flores]

Hi Sam,
The original cap voltage rate is 600V. Maybe you are wright, I'll need to use a higher voltage rated cap, that can absorb the arcing...Do you have experience with this type of problem on a B&H projector before?
Thank you
Osvaldo