Re: [Frameworks] Steenbeck ST928 - polygon prism seized

2017-12-19 Thread Francisco Torres
Bad belts are the cause of many problems, even machines that are not
used too often get their belts ruined by just ageing. The plastic gets
very brittle with age even if taken care of. Recently I found some
belts that were not even used and the plastic had all but turned to
dust.
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Re: [Frameworks] Steenbeck ST928 - polygon prism seized

2017-12-18 Thread graemehogg


Funny. Similar thing happened to me recently. Remmeber that when belts 
perish they leave steel cables that can damage mech if you keep trying to
operate the machine. If you keep trying to turn the seized picture head 
you will also blow the controller card.


I suggest opening the hood up and examining all the gears and drive areas 
un der the prisms. If belts look old, snip them out. Snip out remaining 
cables too if belts are perished.





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On Sat, 16 Dec 2017, Jean-Pierre Marchant wrote:


Hello all, 
I have an 8 plate Steenbeck in my home studio which has 2 screens. Overall it 
works ok but it's got one big problem: the left hand
polygon lens does not want to turn at all. The right polygon lens works fine. I 
would like to get the left one to work so that I
can run a picture film through it with sound. 

Something details I've noticed: 
1) as expected, when the machine is powered up the right polygon spins forward 
and backward by toggling the clutch/brake switch
next to the speed control lever. I've noticed that when the clutch/brake switch 
is ON, I can't move the right polygon at all...it
is seized up - as it should be. However, when it is in OFF, I can move the 
polygon by using my finger - ie it spins freely. 
2) The left polygon seems to be stuck all the time whether its switch is in ON 
or OFF. When I toggle the clutch/brake switch for
it I can hear the clicking sound of a relay and something does appear to move 
slightly on the motor shaft for that polygon (I've
looked at it by taking off the panels and looking underneath). 
4) So I'm guessing that it's either a mechanical issue that has seized up the 
gears, or it's an electrical issue preventing the
gear shaft from releasing for that left side polygon.

I've checked my relays and fuses and they appear to be ok - I tested some with 
a multimeter, and for others I swapped around
similar relays and everything is still the same. The belt for the polygon shaft 
looks like it is on properly and in 'ok' shape, if
a bit oily and dirty. 

Does anyone have any advice or any idea what the problem could be? Any 
help/advice would be welcome. 

Sincerely,

JP Marchant

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