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Topic: GS1200 Blower Motor Connections
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Paul Adsett
Film God
Posts: 5003
From: USA
Registered: Jun 2003
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posted October 14, 2019 02:16 PM
The big transistor checked out ok. I got the new large Matsushita relay installed on the board as well as new 1B2C1 and 1B2Z1 rectifiers. I also replaced the motor governor board. The projector is now fully functional in all modes, and the original problem with the take up not working is now gone.
I still have one thing to do and that is to find an inductor coil for the blower motor, since the original has broken off and there is no way to solder it back on as there is no wire sticking out from it. For now I have just cut it out and reconnected the wire directly from the relay board to the motor. Consequently I can hear some RF interference from the fan motor on the sound. I am trying to find a suitable substitute inductor. Any suggestions much appreciated.
Needless to say I am delighted to get this wonderful projector fully functional again, and I cannot thank Phil, Thomas, and Leon, enough for helping me through this complex repair process.
When I first switched the machine on after all the repair work, I had no idea what to expect, but my reaction was something like this: ![[Big Grin]](biggrin.gif)
https://www.youtube.com/watch?v=QuoKNZjr8_U
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The best of all worlds- 8mm, super 8mm, 9.5mm, and HD Digital Projection,
Elmo GS1200 f1.0 2-blade
Eumig S938 Stereo f1.0 Ektar
Panasonic PT-AE4000U digital pj
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Phil Murat
Jedi Master Film Handler
Posts: 671
From: Villeneuve St Georges, France
Registered: Dec 2015
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posted October 15, 2019 01:07 AM
Hi Paul,
Thanks for your comments and happy you get your machine back to work, "Congratulations" ![[Wink]](wink.gif) !!!.
It is normal you observe "noises" in sound as 35V used for fan motor is common with 35 V comming to Amplifier.
Concerning "green" inductors , this system is more efficient than a capacitors system because inductors work as a plug and is designed to cut a specific noise Frequency Band.
A capacitors system is supposed to work too but instead to work as a plug it works like (more or less) as a short cut and not for a specific frequency.
In case a capacitor fails , it will probably short cut circuit, damaging last transistor (Fan motor feeder).
However, "Inductors" are 100% fail safe !!
Frequency of the noise depends on Motor Speed X Number of inner copper collectors.
In reference to the schema posted above in this TIP , you need 3 unpolarized capacitors (propylen) to replace the dual inductances system :
- 1 Capacitor 470nf (Nano Farad)
- 2 Capacitors 47nf (Nano Farad)
Anyway, as it is highly recommended to keep this inductors system as noise suppressor, the good new is that an inductor can be done by yourself , like a copy of the original , knowing diameter of wire, diameter of core, total lengh , and keeping ferrite core.
[ October 15, 2019, 04:19 AM: Message edited by: Phil Murat ]
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Phil Murat
Jedi Master Film Handler
Posts: 671
From: Villeneuve St Georges, France
Registered: Dec 2015
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posted October 15, 2019 10:12 AM
Hi Paul,
Not tested yet but I have just found that :
http://users.telenet.be/h-consult/Txradio/selfBerekening.htm
This is a little program in direct use.
Calculated value is (more or less) theoretic, because a same inductor will offer a fluctuating value depending on current fluctuation (this is the case because Fan motor has 2 different speeds)......
Generaly , at the end, the best way is to plug an oscilloscope and to determine if signal recorded is satisfactory.
Anyway when you don't ear anymore noise, game is won
Concerning current crossing inductors , take a safety margin :
If Fan Motor power is around 30W-40W, voltage is 35V , stable current is around 1 to 2 Amps ![[Roll Eyes]](rolleyes.gif)
Frequency value to cut : using your ears you can determine an approximative value of the noise .You can Try 1000 HZ for exemple
An other one site but in French language (not tested) :
http://www.tavernier-c.com/bobinages.htm
It seems the usual name in English language for this inductor typical use is "Choke Coil" (To be confirm)
To give an other idea, an other product exemple, may be very closed, with detailed datasheet :
http://www.yfbalun.com/English/productshow_199.html
or
http://www.yfbalun.com/English/products_t29.html
[ October 16, 2019, 07:02 AM: Message edited by: Phil Murat ]
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Paul Adsett
Film God
Posts: 5003
From: USA
Registered: Jun 2003
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posted October 19, 2019 10:45 AM
Well I went down to Radio Shack and picked up this 100 microhenry RF choke. I covered it with a tube of heat shrink and spliced it into the (broken) fan motor lead wire. I then switched on the projector, turned the lamp on so the fan was running at full speed, plugged in the earphones, and low and behold Zero EMI from the fan motor. This choked totally killed the noise. Stereo sound is now faultless. No doubt this particular choke is overkill, but it does the job, and there is plenty of room to solder it in by the motor.
Ain't science wonderful! ![[Smile]](smile.gif)
--------------------
The best of all worlds- 8mm, super 8mm, 9.5mm, and HD Digital Projection,
Elmo GS1200 f1.0 2-blade
Eumig S938 Stereo f1.0 Ektar
Panasonic PT-AE4000U digital pj
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