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Author Topic: OH NO another Beaulieu 708 stereo issue
Mark L Barton
Jedi Master Film Handler

Posts: 584
From: Bristol, South Glos, England
Registered: Mar 2009


 - posted December 07, 2018 02:57 PM      Profile for Mark L Barton   Email Mark L Barton   Send New Private Message       Edit/Delete Post 
Having repaired the audio side of my 708, all was ging well, great picture and sound when al of a sudden the projector speeds up, with voices high pitched and fast. Now, upon repairing the sound side I did notice that the capstan drive belt was very loose, ie the capstan motor was not effectively turning the flywheel. Could this cause that sped up effect. Also when I switched to 18fps there was no reduction in speed, neither was there any speed change using the +/- speed adjust.
Once again gang....HELP!!!!!!!!!!

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Chip Gelmini
Phenomenal Film Handler

Posts: 1604
From: Brooksville, FL
Registered: Jun 2003


 - posted December 07, 2018 05:24 PM      Profile for Chip Gelmini   Email Chip Gelmini   Send New Private Message       Edit/Delete Post 
Check the hertz position I know on some machines it cause a problem it could be the wrong setting? Just a guess I am not an expert on this.

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Nantawat Kittiwarakul
Expert Film Handler

Posts: 190
From: Rajburana, Bangkok, Thailand
Registered: Aug 2017


 - posted December 07, 2018 07:27 PM      Profile for Nantawat Kittiwarakul   Email Nantawat Kittiwarakul   Send New Private Message       Edit/Delete Post 
Is the main drive motor of the dc type?
If yes,the motor drive circuit might had gone busted. [Frown] Further inspection&repair needed.

BTW this is exactly the same problem as my Ricoh Super8 sound projector I recently acquired. Still trying to figure out the most practical repair approach.

--------------------
Just a lone collector from a faraway land...

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Phil Murat
Jedi Master Film Handler

Posts: 597
From: Villeneuve St Georges, France
Registered: Dec 2015


 - posted December 08, 2018 02:45 AM      Profile for Phil Murat   Email Phil Murat   Send New Private Message       Edit/Delete Post 
Hi Mark,

That looks like a BD646 ( motor power regulator) typical failure.
Please, report to my special infos on post for your sound problem.
Measure BD646 insulation from case and let me know.

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Mark L Barton
Jedi Master Film Handler

Posts: 584
From: Bristol, South Glos, England
Registered: Mar 2009


 - posted December 08, 2018 04:54 AM      Profile for Mark L Barton   Email Mark L Barton   Send New Private Message       Edit/Delete Post 
Thank you Phil. Your help is invaluable. Do you happen to have a picture of that regulator on the circuit board? Do you know if I can buy it, assuming its faulty. I am waiting for a new capstan drive belt. I tried the projector today and it worked correctly, so I am assuming its an intermittent issue? Would an irregular running capstan flywheel cause a problem??? Merci

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Phil Murat
Jedi Master Film Handler

Posts: 597
From: Villeneuve St Georges, France
Registered: Dec 2015


 - posted December 08, 2018 05:12 AM      Profile for Phil Murat   Email Phil Murat   Send New Private Message       Edit/Delete Post 
Hi Mark,

Have a look there :

BD646 : SUPPLIED BATCH

I have checked with UK destination, shipping is free!!!

May Ebay Too can supply but probably for higher money.

So.......

Do you confirm your machine is running "smoothly" at this time and main motor is regulating ???
Did you do this test :
Run your machine on playing sound mode and push with your finger the black rocking guide (from outside to capstan direction).
If you can ear main motor idling , that means main motor is regulating.

In that case power of immediatly the machine, and unplugged it, as it is possible BD646 is not properly coolled :

Check BD646 installation and renew white cream (heating dissipation compound between BD646 lug and casing).

A common Heating Dissipation Compound is supplied by Dow Corning Cy.

THIS IS IMPORTANT TOO :
BEFORE TO POWER ON MACHINE , MEASURE ELECTRICAL RESISTANCE BETWEEN CASING AND BD646 LUG WHICH HAS TO BE VERY VERY HIGH (May BE AROUND 45 MEGA HOMS !!)

FINAL RELEASING TEST :

To insure BD646 is NOT over heating put your finger on BD646 plastic case. if you can not stand Heat that means temp is too high. (From my side I use an Infra Red Thermometer)

Let us know

[ December 08, 2018, 07:42 AM: Message edited by: Phil Murat ]

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Mark L Barton
Jedi Master Film Handler

Posts: 584
From: Bristol, South Glos, England
Registered: Mar 2009


 - posted December 08, 2018 05:39 AM      Profile for Mark L Barton   Email Mark L Barton   Send New Private Message       Edit/Delete Post 
Thank you Phil. Yes I can see those items on teh circuit board. So, if needed I could simply change them for new ones! You mentioned heat dissapation cream, I am thinking that the projector goes fast after it has heated up, once cooled down it seems fine, do you think U need to re install that cream? Thank you.

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Phil Murat
Jedi Master Film Handler

Posts: 597
From: Villeneuve St Georges, France
Registered: Dec 2015


 - posted December 08, 2018 07:23 AM      Profile for Phil Murat   Email Phil Murat   Send New Private Message       Edit/Delete Post 
//////////////// Just Updated Informations /////////

Absolutly Mark.

Renew white Termal Dissipating compound, a thin homogeneous layer only (A thin layer on casing, apply micas shim, put an other layer on micas shim, then reinstall....)
Use Vinyl Glothes to prevent from contact with skin.

Take the opportunity to put this layers for 3 regulators (IC1, IC2, IC3).

Yes, this is what I am thinking. After projector power off and coolled down, It can run properly. However BD646 is probably suffering and could fail later.

Pay particular attention for good fitting for lugs regulators on casing.
Insure you a full surface contact between lugs and case.
For BD646, insure you screw and plastic bushing are well centered in lug hole.
However , do not over tighten screw, plastic bushing is fragile....

At this time , it is not necessary to replace BD646, however it should be a good thing for you to get some of this on left....
[Wink]

INFO:
You can find thermal compound in shop specialised in maintenance computers.
Only use a compound quality which NEVER dry.

Let us know

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Phil Murat
Jedi Master Film Handler

Posts: 597
From: Villeneuve St Georges, France
Registered: Dec 2015


 - posted December 09, 2018 03:30 AM      Profile for Phil Murat   Email Phil Murat   Send New Private Message       Edit/Delete Post 
Hello Mark,

During a "sleeping night" something comes to my mind concerning a possible intermitent speed issue ......

In case BD646 is working properly, not overheating, and offering an obvious dual range (18fps/24fps) :

-Considering the black "rocking sensor" has an obvious effect when projector is playing sound ,I suggest you to check efficiency for pinch roller.
Machine power OFF, insert a portion of film leader between Capstan shaft and Pinch Roller, Turn main knob on Sound Mode and gently pull the leader portion outboard.....
You should observe Capstan shaft and Pinch roller spinning together.
If Leader slides too much "easily" and Capstan Shaft / Pinch Roller don't spin properly , means something is wrong with internal linkage from from cams axis to Pinch Roller carrier.
In that case check linkage inside projector for an excessive play, jams part, soften spring, foreign material blockage , etc , etc....
This is a rare condition, but.......... To tell you the truth I met a funny smilar fault, one time.
I sprayed thin oil (liquid lithium grease or equivalent) and everything was ok after all.

To gain access to linkage, remove Capstan Motor then Flywheel (record washers/bushings position).

Let us know

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Mark L Barton
Jedi Master Film Handler

Posts: 584
From: Bristol, South Glos, England
Registered: Mar 2009


 - posted December 17, 2018 01:53 PM      Profile for Mark L Barton   Email Mark L Barton   Send New Private Message       Edit/Delete Post 
Hello Phil. Regarding BD646 does it have a specific voltage and amps. I am looking at this one on Ebay, is it correct?

https://www.ebay.co.uk/itm/BD646-TRANSISTOR-BD-646-TO-220/191896584559?hash=item2caded816f:g:Sl8AAMXQaZxSC2J4:rk:3:pf:0

merci

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Phil Murat
Jedi Master Film Handler

Posts: 597
From: Villeneuve St Georges, France
Registered: Dec 2015


 - posted December 18, 2018 04:04 AM      Profile for Phil Murat   Email Phil Murat   Send New Private Message       Edit/Delete Post 
Hello Mark,

Yes, it is.

BD646 works under 60V Max and 8A

Once you get it, check engraved reference on upper side (using a magnifying glass as necessary).

Here, You can download BD646 "family" Tech Data Sheet :
For information, TO220 only means a packaging norm .....

BD646

Some info to remove former BD646 from PCB without damaging board tracks :

- Cut the 3 pins and discard former BED646 so that each remaining pin can be pulled out easily.
- Limit soldering heat for just what is necessary for each spot (MAXI 3sec)
- This PCB is not FR4 Epoxy, only bakelite material , so tracks can fail easily if over heated

The last BEAULIEU 708 were fitted with enhanced Green Epoxy Board in production....

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