This is topic Sankyo 600 Micro Switch and Speed Board Testing & Replacement in forum 8mm Forum at 8mm Forum.

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Posted by Janice Glesser (Member # 2758) on May 19, 2015, 05:37 PM:
Steve Carter recently posted that replacing the micro switch on his B&H DCT fixed the intermittent stopping problem on his projector.;f=1;t=009950 Since I've experience the same behavior on my Sankyo 600 I want to locate and test the switches and most likely replace the switch controlling the forward motion. Steve has offered to help me with the re-wiring...however, accessing these switches is not easy and I was hoping to get some suggestions from someone who has worked on this projector. I was also hoping Dogtor Frank might be monitoring and can give some guidance.

I need to know if I can access the switches from the back ... perhaps by removing the transformer...or should I go in from the front. If I go from the front... what should I remove. I'm not sure exactly where the switches are located.

Any help appreciated.

Posted by Janice Glesser (Member # 2758) on May 19, 2015, 08:58 PM:
I have answered some of my own questions after some searching around with a flashlight. I believe I have located the micro switches. There is one on the left of the main switch labeled SS - 10GL and one on the right side of the main switch labeled SS - 5GL. So it looks like I can access the switches from the front.

Now I need to determine which switch controls the forward motion. Any ideas on how to test the switches in-circuit...or do I need to remove them?




[ May 20, 2015, 09:45 PM: Message edited by: Janice Glesser ]
Posted by frank arnstein (Member # 330) on May 20, 2015, 12:04 AM:
Hi Janice
to get to the micro switches you need to go in from behind.
Remove the 4 screws holding the transformer and swing it aside clearing the wiring as best you can. Turn the machine upside down to work on the next part.
You will see a small circuit board over the spot where the switches are. Remove 2 screws and the top of the circuit board swings away exposing the 3 micro switches.You will be able to just clear the flywheel.

good luck Janice
[Wink] [Smile] dogtor frankarnstein.
Posted by Janice Glesser (Member # 2758) on May 20, 2015, 12:40 AM:
Thanks Frank. After removing the front panel and the main switch I could see that getting to the wiring from the front would not work. I'll follow your instructions and go through the back. I'll report back on my progress [Smile]
Posted by Janice Glesser (Member # 2758) on May 20, 2015, 02:01 PM:
I moved the transformer out of the way and removed the 2 screws on the small PCB. It really didn't give me a clear view of the micro switches since they are attached to the underneath of a metal bracket. I also can only see 2 switches connected by two screws and nuts for each switch located on either side of the small circuit board.

Update: I found the 3rd switch. Looks like the SS-10GL and a second SS-5GL are stacked on top of each other.



Do you think I should leave the bracket in place and just remove the switches?..OR remove the entire bracket along with the switches?

[ May 20, 2015, 09:49 PM: Message edited by: Janice Glesser ]
Posted by frank arnstein (Member # 330) on May 21, 2015, 04:37 AM:
Hi Janice

My Sankyo 600 seems to be slightly different than yours as on mine the 3 switches are located directly under the small circuit board.
Yours are located on the other side of the bracket.
So its now up to you to decide wether to remove the bracket with the switches on it or not. I can't advise on this part.
Perhaps if you remove the circlip thats on the shaft, the bracket and switches may come away.

Good Luck.

dogtor frankarnstein [Roll Eyes] [Eek!] [Confused]
Posted by Janice Glesser (Member # 2758) on May 22, 2015, 03:18 PM:
For now I've decided to leave the switches in place and try doing continuity testing on them. I also discovered that the metal bracket the micro switches are attached to is also the main control switch cam holder. Boy am I glad I didn't try and remove it. Re-positioning the cam would have been a nightmare. I found a nice video on YouTube illustrating how a micro switch works and briefly how to test it.
Posted by Janice Glesser (Member # 2758) on May 23, 2015, 08:42 PM:
I don't think the Sankyo designers ever wanted humans to work on this machine. It is so difficult to get to those little micro switches. However with a wiring diagram provided by Phil Mitchell I was able to determine how to do the continuity testing.


I completed the testing. I tested continuity in all forward and reverse positions (no power) turning the main control switch. The meter beeped in testing both the NC and the NO terminal on the two micro switches on the right side in both forward and reverse. However on the 5 GL MS on the left side next to the flywheel the NC terminal only beeped when set to Reverse while the NO terminal beeped on in both Forward and Reverse.

So what does this mean? If the MS on the left is for Reverse (I'm guessing here) and the one on the right for forward are these test results indicating which one maybe bad? Do any of you experts out there have any input. I can post a link to the wiring diagram if that will be helpful.

My meter probe was just a little short to reach the NC terminal on the left I came up with this DIY extender. It's just a piece of wire doubled up and twisted together held by an alligator clip. Allowed me to get under the flywheel to test the NC terminal on the micro switch. Don't worked [Smile]


[ May 24, 2015, 12:15 PM: Message edited by: Janice Glesser ]
Posted by Janice Glesser (Member # 2758) on May 25, 2015, 05:07 PM:
It appears from the lack of response, other than Frank, I'm the only contributor to this thread. Oh well...If anyone ever has an issue with this same projector perhaps it will be of some use to them.

I think since the stopping problem is intermittent and only occurring in Forward, even though the continuity tests on the micro switches appear ok...there has to be something wrong at least with the Forward switch. So I've gone ahead and ordered 2 new switches. I only plan on replacing the forward switch...but just in case the other one is bad too I'll be prepared. I'll follow-up once I get started with the installation.
Posted by Janice Glesser (Member # 2758) on June 03, 2015, 11:26 AM:
UPDATE: I removed the old 5GL micro switch and wired in the new replacement. The good news is that the new switch is working fine. In testing so far there has been no intermittent power losses. The bad news is now the 10GL switch (mounted directly below the Forward 5GL switch) that controls the lamp is not triggering. The switch itself seems to be working when I push the switch manually...but not when mounted in the holder with the other switch. I've tried to replace it exactly as it was before, but I guess it is still not positioned correctly for the main controller cam to hit the lever on the switch properly. It's nearly impossible to see the area where the cam is pushing the switch. So this could be a trial and error adjustment. [Frown] [Roll Eyes] [Eek!]
Posted by Janice Glesser (Member # 2758) on June 07, 2015, 02:04 AM:
Success [Smile] [Big Grin] [Razz]
I finally got the micro switches aligned with the cam. The micro switches are positioned correctly now. The Forward and Lamp positions on the main control switch are working. The micro switches are triggering properly. This was a big relief.

However, replacing the micro switch may have unleased another problem. [Confused] [Mad]
Just as I thought everything was going testing a reel of sound film I discovered that the speed control was no longer working. Switching the 18-24 switch does nothing as well as adjusting the two pots on the speed board has no effect on the speed.

It appears that I've fixed one problem only to break something else I guess. It's running at the faster 24fps speed, but even that is not adjustable with the pots. Does anyone have any idea what could of happened?

[ June 07, 2015, 06:44 PM: Message edited by: Janice Glesser ]
Posted by Janice Glesser (Member # 2758) on June 07, 2015, 06:42 PM:
Moving on to the speed problem
The wiring diagram shows a Silicon NPN Power Transistors (2SD234) connected to the speed PCB. This may also be bad and need replacing. I'll have to test it. The problem I'm having is it's located behind a heat shield in back of the speed board. The screws holding the heat shield to the frame are in very tightly. I've already started stripping the screw heads trying to loosen them...grrrrrgh [Mad] Nothing seems to go easy.

Posted by Janice Glesser (Member # 2758) on September 21, 2016, 06:04 PM:
Well it's been awhile, but I have finally returned to trying to troubleshoot and resolve the speed adjustment problem on my Sankyo 600. As I mentioned in the previous posts...after successfully replacing the micro-switches the motor would only run very fast and could not be controled by the 24 to 18 switch or the speed pots.

I first replaced the NPN transistor...but unfortunately that didn't solve the problem.


Next...I replaced the entire motor control board (speed board) with one from another working 600 projector. Eureka! The speed control was working again. This was good news for me since up until then I wasn't sure if I had mis-wired something while replacing the micro-switches.


I put the questionable speed board into the donor projector and sure enough the speed issue was back. Now that I've contributed the problem to a faulty component on the speed board...I'd like to see if there is a way I can identify the component and replace it. Someone in another thread mentioned replacing the potentiometers...can these go bad? Any suggestions on how to locate a bad component on a PC board? Is it worth the effort?
Posted by Mark Creighton (Member # 5276) on September 27, 2016, 09:15 AM:
Janice, you say that you have a schematic. Does it show voltages for any points on this circuit board? If it doesn't I would try measurements on the good board and compare them to the faulty board.

Good luck.
Posted by Janice Glesser (Member # 2758) on September 27, 2016, 12:51 PM:
Thanks Mark. I'm in the process of doing just that. I am very much a novice when it comes to electronics. I have to take it slowly since I have a tendency to blow things up touching the wrong wires [Eek!] . I have continued this project in another thread specifically focused on the Speed Board.;f=1;t=010987

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