8mm Forum: Fuses etc. - Sankyo Stereo-800

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Posted by Jan Bister (Member # 332) on February 10, 2006, 10:47 PM:

Normally I wouldn't create a new topic just to link to an old one, but I don't think it's getting any attention anymore despite me having added a new post to it recently [Roll Eyes]

so here it is...

Just so hopefully someone can answer my questions regarding the Sankyo unit... There is one more, actually: what rating does the fuse on the sound board have? The one that this particular Sankyo is missing? I may want to remove the wire and solder a fuse holder in there so I can replace the actual fuse. [Smile]

Posted by Kevin Faulkner (Member # 6) on February 11, 2006, 09:20 AM:

Jan, the diagram which Mike P sent me does not show a fuse for the amp board. There is one fuse for the overall machine (5amp) and another one for the motor control board (3amp). Maybe the link was put there by Sankyo who decided not to have that board fused as the input fuse was sufficient.
Kev.

Posted by Jan Bister (Member # 332) on February 11, 2006, 01:14 PM:

Hmm, that surprises me. The way I understood the old thread was that the wiring diagram did have a third fuse, and everyone seemed surprised that Michael Clark's projector did not have it.

Would you be so kind as to forward it to me via email, if you still have it that is? Thanks [Smile]

Posted by Carlos Plaza (Member # 578) on March 12, 2006, 10:50 AM:

This reply is unrelated to this post item...I could not find the original... Posted by Jan Bister (Member # 332) on January 25, 2005
I picked up a Bolex SM8 for a song on EBay. If you are still interested...
Picked up the machine because I already had two 18-5's one standard, one Super 8, both great, etc., and needed Mag sound projector for my film transfer business (yes, I did come up with a way to get lip-sync on transfers to video/DVD, as sound and video capture are done separately).
This machine is built like a tank-and weighs it. It is driven by a fat round belt and the speed (18FPS and 24FPS) is adjusted with a dial that varies the diameter of the motor pulley. The film escapement, sprockets, and reels are all driven from worm gears on a central shaft.
Now, about how it performs:
Sound is not that good...lots of hum, even after replacing the filter capacitors, but has it all solid state components. For capturing sound from this machine, my best results came from adding a Neutrik Speakon connector, off the speaker output, to the case to totally isolate the speaker voltages. I then built a cable with a Speakon connector on one end, and the other end with a T/S phone plug, which plugs into an ground-isolated impedance converter, whih finally plugs into my mixer, which feeds my computer. All this because there is no Line Out.
Why did I do all this? For the fun of it!
Self-threading can be finicky-it seems OK with flexible leaders, but did not do well with a Blackhawk Film of 'The Dentist' until I spliced on some leader. Since I never record on the mag tracks, I cannot report on this.
I don't have a maintenance manual, so perhaps some adjustment would take care of the finicky self-threading, which could also affect the lower loop, sometimes causing the sound to be 'jerky'. When I replace my dead digital camera, I would be glad to send pictures of its innards. If anyone is interested, I do have the owner's manual.
Stay well!

Posted by Jan Bister (Member # 332) on March 12, 2006, 11:30 PM:

[Confused]

Posted by Jan Bister (Member # 332) on April 02, 2006, 05:33 PM:

Sorry to be reviving this dusty old thread yet again, but... this one's for Kevin F. or Rick Scrowonek or Mike Peckham (Rick, I probably misspelled your last name and apologize if so)... I still need that high-resolution scan of the wiring diagram that one of you guys has. Please, please, someone email it to me. - jbister@neo.rr.com

[Smile]

Thanks.

Posted by Jan Bister (Member # 332) on April 02, 2006, 10:38 PM:

OK, this is interesting... I found nothing wrong with the small amplifier board, including the bridge rectifier. But when I looked underneath the large circuit board at the bottom...

...I noticed a copper trace that had busted open. Got curious, went and bridged the broken trace with a piece of green wire (as seen), plugged the Sankyo into the AC outlet, and it went POP. Nothing changed - no sound, but lamp and motor still working. Upon looking again, the other copper trace had blown open.
And both these are directly coming off the black & orange transformer wires which supply about 14-15V AC voltage, according to my voltmeter.

Hmm. So there's a short-circuit down there somewhere. Alas, I'm stumped now.... what could cause this? Another rectifier that was damaged and now presents a short circuit instead of supplying DC voltage to the sound board?

Comments? Thoughts? ...

EDIT

Here's what Michael Clark wrote about how it all started: "Last night I was watching a film, and all of the sudden the projector light went out. The film continued running, with sound, but no light. So I turned the machine off and checked the bulb. I forgot to unplug the machine first, and as I began to loosen the bulb, I heard a pop and sparks flew. Now, there is NO sound, and the smaller, dimmer light under the sound head doesn't work."

I'm beginning to think the pop and sparks was a complete coincidence and never had anything to do with the lamp... the lamp socket itself is in pretty bad shape and I've in fact had the bulb go on and off on me several times, sometimes I would have to wiggle it to get it to come on again. Something else caused a short circuit just as Mike was trying to pull the lamp off, perhaps brought on by mechanical vibrations. I only wish there was some visible evidence of where this happened...! [Frown]

[ April 03, 2006, 01:00 AM: Message edited by: Jan Bister ]

Posted by Kevin Faulkner (Member # 6) on April 03, 2006, 05:19 AM:

I'll get that scan sorted for you Jan. To have that sort of damage it has to be a dead short. Rectifier or Smoothing capacitor is where I would put my money. The other possibility which I wouldnt want to think about quite yet is that you have a short in the output stage.
I would think that it would be worth putting a meter accross the input of the rect block and see if the short is there. Then accross the output and see if that is ok. That way you will determine which side the short is...AC or DC side.

Kev.

Posted by Rick Skowronek (Member # 385) on April 04, 2006, 11:06 AM:

Hi Guys,

Been a lo-o-ong time since I've visited. With the hurricane we had here in S. Fla. (I'm still putting things back together) and me consulting full time 10-12 hours a day, my time seems to blow by. Biggest apologies to Dan Lail. I have a radio of his. Have at least a four hour alignment to do on the FM and still no guarantees.Will try to get to it within the next couple of weeks.

Anyway, Jan, I do have the Sankyo 800 wiring diagram from Mike Peckham. Unfortunately, it's resolution sucks. You can make out the wiring runs butjust barely adequate. I am sending it to you by email tosee if it gives you some guidance. I believe Kevin (as usual) is spot on with his diagnosis. To blow copper traces of that size so quickly means a dead ass short across the transformer windings. Since this is amplifier power and probably other circuits as well, probably means in this order - 1. Bridge rectifier (although somewhat unusual as two diodes in the bridge must fail shorted and they usually fail open. 2. a filter capacitor on the output of the bridge to smooth the rectified AC (more likely) and last, the dreaded output transistor in the audio amp shorted out. If you see no other smoke or burned components those are the likely suspects. Since I don't have any 800 board/circuit schematics all I can tell you is that is most definitely the power for a majority of the electronics (mostly audio) and is a dead short so it shouldn't be too ridiculous to track down. Drag out the ohmeter compadre.

I'll try and help where I can.

Rick

PS - I found the schematic and wiring diagram and have forwarded those to Jan by email. In looking at the schematic, it does not bode well for that projector as the orange lead feeds AC to a bridge rectifier (as suspected) and a filter capacitor then directly (do not pass Go) to the power in the IC type audio power amps. If any one of those four ICs are shorted, it would be nigh impossible to find replacements for them.

Posted by Tony Milman (Member # 7) on April 04, 2006, 02:02 PM:

Umm.

Happened to me on a sub-woofer. Turned out to be the rectifier

Posted by Rick Skowronek (Member # 385) on April 04, 2006, 03:14 PM:

Let's hope that's it. At least those and the capacitor are common parts.

Posted by Kevin Faulkner (Member # 6) on April 04, 2006, 03:53 PM:

Yes if the worst comes to the worst the Rec can be made up with four single diodes or another made to fit but the output IC might be the thing to write of an otherwise nice projector [Frown]

Kev.

Posted by Jan Bister (Member # 332) on April 04, 2006, 06:53 PM:

Wow...

First of all, thanks to Rick for the emails [Smile]

And, well, I'll have to take the machine further apart simply so I can visually inspect the entire circuit board... but from the sound of it, it seems the best thing to do is replace the capacitor and rectifier and then see what happens...about right? And if it is the IC chip, well... then I'll have a very nice silent projector for parts. Sigh [Big Grin]

EDIT: or maybe I could even just skip the AC-to-DC stuff and apply some DC voltage directly to the DC side of the board...hmm... *mad-doctor wheels turning inside brain*...

Posted by Rick Skowronek (Member # 385) on April 04, 2006, 07:26 PM:

Well Mad Doctor, do understand that applying any DC to a shorted circuit will only get you the fireman's award. The objective here is to find out exactly where the short is.

Hopefully, it's the rectifer or capacitor. If it's not, there are ways to circumvent the output ICs. Not easy but possible. From that you can put outboard amps to take the preamped audio and feed it elsewhere. One of the major problems with this is that those same output ICs also feed the Record circuits. Not for the novice, my friend, but possible. It's either this, after troubleshooting, and if it is one of the four output ICs, you now have one of the original Mike Clark boat anchors. You wouldn't be able to Record but may be able to Play back movies. Still probably more trouble than the machine is worth. Sorry for that diagnosis, but sadly may be true. Personally, I hate to give up on anything electronic but, alas, there are those times now with non-servicable electronics.

Rick

PS - Forgot to comment on this - there are 4 ICs in the audio output Jan. Not one. They are the same ICs but they are hooked up in 2 ICs per channel in a push-pull configuration. One IC works for negative going signal and the other works in positive signal. Gives roughly twice the audio output power of a sngle chip. So, basically, you have 4 chips each hooked to the output of the positive voltage from that 14 VAC bridge/capacitor combo. Any one of those shorted can create the problem.

As I said, good luck.

Posted by Jan Bister (Member # 332) on April 04, 2006, 11:44 PM:

Gotcha. Thanks for the tips... Can't wait for this next weekend now. [Smile]

Posted by Kevin Faulkner (Member # 6) on April 05, 2006, 10:56 AM:

Jan, all that Rick says is spot on but you really need to get a test meter to check those resistances accross the rectifier etc.

Kev.

Posted by Jan Bister (Member # 332) on April 05, 2006, 10:45 PM:

I have one already, bought it some time ago specificially for this Sankyo business. [Smile]

Posted by Rick Skowronek (Member # 385) on April 06, 2006, 06:17 PM:

Go Jan, go. And please let all of us know that you found something or what you found. That, of course, unless you set the house on fire at which time we'll , like Mission Impossible, disavow all knowledge of this string and chalk up to our respective mental collapse.

Seriously,

Anything you need, please let us know.

Regards,

Rick

Posted by Jan Bister (Member # 332) on May 06, 2006, 12:24 AM:

OK... (much time has passed once again!...) well, I'm 99% certain it's either the rectifier or capacitor, as shown here...

This is located right behind the AC power socket, neatly tucked away on the main board. (So neatly I had a tough time shooting these pics!) The suspects are a large 25V/4700uF capacitor and a green rectangular rectifier (there is another black one next to it as well).

Anyway... I don't have replacement parts, nor the patience or energy to take the whole projector apart just to even get down there... so my options are 1. have Rick Skowronek perform a repair for me or 2. put it on eBay as a parts machine.

Rick, would you be willing to have a go at it? I'll pay shipping both ways plus a bit extra if you think there's a good chance of repairing the machine... and I do think that the sound board, including ICs, is OK otherwise...

[ May 07, 2006, 01:56 PM: Message edited by: Jan Bister ]

Posted by Rick Skowronek (Member # 385) on May 09, 2006, 01:24 PM:

Hey Jan,

Sorry for being away. Since I've gone back to work as a Bus. Dev. consultant I don't have much time for my "hobbies". It's hard to tell from your pictures but is there a fried look to those components? By the way, according to the schematic the bridge rectifier for the audio circuitry is comprised of two dual diode units hooked up in a bridge configuration. That's probably why you have two right next to each other. It would make sense if one or both may be fried. The cap could have gone and taken them with it also.

Now, as to time to look at it. I still have an older radio of Dan Lail that needs a major alignment for it's FM and it's been sitting for several months now awaiting my time. (Apologies to Dan). If you're willing to hold on for a bit I may be able to squeeze it in sometime in the next few weeks. Of course, the problem always may be deeper than suspected.

Let me know and we'll see what I can do.

Rick

Posted by Dan Lail (Member # 18) on May 09, 2006, 02:42 PM:

Hi, Rick, no hurry! Just wanted to know if all is well in the tropics. [Big Grin]

Posted by Rick Skowronek (Member # 385) on May 09, 2006, 03:42 PM:

Hey Danbo,

Meant to let you know and is my bad. I think about it often but I know it's a dog and still may not be great after a several hour alignment procedure. All else has been exhausted on it though so it's that or nothing. Anyway, gonna try it soon. Hang tight and I'll let you know. Just don't hang too tight. And all is well here, so far with the start of another hurricane season ready to start in another 3 weeks or so. Best to ya!

Rick

Posted by Jan Bister (Member # 332) on May 09, 2006, 09:59 PM:

Hey Rick [Smile]

Thanks for getting around to replying! And no problem, we'll do this whenever it's best for you... obviously I'll let Dan have his turn first [Cool]

and who knows, if I can identify the exact parts that I need, I can replace them myself and then see what happens (btw, yes... you're right, they do look fried). Right now it's not a high-priority item on my to-do list anyway... it's not going anywhere and I have other stuff to play with in the meantime. [Big Grin]

Posted by Jan Bister (Member # 332) on May 26, 2006, 07:55 PM:

There was another 800 being sold for parts on eBay, which I won. Got it yesterday. Motor dead but lamp and sound both work. Cool. This is gonna be a fun weekend - I should get at least one fully working unit out of the two. [Big Grin]

EDIT (a few hours later) Have done some more testing and took advantage of being able to compare the rectifiers in both Sankyo units. Indeed, one of the two rectifiers in the dead-sound Sankyo is fried and short-circuited. Have unsoldered it and was able to make out the writing on it: It's a Toshiba 1B2Z1 (7-A) dual diode rectifier.
I'll probably go ahead and put in the working one from the other Sankyo unit....... [Big Grin]

[ May 27, 2006, 01:47 PM: Message edited by: Jan Bister ]

Posted by Jan Bister (Member # 332) on July 02, 2006, 12:09 AM:

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