8mm Forum


Post New Topic  Post A Reply
my profile | my password | register | search | faq | register | forum home
  next oldest topic   next newest topic
» 8mm Forum   » 8mm Forum   » Repairing a Sankyo Stereo 800 - The Journey (Page 7)

 - UBBFriend: Email this page to someone!  
This topic comprises 9 pages: 1  2  3  4  5  6  7  8  9 
 
Author Topic: Repairing a Sankyo Stereo 800 - The Journey
Janice Glesser
Film Goddess

Posts: 3301
From: Sunnyvale, CA USA
Registered: Sep 2011


 - posted May 04, 2015 02:00 PM      Profile for Janice Glesser   Email Janice Glesser   Send New Private Message       Edit/Delete Post 
Update [Smile] It's been a few months...but yesterday I revisted my Sankyo 800. I got brave enough to remove the bridge rectifier and the big capacitor. It also looks like I have found replacements at my local Fry's Electronics store along with fuse holders and fuses.

After the last test that went up in smoke...I can now see a crack in the bridge rectifier. I think I'll buy 2...just in case I blow it again [Smile]

Out with the OLD...
 -

In with the NEW...
 -

[ May 04, 2015, 07:00 PM: Message edited by: Janice Glesser ]

--------------------
Janice

"I'm having a very good day!"
Richard Dreyfuss - Let It Ride (1989).

 |  IP: Logged

Steve Klare
Film Guy

Posts: 6751
From: Long Island, NY, USA
Registered: Jun 2003


 - posted May 04, 2015 07:12 PM      Profile for Steve Klare   Email Steve Klare   Send New Private Message       Edit/Delete Post 
Godspeed, Janice!

Remember: that capacitor has a polarity and if you install it reversed you will be back to square one!

You can check out a bridge rectifier with your ohmmeter too. With the (-) lead on the rectifier + terminal, you should get low ohms from the (+) lead applied to either "~" terminal, but high with the (+) lead on the plus terminal and (-) on either "~".

Then you do same on the negative terminal but the readings are the opposite of what they are above.

--------------------
All I ask is a wide screen and a projector to light her by...

 |  IP: Logged

Janice Glesser
Film Goddess

Posts: 3301
From: Sunnyvale, CA USA
Registered: Sep 2011


 - posted October 21, 2016 10:49 PM      Profile for Janice Glesser   Email Janice Glesser   Send New Private Message       Edit/Delete Post 
UPDATE: It's been about a year and a half since I worked on my Sankyo Stereo 800. The last time I plugged in the power cord black smelly smoke bellowed out. This was very scary. I had bought some replacements components...but my lack of experience made me hesitant to proceed installing them. However after successfully repairing the PCB on my Sankyo 600 I felt a lot more confident with my soldering skills and pulled my 800 off the shelf to finish soldering in the new parts as was recommended.

I had repaired the broken traces on the two boards and installed new: 1) 1000uf 50V Capacitor 2) Bridge Rectifier 3) Fuse holder and fuse.

 -

 -

The only thing left now was to plug it in and test it. I opened the garage door in case there was a occurrence of the black smoke. But this time I plugged it in and no smoke. Turn on the Forward switch and presto the motor started and takeup spindle turned. Turned on the lamp and the bulb lit up [Smile] It was a great feeling since this machine hadn't run since the day I received it.

ALL IS NOT SUCCESSFUL HOWEVER [Frown] ...
The downside to all this is that there is NO SOUND. No sound from the speaker or from the external speaker plug. When I plug in the power cord on other sound machines I ususally hear a pop...but not hearing anything on this machine. I remember hearing a pop when I first got the projector. However during my testing early on I shorted something....but don't know what that was.

At this point I need to change my troubleshooting focus to the sound issue. I've tested the projector with sound film and everthing other than the sound works great.

Any suggestions on troubleshooting this sound issue would be greatly appreciated.

[ October 22, 2016, 12:46 AM: Message edited by: Janice Glesser ]

--------------------
Janice

"I'm having a very good day!"
Richard Dreyfuss - Let It Ride (1989).

 |  IP: Logged

Andrew Woodcock
Film God

Posts: 7477
From: Manchester Uk
Registered: Aug 2012


 - posted October 21, 2016 11:52 PM      Profile for Andrew Woodcock         Edit/Delete Post 
Simple suggestions to begin with, but have you checked your amplifier internal fuse(s)?

With the previous issue and short circuit resulting, I'd start right at the beginning with this one and check power is even getting to that board initially.

Beyond that, you'd just have to check your way through it with a schematic and known test values (voltages) if your drawings have them on.

At least now, you're in a safe position to have power running through the machine to be able to identify these aspects easier, beyond the fuse of course.

--------------------
"C'mon Baggy..Get with the beat"

 |  IP: Logged

Phil Murat
Jedi Master Film Handler

Posts: 611
From: Villeneuve St Georges, France
Registered: Dec 2015


 - posted October 22, 2016 01:55 AM      Profile for Phil Murat   Email Phil Murat   Send New Private Message       Edit/Delete Post 
Hello Janice,

This is a new Troubleshooting chalenge !!!

I don't know this projector but , this is is a Stereo Machine, so (PROVIDING FUSES ARE OK AND PCB TRACKS TOO...):

- Did you observe lack of sound for Main or both Chanels ?
- There is a low probability both chanels fail in same time but it could be possible if too much current go to the Power Stage Amplifier.

- What kind of Technologie is Power Amp (Hybrid or Classical Transistors)
- What is the condition of Capacitors working for Power Amp.

NB
What is the power of your soldering Iron ? A 15w / 20w is ok.

If "Sankyo" 800 features an "AUX" plug , try to plug it to an outside amplifier (HI FI device) to check sound available and quality.

Let us know

[ October 22, 2016, 04:20 AM: Message edited by: Phil Murat ]

 |  IP: Logged

Andrew Woodcock
Film God

Posts: 7477
From: Manchester Uk
Registered: Aug 2012


 - posted October 22, 2016 02:09 AM      Profile for Andrew Woodcock         Edit/Delete Post 
I don't know this particular either Phil but I'd guess it would utilize an STK chipset similar to the GS1200 or like many other machines from that same era.

--------------------
"C'mon Baggy..Get with the beat"

 |  IP: Logged

Phil Murat
Jedi Master Film Handler

Posts: 611
From: Villeneuve St Georges, France
Registered: Dec 2015


 - posted October 22, 2016 04:21 AM      Profile for Phil Murat   Email Phil Murat   Send New Private Message       Edit/Delete Post 
Hi Andrew,

Some of them are still available (but no longer) .......in former stocks !!!

 |  IP: Logged

Andrew Woodcock
Film God

Posts: 7477
From: Manchester Uk
Registered: Aug 2012


 - posted October 22, 2016 04:39 AM      Profile for Andrew Woodcock         Edit/Delete Post 
Yes Phil, I know. Hopefully janice will find her problem before this stage. From the way she describes things, I am guessing she has no sound from either channel Phil, hence my early suggestion...but we shall wait to hear back from Janice on this one.☺

--------------------
"C'mon Baggy..Get with the beat"

 |  IP: Logged

Janice Glesser
Film Goddess

Posts: 3301
From: Sunnyvale, CA USA
Registered: Sep 2011


 - posted October 22, 2016 03:36 PM      Profile for Janice Glesser   Email Janice Glesser   Send New Private Message       Edit/Delete Post 
Yes Phil ... this could be challenging, but if I can get the sound working again this will be a super nice machine. I've come this far...don't really want to give up now [Smile]

quote:
- Did you observe lack of sound for Main or both Chanels ?
Yes...no sound from either channel...no humming or static...nothing.

quote:
- There is a low probability both chanels fail in same time but it could be possible if too much current go to the Power Stage Amplifier.
The problem I'm having is that I'm not sure where the Power Stage Amplifier is located. Would you be willing to take a look at the schematics and wiring diagrams if I emailed them to you? It may save a lot of guessing and the boards on this projector are infinitely more complex than the Sanyko 600 [Smile]

quote:
- What kind of Technologie is Power Amp (Hybrid or Classical Transistors)
My guess would be Classical...but don't really know the difference. Perhaps the schematics will provide you that info.

quote:
- What is the condition of Capacitors working for Power Amp.
When I identify the Power Amp I'll inspect the caps.

quote:
What is the power of your soldering Iron ? A 15w / 20w is ok.
My iron is 20w.

quote:
If "Sankyo" 800 features an "AUX" plug , try to plug it to an outside amplifier (HI FI device) to check sound available and quality.
I did try the external port with portable speakers with no sound...I'll try the AUX port...but I don't think power is getting to the amplifier.

Andrew: I know this is a very lengthy thread, but if you refer back a few pages you will see that my particular machine did not have any fuses ...except for the one I just installed. There were just wires. So no protection. The sound blew when I was testing the bridge rectifier with the power plugged in and accidentally hit the metal brace with one of the DMM leads.

[ October 22, 2016, 09:19 PM: Message edited by: Janice Glesser ]

--------------------
Janice

"I'm having a very good day!"
Richard Dreyfuss - Let It Ride (1989).

 |  IP: Logged

Andrew Woodcock
Film God

Posts: 7477
From: Manchester Uk
Registered: Aug 2012


 - posted October 22, 2016 11:47 PM      Profile for Andrew Woodcock         Edit/Delete Post 
Ah thanks Janice. As you say, I did miss that point because of the length of the topic.

As you quite rightly point out, you need to establish first why no power at all is getting to the amplifier stage.
It's unusual for there to be no protection to this part of the machine though. Very unusual in fact unless it uses electronic fuse protection?

--------------------
"C'mon Baggy..Get with the beat"

 |  IP: Logged

Phil Murat
Jedi Master Film Handler

Posts: 611
From: Villeneuve St Georges, France
Registered: Dec 2015


 - posted October 23, 2016 12:04 AM      Profile for Phil Murat   Email Phil Murat   Send New Private Message       Edit/Delete Post 
Hi Janice,

Here is a typical "Hybrid Stereo Power" Module and curently available in the 80's :

 -

This one offers something like a 50W power

May be I miss something, but when "AUX" out signal is picked up, "Power Amp" is automatically deactivated as signal is just comming from "PRE AMP" module.

Moreover ,If installed, that means "VU METER" needles are moving during "Playing" operation even if Power Amp deactivated.....

[ October 23, 2016, 02:03 AM: Message edited by: Phil Murat ]

 |  IP: Logged

Janice Glesser
Film Goddess

Posts: 3301
From: Sunnyvale, CA USA
Registered: Sep 2011


 - posted October 23, 2016 04:32 PM      Profile for Janice Glesser   Email Janice Glesser   Send New Private Message       Edit/Delete Post 
Phil...
OUTPUT JACKS
Speakers, headphones, DIN, LINE OUT.
INPUT JACKS
Microphones, DIN, AUX.

The track power indicator light(s) should light up when plugged into the AC. Photo shows that is not happening.

 -

Here is also a picture showing partial components of the bottom PCB. There are serveral IC's placed all over this board. You can see an IC marked TA7183P from this view, however the user manual says the amplifier consists of 13 IC's...11 silicon transistors...and 14 diodes [Smile] No where in the parts lists is there a single IC labeled "amplifier". So you can see it's difficult for me to know what area(s) to begin checking.

 -

I previously did a trace repair going to the power connector. I have checked continuity on that trace and other connections in that area which all check out fine. Since the motor is running then the main power is ok. Any suggestion on testing power going to the amplifier?

 -

If anyone with electrical knowledge wants to chime in here please do so. I don't think you need to know about this particular machine to provide basic troubleshooting knowledge. I would be happy to send schematics and wiring diagrams to anyone who would be willing to take a stab at deciphering them for me. The pages of diagrams themselves are very detailed...but not labeled as per function.

[ October 23, 2016, 10:43 PM: Message edited by: Janice Glesser ]

--------------------
Janice

"I'm having a very good day!"
Richard Dreyfuss - Let It Ride (1989).

 |  IP: Logged

Phil Murat
Jedi Master Film Handler

Posts: 611
From: Villeneuve St Georges, France
Registered: Dec 2015


 - posted October 24, 2016 02:29 AM      Profile for Phil Murat   Email Phil Murat   Send New Private Message       Edit/Delete Post 
Hi Janice,

Due to the pictures, I observe the PCB is Dual lays .

So tracks have to be checked for each side.

No light when machine plugged on means probably no power feeds the Main Sound Card.

I can see also some funny discoloration for some areas on PCB.

I suggest solderings and tracks to be thoroughly check for tiny cracks using a magnifying glass (X3 minimum !!!)

Let us know

 |  IP: Logged

Paul Browning
Jedi Master Film Handler

Posts: 980
From: West Midlands United Kingdom
Registered: Aug 2011


 - posted October 24, 2016 06:50 AM      Profile for Paul Browning   Email Paul Browning   Send New Private Message       Edit/Delete Post 
Janice your latest photo shows two near identical sets of components side by side, with a sliding switch between them, check these upright transistor numbers, as these may be your output transistors, or drivers?. I 'm surprised this does not have the module type stk module fitted as it looks quite a modern machine.

 |  IP: Logged

Janice Glesser
Film Goddess

Posts: 3301
From: Sunnyvale, CA USA
Registered: Sep 2011


 - posted October 24, 2016 03:44 PM      Profile for Janice Glesser   Email Janice Glesser   Send New Private Message       Edit/Delete Post 
Phil...Double layer PCB...That explains the two layout diagrams in the service manual. Oh boy...I certainly hope there isn't any more problem with the traces...repairs could get tricky.

Paul...Good eye! [Smile] I never noticed the duplication of components. Since it's a stereo machine...that would make perfect sense. I'm not sure where you see the switch and which transistors you mention. I can make a guess and post a pic, but it would be easier if you had the PCB layout for reference.

I'm hoping the components that need checking/replacing are in the visable area of the board...otherwise it may require removing the bottom board which looks very complicated.

--------------------
Janice

"I'm having a very good day!"
Richard Dreyfuss - Let It Ride (1989).

 |  IP: Logged

Janice Glesser
Film Goddess

Posts: 3301
From: Sunnyvale, CA USA
Registered: Sep 2011


 - posted October 24, 2016 07:57 PM      Profile for Janice Glesser   Email Janice Glesser   Send New Private Message       Edit/Delete Post 
This thread is picking up again [Smile] I'm sure a lot of my viewers have moved on to other shows...but I hope a few that saw the beginning of the project can tune in again..it's not over yet.

Paul...I think your observation has been very helpful. However to me it appears that these twin sections are probably the input/recording modules. They are connected to the Record switches and all the input sockets.

 -

So if that side is the inputs...by deduction the other side should be the outputs...correct? So I started to look around the power pins. It's very difficult to see with the transformer and bundled wires butting up to that portion of the board...but I did spot something suspicious around the big 4700uf 25v capacitor. There's a dark liquid stain under the cap and the traces don't look broken...but more look like acid was poured on them. Also...the schematics show there should be a fuse where the black wire is located.

Any thoughts...anybody?

 -

[ October 25, 2016, 03:05 PM: Message edited by: Janice Glesser ]

--------------------
Janice

"I'm having a very good day!"
Richard Dreyfuss - Let It Ride (1989).

 |  IP: Logged

Phil Murat
Jedi Master Film Handler

Posts: 611
From: Villeneuve St Georges, France
Registered: Dec 2015


 - posted October 25, 2016 02:06 AM      Profile for Phil Murat   Email Phil Murat   Send New Private Message       Edit/Delete Post 
Hi Janice,

The stain below Big Cap is suspicious, so......

1) Tracks involved seems to be corroded within stain...
2) Unfortunately, Copper tracks are not protected with Tin to prevent from corrosion (Sorry , but Not very professional...)
3) In case you need to "upgrade" by adding a fuse (Size : 5x20mm) :

Normaly, you can install a crystal plastic cover , sold seperatly

 -

4) Calculate Fuse "Rating" : For DC Current, P=UxI.
You know P (Check in "User Manual"), Measure U (Ex: 20 V), Deduce I max.....
Only Install "Fast" Fuse.
NEVER Use "Delayed" Fuse...

5) Old Capacitors leaking is a common failure (In that case , this is the filtering Cap of Amp Power Supply. It can short circuit Power Supply once failed:
So, pay particular attention to Diodes Bridge (or Rectifier) and Power Regulating Transistor conditions as necessary.

6) Reinforce PCB "Power" tracks (mean allowing more current capacity) adding a "generous" tin lay on the tracks.

Hold On !!

Let us know

[ October 25, 2016, 12:06 PM: Message edited by: Phil Murat ]

 |  IP: Logged

Andrew Woodcock
Film God

Posts: 7477
From: Manchester Uk
Registered: Aug 2012


 - posted October 25, 2016 04:28 AM      Profile for Andrew Woodcock         Edit/Delete Post 
Or Ivy Watts (as spoken) as we affectionately remember the simple equation as. [Big Grin] [Big Grin] [Big Grin]

As in I(current)xV (voltage) =Power (Watts) ...in a D.C. circuit.

--------------------
"C'mon Baggy..Get with the beat"

 |  IP: Logged

Phil Murat
Jedi Master Film Handler

Posts: 611
From: Villeneuve St Georges, France
Registered: Dec 2015


 - posted October 25, 2016 08:10 AM      Profile for Phil Murat   Email Phil Murat   Send New Private Message       Edit/Delete Post 
Andrew, I have just realised the mnémonic !!!

5 Hours at least , to go to my brain..... [Wink]

 |  IP: Logged

Paul Browning
Jedi Master Film Handler

Posts: 980
From: West Midlands United Kingdom
Registered: Aug 2011


 - posted October 25, 2016 11:14 AM      Profile for Paul Browning   Email Paul Browning   Send New Private Message       Edit/Delete Post 
Hi Janice, send me your circuit diagrams, i'll see if I can find the components and where they might be in the projector. I have checked the spec on this machine and the internal speaker power is only 2 watts, so we are not looking for anything too big really, although it could intergrated into another chip. The cap leakage has damaged the tracks underneath, you will need to check this for continuity, the cap can be checked relatively easily when out. I wonder why the fuse was substituted, this is a safety feature and for a wire ??.

 |  IP: Logged

Andrew Woodcock
Film God

Posts: 7477
From: Manchester Uk
Registered: Aug 2012


 - posted October 25, 2016 11:21 AM      Profile for Andrew Woodcock         Edit/Delete Post 
As Paul highlights here, this machine does now appear to be well tampered with over the years and will take some extensive repairing to get fully operational again by the looks of things.

I just hope the board can still be serviceable in the future.

Removing a fuse circuit is a definite no no to begin with to whoever previously owned this machine

--------------------
"C'mon Baggy..Get with the beat"

 |  IP: Logged

Janice Glesser
Film Goddess

Posts: 3301
From: Sunnyvale, CA USA
Registered: Sep 2011


 - posted October 25, 2016 02:53 PM      Profile for Janice Glesser   Email Janice Glesser   Send New Private Message       Edit/Delete Post 
@Phil...The leaky Cap looks like a good place to start. I'm going to order a new one. I already have a second fuse holder from when I installed a fuse on the top Speed Board PCB. The package I ordered came with two holders (with tops) [Smile]

 -

Once I get the cap removed it will be easier to see how much damage was done to the traces.

@Paul...PM me your email address. I'll send you the service manual.

@Andrew...The lack of fuses in this machine has been discussed and yes it's unfortunate. Someone else posted they had the same model machine and it too had no fuses. Mine doesn't appear to ever have had any fuses. So, I don't think this projector has been tampered with... I think it's a design flaw that was later corrected or maybe these were prototype machines...who knows. [Confused]

Also from what I can see in the two layers of traces (one layer on each side of the board).I think it can be repaired separately without interfering with the other side. Let's hope so. [Roll Eyes]

--------------------
Janice

"I'm having a very good day!"
Richard Dreyfuss - Let It Ride (1989).

 |  IP: Logged

Andrew Woodcock
Film God

Posts: 7477
From: Manchester Uk
Registered: Aug 2012


 - posted October 25, 2016 03:16 PM      Profile for Andrew Woodcock         Edit/Delete Post 
Yes, i hope it can for you Janice.

--------------------
"C'mon Baggy..Get with the beat"

 |  IP: Logged

Paul Browning
Jedi Master Film Handler

Posts: 980
From: West Midlands United Kingdom
Registered: Aug 2011


 - posted October 25, 2016 03:46 PM      Profile for Paul Browning   Email Paul Browning   Send New Private Message       Edit/Delete Post 
PM SENT Janice.

 |  IP: Logged

Paul Browning
Jedi Master Film Handler

Posts: 980
From: West Midlands United Kingdom
Registered: Aug 2011


 - posted October 26, 2016 12:05 PM      Profile for Paul Browning   Email Paul Browning   Send New Private Message       Edit/Delete Post 
Hi Janice, check components 647 on page 019 of your service manual, x 4 upright fixed ic's with heat sinks. If you get the numbers off these components we can google the numbers to check there use. The only other transistor is 622 on the same page, but there is only 1 of this item, but it does have a large heatsink, so there is some power going through it, could be a regulator though, a number will pinpoint its general use. The 647 might be npn and pnp complimentary, never seen them in that design before, maybe a lack of space dictated this ?. Your last picture are these in that picture, could be them, get the number off them please.

 |  IP: Logged



All times are Central
This topic comprises 9 pages: 1  2  3  4  5  6  7  8  9 
 
Post New Topic  Post A Reply Close Topic    Move Topic    Delete Topic    next oldest topic   next newest topic
 - Printer-friendly view of this topic
Hop To:

Visit www.film-tech.com for free equipment manual downloads. Copyright 2003-2010 Film-Tech Cinema Systems LLC

Powered by Infopop Corporation
UBB.classicTM 6.3.1.2