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Topic: Repairing a Sankyo Stereo 800 - The Journey
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Janice Glesser
Film Goddess
Posts: 3468
From: Sunnyvale, CA USA
Registered: Sep 2011
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posted October 23, 2016 04:32 PM
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 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).
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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 25, 2016 02:06 AM
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 ]
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Paul Browning
Phenomenal Film Handler
Posts: 1006
From: West Midlands United Kingdom
Registered: Aug 2011
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posted October 26, 2016 12:05 PM
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.
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