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Old 22nd October 2005, 05:43 PM   #21
anatech is offline anatech  Canada
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Hi gregg,
It sounds as though the board insn't getting any voltage delivered to it at all. Power supply or switching problem? Either that or we need a real schematic for it.

Please measure the different wires around the board and tell me if you get any readings. Set your meter range to 15VDC. We normally see 12 ~ 14 VDC to run these boards.

-Chris
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Old 22nd October 2005, 06:26 PM   #22
gwyz is offline gwyz  United States
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Hi Chris,

I will attempt to do more tests. In the mean time I had sent you another PDF with photos of the circuit boards.

Also, I found this site that lists my problem as being common.

http://www.euras.com/repair_tips_1/S...00A_Sansui.htm

Is anyone registered with this site? I tried to register, but they require a PC computer. I use a Macintosh, so I can't sign up with them. It's frustrating knowing that they have the problem documented **AND THE SOLUTION**, but I can't register with them because I don't own a PeeCee.

:-(

-Gregg
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Old 22nd October 2005, 06:32 PM   #23
anatech is offline anatech  Canada
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Hi Gregg,
That sends you to the "send me money" page. No further. I think it's for the 5000A anyhow.

Your fault is not "no fm stereo". The fault you have is "no sound on fm". Aren't you glad you didn't spend the money?

-Chris
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Old 22nd October 2005, 06:50 PM   #24
gwyz is offline gwyz  United States
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Quote:
Originally posted by anatech
Hi Gregg,
That sends you to the "send me money" page. No further. I think it's for the 5000A anyhow.

Your fault is not "no fm stereo". The fault you have is "no sound on fm". Aren't you glad you didn't spend the money?

-Chris
--------------------------
Hi Chris,

You're probably right.

I sent you a new set of photos of the MPX section.

smiles,

Gregg
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Old 22nd October 2005, 09:43 PM   #25
Netlist is offline Netlist  Belgium
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Well, thanks Chris and Gregg for all the nice pictures and schematics but indeed, as Chris says, we need the real schematic.
Pictures of the block diagrams are fine and so are the print component layout's but even a schematic from the 999 is confusing because of other part numbers an small differences.
Thanks nevertheless.

Looking at the few manuals I have from Sansui from those days, it appears the the schematic was a separate paper from the manual. So I reckon Gregg doesn't have it.
Here's a link to the manual in case you would be interested. It's not free but a bargain for a decent manual.
http://gallery.bcentral.com/GID48840...Bsearch&Page=2

-=Hugo=-
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Old 22nd October 2005, 11:44 PM   #26
anatech is offline anatech  Canada
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Thanks Hugo,
Not bad for $10.00. That would have everything needed to troubleshoot this thing. Something to consider Gregg. If I had it, I'd give the schematic to you.

-Chris
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Old 23rd October 2005, 12:03 AM   #27
gwyz is offline gwyz  United States
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Quote:
Originally posted by Netlist
Well, thanks Chris and Gregg for all the nice pictures and schematics but indeed, as Chris says, we need the real schematic.
Pictures of the block diagrams are fine and so are the print component layout's but even a schematic from the 999 is confusing because of other part numbers an small differences.
Thanks nevertheless.

Looking at the few manuals I have from Sansui from those days, it appears the the schematic was a separate paper from the manual. So I reckon Gregg doesn't have it.
Here's a link to the manual in case you would be interested. It's not free but a bargain for a decent manual.
http://gallery.bcentral.com/GID48840...Bsearch&Page=2

-=Hugo=-
----------------------------------
Hi Hugo,

I checked that link. That is the *exact* same manual that I already bought. The cover photo is identical to mine and it's the same price I paid. Except I bought mine from a dealer on ebay. It is not really a "Technical" Service Manual. It is a "User" Service Manual.

The difference is apparent in the troubleshooting section. It lists a bunch of obvious dumb solutions and then suggests that if the problem is anything more complicated, you should take the unit to an authorized professional for repair. Only a *User* type Service Manual would say that.

Anyway, that *is* the exact same manual that I already wasted $10 bucks on.

I wrote an email to the guy I bought it from, but I don't expect to get anywhere. No doubt he did give me a full copy of what he had. What else can he do besides give me what *Sansui* was calling a "Service Manual?"

Anyway, thanks for posting the link.

Sincerely,
Gregg
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Old 23rd October 2005, 06:03 PM   #28
gwyz is offline gwyz  United States
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Hi Chris,

Okay, now I'm getting somewhere!

I tested that board. Keep in mind that I am essentially a blind man just probing for voltage readings. The bottom line is that I am satisfied there is voltage getting to the board. There are several wires all leading in at the same spot, and I get a reading of 24 volts DC.

I remembered that Hugo mentioned it looked to him as if the circuit with the resistor that had no voltage (R426?), appeared to run through the Stereo Indicator light. So, I followed the red and orange wires. Each wire leads to two separate circuit boards underneath the unit. The Orange wire leads to Circuit Board F-1041, and the Red wire leads to Circuit Board F-1137. Needless to say, *neither* of these boards are shown in that worthless "Service" Manual I bought.

When I try to unscrew the bulb from the socket, there is VERY LOUD popping noises coming from the speakers. (Note: The bulb is not blown, but it doesn't light). Since the wires from this socket only lead to those two circuit boards, I began checking the boards.

The F-1137 Circuit Board which the Red wire goes to has two Zener Diodes, ZD001 and ZD002. One of them (ZD001) has been replaced. The wires were cut above the circuit board and the new part was soldered onto the old wires. This part is different than ZD002, in that it is made of metal. It looks like a "can" with a wire coming out of the bottom (the dead side), and another wire coming out of the top (the "arrow" side). There is no voltage on the end of this part that is NOT the "arrow" side. I did tests as follows:

----------
ZD001 (the replaced Diode in question - metal "can" type)

On the side with the arrow the voltage is: 24 VDC
On the other side the voltage is: 0 (dead).

Note that when testing on the side with the arrow, if I get too close to the "can," it arcs between the can and the test lead.
----------

ZD002 (Original part - color black)

On the side with the arrow the voltage is: 12.5 VDC
On the other side the voltage is: 4.5 VDC

Note that those voltage readings go up "slowly" (incrimentally) to those readings listeded above, when connecting the test leads.
----------

I have attached a photo of the board, with a red arrow pointing to the part in question.

Now what?

Thanks, (as always).

-Gregg
Attached Images
File Type: jpg f-1137_zd001.jpg (24.9 KB, 186 views)
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Old 23rd October 2005, 07:28 PM   #29
gwyz is offline gwyz  United States
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Hi Guys,

NEVERMIND

I removed the part, and by sheer coincidence I happen to have a NEW spare. It made no difference, and the test results are identical.

When I test the old one against the new one, they both show the same measurements with regard to resistance (one way), etc...

Whatever the problem is, it is *NOT* the ZD001 diode. That part was definitely replaced at some point, but it is good.

The arcing I saw was the test lead touching the can which is essentially the same thing as touching the wire on the other side of the can. The new part did the same thing.

Oh well, back to square one. (No, square *ZERO* is more like it).

:-(

-Gregg
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Old 23rd October 2005, 07:51 PM   #30
Netlist is offline Netlist  Belgium
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What you measured on the diode is normal.
In simple terms, the anode, which you call the dead side is connected to the AC wire of the transformer, enventually via a fuse and/or a safety resistor.
The cathode, which you call the arrow side, carries the DC voltage and that is your 24VDC.

/Hugo
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