TU 9900 Problems

I've already checked out how to build a DBT and since I do all of my own home electrical work I have most if not all of the pieces to build one.

I've also read what a diode does is to (don't know exactly how to phrase it) cancel either the positive or negative of AC.

Thanks again Mike. No matter how this turns out I am and will be grateful for your help.

I also went ahead and ordered an Extech EX330.
 
Super is donating diodes to the cause ! OE stuff too~
Ok your DBT would need a REALLY small bulb. your unit draws 20 watts at full tilt boogie. So for these tests a 10 watt ( or even an 8 will do ) if you have the goods start building one…. if nothing else you will need one in the future.

A diode is "LIKE" a one way check valve.. depending how it is hooked up ( and remember AC is a sine wave ) a single diode in series with a transformer will only conduct on the positive 1/2 of the wave, as the wave goes negative, no current flows.
http://www.youtube.com/watch?v=DSddVV5yzFM
http://www.youtube.com/watch?v=ZWv39XQLZ4M
http://www.youtube.com/watch?v=Y8Lo80UwjO8
 
I'll take inventory and start building. I'll get back to you when the task is completed. My line of thinking has always been, I'd rather have too many tools than not enough.

I also want to thank Super for the diodes.
 
At minimum DBT
Plug ( with wire attached )
Socket ( AC )
Socket for bulb and a couple of the edison screw in "Y"'s for BONUS
I like those Edison base to 2 pin plug style
4S box
2 gang cover (switch / outlet )
1/2 cord grip connector.
Misc hook up wire

So in series, AC HOT, switch, light bulb filament or filaments in parallel Hot to ac socket. (RETURN ) Neut in socket home run to plug. Ground Home runs + can of 4S

Remember to break the HOT and neut tabs on the AC socket
 
Your long lost brother in Japan TU-9900 White face

I never knew there was a different cosmetic version of this tuner....
So here is some eyecandy
 

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Awesome looking tuner!

I had company most of the day yesterday so I couldn't go get the parts that I needed. I had most but not all. I'm going to get the parts before I go to work today and it shouldn't take long to assemble the DBT.
 
Great
Super just left me an IM DIODES AWAY..In the mail
I'll be on & off today.. probably good past noon PST


Wow mis spell city LOL
 
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Doing ok soldering, could be better.

I'll de solder D-02. I'll post back when that's completed.

Do I need to go ahead and solder the C-01 leg back?

The smallest bulb that fits a large socket that I could find was a 15 watt. Will that work or do I need to find a 10w or an 8w?

Lowes 1 amp fuses are $1.68 for 5.
 
I would get the 8 AND 10 on a Y so you can add or subtract protection…
Forget the cap for now
Once you get that diode out , do you know how to do a diode test on your digital meter?
 
D-02 is out. I don't know how to check one but I do a google search and try to find out.

Should have already done that but didn't think about it.



EDIT; I couldn't find a way to test a dual diode. I'm going to assume (but I'm probably wrong) by the diagram on top of the diode that the outer legs are the anode and the center leg is cathode.

If that is true my reading on one side (+on anode and - on cathode) is 604 in the diode setting. When reversing the polarity on the same 2 legs it reads 1 in the fourth position to the left. Open circuit? The other side with + on anode and - on cathode reads (assuming that I'm correct about which is which) is 002. When I reverse the polarity the reading is 002.

If I'm testing correctly the last two readings would be bad?
 
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WOAH Nellie… it might be late and all that D-02 is common ANODE
Easy trick spell cathode ( mentally ) with a K so if you break that down
Kathode K anode
l = cathode and <= anode

a " dual diode " is nothing more than 2 diodes soldered together and stuffed in a nice plastic mold. Just treat each one as a single diode.

SO in Diode test,
Test #1: With positive ( red ) from the meter on the middle pin COMMON ANODE, hook the BLACK lead to either outer pins ( CATHODE with a K ) one at a time.This SHOULD read ~ .500 to .600 ( depending on the device , your milage will vary ). the POINT is it's conducting...

Test #2 If you FLIP the leads you should get BUPKIS ( black on center ) red on outside pin ( one at a time ).If you do get a reading other then "DUH"( the same reading when the leads are connected to NOTHING ) on the meter.The diode is leaking or shorted internally.

to test D-01 ( which is common KATHODE ) reverse the procedure
 

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I figured that I would be wrong.

Test #1-red on center pin and black on outside pins
side A reading-l in the 4th position from right
side B reading-004

Test #2-black on center pin and red on outside pins
side A reading-614
side B reading-004

Test repeated with new DMM

Test #1
A-.0L
B-0.000

Test #2
A-.551
B-0.000
 
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I "ASSUME" that the "A" test is proper polarity and the "B" test is reversed polarity ?
NOW tell me what happens on the meter when you touch the red & black leads together.. Since we're doing this repair via remote ( and my Oujai board pointer is missing ) I have to be real specific to make sure I don't send you on a WILD goose chase!
( betting the meter will say OL again when you touch the leads together )
 
Test #1
Side A is + on the center pin and - on the left outside pin. Reading is OL
Side B is + on center pin and - on the right outside pin. Reading is 0.000

Test #2 (Polarity Reversed)
Side A is - on center pin and + on left outside pin. Reading is .551
Side B is - on center pin and + on right outside pin. Reading is 0.000

With meter in diode position and leads not touching it reads OL
With meter in diode position and leads touching it reads 0.000

The manual states that an open device reads OL

On the diode both arrows are pointing toward the center. ---->l----l<----
Is it possible that this diode is in the wrong position? I did take out D-02 and it didn't look like it had been changed.

Side B with both readings of 0.000 would mean it was bad?

I went over the tests again with the same results.
 
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Well ANOTHER Sansui OH BY THE WAY in the DOCS
D-02 on the Schematic is common anode.
D-02 on the silk screen is common KATHODE
D-02 Is closest to the fuses
D-02 is Black ( correct ) ?

Your test results:
Test #1
Side A is + on the center pin and - on the left outside pin. Reading is OL (OPEN)
Side B is + on center pin and - on the right outside pin. Reading is 0.000
( SHORT )

Test #2 (Polarity Reversed)
Side A is - on center pin and + on left outside pin. Reading is .551
(Correct)
Side B is - on center pin and + on right outside pin. Reading is 0.000
( SHORT )

Which MEANS
The right side of this device is NOT a diode but a straight WIRE ( BAD )
This ALSO MEANS raw AC was getting into the circuit down stream (BAD)
( This was also "SUSPECTED" based on your earlier tests )

Repeat with the OTHER diode…

And suggestion ( to help learning )
Test A
Do 1 side then the flip
Test B
Then the other side and then the flip

Look at you GO!
 
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