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Grundig DVD GDP 1100 blow fuse?

 
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vibrato



Joined: 19 May 2008
Posts: 1

PostPosted: Mon May 19, 2008 8:12 pm    Post subject: Grundig DVD GDP 1100 blow fuse? Reply with quote

I cant understand what is going on....
I cant find a schematic or service manual.....
How can i check if the T701,JTP1101-BA4043 is ok?
Thanks for any help!
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torbjorn



Joined: 07 Jun 2007
Posts: 370
Location: Sweden

PostPosted: Tue May 20, 2008 7:19 am    Post subject: Reply with quote

I suppose that you mean that the mains fuse blows instantly when you connect mains voltage to the unit?

If the power supply is of the usual type for simple DVD players, set top boxes etc - a standard type switched mode power supply - then you should first make sure that there are no obvious short circuits on the primary side.
Check the mains rectifier diodes, the switching transistor (in some cases, it might be integrated into the controller IC), interference suppression capacitors at the mains input, and the big electrolytic cap.

Usually, the switching transistor is a N-channel mosfet. When testing it with a DMM with diode test feature, you should get infinite resistance between drain and source with the drain positive, and one diode voltage drop (0,4 - 0,8 V) with the drain negative. The gate shall show infinite resistance to all other pins. When such transistors fail, they usually get a complete short from drain to source. If the transistor has failed, the controller IC will usually also fail unless there are protective devices (series resistor and zener diode to ground) between its drive pin and the transistor's gate. Then, those devices will blow instead. Also, check out all components that may have been subjected to the short circuit current, in particular any resistors in series with the source of the switching transistor or the mains rectifier bridge.
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PostPosted: Tue May 20, 2008 4:15 pm    Post subject: Reply with quote

Hi torbjorn and thanks for your help!

It was 2 of the mains rectifier diodes that blows the fuse! Replace them and fuse ok now.
Now I'm measure with no load:

+12v=9.7v
-12v=-9.7v
+5v=4.7v
3.3v=4.2v
-21v=-17.2v
-FL=-14.3v
+FL=-11.3v

I think thats no good.
Also i'm hearing something like blowing whistling ffsssssssss......
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torbjorn



Joined: 07 Jun 2007
Posts: 370
Location: Sweden

PostPosted: Wed May 21, 2008 8:21 am    Post subject: Reply with quote

It is quite common that such power supplies do not work properly without load. Try loading down the +3,3V and +5V with some 0,2 - 0,5 A by resistors and see if it works better then.
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PostPosted: Wed May 21, 2008 3:36 pm    Post subject: Reply with quote

Well i put the cable (load) and i hear tik tik tik tik.
Then smoke came out from a coil (100K) near the 1N5822.
How can i check the TNY268P?
Schematic?

I will post voltages soon....
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torbjorn



Joined: 07 Jun 2007
Posts: 370
Location: Sweden

PostPosted: Thu May 22, 2008 8:07 am    Post subject: Reply with quote

Background information about the TNY268 - example schematics, datasheets, application notes etc can be found at the manufacturer's website, http://www.powerint.com/tiny2product.htm .
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