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Pioneer AVIC-D3

markm6164

Jan 22, 2012
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Hi guys

I needs some advice. I have a pioneer sat nav stereo AVIC-D3 here that was working fine but was removed from a car and left in storage. Now when i power the unit up the LCD back light will power up for a moment then goes out and will not power after that. All other functions work, touch screen works fine which you can just make out with no back light. The back light is a cold cathode florescent lamp and when it lights briefly on start up i measure 60v at the lamp but this drops to 0 and i have no light . I have a very good service manual for it and i need some help testing the circuit please.

Here is the manual (you have to search AVDI-D3, i tried to upload but i couldn't get it to work, sorry!!) http://elektrotanya.com/?q=showresult&what=L19HP03U&kategoria=&kat2=all

The driver circuit for the back light is on pages 28-29 and the connector for the back light is CN5006

Regards

Mark
 

markm6164

Jan 22, 2012
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I will try again and upload the circuit diagram again tonight as I know it's easier for you guys. Maybe some pictures of the board too but I think it's multilayer and the diagram is pretty good anyway.
 

GreenGiant

Feb 9, 2012
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I would reason a guess that it is the tube not the driver circuit, I know that they can be finicky sometimes.

Try powering the unit with nothing connected and see what you get for voltage

Also the link you posted does not yield any results for "AVDI-D3"
 

markm6164

Jan 22, 2012
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I would reason a guess that it is the tube not the driver circuit, I know that they can be finicky sometimes.

Try powering the unit with nothing connected and see what you get for voltage

Also the link you posted does not yield any results for "AVDI-D3"

Hi

The backlight does come on briefly during start up of the stereo. Could this still be a faulty backlight?

Also my apologies you have to search AVIC-D3. My typo mistake.
 

GreenGiant

Feb 9, 2012
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Hi

The backlight does come on briefly during start up of the stereo. Could this still be a faulty backlight?

Also my apologies you have to search AVIC-D3. My typo mistake.

yes it could still be the backlight, look at fluorescent lights, when they go they dont usually pop like regular light bulbs, they will dim, flicker, toggle on and off, then die
Thats the nature of fluorescent lights.
 

markm6164

Jan 22, 2012
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yes it could still be the backlight, look at fluorescent lights, when they go they dont usually pop like regular light bulbs, they will dim, flicker, toggle on and off, then die
Thats the nature of fluorescent lights.

Thank you for your advice.

Also if i have done this right here is the download link to the service manual.

http://www.mediafire.com/?2msxmb6ym4kb4s6

Also can i build a circuit on my breadboard to test the backlight on its own to see if has failed?
 

markm6164

Jan 22, 2012
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Page 202 of the manual has some test point checks to do. I might scope these first and see what results i get.
 

markm6164

Jan 22, 2012
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UPDATE:

I decided to test the voltages on the monitor board and found all voltages to read low. The 5v regulator had no input so i traced it back to the main board and found a blown SMD fuse rated at 1A. I have uploaded at snap shot of the circuit diagram. FU1864 was blown and i have checked C1863 and C1864 for short circuit but both test ok. I will continue testing. I have to order some SMD fuses but while i wait can i solder in a larger 1A rated fuse to test the circuit?

avic-d10.jpg
 

markm6164

Jan 22, 2012
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Ok so i replaced the 1A SMD fuse but it hasn't made any difference to my original fault but all the TP voltages are good now. I have scoped the output signal from the two switching mosfets.

Here is a picture of the inverter circuit (not much use)

avic_p12.jpg


Here is the output of the fet Q5903 after the capacitors. I measured it at the transformer pin 3.

avic_p11.jpg


Here is the output of the other fet Q5904 which has no capacitors in circuit. i measured this at the transformer pin 5.

avic_p10.jpg


The scope is set to 0.5v per division but my scope probes are x10 attenuated so thats 5v per division. The time base is set to 5µs per division.

The signal can only be measured for a few seconds at power up when the back light briefly comes on then turns off and won't come on.

If the cold cathode tube was at fault wouldn't i still get a signal there even it it doesn't light? Seems to me the tube isn't being driven??

I really need some help with this please.
 
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markm6164

Jan 22, 2012
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Can anyone tell me if I inject a 50kHz 10v peek to peek square wave into the inverter switching transformer will the be ok to light the back light for test?
 

davenn

Moderator
Sep 5, 2009
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Backlight ? on an LCD display ?
inverter switching transformer ? tell us more about its ratings else we wouldnt have a clue


Dave
 

markm6164

Jan 22, 2012
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Hi Dave

The AVIC-D3 is a car audio unit with touch screen. The backlight for the screen is a cold cathode fluoresent lamp. When i power the unit the backlight comes on for about 2 seconds the shuts down. Everything else works because if i put a seperate light source behind the display i can see clearly everything on the display and the touch screen responds. It just seems to be the backlight that isn't on.

The back light is driven by a OZ961ISN ccfl driver chip. I can't find a data sheet for this only the OZ962 16pin driver chip. The OZ961 drives two TS8M1 fet chips which provide a square wave 50kHz signal to the boost transformer to drive the ccfl. I can't find the ccfl specs sorry but in a previous post i have included a link and download to the service manual, which is very good, with relevent pages listed. Also i have provided 2 pdf's of just the inverter circuit.

A post from another user suggested the ccfl may have failed hence why i want to power the ccfl to see if infact it has failed. The signal i measued, on a previous post, is when the screen lights and i measured it from the transformer primary side. The 50Khz signal i get corresponds to what the service manual describes in the adjustments section. There is no signal there when the ccfl isn't lit. If it was just a faulty ccfl would the signal still be there all the time? The driver chip has a feed back circuit and overload protection circuit. Maybe this is why the screen shuts down or maybe the ccfl is infact faulty.

Regards

Mark
 
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markm6164

Jan 22, 2012
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The enable pin (pin3) on the driver chip has a 5v feed all the time. If i short out the ''enable pin'' pin 3 on the driver chip the chip shuts down. When i remove short the driver chip restarts and the backlight comes on then turns straight off. It like its sensing a fault with the over voltage protection but on the ovp pin when the backlight lights i read 4v and when the backlight is off i read 0v.

avic-d11.jpg
 

markm6164

Jan 22, 2012
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I got this unit working guys. I found i had 4v on pin 10 of the OZ961 driver chip. The threshold is 2.75v i believe. Anyways i connected a LED from pin 10 to ground and now everything works perfect. Anyone got any thoughts on a true fix? I might leave led in if not. All seems ok with it in. Not sure on life of led in there though.
 
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