Car Radio

[ipbr21054a]

hi
Basically car radio just stopped working.
Tried another head unit but no luck.
If I take this unit apart coul you assist / advise me trying to track the fault.
Fuse is fine.
Swapped donar but droll the same.
No backlight.
Will accept / reject cd but no spinning once in unit.

Thanks.

 

[davenn]

hi
Basically car radio just stopped working.
Tried another head unit but no luck.
If I take this unit apart coul you assist / advise me trying to track the fault.
Fuse is fine.
Swapped donar but droll the same.
No backlight.
Will accept / reject cd but no spinning once in unit.

Thanks.

hi
welcome

well it would help if you told us lots more about the radio
for a start, make and model would help

have you searched for a service manual yet ??
something else you need to do

Swapped donar but droll the same.

have absolutely no idea what that is supposed to mean ???

 

[ipbr21054a]

Sorry didn't check before I pressed button.
Sony MEX BT3900U

I am looking for a manual.

Last message was supposed to say, Swapped head unit with a donor but still the same & my head unit also works on donor vehicle.

 

[Gryd3]

Can you please clarify for us what you mean when you move the 'head-unit' to a donor car?
I'm 'assuming' that you are simply moving the faceplate from one unit to another... because if you swapped the whole assembly from one car to another and it *works* in the other car, then it's time perhaps to check for wiring faults or mounting issues in the problem car.
I can't think of any good logical reasons a CD would spin in one car and not the other if you move the entire unit over.

 

[davenn]

Can you please clarify for us what you mean when you move the 'head-unit' to a donor car?
I'm 'assuming' that you are simply moving the faceplate from one unit to another...

yes, just the front face with the controls .... it proves that it is OK and that the fault is in the main section

If I take this unit apart coul you assist / advise me trying to track the fault.

take several sharp and well lit pix of both sides of the main board

99% probability that you will need that manual

 

[ipbr21054a]

Hi,
Yes the front panel was taken from the unit that has no background light / inoperative state etc & put on the same make / model unit in our other car.Once swapped over it works fine so then my front panel is ok.
I have checked to see if 12v constant & 12v switched live is present to the radio outside connection as is working as it should be.There is also an earth at this point.

I will take the unit apart and post pictures,thanks

 

[ipbr21054a]

Hi,
Here are the pictURES.
Please advise if clear enough for you.

 

[ipbr21054a]

Hi,
Can you advise if these were clear enough for you,otherwise i will take 2 new photos in the morning.

 

[davenn]

Hi,
Can you advise if these were clear enough for you,otherwise i will take 2 new photos in the morning.

great pix ....

I don't see any obvious parts that have cooked other than the arrowed possibility in the below image
I cannot quite tell if it is a burn mark or part of the component markings ??



have a real close look under a illuminated magnifier

Dave

 

[ipbr21054a]

Ok
I will look now.

 

[ipbr21054a]

It just looks like a marking in the chip.
Looking at the others they also have the same hole / crater

 

[davenn]

Looking at the others they also have the same hole / crater

no probs ... that's just the pin one indicator then

a schematic of the power supply area would be really helpful

keep digging for service info

 

[ipbr21054a]

I have the schematic now.
To large to put here so please download from me storage area.

http://www.mediafire.com/file/pq3prq63xo2j51k/BT3900U_SERVICE_MANUAL.zip

 

[davenn]

I have the schematic now.
To large to put here so please download from me storage area.

http://www.mediafire.com/file/pq3prq63xo2j51k/BT3900U_SERVICE_MANUAL.zip

cool have it downloaded .... let me take time to have a gander at it


what country are you in ? so I know what version of this unit you have

 

[ipbr21054a]

Hi,
I am in the uk.

Some info for you.
Old radio out & this radio in,connected with the standard loom so straight forward swap.
Ignition turned off and beep beep present to advise front panel still connected.
Inserted CD & started to play.
Then all went quiet.

Put original radio back in & working fine.
Swapped again for this radio but nothing.

Put front panel from now dead radio onto my Mrs radio and works fine "she has same radio"

I have 12v switched at rear of dead radio.
I have 12v permanent at rear of dead radio.
I have earth at rear of dead radio.

I can put a CD in the slot,you hear motor spin as it accepts / takes in CD but then nothing.

I did read that the red/yellow wire "12v switched+ 12v permanent" must be connected together or no display/lights will show thinking unit is dead ?

This might help you but i think we got it covered.
Anything you need help with ive got it to one side in bits.

Thanks very much

 

[davenn]

I have 12v switched at rear of dead radio.
I have 12v permanent at rear of dead radio.
I have earth at rear of dead radio.

OK good ... was going to ask abt that

I did read that the red/yellow wire "12v switched+ 12v permanent" must be connected together or no display/lights will show thinking unit is dead ?

the +12 switched is via the acc ignition key switch
the +12 permanent keeps the unit in a powered standby mode ... keeps the clock on time and other things

when I get a chance I will get you to start looking for voltages on the circuit board ... will point out some locations
I want to see if power is getting from the rear connector to IC301 --- the main regulator chip ... it has multiple output power rails at various voltages

 

[ipbr21054a]

OK,
Please send screen shot from point to point that you would like me to check.

Thanks for the help.

 

[davenn]

OK some pix






Now you need to be VERY careful doing the testing. you don't want to accidentally short out 2 pins or wires that shouldn't be shorted

make sure there are no tools/bits of wire on the bench under the board
power the board up as it is shown in the pic above with a PSU putting out 12 - 14VDC

with multimeter on VDC and negative probe on negative line, you should have full 12+ (12 - 14V) on every one of those purple jumpers
as shown on the board in the bottom pic

you mentioned a fuse a wayyyyy back ... I assume you meant the 10A one on the back of the radio ?


Dave

 

[ipbr21054a]

Hi,
With the first green image where is that in relation to the image i sent you of the board ?

Just to be sure i am connecting power to the wires that come from the rear of the unit correct,as in the red yellow & black above ?

 

[ipbr21054a]

Hi,
Powered up like this,
Red & Yellow wire joined together outside of radio with positive supply.
Black also joined outside of radio with negative power supply.
Readings taken from brown side circuit board as in photo

JW201 = 12.22v
JW202 = 12.23v
JW216 = 12.22v
JW217 = 12.22v
JW215 = 12.23v
JW214 = 12.22v
JW394 = 12.22v