BLAUPUNKT VW GAMMA REPAIRING & UNLOCKING
I got yesterday into my service center a nice job from a customer. He brought his car radio to me for repairing the tape mechanism because the tape player cannot play the tape and the mechanism gives a squeeze noise. I decide to let a try even if it is an old model of car radio but! be careful with car audio equipment repairing! Why? it can be a trap, because of the security code of the radio equipment .I know from my experience this model of car radio have a security code and it will be activated if the device is disconnected from the car or the car battery is disconnected for some reason from the car.
Therefore, I call back the customer and asked for the radio code, he told me, he does not have any code and he does not know his radio have a code…This part is the trap. The car radio can be stolen or you have to do extra job for the customer because he/she maybe doesn’t know there is a code, and wish to repair the radio and use the car radio as before, but won’t pay for the decoding of the device. In some newer cars, it is very hard to unlock the audio-video equipment if you have no experience and no tools. This could be very expensive for you, if the customer says it is locked because of your fault, and it was not locked before disconnected from the car.
Ok, let us go!
This is the equipment:
When I connected the power source to the equipment, I got as I supposed the SAFE on the LCD that is meaning the car radio is locked and has to be unlocked with the code which should be entered by the owner or have to unlocked by a specialist if the owner don’t know the code.
Unlocking process is coming later in this article.
I pull out that piece of tape. Inspected the other parts for other mechanical problems, I found everything was fine. Now we go to the part two. We unlocking the car radio, because the user does not know the right code. In this device the unlock code is stored in the SPI (Serial Peripheral Interface) eeprom.
For first, we have to find that tiny SMD (Surface Mount Device) IC, which name is ST95160 it is located under the tape mechanism, so we have to pull out the mechanism. Be careful, you have four screws to take out. Then pull up with the fingers the flat cable on the left side. You do not have to disconnect the white cable bond on the right side.
My method to read and write an eeprom is to take it out from the circuit, so you can avoid “waking up” the CPU and damaging the firmware. You can even shorten the oscillators on the board but all this stuff is too sketchy for me and I always take out the eeprom and put it in the programmer.
In this case, this is an ST95160 SPI eeprom and I use the PonyProg eeprom programmer. I have to build quickly a programmer, which you can see in the picture. This is a simple programmer for 95XXX and 25XXX eeproms. With this programmer, you can use the PonyProg software on Windows XP or Windows 7 OS.
In the device list, select the 25160 device because the 95160 is the same IC and there are no 95160 in PonyProg.
You can download PonyProg from www.lancos.com
I made a backup of the original eeprom.
ALWAYS BACKUP THE CONTENT OF THE ORIGINAL EEPROM!
I wrote content into the eeprom, with a known code. I put into the four digit code by pressing the numbers 1, 2, 3 and 4 on the number pad on the radio. The first number pad is the first digit of the code, the second number pad is the second digit and so on to the last digit. After that you have to press the right arrow on the radio and wait until on the LCD writes “Learning”, then you hade correctly entered the unlock code.
The car radio still plays tapes and the code no more mystery for the owner. If there is a section, where I can upload the eeprom content for these device please let me know and I will share it.
The job is finished. Below is the link to the eeprom file:
This article was prepared for you by Christian Robert Adzic from Novi Knezevac-Serbia
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