A little success story of a car radio repair gone right.
A few weeks ago my girlfriend's car radio stopped working. The car is a Holden Astra model ST from 2001 released for the Australian market. On the (UK-based) 'Astra Owners Website' they also refer to this model as either a Vauxhall Astra Fourth Generation (or Mk 4) or Opel Astra G.
The car radio is a Blaupunkt 520. It's a smart-ish radio in that it communicates with an external display higher up in the centre console and shows things like radio station, volume, CD track etc..
So at one point a few weeks ago the output volume suddenly started dropping. I was listening to some music on CD and the volume coming out of the speakers dropped to almost nothing over a period of maybe 10 seconds. I tried compensating by turning the volume up but it really was getting quieter and quieter. I switched on the FM radio but it was also very very quiet; almost no output volume. I switched off the radio and drove home.
This couldn't be a fuse or so because the radio and all the controls still worked; it was just very very quiet. Since the symptoms were the same when either listening to CD or radio I assumed that the fault was in the final output amplifier.
Since I didn't really wanted to open up the radio and swap out these chips I thought it would be simpler to just look around for a second-hand Blaupunkt 520 radio. Someone on eBay had one on sale for $20 ex shipping. Unfortunately he didn't have the security code.
The security code is important because it locks down the radio if the battery power is removed. I knew our radio's code but that didn't help as the code is programmed inside the radio. Change the radio and you'll need a new code. There are usually ways to recover (or maybe reset) the code through the official car dealership, e.g. in case you've lost your code or bought a car without knowing the code from the previous owner.
I decided to take the risk and buy the radio on eBay in the hopes of being able to reset it through a local Holden dealer. My girlfriend is the first owner of her Astra and has all the official paperwork to prove so. I thought it would be a (perhaps somewhat costly) breeze to recover the replacement radio's code.
The radio from eBay arrived shortly after the purchase and we began inquiring with several Holden dealers in the area to get an idea of what it would cost to have the radio code recovered. I must say this was a very unsatisfying experience. The feedback from the local dealers can be summarised as a mix of hostility, unhelpfulness, rudeness and sheer incompetence. Some seemed to insinuate that we had a stolen radio, others flat-out refused to help and some gave us the idea that our problem wasn't worth their time even though we were well prepared to pay for the recovery service.
The next step was to look for an online radio-code recovery service. Yes they exist, but we weren't successful with them either. Websites that offer these services ask for a couple of details and then (if all goes well) instantly produce a code that you can use straight away to unlock your radio. The website I found asked for the Blaupunkt 520's serial number and part number. Well, the serial number was printed on a sticker, but the part number was missing. I looked everywhere, even inside the radio, but was not able to find the part number. I figured that probably any website that offers these instant-code-generator services operates in the same way and not having a critical piece of information will probably mean that any other code generating website would also not be able to help.
After calling another Holden dealer I finally got some good information. In order to recover the radio code they would also need the VIN (chassis number) of the car that the radio originally came out of. I asked the eBay seller but he said he was unable to recover this information.
Hmm... what to do.
Since I already had the radio open at this stage I noticed the two final amplifier ICs.
(Grey and black ICs that are backed up against the two copper heat sinks)