Great information - I like the photos you posted.
Never seen that tool.
I have a 754 radio that does not work and that tool
just might revive it. The only problem is getting access to that tool.

 

Well, for you, Carl, all you need to do is run over to Charlotte. The rest of us might have a bit harder time.

 

Other than for reasons of nostalgia, why bother reviving an old radio when new radios are far superior and cheaper?

 

Agreed that new radios are much better than the old technology, however for some, we prefer that the aesthetics remain original in these cars - for me, that is the sole reason.

 

Agreed. In fact I still have my old Becker... but it's in a Benzi-Box.

Sidebar with apologies:

After loosing a few radios to the poor misunderstood youth of the 80's, I had a Benzi-Box installed. The problem of stolen radios became so pervasive that some enterprising folks started marketing stickers for the Mercedes owners windows with the words "No Radio", just to stop the thieves before doing damage. I never locked my 107 as to avoid the costly damage done to rag top... or when the hardtop was on... glass, but that didn't stop the drug crazed guy that stole my radio from first slitting my top.

 

I had my radio reconditioned primarily to deactivate the theft deterrent system. I thought about getting an aftermarket unit but just didn’t care for the looks of the new radios.

 

I spent a weekend installing a 'BETTER' quality radio in a poxy Renault back in the 80's. One of the local scum must have seen me working on it because the next day it was gone. They broke the rear quarter-light which really pissed me off because the doors were not locked.

 

I suspect you're not a fan of income redistribution. :smile

 

I am more belligerent than I was back then. I now believe an Eye for an Eye... Translated as : You touch my Radio and I get a new pair of balls to dangle from my mirror.

 

You may be more right than you think. I wasn't going to tell this part of the story but now that you mention being more belligerent now than you were then... here goes. I caught the kid that stole my radio (it was the second radio, I already had the original radio stolen). I took pity on him (hey I was only about 35 myself at the time) and told him to hand me the radio and I'd let him leave. He handed me the radio... wires hanging out an all... and walked away. I don't know if I would be as forgiving today.

 

As my mother used to tell me. "I am not given to violence but for you I will make an exception".

 

lol.

 

Jyuma, initial read through came out --

"...told him to hand me the radio and I'd let him live."

Just goes to show how I feel on the topic. I had Becker rebuild my Europa II, and would kill the bastard that screws it up.

 

My guess is that at power on the microprocessor looks for a high or low voltage on a specific pin and if it sees it then it unlocks. That would make the innards of the tool trivial - press the green button and it connects the relevant pin to postive or GND. All pins are included on the tool just so the user can't screw up how to plug it in.

Would be nice if the schematics of the radio could be obtained from somewhere.

Perhaps Becker can provide details of the tool? A mechanic probably doesn't know if instructions were included with it - just follow the instructions and job done.

"Last microprocessor in the UK"... I wonder if that line is used on all customers? Sorry, I am getting more cynical with age...

Andy

 

I have the schematics somewhere, I can email them if needed.

I also assumed a similar process, although I couldn't unlock the radio by trying various resets like that. If there are any electricians present who might have ideas, am happy to try.

Becker didn't want to engage me in conversation about the tool, my guess is that it's their proprietary info and helps them make a living, so fair enough.

"last processor" - well, I considered it, but I actually got the sense he wanted to keep it rather than sell it to me.

 

Please send me the schematics?

 

Please PM me the schematics.

Andy

 

Please send me the schematics or just the pin out diagram, I'm trying to restore a becker754 to my 82 but might give up if I need to reset it.

 

PM sent.

 

I think it was blocked because you are new member. Not sure how to get around it.

Andy

 

Minimum number of posts required before PM is allowed. I don't remember the number.

 

We worked it out. I think it is 10 posts.

 

Microcontroller is M3872 from SGS. It's not enough to replace it, it would need to be programmed as well. Has 4Kb of ROM and 128 bytes of RAM. Perhaps the UK guy scavenged them from working units that were not locked.

The mechanic's tool connects to a 12-pin connector. Hopefully the number of each pin is shown on the circuit board next to the connector. As best as I can work out:

1 - LCD enable 1 out
2 - LCD enable 2 out
3 - data in/out
4 - clock out
5 - button data in (serial)
6 - on button
7 - off button
8 - five lamps
9 - single lamp
10 - no connection
11 - Positive out
12 - GND

Because the tool has two buttons perhaps one correponds to the on button (green?) and the other corresponds to the off button (red?). If so try connecting pin 6 to pin 12 and power on. Although if that works then why bother with the tool in the first place?

Unlocking could be more complex than that. It could look for a specific set of buttons being held down at power on. Think Ctrl+Alt+Del for Windows.

Or they could have made it even more complex and have a sequence of button presses in the right order and too quickly for a human to do. Think combination lock.

Andy

 

MoonUnit drew my attention to IC906 where power is on pin eight and is maintained by a 3.4V battery.

This is a PCD8571. This is an eight-pin serial RAM chip containing 128 bytes. If the battery dies the contents of this RAM chip also die.

My guess is that when new from the factory this part is programmed with some magic value that tells the radio to work. When the battery dies the contents are lost and the microcontroller shows dashes. Then when the workshop tool is connected it gives the microcontroller a specific sequence of some kind of signal or signals which instruct it to restore the contents of the RAM chip and it works again.

In theory it would be possible to take a working radio and connect some test hardware into the circuit then read out the contents of the RAM chip. It might then be possible to restore a locked radio by again connecting some test hardware and reprogramming the RAM chip. Tedious work, time consuming and not easy for anyone to just DIY.

Andy

 

Hi Andy,

I had exactly the same thoughts when I looked at it. I assumed the PCD8571 held some 'key' value that enabled the main microprocessor to start up properly. However, a common use for that chip is storing phone numbers in phone systems, and I thought it may just exist to store the radio presets. I am not sure what the battery does - it could be that it's to keep the code alive if the car battery is disconnected or flat. When the radio is removed from the car, in addition to the 4 pin power plug, there is a 5 pin 'anti-theft' plug which connects in to the same circuit as IC906. If one assumes the key code lives in this chip, then one might assume that a) the on-board 3.6v battery keeps it in memory for normal times unless b) the 5 pin anti-theft plug is pulled, in which case some wiping event is triggered (my electronics isn;t good enough to work out what happens if that plug is removed).

Thus, a radio with flat onboard battery could continue to work provided the car battery is still powering the radio, but if the car battery dies, the radio would 'dash out'.

Simply replacing the battery doesn't fix the problem.

Removing the anti-theft circuit doesn't fix it either, but in the two radios I have the do work, the anti-theft circuit has been removed.

All the online resources I found said to not re-connect the anti-theft plug, if still in the car.

The only thing I could think of to do next was to remove the IC906 from a working radio, read it with an EPROM reader, program a new chip and solder that into the broken radio. The risk of course is that I damage the good radio in the process and I thus lost my nerve.

I am also pretty sure the main processor has its own memory and it's quite possible that IC906 is a red herring here, and the code in the microprocessor needs to be re-programmed. Certainly, my UK repair man suggested that the main chip needed to be replaced. There was no mention of the small IC906.

So - if anyone has any other ideas, I am all ears - ideally I'd love to either buy that tool or maybe it's possible to find someone in the states who can investigate 'cloning' it, depending on what it does.

If it's a simple as the tool holds various pins high or low on startup, that should be easy to replicate. It could be that it re-programmes the main microprocessor instead.

Thoughts?

 

You can't remove IC906 because it is RAM not EPROM. As I mentioned before as soon as it loses power it will lose it's contents.

Replacing the battery wouldn't fix it because it's already too late - data has been lost. Now it needs to be restored to factory status.

The theft status needs to be stored somewhere. It's not likely to be stored in the microcontroller as I doubt it has the ability to do that. It would need EEPROM which wasn't common in the mid-80s microcontrollers. Also in-circuit reprogramming was not common. I wasn't able to find a copy of the datasheet to confirm. Basic search indicated this is simple ROM and RAM only.

IC906 is maintained by the battery so that seems to be the most likely place. There is room to store this single status bit along with phone numbers.

If the UK repair person says the microcontroller needs to be replaced then how does he explain that others have been able to unlock their units using the tool instead of replacing the microcontroller?

It seems the battery is either not used or maintained by the anti-theft connector. If your unit has the connector missing then when the battery eventually dies I would expect it to lock again.

The way I would read out IC906 would be using a jig with pogo pins - no hardware modification required. Same for reprogramming.

Andy

 

"You can't remove IC906 because it is RAM not EPROM. As I mentioned before as soon as it loses power it will lose it's contents."

Meaning that if I did remove it from the good radio, it'd lose it's contents and I'd be stuffed?

I figured that would be the only way to read it, once it's isolated from its connections to the processor. I have seen various HEX dumps of files that people claim are from IC906 and work, I'll attach some for your enjoyment.

I assumed the microprocessor was reprogrammable, so the tool could reprogram it via the faceplate connection. I am also assuming that Becker had the microprocessors made pre-programmed and the repair guy has one of these left.

BTW, the closest I got to establishing the indentity of the processer was a phillips 80C31, I will attach the datasheet.

We need the tool, really.

 

Do we have a house number on the ram chip ic906. The dumps images listed here are possible to be the contestants in the eeprom in the tool itself. From what I see the tool sends serial data from its onboard eeprom to the radios ram chip. I wish I had a snapshot from the tool as well as images of the tool apart. I’m thinking the images are from the tools eeprom. The ram chip on the radio would be hard and delicate to read. But if I had a good one I would read it. The only way that I know to read the ram in the radio is have a data sheet of the ram ic. Careful solder wires to the ic’s power and ground from top side and carefully use solder sucker to extract the ic pins leaving the power and ground connected to external power with the wires on top of the ic. Use a small wire that could carefully be wrapped underside the pin so solder won’t flow away and fall off. Losing power and data. Then breadboard the ram and put its data lines to led’s and address the ram with switch data also read lines as well. Advance through address and record the led state. This would be a long shot and some really fine solder removal skills not to touch pins.

 

Looks like those hex dumps are from a 24C01 which is an EEPROM. Didn't see that on the schematic, but if it's on there somewhere then it could also hold the theft status.

Andy

 

Yes - I think they are. I got them from various sites on the net. I tried without success to program the IC906 and put the failure down to it being still on the circuit board and thus not being powered properly by the programmer (clip on lead). But more fundamentally, if IC906 isn't an EPROM in the first place, it wouldn't have worked [slap forehead].

 

There is a good chance you have damaged IC906 by doing that. IC906 uses I2C and has a different pinout to an EEPROM.

Andy

 

There is a good chance you have damaged IC906 by doing that. IC906 uses I2C and has a different pinout to 24C01.

Andy

Hmm, well that's not good, I'll have to go back to see exactly what I did try to do. I've been ferreting around in the dark on this and had come to believe the tool was an urban legend, so to see it here is exciting ...

 

I looked again at the schematic - can't see a 24C01 on there... if you know where it is please post an image of that part of the schematic.

Andy

 

I don't believe there is a 24C01 - I think it's being confused with the PCD8571 chip. Certainly, when I was looking into all this a while back, I found a Polish site, which I thought implied the RAM chip was / could be replaced by an EPROM. See https://www.elektroda.pl/rtvforum/topic129638.html#16980526 although you have to put the posts through google translate. Some tantalising hints.

Also, this page -= CODEDRADIO =- Base navigation suggests the main processor is an 80C31 (search for radio BE754).

 

Subscribed - you guys are going to gonkulate this out, I just know it.

 

The entry for BE754 on the Polish site doesn't match up with the schematic.

8051 was a core type and many silicon vendors made derivatives over a period of 25+ years. It's possible that the SGS part used in this radio is an 8051 but that information doesn't help much without the SGS datasheet.

Probably your best course of action is to send your radio to Becker and have them unlock it and I believe they can deactivate the anti-theft feature.

Andy

 

I noticed on the schematic there is a key that has a symbol that looks like a keyhole. Does this button actually exist?


Andy

That button is actually a depiction of an aerial. On the 754 model, it does not exist, but on the 755 model (which I think is a US version) it does, and successive presses increases the scanning sensitivity when scanning for channels.

 

Thanks for posting this. I'm getting a new (old) Becker this week from a parts car.