Vintage Blaupunkt car cassette radio problems

[Reesatta]

Hello,

Not sure if these are common problems or maybe a bit advanced for the forum, but I'll give it a try. I've got a 1980's Blaupunkt car cassette radio (see images for model number, because I'm unsure), and both its cassette and radio functions are defect. I don't have a car to try it in because it's actually a friend's, but I've built my own 12V power adapter, and I'm using a loose 75 Ohm FM/AM car antenna for the radio functionality. I know a thing or two about electronics, but this thing seem almost impossible to take apart (apart from the top and bottom metal pieces), which makes it hard for me to check some of the interior and its components for errors etc. So, I don't have that much to inspect.

The problems:

1. Radio. It seem totally dead. It should have several red lights turning on when you turn the right knob, which I guess is for AM frequency, and the two buttons below I guess controls the FM frequency. They don't light up when you turn or press any of the mentioned controls. I'm not sure about the buttons, so I've tried pressing L, M, and U (which all stay pressed) while trying to change the frequency (tell me what these mean). However, I once managed to - before I bought the antenna - get a static noise signal with a freaking small wire, which I put inside the antenna input. The red lights showed up, but I never got to any radio stations, even though the lights changed as they probably would when I turned the AM knob (nothing happened when I pressed the FM buttons). I never managed to redo this, not even with the real antenna, which is weird. Anyway, where could the error be located? What seem to be wrong with it? I tried cleaning the black stripe which the AM knob is connected to (image A3, upper left corner below the knob, also A9 zoomed in), by the way.
2. Cassette. It should play instantly when you insert a cassette, but instead some kind of spring mechanism push it out; it doesn't stay in. A couple of times I managed to insert it and it stuck as it should, but it didn't run. Pressing both the forward and backward buttons acts as an eject. The part that I've taken interest in from this mechanism can be seen in image A3 and A4 below the "black and silver wheel" in the middle, and it's the white thing. This thing is being pushed back when you insert a cassette, and the second step should be the tightening/spinning mechanism, which should rise from below (sorry, I don't know the correct terms for everything). This mechanism is triggered by the metal thingy to the left of the white thing by being pressed backwards, which I can force with a metal spudger (must be a quite hard item because it's quite strong). However, you must hold it in this position, because both the white and metal thing recoil. I guess both these mechanisms could be partly electrically triggered in order to work. So, what seem to be the problem here?

Additionally, on the bottom of the unit I found some weird thing among the electrical circuits (image A5) on the circuit board between the brown wires in the lower middle. Two circuits seem to be disrupted by physical damage to the board. I'm not sure if it's intentional by design or actual damage. Anyway, I repaired these two traces with two wires (image A6). I'm not sure what this does, though. I hope I didn't do something bad. The result is still the same with both my problems and the unit doesn't seem to act any different, or shorting itself. Is this kind of disruption of a circuit common on circuit boards? At least I've never seen anything similar. Should I maybe remove my wires? By the way, the circuits above (middle top) that looks dirty are whole. I'm trying to search for irregularities with a multimeter.

Anyone able to help me troubleshoot this? I'd be glad to at least fix one of the problems, or maybe just discover the exact problem/s. I replaced the belt, by the way. There are 10 attached images for analysis. Tell me if you need an image of something specific.

Click to read more...

 

[hispls 5,000+ posts]

Wow, that's ancient. Honestly I don't think anybody even repaired those back when they were new (and expensive). You're well beyond the age where stuff is likely to fail with no visible signs and I can't imagine you'd ever find parts.

If this is just a personal challenge for you, good luck, but I can't think of anybody who would even know where to start troubleshooting something like this and it's likely whoever designed these is senile or dead by now.

 

[Lasherž]

Hello,

Not sure if these are common problems or maybe a bit advanced for the forum, but I'll give it a try. I've got a 1980's Blaupunkt car cassette radio (see images for model number, because I'm unsure), and both its cassette and radio functions are defect. I don't have a car to try it in because it's actually a friend's, but I've built my own 12V power adapter, and I'm using a loose 75 Ohm FM/AM car antenna for the radio functionality. I know a thing or two about electronics, but this thing seem almost impossible to take apart (apart from the top and bottom metal pieces), which makes it hard for me to check some of the interior and its components for errors etc. So, I don't have that much to inspect.

The problems:

1. Radio. It seem totally dead. It should have several red lights turning on when you turn the right knob, which I guess is for AM frequency, and the two buttons below I guess controls the FM frequency. They don't light up when you turn or press any of the mentioned controls. I'm not sure about the buttons, so I've tried pressing L, M, and U (which all stay pressed) while trying to change the frequency (tell me what these mean). However, I once managed to - before I bought the antenna - get a static noise signal with a freaking small wire, which I put inside the antenna input. The red lights showed up, but I never got to any radio stations, even though the lights changed as they probably would when I turned the AM knob (nothing happened when I pressed the FM buttons). I never managed to redo this, not even with the real antenna, which is weird. Anyway, where could the error be located? What seem to be wrong with it? I tried cleaning the black stripe which the AM knob is connected to (image A3, upper left corner below the knob, also A9 zoomed in), by the way.
2. Cassette. It should play instantly when you insert a cassette, but instead some kind of spring mechanism push it out; it doesn't stay in. A couple of times I managed to insert it and it stuck as it should, but it didn't run. Pressing both the forward and backward buttons acts as an eject. The part that I've taken interest in from this mechanism can be seen in image A3 and A4 below the "black and silver wheel" in the middle, and it's the white thing. This thing is being pushed back when you insert a cassette, and the second step should be the tightening/spinning mechanism, which should rise from below (sorry, I don't know the correct terms for everything). This mechanism is triggered by the metal thingy to the left of the white thing by being pressed backwards, which I can force with a metal spudger (must be a quite hard item because it's quite strong). However, you must hold it in this position, because both the white and metal thing recoil. I guess both these mechanisms could be partly electrically triggered in order to work. So, what seem to be the problem here?

Additionally, on the bottom of the unit I found some weird thing among the electrical circuits (image A5) on the circuit board between the brown wires in the lower middle. Two circuits seem to be disrupted by physical damage to the board. I'm not sure if it's intentional by design or actual damage. Anyway, I repaired these two traces with two wires (image A6). I'm not sure what this does, though. I hope I didn't do something bad. The result is still the same with both my problems and the unit doesn't seem to act any different, or shorting itself. Is this kind of disruption of a circuit common on circuit boards? At least I've never seen anything similar. Should I maybe remove my wires? By the way, the circuits above (middle top) that looks dirty are whole. I'm trying to search for irregularities with a multimeter.

Anyone able to help me troubleshoot this? I'd be glad to at least fix one of the problems, or maybe just discover the exact problem/s. I replaced the belt, by the way. There are 10 attached images for analysis. Tell me if you need an image of something specific.

Friendly suggestion is to try out EEVblog.com if you want to get some real electrical advice on that. You may get lucky and one of the savants will piece together the circuit for you. If you have a wiring diagram I can try and help piece it together for you based on that, but otherwise it's pretty advanced for this forum unfortunately.

From a preliminary look I don't like the appearance of that Tantalum capacitor. Has it blown its top? Also it appears that you've got some stray wire strands coming out from your bottom bodge wire (top joint). Make sure they're electrically isolated if they're supposed to be.

If you're having issues with mechanicals not latching you should try and check those solenoids for issues as well.

 

[Reesatta]

Friendly suggestion is to try out EEVblog.com if you want to get some real electrical advice on that. You may get lucky and one of the savants will piece together the circuit for you. If you have a wiring diagram I can try and help piece it together for you based on that, but otherwise it's pretty advanced for this forum unfortunately.

From a preliminary look I don't like the appearance of that Tantalum capacitor. Has it blown its top? Also it appears that you've got some stray wire strands coming out from your bottom bodge wire (top joint). Make sure they're electrically isolated if they're supposed to be.

If you're having issues with mechanicals not latching you should try and check those solenoids for issues as well.

Yeah, I guess EEVblog maybe could help. Thanks. Sadly I don't have a wiring diagram, and I can't seem to find one on the internet. That would make it a bit easier for me, as well.

If you're talking about the tantalum capcitor to the right of the "wiring/bridge repair" that I did, it does indeed look a bit sketchy as it is flat and not rounded on the top, if that's what you're thinking about. However, it looks fine to me, other than looking unfamiliar.

About the wire you're talking about, that's probably fabric from the insulation. I think it's done by the manufacturer (brown wires), but it could also be some weird repair done by someone else, because I thought it looked a bit sketchy. My black wires that I added to bridge repair the circuits are not isolated, though. As mentioned, I'm not even sure they should even be there bridging the circuit, I just thought the "damage" to the board looked unusual.

Thanks for the reply. I'll look into the things you suggested.