our garage guy needs PH help!
Discussion
Hello all. Our Golf Mk 4 is at this very moment in our friendly local garage to have its original (Gamma?) radio sorted out. FM reception is patchy and MW non-existent. Garage guy Simon has got the headlining down and has found the power pack for the bee-sting aerial. He has measured voltage coming into that pack at 1 volt, same as the voltage he's measured coming out of the back of the radio. He's admitted that he has no idea if one volt is the correct amount in this scenario and after ringing a couple of his radio expert mates he's feeling a bit better because they don't know either, hmmm. He checked the connections at the back of the radio after noticing they didn't look that clever but sorting them out has not worked as there's still no MW, just static.
He's stopped the clock on this job now. I said I'd check in with the ever-helpful and brainy PH massive to see if they had any thoughts on it. Anybody know if 1 volt is right for a car radio and its aerial? If not, what should it be, and what would mend it? I will send ten quid to rednose day if there's a winning suggestion. Thanks.
He's stopped the clock on this job now. I said I'd check in with the ever-helpful and brainy PH massive to see if they had any thoughts on it. Anybody know if 1 volt is right for a car radio and its aerial? If not, what should it be, and what would mend it? I will send ten quid to rednose day if there's a winning suggestion. Thanks.
tonym911 said:
The fact that it's an amplifier at the aerial end, but it's showing the same voltage as what's coming out of the radio, makes me wonder about how much amplifying it's actually doing. I think I might get Simon to replace the amplifier and then see what occurs.
If he's measuring the output from the radio and the input of the amp, nothing's being amplified yet so it will be the same reading.SlimRick said:
If he's measuring the output from the radio and the input of the amp, nothing's being amplified yet so it will be the same reading.
Yes I did wonder that as I was typing it, just grasping at straws here really. The level of knowledge in the trade about car radios seems surprisingly small. I was trying to engage a 'specialist' in conversation about the PURE DAB radio I've bought to add to the Golf once its own radio is mended (it's a birthday present for the missis) and he was what I can only describe as aggressively hopeless. tr7v8 said:
Not worked on Car stuff for years but certainly all that I did used 12V for the amp. So you should have 12V out the back of the set. I assume the radio is turned on when he's checking? It might be worth powering the amp through a fuse direct from a 12v source.
Thanks for this, I'll check in with Simon. Is there no Haynes manual section on this? By saying there is no MW what do you mean -- you can get VHF but not MW?
Surely, you can find another VW car that has the same radio that works fine do a swap over and see if it's the unit's fault or it lies with the amplifier on the antenna end...
Surely, you can find another VW car that has the same radio that works fine do a swap over and see if it's the unit's fault or it lies with the amplifier on the antenna end...
SlimRick said:
If he's measuring the output from the radio and the input of the amp, nothing's being amplified yet so it will be the same reading.
Not relevant I assume he is measuring the power feed from both not the RF so it will be te same both ends any way, working or not. I assume as my other post 12V.dvance said:
Is there no Haynes manual section on this? By saying there is no MW what do you mean -- you can get VHF but not MW?
Surely, you can find another VW car that has the same radio that works fine do a swap over and see if it's the unit's fault or it lies with the amplifier on the antenna end...
No MW at all, just static. VHF is there, but reception is very variable. The signal regularly (ie three or four times a minute) drops out altogether for a couple of seconds. Reception generally (on FM I mean) seems to be better in big cities. I live in Wiltshire. Just wondering if the radio is generally buggered and I should just replace it, it's a '99 car at the end of the day. But do radios 'wear out'?Surely, you can find another VW car that has the same radio that works fine do a swap over and see if it's the unit's fault or it lies with the amplifier on the antenna end...
No, Simon's one of the good guys. tonym911 said:
No MW at all, just static. VHF is there, but reception is very variable. The signal regularly (ie three or four times a minute) drops out altogether for a couple of seconds. Reception generally (on FM I mean) seems to be better in big cities. I live in Wiltshire. Just wondering if the radio is generally buggered and I should just replace it, it's a '99 car at the end of the day. But do radios 'wear out'?
Some radios have a fuse in the aerial output feed so it could be that. It could well be the head rather than the aerial TBH.Hmm... Radios as all electronics can fail. If you don't have a manual that's going to tell you what voltages/signals to expect where it might be a bit hard to figure out what's wrong unless you can test the different components together with ones that you know work.
Hope you figure it out
Hope you figure it out
Went round the garage this aft. When Simon put his multimeter on the end of the cable that runs from the radio to the aerial (the cable under the headlining) the radio began picking up MW. Suggesting that the fault lies with the aerial. There'll be a new one arriving tomorrow so we're hoping that'll do the trick.
dvance said:
Hmm... Radios as all electronics can fail. If you don't have a manual that's going to tell you what voltages/signals to expect where it might be a bit hard to figure out what's wrong unless you can test the different components together with ones that you know work.
Hope you figure it out
Thanks Hope you figure it out
For me electricity is something dangerous that you pay for, and that's about where my knowledge ends. I don't mind admitting I've no idea. I thought radios would all be the same in terms of how much juice they draw. The fact that the radio works after a fashion (albeit intermittently) even with only 1 volt showing makes me think that's what it's meant to run on. tonym911 said:
The signal regularly (ie three or four times a minute) drops out altogether for a couple of seconds.
This sounds suspiciously like a failing (leaky)capacitor in the tuning/aerial circuit............. 12v would be the norm for most purposes, but there could be a 1 or 5v switching voltage perhaps.
Have you the Haynes manual ? And does it have a circuit diagram showing the aerial element of the loom ?
tubbystu said:
This sounds suspiciously like a failing (leaky)capacitor in the tuning/aerial circuit.............
12v would be the norm for most purposes, but there could be a 1 or 5v switching voltage perhaps.
Have you the Haynes manual ? And does it have a circuit diagram showing the aerial element of the loom ?
Sadly I only have a Haynes manual for our other Golf, a Mk 2, not this Mk 4. 12v would be the norm for most purposes, but there could be a 1 or 5v switching voltage perhaps.
Have you the Haynes manual ? And does it have a circuit diagram showing the aerial element of the loom ?
Sorry to be so thick but is the tuning/aerial circuit in the head unit? It's the original VW radio/cassette unit, I think it may be called a Gamma but I'm not sure.
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