TMC signal

wnj516 · 13th November 2012, 20:22

Can someone who has TMC running through an Amp supplied by Mark please help, Although mine has worked, it seems to be a bit iffy since installing Primo2 although it did give warning during the weekend. What i would like to know is what is their voltage from the amplifier on the ariel plug (output) when it's disconnected from the TMC socket in the DD unit.I have 12Volts.Is this correct or should it be MilliVolts, and my amp is faulty.
Thanks
Nigel

HarryM1BYT · 13th November 2012, 21:14

I don't have a circuit and cannot easily test Mark's amp, but I would generally expect the output of an RF amp to be DC isolated via an in series capacitor so only the RF signal passed through.

What are you feeding the input to the amp with, tapping off the window radio antenna or the length of wire method I used?

wnj516 · 14th November 2012, 12:13

Hi Harry, the connections to Mark's amp is as per instructions, from the rear screen ariel amp which has 12v supply. Mark's amp is supplied via the switched contact from the DD unit, this supply is fused and feeds the amp and Tv tunner,
I have in the past blown this fuse by pulling out the input plug to the DD (TMC) when the set was ON,so really am looking to see if the TMC amp has blown,could it be the case where on open circuit the plug would have 12v across it and when connected it's dragged down to whatever level!!
The DD unit is seen to scan through FM frequencies but no data found, but it did find data whilst travellin across the Midlands last weekend.
I am not a radio expert but have been in the electrical field all my life and am trying to establish if the TMC amp is faulty before opening it up and checking the components.
Nigel

HarryM1BYT · 14th November 2012, 13:37

Is the 12v the 'full' 12v as in exactly the same voltage as the 12v supply?

If it is, that would suggest it is indeed faulty -even if there is no DC isolation, I would expect the 12v you mention to be -0.7v or so less than the as measured voltage at the 12v input to Mark's amp, due to the drop across the output transisters junction.

A good signal input to the TMC is essential, so I suspect if it worked last weekend it is probably fine. I tried Mark's suggested method of connecting to the rear screen antenna and found it caused some slight detriment to the radio's signal, so rather than use his method for the input to his amp - I simply used a completely completely separate antenna.

For the TMC antenna, I used a length of single wire 6 to 8 foot long, which I tucked up around the headlining towards the front (with Mark's amp installed at the rear, by the radio's amp). That worked fine for months, but I later revised the layout of the wire, so it just circled around the parcel shelf and that seemed to improve it even more. I used the word 'seemed', because it is so difficult to compare reception levels on the TMC. All I could do was count the number of stations it had found before and after changes to the antenna and it always takes it a while to lock onto stations.

The above might be your problem, rather than Mark's amp.

wnj516 · 14th November 2012, 16:32

Thanks again for your reply Harry, i will check the actual voltage again but i do suspect it's slightly down, compared to the battery volts.My battery is all of 8yrs old so it's not top notch.
I will give your modified ariel a try i have nothing to loose and let you know how i've got on.
Before i start i will try and note the stations that are scanned as a before and after.
Nigel

wnj516 · 15th November 2012, 15:50

I checked the output from the amp and it was the same as the supply volts to it @11.9v, so i have purchased an amplifer kit 22db, to replace it with, even if it's not u/s it's out of the equation,so after building it will let you know what results i get.

HarryM1BYT · 16th November 2012, 20:07

Thanks, I look forward to the result...

wnj516 · 17th November 2012, 16:31

Made up the new tmc amplifier and fitted,switched areial leads and got a good reception the radio, switched back to TMC and measured the volts out on the areial lead plug,got 7 millivolts and in the region of 20-25 db.Not the battery volts i had on the original.Took the car out and very quickly 86 incedends reported, so am happy it works well.
The only diffrence in the build of the original amp to the new one is the a link on the circuit board which should only be used if your feeding the power via the co-ax.I powered up the amp on the bench got power supply volts,cut the link and hey presto 90millivolts.When time allows i will check the ""faulty"" amp out on the car, i would assume it will work,otherwise it could be 1 shorted capacitor, allowing battery volts through,or it could be charging and allowing this voltage to appear, all in all glad it's sorted.
Nigel

HarryM1BYT · 17th November 2012, 18:48

Well done!

Judging by what you describe - It sounds as if Mark might have put the link in, when he should not have.

HarryM1BYT · 21st November 2012, 21:05

The out come of this, the fix, has now been posted as a sticky at http://www.the75andztclub.co.uk/foru...d.php?t=129805

13th November 2012, 20:22	#1
wnj516 Avid contributor ZT400 SE Join Date: Jan 2007 Location: Llanelli, S Wales Posts: 155 Thanks: 7 Thanked 15 Times in 15 Posts	TMC signal Can someone who has TMC running through an Amp supplied by Mark please help, Although mine has worked, it seems to be a bit iffy since installing Primo2 although it did give warning during the weekend. What i would like to know is what is their voltage from the amplifier on the ariel plug (output) when it's disconnected from the TMC socket in the DD unit.I have 12Volts.Is this correct or should it be MilliVolts, and my amp is faulty. Thanks Nigel

13th November 2012, 21:14	#2
HarryM1BYT This is my second home 75 Contemporary SE Mk II 2004 Man. Sal. CDTi 135ps, FBH on red diesel, WinCE6 DD Join Date: May 2010 Location: Leeds Posts: 17,273 Thanks: 2,160 Thanked 2,061 Times in 1,586 Posts	I don't have a circuit and cannot easily test Mark's amp, but I would generally expect the output of an RF amp to be DC isolated via an in series capacitor so only the RF signal passed through. What are you feeding the input to the amp with, tapping off the window radio antenna or the length of wire method I used? __________________ Harry How To's and items I offer for free, or just to cover the cost of my expenses... http://www.the75andztclub.co.uk/foru...40#post1764540 Fix a poor handbrake; DIY ABS diagnostic unit; Loan of the spanner needed to change the CDT belts; free OBD diagnostics +MAF; Correct Bosch MAF cheap; DVB-T install in an ex-hi-line system; DD install with a HK amp; FBH servicing. I've taken a vow of poverty. To annoy me, send money.

14th November 2012, 13:37	#4
HarryM1BYT This is my second home 75 Contemporary SE Mk II 2004 Man. Sal. CDTi 135ps, FBH on red diesel, WinCE6 DD Join Date: May 2010 Location: Leeds Posts: 17,273 Thanks: 2,160 Thanked 2,061 Times in 1,586 Posts	Is the 12v the 'full' 12v as in exactly the same voltage as the 12v supply? If it is, that would suggest it is indeed faulty -even if there is no DC isolation, I would expect the 12v you mention to be -0.7v or so less than the as measured voltage at the 12v input to Mark's amp, due to the drop across the output transisters junction. A good signal input to the TMC is essential, so I suspect if it worked last weekend it is probably fine. I tried Mark's suggested method of connecting to the rear screen antenna and found it caused some slight detriment to the radio's signal, so rather than use his method for the input to his amp - I simply used a completely completely separate antenna. For the TMC antenna, I used a length of single wire 6 to 8 foot long, which I tucked up around the headlining towards the front (with Mark's amp installed at the rear, by the radio's amp). That worked fine for months, but I later revised the layout of the wire, so it just circled around the parcel shelf and that seemed to improve it even more. I used the word 'seemed', because it is so difficult to compare reception levels on the TMC. All I could do was count the number of stations it had found before and after changes to the antenna and it always takes it a while to lock onto stations. The above might be your problem, rather than Mark's amp. __________________ Harry How To's and items I offer for free, or just to cover the cost of my expenses... http://www.the75andztclub.co.uk/foru...40#post1764540 Fix a poor handbrake; DIY ABS diagnostic unit; Loan of the spanner needed to change the CDT belts; free OBD diagnostics +MAF; Correct Bosch MAF cheap; DVB-T install in an ex-hi-line system; DD install with a HK amp; FBH servicing. I've taken a vow of poverty. To annoy me, send money.

14th November 2012, 16:32	#5
wnj516 Avid contributor ZT400 SE Join Date: Jan 2007 Location: Llanelli, S Wales Posts: 155 Thanks: 7 Thanked 15 Times in 15 Posts	Thanks again for your reply Harry, i will check the actual voltage again but i do suspect it's slightly down, compared to the battery volts.My battery is all of 8yrs old so it's not top notch. I will give your modified ariel a try i have nothing to loose and let you know how i've got on. Before i start i will try and note the stations that are scanned as a before and after. Nigel Last edited by wnj516; 14th November 2012 at 16:36..

16th November 2012, 20:07	#7
HarryM1BYT This is my second home 75 Contemporary SE Mk II 2004 Man. Sal. CDTi 135ps, FBH on red diesel, WinCE6 DD Join Date: May 2010 Location: Leeds Posts: 17,273 Thanks: 2,160 Thanked 2,061 Times in 1,586 Posts	Thanks, I look forward to the result... __________________ Harry How To's and items I offer for free, or just to cover the cost of my expenses... http://www.the75andztclub.co.uk/foru...40#post1764540 Fix a poor handbrake; DIY ABS diagnostic unit; Loan of the spanner needed to change the CDT belts; free OBD diagnostics +MAF; Correct Bosch MAF cheap; DVB-T install in an ex-hi-line system; DD install with a HK amp; FBH servicing. I've taken a vow of poverty. To annoy me, send money.

14th November 2012, 12:13	#3
wnj516 Avid contributor ZT400 SE Join Date: Jan 2007 Location: Llanelli, S Wales Posts: 155 Thanks: 7 Thanked 15 Times in 15 Posts	Hi Harry, the connections to Mark's amp is as per instructions, from the rear screen ariel amp which has 12v supply. Mark's amp is supplied via the switched contact from the DD unit, this supply is fused and feeds the amp and Tv tunner, I have in the past blown this fuse by pulling out the input plug to the DD (TMC) when the set was ON,so really am looking to see if the TMC amp has blown,could it be the case where on open circuit the plug would have 12v across it and when connected it's dragged down to whatever level!! The DD unit is seen to scan through FM frequencies but no data found, but it did find data whilst travellin across the Midlands last weekend. I am not a radio expert but have been in the electrical field all my life and am trying to establish if the TMC amp is faulty before opening it up and checking the components. Nigel

15th November 2012, 15:50	#6
wnj516 Avid contributor ZT400 SE Join Date: Jan 2007 Location: Llanelli, S Wales Posts: 155 Thanks: 7 Thanked 15 Times in 15 Posts	I checked the output from the amp and it was the same as the supply volts to it @11.9v, so i have purchased an amplifer kit 22db, to replace it with, even if it's not u/s it's out of the equation,so after building it will let you know what results i get.

17th November 2012, 16:31	#8
wnj516 Avid contributor ZT400 SE Join Date: Jan 2007 Location: Llanelli, S Wales Posts: 155 Thanks: 7 Thanked 15 Times in 15 Posts	Made up the new tmc amplifier and fitted,switched areial leads and got a good reception the radio, switched back to TMC and measured the volts out on the areial lead plug,got 7 millivolts and in the region of 20-25 db.Not the battery volts i had on the original.Took the car out and very quickly 86 incedends reported, so am happy it works well. The only diffrence in the build of the original amp to the new one is the a link on the circuit board which should only be used if your feeding the power via the co-ax.I powered up the amp on the bench got power supply volts,cut the link and hey presto 90millivolts.When time allows i will check the ""faulty"" amp out on the car, i would assume it will work,otherwise it could be 1 shorted capacitor, allowing battery volts through,or it could be charging and allowing this voltage to appear, all in all glad it's sorted. Nigel

17th November 2012, 18:48	#9
HarryM1BYT This is my second home 75 Contemporary SE Mk II 2004 Man. Sal. CDTi 135ps, FBH on red diesel, WinCE6 DD Join Date: May 2010 Location: Leeds Posts: 17,273 Thanks: 2,160 Thanked 2,061 Times in 1,586 Posts	Well done! Judging by what you describe - It sounds as if Mark might have put the link in, when he should not have. __________________ Harry How To's and items I offer for free, or just to cover the cost of my expenses... http://www.the75andztclub.co.uk/foru...40#post1764540 Fix a poor handbrake; DIY ABS diagnostic unit; Loan of the spanner needed to change the CDT belts; free OBD diagnostics +MAF; Correct Bosch MAF cheap; DVB-T install in an ex-hi-line system; DD install with a HK amp; FBH servicing. I've taken a vow of poverty. To annoy me, send money. Last edited by HarryM1BYT; 17th November 2012 at 18:52..

21st November 2012, 21:05	#10
HarryM1BYT This is my second home 75 Contemporary SE Mk II 2004 Man. Sal. CDTi 135ps, FBH on red diesel, WinCE6 DD Join Date: May 2010 Location: Leeds Posts: 17,273 Thanks: 2,160 Thanked 2,061 Times in 1,586 Posts	The out come of this, the fix, has now been posted as a sticky at http://www.the75andztclub.co.uk/foru...d.php?t=129805 __________________ Harry How To's and items I offer for free, or just to cover the cost of my expenses... http://www.the75andztclub.co.uk/foru...40#post1764540 Fix a poor handbrake; DIY ABS diagnostic unit; Loan of the spanner needed to change the CDT belts; free OBD diagnostics +MAF; Correct Bosch MAF cheap; DVB-T install in an ex-hi-line system; DD install with a HK amp; FBH servicing. I've taken a vow of poverty. To annoy me, send money.