Roberts R200 Aux Input for Ipod - UK Vintage Radio Repair and Restoration Discussion Forum

frognpuck · 26th Sep 2012, 7:28 am

Hello

This subject has probably been covered before, so bear with me.

I have a Roberts R200 (no.12,789) that performs well apart from some volume control crackle when being turned. (not a big problem).

I would like to fit an auxilary input socket / line in, so I can use my ipod and play a weekend's worth of 50's and 60's music at the next vintage revival festival (Twinwood, Goodwood etc.)

I have tried directly connecting the 3.5mm ipod phono lead to the R200 speaker with some low volume success but obviously would prefer to have some amplification.

Could someone advise how this would best be done?

Please take into account my lack of radio experience, so perhaps a diagram and simple speaker would be best. I do have the 1449 & 1602 service sheets and a soldering iron at the ready. Many thanks.

Refugee · 26th Sep 2012, 9:42 am

It is best to look at how it is done on early car radios.

Use two inches of ribbon cable where the signal passes into the set so that you do not need to modify the cabinet.

The other way would be to fit an adaptor lead with PP3 a connector one end and a PP9 connector the other. This enables a PP3 battery to be used and frees up the space inside the radio so that the MP3 player can be hidden there.

MP3 players have a very short battery life and will require charging so often that the shorter battery life of the R200 will not matter..

I take it that the set will be returned to original after the show?

mhennessy · 26th Sep 2012, 10:17 am

My MP3 player runs for 40 hours from one charge - enough for a weekend - and is small enough to fit inside an R200 with no modification. But once inside, I'd obviously loose access to the buttons, so would have to set up the playlist quite carefully...

But this doesn't help the OP with the electrical connections...

You'd need to inject the signal at the top of the volume control. Then you can tune the radio to a quiet part of the band and plug in the MP3 player...

To identify the connections, look at R8 (the volume control) on the schematic (I'm looking at the version on the Trader sheet). The top of the volume control comes from the detector diode (X1) and the bottom of the volume control is connected to chassis.

You'll need to find a lead with a stereo 3.5mm lead attached. Yes, you could buy the plug and solder your own lead to it, but it's often just as cheap - and less hassle - to get a pre-made lead and cut it to length...

The screen of the lead goes to the bottom of the volume control - the chassis. That's the easy part...

Next, we need to connect the left and right signals together. I'd suggest using a pair of resistors - perhaps 2.2K or thereabouts. Joint them together, connect the L and R audio signals to the ends of the resistors and regard the join of the resistors as the mixed mono signal...

This mono signal needs to be connected to the top of the volume control, but do it via a capacitor. There is DC at the top of the volume control, and it might upset the MP3 player. Something like 10uF would probably be fine - with the positive end probably going to the volume control. I say "probably", but I haven't double-checked, and would do so as part of the job.

It's harder to describe than actually do! If you need help, I'm local, and could be persuaded to solder it all together for you in return for a couple of beer tokens...

BTW, should you prefer to have the MP3 player mounted externally, the suggestion of ribbon cable to avoid having to modify the case was an excellent one

Hope this helps,

Mark

frognpuck · 27th Sep 2012, 8:35 pm

Hi, Many thanks both for the replies. I was going to try and fit it inside the case if possible. Mark, would it be ok if I contacted you direct? I like your suggestions but have a couple more questions and an idea for charging the ipod. Regards Matt

mhennessy · 27th Sep 2012, 11:26 pm

Hi,

No problem - you should be able to send me a PM...

Cheers,

Mark

Xavierj · 23rd Jan 2016, 9:39 pm

Hi guys,
I'm interested by doing the same. Have you managed to get it work?
I have a Roberts Revival 250.
Cheers

mhennessy · 24th Jan 2016, 12:43 pm

Yes indeed. All the information you need is here. But do bear in mind the R250 is a very different beast to the R200...

26th Sep 2012, 7:28 am	#1
frognpuck Retired Dormant Member Join Date: Sep 2012 Location: Worcester, Worcs. UK. Posts: 2	Roberts R200 Aux Input for Ipod Hello This subject has probably been covered before, so bear with me. I have a Roberts R200 (no.12,789) that performs well apart from some volume control crackle when being turned. (not a big problem). I would like to fit an auxilary input socket / line in, so I can use my ipod and play a weekend's worth of 50's and 60's music at the next vintage revival festival (Twinwood, Goodwood etc.) I have tried directly connecting the 3.5mm ipod phono lead to the R200 speaker with some low volume success but obviously would prefer to have some amplification. Could someone advise how this would best be done? Please take into account my lack of radio experience, so perhaps a diagram and simple speaker would be best. I do have the 1449 & 1602 service sheets and a soldering iron at the ready. Many thanks.

26th Sep 2012, 10:17 am	#3
mhennessy Dekatron Join Date: Jul 2007 Location: Evesham, Worcestershire, UK. Posts: 4,244	Re: Roberts R200 Aux Input for Ipod My MP3 player runs for 40 hours from one charge - enough for a weekend - and is small enough to fit inside an R200 with no modification. But once inside, I'd obviously loose access to the buttons, so would have to set up the playlist quite carefully... But this doesn't help the OP with the electrical connections... You'd need to inject the signal at the top of the volume control. Then you can tune the radio to a quiet part of the band and plug in the MP3 player... To identify the connections, look at R8 (the volume control) on the schematic (I'm looking at the version on the Trader sheet). The top of the volume control comes from the detector diode (X1) and the bottom of the volume control is connected to chassis. You'll need to find a lead with a stereo 3.5mm lead attached. Yes, you could buy the plug and solder your own lead to it, but it's often just as cheap - and less hassle - to get a pre-made lead and cut it to length... The screen of the lead goes to the bottom of the volume control - the chassis. That's the easy part... Next, we need to connect the left and right signals together. I'd suggest using a pair of resistors - perhaps 2.2K or thereabouts. Joint them together, connect the L and R audio signals to the ends of the resistors and regard the join of the resistors as the mixed mono signal... This mono signal needs to be connected to the top of the volume control, but do it via a capacitor. There is DC at the top of the volume control, and it might upset the MP3 player. Something like 10uF would probably be fine - with the positive end probably going to the volume control. I say "probably", but I haven't double-checked, and would do so as part of the job. It's harder to describe than actually do! If you need help, I'm local, and could be persuaded to solder it all together for you in return for a couple of beer tokens... BTW, should you prefer to have the MP3 player mounted externally, the suggestion of ribbon cable to avoid having to modify the case was an excellent one Hope this helps, Mark

27th Sep 2012, 8:35 pm	#4
frognpuck Retired Dormant Member Join Date: Sep 2012 Location: Worcester, Worcs. UK. Posts: 2	Re: Roberts R200 Aux Input for Ipod Hi, Many thanks both for the replies. I was going to try and fit it inside the case if possible. Mark, would it be ok if I contacted you direct? I like your suggestions but have a couple more questions and an idea for charging the ipod. Regards Matt

27th Sep 2012, 11:26 pm	#5
mhennessy Dekatron Join Date: Jul 2007 Location: Evesham, Worcestershire, UK. Posts: 4,244	Re: Roberts R200 Aux Input for Ipod Hi, No problem - you should be able to send me a PM... Cheers, Mark

23rd Jan 2016, 9:39 pm	#6
Xavierj Retired Dormant Member Join Date: Jan 2016 Location: Dublin, Ireland Posts: 2	Re: Roberts R200 Aux Input for Ipod Hi guys, I'm interested by doing the same. Have you managed to get it work? I have a Roberts Revival 250. Cheers

26th Sep 2012, 9:42 am	#2
Refugee Dekatron Join Date: Apr 2012 Location: Worksop, Nottinghamshire, UK. Posts: 5,553	It is best to look at how it is done on early car radios. Use two inches of ribbon cable where the signal passes into the set so that you do not need to modify the cabinet. The other way would be to fit an adaptor lead with PP3 a connector one end and a PP9 connector the other. This enables a PP3 battery to be used and frees up the space inside the radio so that the MP3 player can be hidden there. MP3 players have a very short battery life and will require charging so often that the shorter battery life of the R200 will not matter.. I take it that the set will be returned to original after the show?

24th Jan 2016, 12:43 pm	#7
mhennessy Dekatron Join Date: Jul 2007 Location: Evesham, Worcestershire, UK. Posts: 4,244	Re: Roberts R200 Aux Input for Ipod Yes indeed. All the information you need is here. But do bear in mind the R250 is a very different beast to the R200...