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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment.

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Old 27th Sep 2017, 3:32 pm   #1
creaky22
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Default Rotel RX-402 Line-in question

Hello!

Quick question regarding a strange problem I may have when using the line-in on my Rotel RX-402, I bought a phono to 5 pin din connector with understanding that pins 2 and 4 (red and white) would be left and right and pin 3 (black) would be common ground (I checked the lead with a multimeter and that was the case) the 2 remaining connectors (1 & 5) are unused. However when I do this I get no right channel unless I use a pin 2 as ground and 3 as right. L and R works fine on radio. Is something wrong or were some wired up differently?
2 Possibly relevant side notes, I use this for playing music through my phone in the garage and when an album is finished a loud buzz starts until I play more music, also when playing radio I have the volume at 25% but when I switch to phone/line-in I the need volume set at 80% to match the same audio levels?

Thanks
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Old 27th Sep 2017, 3:36 pm   #2
Station X
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Default Re: Rotel RX-402 Line-in question

Perhaps a silly question, but are you aware that the pins in a 5 pin DIN Plug are not numbered sequentially?
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Old 27th Sep 2017, 5:14 pm   #3
TonyDuell
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Default Re: Rotel RX-402 Line-in question

As Graham said, the pins on a 5 pin din plug are not numbered sequentially. It makes sense if you start by considering the 3 pin plug and then fit the extra 2 pins between them. This gives the order 1, 4, 2, 5, 3. Note that pins 1,2,3 are in the same places on the 3 pin and 5 pin plugs.

Pin 2, the middle one, is almost always earth. I can think of some exceptions to this for microcomputer connections, but not for audio. So I would be very surprised if that was not the earth pin on your amplifier.

Conventionally, pins 1 and 3 (the ones also on the 3 pin plug used for mono) are used for the left channel and pins 4,5 for the right channel. On an amplifier, it's normally the case that pin 3 is the left input and pin 5 the right input. Pins 1 (left) and 4 (right) are used for the recording output signal.

[Annoyingly the inputs an outputs are reversed on a tape recorder. This means you can use a straght-wired cable to link it to an amplifier but also that you sometimes need cross-wired cables. Personally I would have always had 3,5 as inputs and had almost all cables cross-wired. But anyway...]
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Old 29th Sep 2017, 11:19 am   #4
creaky22
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Default Re: Rotel RX-402 Line-in question

Ah, thanks for the helpful replies.

I made the mistake of Googling ‘5 pin DIN schematic’ and taking the first result as gospel, all sorted apart from the issue with buzzing after an album has finished playing (using my phone through the input/aux). Any ideas on areas inside the amp that would be worth investigating?

BTW this was a boot sale find, £30 still in original box and packaging with receipts etc and it seems to have had very little use, it’s almost too good to use in my garage.
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Old 29th Sep 2017, 1:59 pm   #5
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Default Re: Rotel RX-402 Line-in question

It may not be the amp at all, I have a phone that I use at work, it is played through a portable radio/cassette/CD player. With a line in this buzzes when the track I'm playing finishes or I put the phone on pause while I'm away doing something. I also have to have my phone's volume up high to match the amplifier in the portable CD player.
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