Rega Planar 2 /NAD 3020A - quiet output on one channel

[John1968]

Hi I am new to AK and would like to thank you in advance for any help you can give me!

As a teenager I loved my hifi but after I got married and space was limited it got put in a box in the loft...where it has stayed for the last 30 years... until last weekend when I connected my TT (Rega Planar 2) to my amp (NAD 3020A) and speakers( AR 18LS) to see what it would do . I was amazed to see that it seemed absolutely fine, but on close examination I can see that the output on one channel of the amp is quiet - but it seems to work OK if I press MONO.

I swapped speakers and cables around which made no difference - it was always the same channel which was quiet. So it looked to me like the problem was in the output from the amp. But I then plugged my iphone into the AUX input using a 3.5mm jack with 2 RCAs ...and both speakers worked fine!

So that got me thinking that the outputs are fine and maybe the problem is either with the TT or with the PHONO input itself...and I am a bit stuck as to what to do next.

I was thinking of plugging the TT into the AUX input to see if it could be heard in both speakers that way (my iphone test confirmed that this one worked fine) and if so then I will know that the TT is not faulty..., but I wasn't sure if this might damage something and so I thought that I would ask an expert for advice before I did anything stupid.

.I also thought about giving it a good clean and so I have a can of Servisol Super 10 at the ready - but tbh I'm not sure how to use it and I dont want to damaging the circuits by being clumsy.

If anyone can help me isolate the fault and give me some idea on how to fix it I would be eternally grateful as it is driving me insane !


Many thanks

John

 

[Crab33]

I once had a NAD 3020 with AR18 speakers - not quite the same as yours but close.

From what you say, it doesn't seem like the turntable is at fault, but you could switch its left/right RCA cables over to check. It could be in the phono-stage of the amplifier. It probably wouldn't do any harm to plug the turntable into the AUX input - the sound will be very low and tinny, but you may be able to check whether the channels are balanced.

If it turns out that the phono-stage is at fault and you don't want to replace the amplifier, all is not lost as you could buy a separate phono pre-amp to plug into the AUX input.

EDIT: Sorry, just read your post again. It could indeed be the TT or phono-stage. Swap around the RCA cables of the TT to check whether the source of the problem is there. This kind of issue can result from a problem with the cartridge wires.

 

[leesonic]

If you have a line level source like a CD player with a volume control, you can feed this into the phono stage of the NAD and see what happens. Start with the volume (on the player) at zero, and slowly increase it until you hear something from the speakers. The volume on the amp can be slightly above zero. The importance here is the source with an adjustable volume control. Just connecting a CD player line output will give a very distorted signal, and may even do damage. I usually use a CD Walkman and use the headphone output.

The input jacks of the NAD are soldered to the PCB. These can and do crack, resulting in the loss of signal from one channel. If you remove the bottom panel, you should be able to see this. If you can use a soldering iron, you can fix it.

The NAD 3020 and AR18 combination was recommended by What HiFi magazine back in the day. It's a good combination. Larger AR speakers in that same series (28, 38, 48, 94) will give you more bass.

Lee.

 

[John1968]

Hi - thanks for your replies

I have done what you both kindly suggested....so here's what I found (my brain is frazzled so not sure what any of it points to!)

in the current set up :TT in the PHONO input : the L output was working but R wasn't (unless MONO was pressed) and my iphone playing through the AUX input - both L&R outputs were working

-SO...

1. switching over the TT's RCAs in the phono slots - made the R output work but the L output stopped working
2. adding a portable CD player to the AUX - L output working R not working (unless MONO pressed)
3. adding the portable CD player to the PHONO input - L output working R not working
4. adding the portable CD player to the TUNER input - L output working R not working
5. adding my iphone to the TUNER input - both L and R outputs working
6. adding the TT to AUX input - L output working R not working ( unless MONO pressed)

Does any of this make it any clearer!!

Many thanks for your sleuthing skills..

 

[Crab33]

Quite baffling... I'm surprised that more people haven't jumped in to offer their two pennies' worth.

So, I think it's established that the fault is not in the output stage of the amplifier. It seems that the problem occurs with all sources and inputs except when using the iPhone. I've no idea why this might be.

Since switching over the RCA cables of the TT also switched the channel problem, this suggests there is a fault in the turntable. Perhaps you have two faults - one in the turntable and one in the amplifier. But what is bizarre is that the R channel worked in this case, while it was failing in all other scenarios except with the iPhone.

Myself, I would give up at this stage and get a new amplifier, not being a practical person or a fixer However, you may still find that you have a fault in the turntable.

 

[John1968]

Yes - feel like giving up on it too! I wish there was some kind of flowchart that I could follow to try and see where the problem is - agree that it may be both the TT and the amp! .
Last resort is to clean the amp to see if that makes any difference - have got a can of Servisol Super 10 but I've no idea what to do with it and what I should try and clean, and more importantly what I should leave alone!

Cheers

John

 

[Montycat]

I would get inside the NAD and clean the controls with Deoxit or the Servisol. You might have intermittent contact on a source switch for example due to contamination. While you have it open, hook up a source and tap around inside with something non conductive like a chopstick. If there is a bad solder joint this might pinpoint it.

You can also use the iPhone into the Phono input but make sure you have the volume output on the phone set very low, like 10%, so you don't overload the amp. It won't sound good but that's not the point.

The NAD has jumpers from preamp to power amp, doesn't it? Pull those and clean them then reinsert them.

 

[geespot]

Try using different cables. Check the wires going into the cartridge on the TT.

 

[jrtrent]

Quite baffling... I'm surprised that more people haven't jumped in to offer their two pennies' worth. . . Myself, I would give up at this stage and get a new amplifier, not being a practical person or a fixer However, you may still find that you have a fault in the turntable.

I'm not a fixer, either. I don't know the OP's location or service options, but I have both dealers and service centers I trust enough to take the two pieces to and let them sort it out. They can help me determine if repairing any faults found makes sense or if it's best to just buy a new component or two.

 

[Coshac333]

but I have both dealers and service centers I trust enough to take the two pieces to and let them sort it out. .

the problem is either with the contact or with the electronic element. It only takes an oscilloscope, a specialist and 15 minutes of time.

 

[leesonic]

So you're saying when you use the tuner input, you get output from both speakers?

 

[maxhifi]

I think the NAD probably has cracked solder under the input jacks as this design is prone to, per @leesonic above. Additionally, there may be an issue with the turntable. Since the issue is not in the power section of the amplifier they shouldn't be an expensive repair. I believe it is time to involve a tech.

 

[John1968]

Hi thank you all for your your thoughts and advice - looking at my earlier comment, I made an error with the TT through the tuner it was only the L output that was working. The only scenario where L output isn't working is when a portable CD player is played through the AUX - when the R output works but L doesn't.

The only scenarios where both outputs work is when I play the iphone via a headphone jack into the AUX ...or if I push MONO - no idea why on either count!

So I think I will need to go to a tech and firstly play TT through a different amp to see if that makes any difference and to just hand over my amp to sort out the inputs.

Thanks for much for everyone's replies- am greatly relieved that it wont be an expensive fix!

All the best

John