NAD 3020 phono issue - UK Vintage Radio Repair and Restoration Discussion Forum

richhutch · 11th Sep 2022, 1:12 pm

Put together a wee vinyl playing system for my stepson (Dual 505-3, NAD 3020, Tannoy Mercury M2) and was working great but phono input is now dead. No sound at all. When I plug turntable into tuner or tape input I do get sound but, as you would expect from a turntable, very low volume, so it looks like phono input/pre-amp is the issue. Amp plays CDs through the Aux input no problem. Any comments on what my options are would be much appreciated.

Station X · 11th Sep 2022, 1:27 pm

Seems odd that both channels have failed. Do the other inputs work correctly when fed with a suitable signal?

paulsherwin · 11th Sep 2022, 1:46 pm

As Graham says, it's extremely unlikely that both channels have failed at the same time unless there's a power supply fault. Check for volts on the op-amp pins and power rails.

richhutch · 11th Sep 2022, 2:14 pm

Thanks guys. Other inputs seem to work fine. He did report to me that he was only getting sound from one speaker for some time and he’s brought it me to check and no sound from either channel with phono. So maybe one channel went some time ago and the other more recently. Paul, not really a electronics guy so could you explain your advice a wee bit more.

Kentode · 11th Sep 2022, 2:14 pm

Open it up and look carefully at the other end of the phono inputs, there may be a fractured solder joint caused by overenthusiastic wiggling when pushing in the RCA jacks.

richhutch · 11th Sep 2022, 2:18 pm

Thanks Ken. Will try that.

Thanks guys. All help and suggestions gratefully received.

ms660 · 11th Sep 2022, 2:25 pm

Unless I'm looking at it wrong, according to the schematic I'm looking at phono relies on 16 switch contacts making to function properly.

Lawrence.

paulsherwin · 11th Sep 2022, 2:41 pm

I also thought of dirty switch contacts, but that is unlikely to cause a sudden and complete loss of signal across both channels. I suppose something may have physically broken - the 3020's switchgear isn't the highest quality.

Rich, if you really have no electronics experience, no test gear and no soldering iron, you are very unlikely to be able to sort this out yourself. It's probably best to bite the bullet and pay a professional to fix it.

richhutch · 11th Sep 2022, 3:46 pm

I do have a testing multimeter and I can handle a soldering iron OK. I’ll open her up and have a look.

Craig Sawyers · 11th Sep 2022, 4:31 pm

Peering at photos on the web, I'm almost certain that the manufacture was subcontracted to Taiwan. We did exactly the same thing with Cambridge Audio stuff of the same era, and they came back looking identical to that appearance. We finally got a product, complete, boxed and shipped from Taiwan for less than the parts cost of a UK build.

The problem is that the circuit board is single sided SRBP, so has every possibility of broken solder joints, particularly in the region of the input connectors, which are exposed and vertical facing - so plugging things in and out puts strain on the board and solder joints.

Craig

paulsherwin · 11th Sep 2022, 4:58 pm

You are quite right, all the 3020s were contract built in Taiwan, and some of the internal construction isn't pretty. They do sound good though.

Rich, look for dry and broken joints where the input sockets join the main PCB. If all is well, use your DMM to measure the volts on each of the preamp op-amp pins (from memory, there's only one). If you don't see any volts then power to the preamp has been lost somehow. If you see volts then the fault is elsewhere.

Take care not to cause any shorts when using the meter probes.

Craig Sawyers · 11th Sep 2022, 5:08 pm

Indeed they did sound good. They were a landmark design. And like the Cambridge Audio stuff, they were built to the UK electronic design. They even looked identical in appearance to a UK built product - you could only tell it wasn't a UK build by taking the lid off.

But a bit like an intermittent fault in my Quad 33 preamp, which was definitely UK built in Huntingdon, someone on the list said "resolder every joint" - and that cured the problem perfectly.

So maybe with the 3020 before overthinking the source of the problem, resolder every single solder joint.

Craig

Goldie99 · 11th Sep 2022, 5:16 pm

There's no op-amps in a NAD 3020 Paul - they're completely discrete.

From memory, the phono PS voltages are the same as used in the pre-amps, so if the other inputs are working, it's unlikely to be a PS issue - my money would be on dry / broken joints as well, although there are other possibilities esp. if it's one of the variants with MM/MC switching and the mess of glue that usually holds that lot together... a couple of clear photos above below the phono section might help pin it down.

I've come across bad joints in them, but never come anywhere even close to resoldering everything - in my (limited) experience, their poor reputation is often worse than reality.

Alan

paulsherwin · 11th Sep 2022, 5:30 pm

Thanks for that Alan, I'm obviously misremembering. It's a long time since I've been inside one.

richhutch · 11th Sep 2022, 5:57 pm

Opened unit up and soldered joints below phono inputs look OK. Any thoughts guys?

Bazz4CQJ · 11th Sep 2022, 6:43 pm

Think hard about what went on between the time when it was working great and the time it was dead. What changes went on that could have upset it?

My NAD 3020 does not like to hear of such things

.

B

stevehertz · 11th Sep 2022, 7:04 pm

Just resolder any soldered connection that looks even vaguely 'dry' or poor. It wouldn't take an hour to go over every joint on the PCB. Use some proper switch cleaner and spray it onto the switch contacts (as best as you can access them), then operate the switches many times.

Craig Sawyers · 11th Sep 2022, 7:10 pm

Well currently it is a bit of a mystery. What cartridge is in the deck?

And with the volume very low (so you don't stuff your speakers!), what happens if you put a finger in each phono input? Can you hear a hum?

Craig

Bazz4CQJ · 11th Sep 2022, 7:56 pm

As per post #2, seems odd that both channels went down at the same time.

B

richhutch · 11th Sep 2022, 8:14 pm

Spoke to stepson tonight and he tells me that one channel went down then some weeks/months later the second channel went down. He doesn’t live with us so I can’t be any clearer on dates. Solder joints on pc look fine but was wondering about on the phono input side. Could there be a tiny break at the top of the strip that connects the inner part of the connector to the solder joint on the other side of the pc? Can anyone explain, in words of one syllable please, how I could use a multimeter to test the connections from phono input to the solder joints on the other side of the pc? Thanks to all.

11th Sep 2022, 1:12 pm	#1
richhutch Triode Join Date: Jan 2021 Location: Glasgow, Scotland, UK. Posts: 12	NAD 3020 phono issue Put together a wee vinyl playing system for my stepson (Dual 505-3, NAD 3020, Tannoy Mercury M2) and was working great but phono input is now dead. No sound at all. When I plug turntable into tuner or tape input I do get sound but, as you would expect from a turntable, very low volume, so it looks like phono input/pre-amp is the issue. Amp plays CDs through the Aux input no problem. Any comments on what my options are would be much appreciated.

11th Sep 2022, 1:46 pm	#3
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,947	Re: NAD 3020 phono issue As Graham says, it's extremely unlikely that both channels have failed at the same time unless there's a power supply fault. Check for volts on the op-amp pins and power rails.

11th Sep 2022, 2:14 pm	#4
richhutch Triode Join Date: Jan 2021 Location: Glasgow, Scotland, UK. Posts: 12	Re: NAD 3020 phono issue Thanks guys. Other inputs seem to work fine. He did report to me that he was only getting sound from one speaker for some time and he’s brought it me to check and no sound from either channel with phono. So maybe one channel went some time ago and the other more recently. Paul, not really a electronics guy so could you explain your advice a wee bit more.

11th Sep 2022, 2:14 pm	#5
Kentode Octode Join Date: Mar 2015 Location: Yorkshire, England. Posts: 1,301	Re: NAD 3020 phono issue Open it up and look carefully at the other end of the phono inputs, there may be a fractured solder joint caused by overenthusiastic wiggling when pushing in the RCA jacks. __________________ Regards, Ken. BVWS member

11th Sep 2022, 2:18 pm	#6
richhutch Triode Join Date: Jan 2021 Location: Glasgow, Scotland, UK. Posts: 12	Re NAD 3020 phono issue. Thanks Ken. Will try that. Thanks guys. All help and suggestions gratefully received.

11th Sep 2022, 1:27 pm	#2
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: NAD 3020 phono issue Seems odd that both channels have failed. Do the other inputs work correctly when fed with a suitable signal? __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

11th Sep 2022, 2:25 pm	#7
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: NAD 3020 phono issue Unless I'm looking at it wrong, according to the schematic I'm looking at phono relies on 16 switch contacts making to function properly. Lawrence.

11th Sep 2022, 2:41 pm	#8
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,947	Re: NAD 3020 phono issue I also thought of dirty switch contacts, but that is unlikely to cause a sudden and complete loss of signal across both channels. I suppose something may have physically broken - the 3020's switchgear isn't the highest quality. Rich, if you really have no electronics experience, no test gear and no soldering iron, you are very unlikely to be able to sort this out yourself. It's probably best to bite the bullet and pay a professional to fix it.

11th Sep 2022, 3:46 pm	#9
richhutch Triode Join Date: Jan 2021 Location: Glasgow, Scotland, UK. Posts: 12	Re: NAD 3020 phono issue I do have a testing multimeter and I can handle a soldering iron OK. I’ll open her up and have a look.

11th Sep 2022, 4:31 pm	#10
Craig Sawyers Dekatron Join Date: Nov 2010 Location: Oxford, UK. Posts: 4,984	Re: NAD 3020 phono issue Peering at photos on the web, I'm almost certain that the manufacture was subcontracted to Taiwan. We did exactly the same thing with Cambridge Audio stuff of the same era, and they came back looking identical to that appearance. We finally got a product, complete, boxed and shipped from Taiwan for less than the parts cost of a UK build. The problem is that the circuit board is single sided SRBP, so has every possibility of broken solder joints, particularly in the region of the input connectors, which are exposed and vertical facing - so plugging things in and out puts strain on the board and solder joints. Craig __________________ Doomed for a certain term to walk the night

11th Sep 2022, 4:58 pm	#11
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,947	Re: NAD 3020 phono issue You are quite right, all the 3020s were contract built in Taiwan, and some of the internal construction isn't pretty. They do sound good though. Rich, look for dry and broken joints where the input sockets join the main PCB. If all is well, use your DMM to measure the volts on each of the preamp op-amp pins (from memory, there's only one). If you don't see any volts then power to the preamp has been lost somehow. If you see volts then the fault is elsewhere. Take care not to cause any shorts when using the meter probes.

11th Sep 2022, 5:08 pm	#12
Craig Sawyers Dekatron Join Date: Nov 2010 Location: Oxford, UK. Posts: 4,984	Re: NAD 3020 phono issue Indeed they did sound good. They were a landmark design. And like the Cambridge Audio stuff, they were built to the UK electronic design. They even looked identical in appearance to a UK built product - you could only tell it wasn't a UK build by taking the lid off. But a bit like an intermittent fault in my Quad 33 preamp, which was definitely UK built in Huntingdon, someone on the list said "resolder every joint" - and that cured the problem perfectly. So maybe with the 3020 before overthinking the source of the problem, resolder every single solder joint. Craig __________________ Doomed for a certain term to walk the night

11th Sep 2022, 5:16 pm	#13
Goldie99 Heptode Join Date: Jul 2014 Location: Boston, Lincolnshire, UK. Posts: 995	Re: NAD 3020 phono issue There's no op-amps in a NAD 3020 Paul - they're completely discrete. From memory, the phono PS voltages are the same as used in the pre-amps, so if the other inputs are working, it's unlikely to be a PS issue - my money would be on dry / broken joints as well, although there are other possibilities esp. if it's one of the variants with MM/MC switching and the mess of glue that usually holds that lot together... a couple of clear photos above below the phono section might help pin it down. I've come across bad joints in them, but never come anywhere even close to resoldering everything - in my (limited) experience, their poor reputation is often worse than reality. Alan

11th Sep 2022, 5:30 pm	#14
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,947	Re: NAD 3020 phono issue Thanks for that Alan, I'm obviously misremembering. It's a long time since I've been inside one.

11th Sep 2022, 5:57 pm	#15
richhutch Triode Join Date: Jan 2021 Location: Glasgow, Scotland, UK. Posts: 12	Re: NAD 3020 phono issue Opened unit up and soldered joints below phono inputs look OK. Any thoughts guys? Attached Thumbnails

11th Sep 2022, 6:43 pm	#16
Bazz4CQJ Dekatron Join Date: Apr 2009 Location: Oxfordshire, UK. Posts: 4,935	Re: NAD 3020 phono issue Think hard about what went on between the time when it was working great and the time it was dead. What changes went on that could have upset it? My NAD 3020 does not like to hear of such things . B __________________ Saturn V had 6 million pounds of fuel. It would take thirty thousand strong men to lift it an inch.

11th Sep 2022, 7:04 pm	#17
stevehertz Dekatron Join Date: Sep 2011 Location: Rugeley, Staffordshire, UK. Posts: 8,831	Re: NAD 3020 phono issue Just resolder any soldered connection that looks even vaguely 'dry' or poor. It wouldn't take an hour to go over every joint on the PCB. Use some proper switch cleaner and spray it onto the switch contacts (as best as you can access them), then operate the switches many times. __________________ A digital radio is the latest thing, but a vintage wireless is forever..

11th Sep 2022, 7:10 pm	#18
Craig Sawyers Dekatron Join Date: Nov 2010 Location: Oxford, UK. Posts: 4,984	Re: NAD 3020 phono issue Well currently it is a bit of a mystery. What cartridge is in the deck? And with the volume very low (so you don't stuff your speakers!), what happens if you put a finger in each phono input? Can you hear a hum? Craig __________________ Doomed for a certain term to walk the night

11th Sep 2022, 7:56 pm	#19
Bazz4CQJ Dekatron Join Date: Apr 2009 Location: Oxfordshire, UK. Posts: 4,935	Re: NAD 3020 phono issue As per post #2, seems odd that both channels went down at the same time. B __________________ Saturn V had 6 million pounds of fuel. It would take thirty thousand strong men to lift it an inch.

11th Sep 2022, 8:14 pm	#20
richhutch Triode Join Date: Jan 2021 Location: Glasgow, Scotland, UK. Posts: 12	Re: NAD 3020 phono issue Spoke to stepson tonight and he tells me that one channel went down then some weeks/months later the second channel went down. He doesn’t live with us so I can’t be any clearer on dates. Solder joints on pc look fine but was wondering about on the phono input side. Could there be a tiny break at the top of the strip that connects the inner part of the connector to the solder joint on the other side of the pc? Can anyone explain, in words of one syllable please, how I could use a multimeter to test the connections from phono input to the solder joints on the other side of the pc? Thanks to all.