I have an old, old NAD 304 integrated amp which I bought on my grad student budget years ago and guess what, I am still using it with a NAD 512 CD player.
A while ago the 304 started loosing signal at low levels. It fades one channel at a time, at first it was just the left channel, now it's both. The fading in two channels isn't simultaneous. It occurs more often after a few minutes of playing, rather than when the amp's just turned on.
Sometimes I hear intermittent problem that sounds like a bad wire contact, i.e. "scratchy".
Checked all wire connections, headphone output doesn't have the same problem. What could it be and what should I check/replace?
A while ago the 304 started loosing signal at low levels. It fades one channel at a time, at first it was just the left channel, now it's both. The fading in two channels isn't simultaneous. It occurs more often after a few minutes of playing, rather than when the amp's just turned on.
Sometimes I hear intermittent problem that sounds like a bad wire contact, i.e. "scratchy".
Checked all wire connections, headphone output doesn't have the same problem. What could it be and what should I check/replace?
Hi Dima, Sounds to me like dirty pots / switches, If it is, you have to either clean them, Or replace, You can buy contact cleaner, but you can never really get them clean unless you take them to bits, Dont know if you can do that with nad gear? then you need a thin smear of conductive grease in the tracks...
Try some judicious twiddling of the vol, bal, tone, etc and wiggle the buttons to see if it kicks back in to life!
Had a 3020 yonkers ago, good amps as I remember!
Try some judicious twiddling of the vol, bal, tone, etc and wiggle the buttons to see if it kicks back in to life!
Had a 3020 yonkers ago, good amps as I remember!
Thanks Rocco. Yes, I like the sound a lot. It's supposed to be "like" tube sound, even though it's solid state.
I tried changing bass and treble while the problem occurs and it didn't do a thing to the fading. What does have an effect on it is changing balance or volume. I assume that's because it has to do with voltage on those bad contact surfaces.
My next step is taking the baby apart and trying to clean moving parts.
I tried changing bass and treble while the problem occurs and it didn't do a thing to the fading. What does have an effect on it is changing balance or volume. I assume that's because it has to do with voltage on those bad contact surfaces.
My next step is taking the baby apart and trying to clean moving parts.
The NAD304 has 4 resistors that always drift high in value causing all kinds of problems.
I don't remember the numbers but it's one in each power amp, 47k supplying the zener references for the folded cascodes. Replace these with a 2W or so resistor so it won't happen again.
There are also 2 in the preamp power supply. They are in series with the collectors of the lowest voltage regulators. About 150-200 ohms or something I believe, check the schematic. Use a higher wattage resistor for the replacement here too.
I don't remember the numbers but it's one in each power amp, 47k supplying the zener references for the folded cascodes. Replace these with a 2W or so resistor so it won't happen again.
There are also 2 in the preamp power supply. They are in series with the collectors of the lowest voltage regulators. About 150-200 ohms or something I believe, check the schematic. Use a higher wattage resistor for the replacement here too.
Thanks Highspeed,
I came to the conclusion that this relay was involved when loss of signal appeared on the right channel of my NAD 304. You're the first person on all the forums around the world discussing about this problem who confirmed what I was suspecting.
Would you have an idea of a relay that could be used as a replacement for TAIKO DGX2-24M? I tried to find this relay on the internet but without any result. No wonder, after 15 years...
Thanks again.
I came to the conclusion that this relay was involved when loss of signal appeared on the right channel of my NAD 304. You're the first person on all the forums around the world discussing about this problem who confirmed what I was suspecting.
Would you have an idea of a relay that could be used as a replacement for TAIKO DGX2-24M? I tried to find this relay on the internet but without any result. No wonder, after 15 years...
Thanks again.
Thanks rocco gibralter, megajocke, and Highspeed.
I am writing this to the sound of the NAD304 that seems to be clean once again.
Here is a synopsis of the problem and the solution in case anyone chooses to follow my steps.
Problem:
NAD304 integrated amplifier. One channel at a time fading out. The problem had started in the right channel and the left also became affected. Sometimes fading out was accompanied by a scratchy sound like that of a loose contact. The problem(s) was intermittent and it could always be "fixed" by increasing the volume. It wasn't present in the headphone output.
Solution:
1. R333 and R334 replaced with new 47K resistors, both 2 W. (You'll have to bend the pins to adjust for slightly bigger size of the 2Watts.)
2. Speaker relay taken out, taken apart and the contact surfaces gently sanded with fine sand paper. I reinstalled the same old relay.
My relay is:
DEC, 24 VDC, 6-pin relay. I understand that there might be different kinds of this relay in NAD304 and it might be easier to find a replacement for those.
3. After 1 and 2 I found that I still had the scratchy sound in one channel. Tapping on the components pointed to the source switch (CD, Phone, etc). This needs to be cleaned, most likely, however this problem isn't nearly as bad and simply hitting the switch couple of times fixes it for the time being.
I am writing this to the sound of the NAD304 that seems to be clean once again.
Here is a synopsis of the problem and the solution in case anyone chooses to follow my steps.
Problem:
NAD304 integrated amplifier. One channel at a time fading out. The problem had started in the right channel and the left also became affected. Sometimes fading out was accompanied by a scratchy sound like that of a loose contact. The problem(s) was intermittent and it could always be "fixed" by increasing the volume. It wasn't present in the headphone output.
Solution:
1. R333 and R334 replaced with new 47K resistors, both 2 W. (You'll have to bend the pins to adjust for slightly bigger size of the 2Watts.)
2. Speaker relay taken out, taken apart and the contact surfaces gently sanded with fine sand paper. I reinstalled the same old relay.
My relay is:
DEC, 24 VDC, 6-pin relay. I understand that there might be different kinds of this relay in NAD304 and it might be easier to find a replacement for those.
3. After 1 and 2 I found that I still had the scratchy sound in one channel. Tapping on the components pointed to the source switch (CD, Phone, etc). This needs to be cleaned, most likely, however this problem isn't nearly as bad and simply hitting the switch couple of times fixes it for the time being.
Thanks a lot. Found it in France at radiospares france.
http://radiospares-fr.rs-online.com...earchProducts&searchTerm=jw2sn+dc+24v&x=0&y=0
http://radiospares-fr.rs-online.com...earchProducts&searchTerm=jw2sn+dc+24v&x=0&y=0
Hello every one,
Hello Highspeed,
I'm sorry for coming back on this relay subject.
This relay JW2SN-DC24V you recommend isn't that easy to get, except if you're a professional. I've been on sites selling electronics for amateurs and can't find the exact matching specifications in other models.
Here are thes specs for the
Panasonic JW2SN-DC24V you recommend
Technical/Catalog Information: JW2SN-DC24V
Vendor: Panasonic Electric Works
Category: Relays
Relay Type: General Purpose
Mounting Type: Through Hole
Termination Style: PC Pin
Circuit: DPDT (2 Form C)
Contact Rating @ Voltage: 5A @ 250VAC
Coil Voltage: 24VDC
Control Off Voltage (Min): 2.4 VDC
Control On Voltage (Max): 16.8 VDC
Coil Current: 22mA
Coil Type: Standard
Lead Free Status: Lead Free
RoHS Status: RoHS Compliant
Other Names: JW2SN DC24V
JW2SNDC24V
255 1118 ND
2551118ND
255-1118
I found another relay (look for specs underneath) wich has the same specs except it's single throw which should be sufficient for our purpose (switching speakers on and off). Hence there's no need to cut extra lugs like on the JW2SN-DC24V .
Furthermore it's Form A whitch means that default state is open (speakers off when no current applied to the relay coil) which seems to perfectly match our needs.
Am I right Highspeed?
(I Visited
http://zone.ni.com/devzone/cda/tut/p/id/4782
to learn more on Relay Forms)
So here's the relay I found.
Panasonic JW2ASN-DC24V
Technical/Catalog Information: JW2ASN-DC24V-TUV
Vendor: Panasonic Electric Works
Category: Relays
Relay Type: General Purpose
Mounting Type: Through Hole
Termination Style: PC Pin
Circuit: DPST (2 Form A)
Contact Rating @ Voltage: 5A @ 250VAC
Coil Voltage: 24VDC
Control Off Voltage (Min) 2.4 VDC
Control On Voltage (Max) 16.8 VDC
Coil Current 22mA
Coil Type: Standard
Lead Free Status: Lead Free
RoHS Status: RoHS Compliant
Other Names: JW2ASN DC24V TUV
JW2ASNDC24VTUV
And another one from OMRON
Omron G6b-2214P-USDC24
Technical/Catalog Information: G6B-2214P-US DC24
Vendor: Omron Electronics Inc-ECB Div
Category: Relays
Relay Type: General Purpose
Mounting Type: Through Hole
Termination Style: PC Pin
Circuit: DPST (2 Form A)
Contact Rating @ Voltage: 5A @ 250VAC
Coil Voltage: 24VDC
Control Off Voltage (Min): 2.4 VDC
Control On Voltage (Max): 19.2 VDC
Coil Current: 12.5mA
Coil Type: Standard
Lead Free Status: Lead Free
RoHS Status RoHS: Compliant
Other Names G6B 2214P US DC24
G6B2214PUS DC24
Z760 ND
Z760ND
Z760
There are slight differences with PANASONIC but does it work?
I found that Digi-key is the best choice to get components but in Europe you can't get all the references (for instance impossible to get the PANASONIC JW2SN-DC24V-TUV but I can get the Omron G6b-2214P-USDC24). After adding the shipping + custom taxes the relay's cost can be multiplied by more then 5.
Other solution having it shipped by a friend of mine in Montreal...
Hello Highspeed,
I'm sorry for coming back on this relay subject.
This relay JW2SN-DC24V you recommend isn't that easy to get, except if you're a professional. I've been on sites selling electronics for amateurs and can't find the exact matching specifications in other models.
Here are thes specs for the
Panasonic JW2SN-DC24V you recommend
Technical/Catalog Information: JW2SN-DC24V
Vendor: Panasonic Electric Works
Category: Relays
Relay Type: General Purpose
Mounting Type: Through Hole
Termination Style: PC Pin
Circuit: DPDT (2 Form C)
Contact Rating @ Voltage: 5A @ 250VAC
Coil Voltage: 24VDC
Control Off Voltage (Min): 2.4 VDC
Control On Voltage (Max): 16.8 VDC
Coil Current: 22mA
Coil Type: Standard
Lead Free Status: Lead Free
RoHS Status: RoHS Compliant
Other Names: JW2SN DC24V
JW2SNDC24V
255 1118 ND
2551118ND
255-1118
I found another relay (look for specs underneath) wich has the same specs except it's single throw which should be sufficient for our purpose (switching speakers on and off). Hence there's no need to cut extra lugs like on the JW2SN-DC24V .
Furthermore it's Form A whitch means that default state is open (speakers off when no current applied to the relay coil) which seems to perfectly match our needs.
Am I right Highspeed?
(I Visited
http://zone.ni.com/devzone/cda/tut/p/id/4782
to learn more on Relay Forms)
So here's the relay I found.
Panasonic JW2ASN-DC24V
Technical/Catalog Information: JW2ASN-DC24V-TUV
Vendor: Panasonic Electric Works
Category: Relays
Relay Type: General Purpose
Mounting Type: Through Hole
Termination Style: PC Pin
Circuit: DPST (2 Form A)
Contact Rating @ Voltage: 5A @ 250VAC
Coil Voltage: 24VDC
Control Off Voltage (Min) 2.4 VDC
Control On Voltage (Max) 16.8 VDC
Coil Current 22mA
Coil Type: Standard
Lead Free Status: Lead Free
RoHS Status: RoHS Compliant
Other Names: JW2ASN DC24V TUV
JW2ASNDC24VTUV
And another one from OMRON
Omron G6b-2214P-USDC24
Technical/Catalog Information: G6B-2214P-US DC24
Vendor: Omron Electronics Inc-ECB Div
Category: Relays
Relay Type: General Purpose
Mounting Type: Through Hole
Termination Style: PC Pin
Circuit: DPST (2 Form A)
Contact Rating @ Voltage: 5A @ 250VAC
Coil Voltage: 24VDC
Control Off Voltage (Min): 2.4 VDC
Control On Voltage (Max): 19.2 VDC
Coil Current: 12.5mA
Coil Type: Standard
Lead Free Status: Lead Free
RoHS Status RoHS: Compliant
Other Names G6B 2214P US DC24
G6B2214PUS DC24
Z760 ND
Z760ND
Z760
There are slight differences with PANASONIC but does it work?
I found that Digi-key is the best choice to get components but in Europe you can't get all the references (for instance impossible to get the PANASONIC JW2SN-DC24V-TUV but I can get the Omron G6b-2214P-USDC24). After adding the shipping + custom taxes the relay's cost can be multiplied by more then 5.
Other solution having it shipped by a friend of mine in Montreal...
I've made my repair.
My NAD304 is now working perfectly well.
I used the FINDER 40.52.7.24.0000 RELAY (it's german)
http://www.findernet.com/en/products/profiles.php?lang=en&serie=40&doclang=en
easy to find here in europe.
I just had to cut 2 two extra lugs.
For this repair I had to buy a good soldering station. A GOOT soldering station, japanese. very nice.
Thanks again Highspeed for your good advice
My NAD304 is now working perfectly well.
I used the FINDER 40.52.7.24.0000 RELAY (it's german)
http://www.findernet.com/en/products/profiles.php?lang=en&serie=40&doclang=en
easy to find here in europe.
I just had to cut 2 two extra lugs.
For this repair I had to buy a good soldering station. A GOOT soldering station, japanese. very nice.
Thanks again Highspeed for your good advice
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