NAD Owner's - Unite

[Electone]

See if there any small caps in the signal path you can replace with WIMA films. I did this on a 2600 power amp for a fellow AKer, and it really sounded great after that.

Lee.

Yes, there are a few .47uf, 1uf and 2.2uf caps that can be replaced with films. I'll have to look into that, thanks.

 

[Cope]

I bought my 7155 new in 1985, and picked up a clean 7125 a few months later for a bedroom system. The 7155 runs like new, and the 7125 is siting idle now. I recently picked up a clean 6240 cassette deck and a new C516BEE CD player.

 

[Hak Foo]

I got a 7100 from the local thrift shop over the weekend. Loving the tuner-- probably the cleanest FM sound I've had, and a signal-strength meter that's actually pretty useful for a digital bar-graph style one.

However, I am a little nervous about long-term reliability. It's too modern and integrated for "every component can be replaced out of the Mouser catalog". Twice in my use it's had a seemingly random signal-drop-out event-- either a whole channel lost or a significant loss of volume. First time was for just a couple of seconds, cleared itself, and I thought it was because I was fiddling with a source-selector box and loosened contact, but the second time I was on FM. (The loss persisted on station change, but didn't come back after power-cycling trhe unit). The right side of the unit seems to run warmest, although that could be that the components are closer to the top so I can feel it more The visible capacitors didn't look visually alarming- no bulging or popped tops, but I'm still in the learning phase of "how do I differentiate leaking out the bottom from the stuff they seem to use to glue down capacitors during assembly, particularly after 25 years?".

Wondering if this is a known problem... most of the discussions I found on repairability for this range were either rambling stories to nowhere, or the usual "it costs more than it's worth to fix" handwave.

Edit: It did it again. Right channel completely silent. Dialing the balance knob all the way to the right only silenced the left channel. Seemed to affect multiple sources. Got a crackle briefly fiddling with it, and possibly also when tapping the speaker. Power-cycling the reciever brings the channel back.

 

[CKDC]

^^^ At minimum, you need to clean the pots in that receiver.

Re-flowing connections would be another step.

 

[Goldie99]

The NAD 7100 sounds suspiciously like dirty / worn relay contacts to me - try tapping the output relay(s), that usually gives a good idea if they're dirty / knackered - if they are, cleaning the relay contacts (v. carefully) may help for a while, but ultimately you'd want to replace the relay(s).

It would also be worth studying the schematics, and cleaning all the switches & pots properly as well.

 

[leesonic]

I got a 7100 from the local thrift shop over the weekend. Loving the tuner-- probably the cleanest FM sound I've had, and a signal-strength meter that's actually pretty useful for a digital bar-graph style one.

However, I am a little nervous about long-term reliability. It's too modern and integrated for "every component can be replaced out of the Mouser catalog". Twice in my use it's had a seemingly random signal-drop-out event-- either a whole channel lost or a significant loss of volume. First time was for just a couple of seconds, cleared itself, and I thought it was because I was fiddling with a source-selector box and loosened contact, but the second time I was on FM. (The loss persisted on station change, but didn't come back after power-cycling trhe unit). The right side of the unit seems to run warmest, although that could be that the components are closer to the top so I can feel it more The visible capacitors didn't look visually alarming- no bulging or popped tops, but I'm still in the learning phase of "how do I differentiate leaking out the bottom from the stuff they seem to use to glue down capacitors during assembly, particularly after 25 years?".

Wondering if this is a known problem... most of the discussions I found on repairability for this range were either rambling stories to nowhere, or the usual "it costs more than it's worth to fix" handwave.

Edit: It did it again. Right channel completely silent. Dialing the balance knob all the way to the right only silenced the left channel. Seemed to affect multiple sources. Got a crackle briefly fiddling with it, and possibly also when tapping the speaker. Power-cycling the receiver brings the channel back.

Sounds like a bad relay. As for being worried about long term reliability, you might want to consider recapping it, or having someone else do the work for you if you are unable to do it yourself. It's not really the circuit design that can make them unreliable, it's the cheaper components. It's funny, a lot of big name manufacturers got burned using cheaper capacitors, but the mud only seems to stick to NAD.

https://en.wikipedia.org/wiki/Capacitor_plague

Lee.

 

[Hak Foo]

The relay was my first thought also since everyone seems to say it's a problematic part of the 7100. What's interesting is that relays E601 and E602 appear to be different in spite of the service manual suggesting they're the same. One has a small hole on the top with a visible metal pin and the other doesn't. I wonder if one was replaced already, or if it was just a mixed lot.

I will have to run it open-case for a while so I can get it to fail again and see if smacking the relays helps.

I'm familiar with the Capacitor Plague, leesonic, but wasn't that more circa early 2000s? I can recall losing a $350 LCD monitor from 2003 to burst capacitors, and of course, the fact there are virtually no surviving Pentium 4 or Athlon XP motherboards. I don't doubt there could be bad capacitors, but one of the benefits of sticking with older gear is that you can systematically avoid that entire era.

 

[Cope]

I have an NAD 7175PE that needs service and am looking for someone that's familiar with the brand, not just someone that 'repairs' stuff. Can any of you guys point me to someone that's 'NAD knowlegeable'? NAD Canada pointed me to someone in Texas. I called them and he said they've only worked on 5 NAD products (not 7175PE) since the early 90's! I've always been a little suspicious of 'authorized service centers' but I certainly trust the opinions here. I'll take any help I can get. Thanks in advance!

NAD US gave me Bammel TV in Houston. I took my NAD 7155 to them for service and was pleased with the results. IIRC, they are factory warranty for NAD. +12814440287

 

[Hak Foo]

So I leave it running for like 3 hours wuth the top open, so I can see if tapping the relay fixes it, and of course it doesn't go silent NOW. However, if I were to replace the relays on the 7100, I'm wondering what to get. Another thread mentions that the original relays (VB-24MB-TV3) are obsoleted, and the new replacement from the manufacturer is the FTR-F1 series.

Edit: Ran it again tonight... went very quiet in one channel (not completely silent, although I've been using different, more sacrificial speakers for this test compared with my original experience), but the moment I tapped E601 the channel came back.

Would the FTR-F1AA024V do the trick? Trying to compare datasheets, the new one has a somewhat lower power rating (530 mw vs 700) and a higher coil resistance (1100 ohms vs. 820). I'm not sure if those are material for this application, though.

I've read suggestions to use an Omron g2r-24-dc24 relay. Those have specs almost matching the FTR-F1, but at twice the price and you have to cut off unwanted extra contacts. However, I'll defer to people who read more data sheets than I do.

FWIW, I was finally able to see the labeling on the back side of the relay with an opening at the top; it's made by NEC. The other one, a sealed top unit, has markings of specs, but I didn't recognize a manufacturer's logo. Anyone who's worked on one of these before know if either of those sound like a original parts?

 

[Hak Foo]

Okay, after spending more time considering relays than NAD ever did , I bought four FTR-F1AA024Ts (anticipating a 50% destruction-in-installation rate). IBy the time I get them, I'll be a bit busy, so it might be a while before we have either confirmation of compatibility, or a smoking pile of Taiwanese-pretending-to-be-British audio gear sitting on my workbench.

It's nice to look in older threads and see stuff like "here's the currently recommended replacement for (insert obsolete part here) but I have the feeling even those eventually get obsoleted (or at least fail to automatically update when cheaper/superior replacements become available)

That would actually be a really cool browser extension-- when you moused-over a component name, it would pop up an info box and list pricing and equivalents.

 

[Goldie99]

I've not worked on a 7100, but from the data sheets, the original VB-24MB-TV3 relays (E601 & E602) were both DPST-NO, nominally 24V, 820R, ca. 700mW, indeed long since obsolete.

Just comparing on Mouser, the FTR-F1AA024T is also DPST, with nominal 24V, 1.1k, ca. 530mW, and should fit OK in terms of footprint, but may not be ideal vis a vis coil ratings - you might need to adjust R627 to get the correct voltage drop across the new relay coils. I can't follow the voltage / resistances shown on the schematic I have, at least not in terms of calculated values, so I'm not sure if R627 is actually 330R or if it's a mistake on the schematic etc.... it may be prudent to check what voltages / resistances you have in that circuit before / as you remove the old relays.

Too late now, but I'd probably have chosen an alternative Omron option - the G2RG-2A4-DC24, 24V, 720R, 800mW, may have been slightly closer to the original coil specs., and contacts rated for 8A rather than the original 5A.

 

[Hak Foo]

Interesting. I guess it's true that saying "If you want to learn something, don't ask about it, just post something wrong and wait to be corrected" I hadn't even seen the G2RG series-- I saw mentions of the G2R series and someone mentioned swapping in a G2RL (even higher coil resistance, otherwise seems to be a smaller-form-factor version of G2R) in a similar application on a Sherwood (see http://audiokarma.org/forums/index.php?threads/speaker-relay-for-sherwood-ad-2220-cp.463729/)

From an abstract perspective, I'd expect these are the sort of specs where exact matches aren't critical-- it's almost a digital signal in play (protection on/off) so as long as there's enough signal to fire the relay,

(repeating mantra-- "I'm still only $35 into this either way, I'm still only $35 into this either way...")

 

[Goldie99]

I wouldn't worry about it - as long as you check the voltages across the coils & the values for R627, I doubt it's a problem. If the schematic values are right, then the original relays were running well below the nominal values anyway.

 

[leesonic]

When I restored a NAD 2700 power amp for a fellow AKer, I could not find any relays anywhere, until I found them at Newark.

http://www.newark.com/webapp/wcs/st...estType=Base&partNumber=74R1551&storeId=10194

Or If the link doesn't work, their part number is : 74R1551, or Manufacturer Part No : SRKU-1CT-SL-24VDC

Lee.

 

[Hak Foo]

I did the relay swap on my 7100 today. It didn't immediately catch fire and seems to click on sensibly with headphones, but I haven't done much more testing yet. I noticed the problematic one was a NEC MR72A-24U with a 5A rating and a measured coil resistance ~1100 ohms. The other one, just swapped since I had parts anyway, was the listed-in-the-manual Fujitsu VB.

I was originally thinking that this meant it had been replaced already, but most search results for that model number are people mentioning problems with that series of relay in other NAD models of similar vintage. So now I'm picturing an assembly line, with a huge bucket marked "World's cheapest relays" mixing several brands.

I was entertained to find that my 2015-model mobile phone's IR blaster was capable of turning the unit on and off (although not changing inputs and radio presets, but that's likely just a configuration issue)

 

[Goldie99]

I just had another look at the schematic for the 7100, and noticed something I'd missed last time - the speaker switching via S601-A / S601-B - that explains why the values were looking strange to me previously, it's not 2 relays in parallel, that I'd incorrectly assumed previously, but one or the other. I suspect what's happened in the past is that someone has probably had a relay problem with E-601 (the relay for speakers 'A', so likely to be the most used relay), and just replaced it with the NEC item without checking the relay coil current / power requirements...... I don't think it's the original part.

The original Fujitsu VB item would have operated at 820R, 24V, equiv. to ca. 30mA coil current, and ca. 720 mW - that's calculating with a 35V supply to R627 (it'll actually be a bit lower) - very much the spec. values for the Fujitsu VB relay, and what I was expecting to find originally.

The NEC relay, at 1100R & 24V, would have run ca. 24 - 25 mA, and, if R627 is still 330R, ca. 660 mW - possibly in excess of the NEC relay specs. ? I couldn't find a datasheet for the NEC item (are the specs. marked on it ?), and I'm not sure if that would explain why it was failing again now, but it wouldn't help....

I'd recommend again to check the value of R627, and to measure the actual voltage drops across the new relay coils - adjust R627 accordingly.

 

[Hak Foo]

I'd recommend again to check the value of R627, and to measure the actual voltage drops across the new relay coils - adjust R627 accordingly.

View attachment 785810

The colour code on 627 is indeed 330 ohms. Can't actually probe it without removing a lot of front-panel paraphenalia.

The relay leads are completely inaccessible in a live situation. You have to bolt it back together at least somewhat so it doesn't just flop apart while testing, and doing so covers the relays under a metal plate with a 2kg transformer bolted to it. So it looks like I'll have to rely on math instead.

If the replacement relay dies quickly, I'll have to rip it open anyway and can look into replacing R627. Using the 35v figure, it looks like swapping in a 470-ohm would get down to ~22mA and 550mW on the coil... might go a bit higher, but I think I have a big pile of half-watt 470s somewhere.

 

[Goldie99]

Now both relays are the same, you could also drop the relay currents by just switching both speaker relays on all the time - that'll drop them to ca. 20mA @ 22V (ca. 435 mW ea.)

 

[kjello]

Out of curiosity, what is, or was, NADs most powerful power amp they've ever produced?

I belive its the NAD 208 from 1992

250 watts per channel into 8Ω
20Hz to 20kHz / THD: 0.03%
Damping factor: 200
Gain: 29 dB
Input sensitivity: 1.6V
Signal to noise ratio: 120dB
Speaker load impedance: 2Ω (minimum)
Dimensions: 435 x 175 x 370mm
Weight: 17.3kg

 

[xero-D-hero]

My list of NAD gear:

1. Would be my 3140 Integrated (also has the optional MH20 rack handles),this is my bench b!tch,it was bought cheap off CL and lives in the basement towards the top of a budget minded 2 post telco rack (w/some spare sheves from my OmniMount RE27 enclosure). I figured it would be a perfect test mule because of all the available inputs,as well as the pre-out/amp-in option,so it can easily be hooked up to test most anything audio related. It has a pair of Optimus Pro7AV speakers for the "bench" speakers (on the optional RS stands) ,the other pr. of speaker outputs are used strictly for testing speakers. I usually have an Mp3 player running into one of the inputs so I can use it for general listening duty if I dont wanna use my other system down there (JVC RX318b receiver w/AudioSource EQ100 & 4x Klipsch KSB 1.1 speakers). I also have another pair of NOS MH20 rack handles for the "matching" 2140 power amp should I ever decide to pick one of those up and bridge the 3140 to use in tandem w/the 2140 for more wpc.

View attachment 717725

View attachment 717726

View attachment 717727

2. My Monitor series stack,1300 preamp,2600 power amp,and a 4300 tuner. This threesome is just patiently waiting to find it's home and get a chance in the rotation.

View attachment 717728

3. Next up is the 106 preamp,this is one of the more unique NAD preamps I've come across,basically a later variant of the 1000s preamp (same manual for both). The lineage of which traces back to the consumer oriented Monitor series via the more basic 1000 preamp (hence how I came across it). The most unique feature of these 1000s/106 preamps is that they have XLR outputs in addition to the two sets of RCA pre-outs,as well as some other unique features that the consumer version of the 1000 Monitor series preamp does'nt have,and oddly enough the 1000s/106 was considered a TOTL for that series despite it's far more basic appearance.

Anyhow that 106 preamp is on it's way here as I write this (thus no pics),and I'm anxious for it to get it here so I can look it over some. My "plan" is to use this preamp for a nice nearfield system w/my desktop computer set-up giving it all an appearance that would look very much at home in most any pro-sumer studio. This 106 preamp will almost certainly get those NOS MH75 rack handles that you can see on my 1300 preamp at the moment. And I'm sure I'll figure out some sorta rack mount set-up for it as I'm WAAAYYY into the whole "rack thing" (have a 27ru Adcom rack,12ru Sansui AU/TU-217 rack,as well as that 2 post telco rack).

Right now I'm just trying to decide between active or passive monitors,and to be honest I'm on the fence here,as it would cost about the same either way.

Anyhow,for headphones w/this preamp I plan to track down some AKG K240DF 600 ohm cans as the headphone amp is this 106 preamp is supposed to be the $#!t for driving high impedance cans with ease (the headphone section puts out something like 8v into 600 ohms!). Plus I figure I can try it out with my AKG K140 600 ohms cans from my vintage Kenwood silverface system to see just how nice that headphone section really is before I decide if I wanna pony up for those K240DF.

Anyhow,that's my NAD gear right there.

FWIW

Bret P.

Add to ^^^^ that ^^^^ a 2140 power amp (the matching power amp to that 3140 integrated amp).
So now if I want to I can bridge both those and bump up the wpc.

But I'll probably go ahead and drive those Pro7AV with the 3140 and use the 2140 to power a passive subwoofer to help out those Pro7AV some.

Pic of the recently acquired 2140 in that telco rack: (note that it too has the MH-20 Rack mounts/handles as well)

You can also see that the JVC reciever and AudioSource EQ-100 are outta there and a Magnavox CDB-500 CDP and Nikko EQ1 have taken up residence in their place(s).
The open space above the 2140 is where I'm tentatively planning to put the active crossover for the passive subwoofer.

Also,here's a pic of that 106 preamp I mentioned in my earlier post & the rig it's being used with:

This rig is:
Source is my desktop PC via the SB Zx optical out going thru a Monoprice powered splitter into a Parasound D/AC-1000.
From there the signal goes to the NAD 106 preamp that has a DOD 830 Ser. II EQ in the tape loop (not used much @ the moment).
From the NAD 106 preamp the signal is sent via XLR outputs to a ElectroVoice 7100 power amp (1ru dual mono design).
Speakers are Canton GL-260 that are supported by a Canton AS85-SC sub that bolsters the sub bass response very nicely.
Headphones are AKG K240DF (high-impedance) & Sony MDR-7506 (low impedance),headphone hangers are Brainwavz hengja.
XLR & RCA cables are all Mogami,the optical cables are from Emotiva.
Power is supplied by a Middle Atlantic PD-915-R power center.

This system is currently my best sounding system,SQ for both the headphone & nearfield sides of this rig is top notch,I am very happy with how it all turned out.
Also note that the 106 preamp has the RH-75 rack mounts/handles (w/black inserts).

Also,I finally got a full set of rack mounts/handles (w/red inserts) for that Monitor series stack I posted earlier (1300/4300/2600)
I just gotta install them and then find a decent rack for that system to go into.
No pics yet but maybe after I get the those rack handles installed.

That pretty much brings me up-to-date on my NAD stuff...



Bret P.