QRX-9001 Problem(s)?! Advice?

[Relayer]

Hi all,

This is my first post, but I've been reading for quite a while... I'm a novice with quad, or high end audio/electronics in general -- not really an audiophile, just a big 70s music fan.

This summer I started reading about quad (mostly on the sleeves of some lovely CTI quads a friend was selling) and ended up taking the plunge -- I bought myself a beautiful QRX-9001 through Ebay (along with one of those CD-4 cartridges from Ed Saunders for my Dual 1229) and life in quad has totally exceeded my wildest expectations.

I knew it would be a huge step up from my Denon 5.1 setup, but I was totally blown away by the Sansui sound. Using the same speakers really brought home how important a good receiver is.

Anyways, on to the problem: channels are cutting out on me!

When I first got the unit, the right channel was cutting in and out a lot, and sometimes crackling a bit.

I was advised to leave the unit on 24/7, and doing this seemed to clear things up nicely (magically!). [As an aside, is this recommended? I understand switching an amplifier on and off is hard on it, but is this really the best practice (I worry about the "wasted hours" I'm putting on it)?]

Recently, the left channel has started cutting out a lot (the right is now rock solid, though). At first I thought it was the headshell on my turntable, because I didn't notice the problem when I played CDs... but now I'm experiencing the problem in all modes (tuner and all). It'll stay off for half the duration of a CD... sometimes it'll come in and out for a few seconds at a time, but more often it'll come on and then remain on for the rest of the time.

I know that power is getting to all the speakers, because using the QS synth modes will send a weak signal out of the left front speaker (I guess this is a normal function of the Variomatrix circuitry or whatever it's called?), and both rear speakers are fine (I think). But when the full left channel cuts IN, the drastic improvement of the sound makes me fully aware that something had previously been amiss.

In CD-4 mode, I notice a lot of static and cutting in/out on the front left channel when I play the CD-4 carrier signal test record, while the other three channels are completely stable, loud, and clear.

When the left front channel isn't working in the various quad modes, it also doesn't work in 2-channel mode, so I don't think it's a problem with the quad circuitry.

So, my question is: does anyone have a diagnosis for this problem? A relatively easy/cheap solution?

I know the ideal thing is to have the legendary QuadBob do a full overhaul of the 9001, and this is definitely part of my long term quadraphonic plan, but I can't really afford such a comprehensive overhaul in the near future.

If it was a simple job without much risk, I would take it to a trusted local technician for an interim solution (anyone know anyone with quad expertise in the Toronto area?), but if it sounds like a big job it might be best left for a complete overhaul... in which case I will just live with the problem until I can ship it out to QuadBob.

Anyways, I'd really appreciate whatever advice/feedback you experts can provide.

Cheers everyone!

[I'm off to listen to Airto's 'Fingers' in SQ now... hopefully with all 4 channels in full swing.]

 

[Scottmoose]

First of all, welcome! The more the better!
Now, to business. It sounds like you've got a basically nice piece of kit that just needs an overhaul. People often forget electronics need this too, especially 25-30 year old bits of kit. A washing machine or car wouldn't keep going that long with no servicing.
OK, there are people here better qaualified than me to give an answer, but in my experience, -the symptoms you describe are fairly typical of an old piece of kit, mono, stereo, quad or whatever. The good news is there doesn't sound to be anything wrong with those irreplaceable circuits / processors themselves. What it sounds like you are suffering from are dry joints, probably some past it soldering & wiring, and a desperate need for new caps in everything from the power supply to analogue stage. Don't panic -it's not as drastic as it sounds -I've practically rebuilt a Musical Fidelity A1SE pre / power stereo amps from the late 1980's, and I'm not so good with a soldering iron, so if I can do it, so can you. BUT -this is rare quad gear. Fry a chip, and the amp's had it; there's no spares for these (or very few), so I'd avoid anyone playing with it who isn't 100% familiar & confident with rare quad gear. Especially as yours is one of the top bits of kit. Me -I'd wait, and get QuadBob to give it a complete overhaul when you can afford it. After near as damnit 30 years, it deserves one for it's services!
Leaving amps on? There's many schools of thought on this one. Ignoring the mythical rubbish about 'burn in', and 'warming up' you'd save a little mechanical wear and tear on the switch by avoiding switching on and off, but really, it's a misguided hold over from the time of valves, which needed to be kept at a fairly constant level / tempertature. As a rule, there's no scientific reason or requirement with solid-state equipment for you needing to have it on at all times, unless you like running up your electicity bill, or the kit is designed to work optimally at a set resistance (which increases with temperature); though you won't kill it by doing so.
All of this assumes that everthing is in perfect condition with no problems though. The reason yours seems to be behaving a bit more now is probably due to the increase in internal temp with it being switched on 24/7, which could, for example, cause dodgy joints etc to expand and make better contacts, and staballise leaking caps.
That's my twopence worth -tech-heads -over to you!
Scott

 

[Lugia909]

Another reason to opt for the QuadBob treatment, btw...

If you check another thread on here about "the greatest CD-4 demod ever" or something to that effect, you'll find that the device in question is likely residing inside that very QRX-9001. Apparently QuadBob found a unit with something akin to 'the magic settings' that result in what he and some others consider to be 4-channel perfection, and was able to replicate the same calibration settings on another '9001. A local tech might be able to put it up to snuff, but this bit of voodoo will be beyond them, especially given that CD-4 repro is one of the tweakiest aspects of quadrophonics.

So, yeah...it'll cost...and I know it'll cost because I'm currently looking at budget/timetable for a QuadBob treatment on my recently-found '7001. But given the benefits and the expertise, well...

ADDED: Aha! Here's the thread in question: https://www.quadraphonicquad.com/forums/showthread.php?t=2099&page=1

 

[JonUrban]

To those with 7001s considering getting the "full" QuadBob treatment, a thought:

Wouldn't it be a better deal in the long run to sell the 7001, get a 8001/9001 off of eBay or somewhere, and pay to have THAT unit upgraded? I mean, you could probably sell your 7001 and then find a good deal on an 8001/9001, then spend the $$$$ on upgrading that.

If I had a 7001 and had QB do it, there would always be in the back of my mind that "maybe I should have gone for the bigger/newer tech unit?"

Not that a QB 7001 would be bad, it's just that I always think of the "top of the line", esp if you are going to invest a lot of money in a restoration (which is worth every $, BTW )

 

[quadanasaziland]

I would agree with Jon on this but with just a couple of *'s. I would not have done a 7001 in hind site except that mine is a 777 and rare as hens teeth. And a resto on 7001 is considerably cheaper. I run external amps so I'm not concerned about the 35wpc compared to 60wpc. Also the 7001 gives you one more set of 4 channel inputs.

 

[JonUrban]

Dave,

I "second" the asterick for 777's. I have only seen one 777, and that was a new one in Italy - from the same place I got my 999.

Rare beasts, indeed!!

(Anyone ever seen (or know of) a QRX-888???)

 

[BlackDog]

Gents,
Would it be worth keeping the 7001 just for the vario-matrix board alone?BlackDog

 

[quadanasaziland]

(Anyone ever seen (or know of) a QRX-888???)

Apears not, Bob and I were just talking about this the other day. Can't figure why (not)?
There was a euro version of the 8080, the 880 that was black faced.

 

[quadanasaziland]

Gents,
Would it be worth keeping the 7001 just for the vario-matrix board alone?BlackDog

To be sure!!!!!

Don't get us er me wrong (I don't want to speak for Jon).

The 7001 is an awsome unit only bettered by the 8001, 9001 and in some ways better.

1. No pass through joints to worry about so it is a much more reliable beast. This is one of the reasons it is cheaper for a QB resto.

2. CD-4 adjustments are on the front as opposed to being on the back of the 9001 which makes it infinately easier to set up the CD-4.

3. 7001 has two 4 channel tape loops which are a nice thing to have!

35 wpc (pre 1980) roughly compares to 100 wpc (post 1980) and frankly has more guts, balls so on........ than any 100wpc modern amp. IMHO

The 7001 was the state of the art in 1975 no doubt about it and betters any thing made by any other manufacturer before or after, hands down!!!! quote me on that!!!!

 

[BlackDog]

Doctors, My last post was to cryptic. I have a 7001 but just signed up for the BIG SALAD from the QB. That will make 2 QRX-5500, QRX 7500,
QRX 7001 a 9090DB and the 9001. The parts for the 00 series can either be had or swiped but if your going to put money in the 01's and this is if i understand this correctly you can replace everything except the chips on the vario-matrix boards and therefore you would want a backup for those to secure your investment. So if you have spent 200 dollars on a 01 machine and it's not the 9 series doesn't make sense to just keep it and bite the bullet by buying one from Bob knowing that anything that goes wrong can be repaired (once)? BlackDog My wife would love to hear that this is not so!

 

[JonUrban]

I say "Go for the "QB" unit!

 

[QuadBob]

Hi Relayer,

First off thanks to all for their comments!

Now lets deal with your original post:

So, my question is: does anyone have a diagnosis for this problem?

Yes, it is most likely due to a failure we commonly refer to as the "pass-through joints". This will cause intermittant channel weakness or drop-out, and often varies based upon temperature. But, it can also be caused by the function select switches themselves.

A relatively easy/cheap solution?

No, unfortunately the board that contains the 54 joints that must be resoldered (and pinned when I do them), are right in the "heart" of the receiver. To even get at it to work on, you have to totally disassemble the face of the receiver (including the front frame member), just to get the board out and hanging by its hardwiring, so you can work on both sides of the pcb.

Time required for "me" as I've done so many of them is 6-10 hours of labor just to gain access and then resolder/pin the joints. Once that's done I then verify/troubleshoot the associated switch contacts to make sure they are good, and rebuild the contacts in the switches as necessary to make sure everything is working properly.

I know the ideal thing is to have the legendary QuadBob do a full overhaul of the 9001, and this is definitely part of my long term quadraphonic plan, but I can't really afford such a comprehensive overhaul in the near future.

A total restoration is the obvious long term solution. Just email me when you'd like to get scheduled for that. But, even doing just a "simple" repair of those pass-through joints is an extremely hard proposition.

If it was a simple job without much risk, I would take it to a trusted local technician for an interim solution (anyone know anyone with quad expertise in the Toronto area?), but if it sounds like a big job it might be best left for a complete overhaul... in which case I will just live with the problem until I can ship it out to QuadBob.

As it sounds like you don't already have a "trusted local technician" that you're familiar with, I'd be extremely hesitant taking a "chance" with someone you don't really know. You could easily end up flushing money down the drain. If someone could actually recommend an honest and knowledgeable tech......you might consider it. But, just realize that he will have to go right into the messiest, toughest to troubleshoot part of the receiver after doing a major teardown to attempt the repair. And, all the "stereo" experience in the world won't help a lot in this area, as no "stereo" or even the earlier Sansui quads (500 series, 7001) used this design. The schematics aren't much help at all either......the joints aren't shown, and the separate function switches are "treated" as one gigantic switch in the Sansui design! It still can run me in circles at times!

So, if you really want to keep it and enjoy it.......you really are probably better off to save your $$ until you can go the complete restoration. And, as a sideline.......the receiver will be much better off if you don't keep trying to run it until then......as you could easily develop much more serious problems due to the age of the caps in there.

Best of luck, whatever you decide to do!

 

[Lugia909]

Just an aside here...the main reason I'm likely to stick with the '7001 is because of what I intend to use it for: a playback/monitoring amp in one section of my studio, namely where I do a lot of 'off the desk' work. Surprisingly enough, some of my compositions still use that venerable 4.0 discrete channel format, or odd variants of it. So it's important to me to have something that works nicely in close-in listening in 4 channels. Plus, having the CD-4, etc capabilities is nice if I want to do any transfers or, even more twistedly, sampling in quad.

For serious electroacoustic work in spatial arrangements, quad is FAR from dead. I've studied in the past few years with Karlheinz Stockhausen, more or less the Godfather of Multichannel, and he refuses to use 5.1 or any modern surround methods because he doesn't like the way the rear/center channels have certain limitations as far as frequency range, etc. When he says that something has to move in the listening space, he insists on at least four...sometimes more...discrete channels to make it happen. And I've gotta agree...it's the right way to do it.

So my '7001, post-QB redux, will be sitting by my writing desk, probably connected to something small but very flat-range for speakers, and one of those 'tape' I/Os will be going to one of the computers there. The other, probably to/from a tape (yes, that flimsy magnetic stuff) workbench I'm planning, and the 7001's A->B and B->A capabilities will be a huge assist in routing for those. In other words, it's going to _work_...and I don't use things in those playback chains that aren't top-shelf. For quad, that means Sansui or probably only a few other things. It's good enough for studio work but at the same time it'll give me 'real-world' playback that I can trust for testing mixes.

Anyway, just an FYI there, folks...others might want the trade-up to the 8/9001, but for me this is exactly the ticket.

 

[QuadBob]

I can certainly see both sides of this issue! I lived with a QRX-7001 for almost 12 years.......so I still have a "soft" spot for it!

If you're on a budget, the 7001 is easier to find, cheaper to buy, and costs only 50% of what it takes to do a 8001/9001, for which you get the same decoding ability, plenty of 4 channel functionality, and if you run outboard amps.........then the lower powered and slightly less clear amp section is immaterial.

But, a restored and modified QRX-8001/9001 is "art" in engineering! Looks, sound, and performance that none of its peers can match! :sun

 

[quadanasaziland]

Doctors, My last post was to cryptic. I have a 7001 but just signed up for the BIG SALAD from the QB. That will make 2 QRX-5500, QRX 7500,
QRX 7001 a 9090DB and the 9001. The parts for the 00 series can either be had or swiped but if your going to put money in the 01's and this is if i understand this correctly you can replace everything except the chips on the vario-matrix boards and therefore you would want a backup for those to secure your investment. So if you have spent 200 dollars on a 01 machine and it's not the 9 series doesn't make sense to just keep it and bite the bullet by buying one from Bob knowing that anything that goes wrong can be repaired (once)? BlackDog My wife would love to hear that this is not so!

Blackdog,

Bob and I were talking yesterday and we both come to the conclusion that this is cryptic also @: maybe we are just slow on the uptake? Can you break this down for us simple folk?

 

[BlackDog]

I was trying to say that if you had a 7001 that you had purchased and then were thinking of going the 9001 route you might consider keeping the 7001 as a resource for the vario-matrix chips rather than selling it for 2 or 3 hundred dollars. The reality of irreplaceable parts is new to me so I have choosen to err on the side of caution. It's not much of an issue now and perhaps it never will be an issue but I like knowing that if anything weird happens like my granddaughter spills soda on the receiver... it's cool. Just as a matter of interest how many vario-matrix of the 01 series were made?

 

[QuadBob]

Caution and backups are good!

Those Sansui ic's are made of unobtanium just like the TATE ICs.....which is why the restoration besides being an audible improvement also helps tremendously to keep everything working as designed!

Of course in your scenario:

It's not much of an issue now and perhaps it never will be an issue but I like knowing that if anything weird happens like my granddaughter spills soda on the receiver... it's cool.

Remember you can always make more grandchildren! :yikes

 

[Timm Rautmann]

Hi there anybody!
I have two Sansui QRX x001 series receivers, one 7001 & 8001. Beside the fact that the 8001 looks better, bigger than the 7001, I still prefer my 7001. The reason is simple: I always have problem with the 8001, while the QRX 7001 never made trouble! Only one light sometimes does not work. Both of my QRX have a fixed preamplifer output, which I upgraded by myself, Thus I do not necessarily need the top of the line 9001, only because it looks better. With my active powered monitors I beat the 9001 100 wpc in a heardbeat.
I have the power amps in my speakers adding up to 180 wpc sinus active an have additional 240 wpc sinus active for the center channel seperately balanced.

My point here is that everybody calling a 7001 or 8001 their own does not need a 9001, if he/she has a fixed preamp output. All QRX x001 series are perfect in regard to the onboard QSD 2 and to be honest the inbuild QSD 2 is what makes the QRX x001 series interesting!
Or am I wrong??
Timm

 

[QuadBob]

Hey Timm,

You certainly make a valid point......the QRX-7001 doesn't suffer from the "design" flaws of the QRX-8001/9001 chassis. So, strictly from a design/engineering viewpoint the QRX-7001 is simpler and more trouble-free.

But, the question I think the other posters were asking/commenting on was "If all worked perfectly would you prefer the QRX-8001, 9001 or 7001"?

A complete restoration/modification would allow you to evaluate them based strictly on performance/looks......instead of on which worked. And, with the time/$$ required for the restoration which would be the best "investment"?

That is why I mentioned that it depended on what you could afford....as the cost of restoring a QRX-8001/9001 is double that of a QRX-7001.....just because of the time and complexity differences.

And, while you are totally correct about the identical Vario-Matrix decoder in all three. The real differences are:

1) Looks.......output meters, unique dial display of the 8001/9001
2) Better sounding amp section in the 8001/9001......although you're correct that if you run outboard amps this advantage doesn't matter.
3) Increasingly better AM/FM Tuner in each model.
4) The "Holy Grail" CD-4 demodulator that I recently discovered in the 8001/9001 which is totally redesigned from the 7001.
5) The unique 2/4 channel Tape 2 loop which allows you to put the V/M decoder either before or after the tape loop.

And, finally with the age of our units........even the trusty 7001 is starting to show its age, I'm seeing more and more of them developing problems......

 

[Timm Rautmann]

Dear Quadbob!
Your modifications to the Sansui QRX x001 should be awesome to what I read so fare, if I had some problems with my Sansui QRX I will contact you! But let me make some comments [please excuse my sometimes terrible German English]:
1. If you have a fixed preamplifer output in the Sansui, what kind of use is the watts YU meter in the Sansui good for? In that case you will use outboard amps and the inboard amp are out of use. I turn them of, when I use my active loudspeakers.
2. Concerning the better FM/AM section in the QRX 9001: Since I work for the German Boardcasting I know [and that is for sure] that the FM sound quality has dropped since the data copmpression is used --- who needs FM Dolby nowadays anyway??
3. Concerning CD-4: The better modifications of CD-4 were developed by JVC anyway, if you possess a CD-4 from JVC a JCV 4dd5 or a JVC CD4 1000, who cares about a Sansui CD-4 “Holy-Grail”?

But the allover perfomance of the Sansui QRX 9001 without any modifications or other units like outboard amps, better CD-4 decoder - I mean the QRX 9001 only by it self- still is best.

But then again I still believe with these above mentioned modifcations the QRX x001 series are quite the same usefull and everybody having a QRX 7001/8001 does not need to upgrade to a QRX 9001.

Still the QSD 2 decoder is the most important topic:
Let me make a last important point here:
The QSD 2 is of importance [may be I should call this an other topic], because the QSD 2 is working on an analogue basis. The Dolby Prologic 2 is working on a digital basis. Now if you possess a high-end digital-analogue converter, you will have fun with the QSD 2, because the full dynamic range will be enjoyable through a QSD 2 , while you will not have the same range of dymanic, when you operate with a Dolby Logic 2 decoder, because the sound quality will then depend on the digital-analogue converters in your receiver [may be in very expensive units high end digital converters will be included- but the cheapest way still will be the QSD 2 or QSD 1]
If I am wrong please correct me!!
Timm

PS: "And, finally with the age of our units........even the trusty 7001 is starting to show its age, I'm seeing more and more of them developing problems......" -- Dear Quadbob -- It is wonderful to know that there is sombody out there who is a specialist of the QRX -- If I can not fix a problem with my QRX I will contact you!!