Pr17LS problem!

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pstrisik
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Pr17LS problem!

Post by pstrisik »

Hi All,

I'm having a bad time in CJ world. Kind of a good news, bad news, good news, bad news story.

I snagged a pair of dealer demo LP-125M's from audiogon at a good price. Yea! They arrived Friday and there was a small tube missing (the M8080/CV4058). Boo! So I'm looking at a new pair of monos I can't play. :( The dealer will replace it and I meanwhile ordered a pair from TubeWorld that should be here about Tuesday. Yea!

Meanwhile, my 17LS is acting up. Boo!

Any help is welcome. I can contact CJ tomorrow. I hope I don't have to send it in.

It plays, then with a fairly light thump, the sound cuts out. I can switch to EPL2 (theater bypass), then back and will return for a while but cut out again. I tried a different input with no change. I tried playing through EPL2, using my pre/pro as the preamp, but it still cut out. I don't think it is due to overheating. There is at least 7" above and I've taken off the plate above the tubes. This should be running cooler than when it was fine for months with the cover on. All the lights stay powered on and the tubes are lit.

Any ideas for troubleshooting? Thanks in advance.

Hopefully, I will get this straightened out and can do some posting about my new amps (LP-125M's replacing Pr11A).

Edit: I realized there is a troubleshooting section. Admin, feel free to move this thread if you feel it's warranted.
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. . . . . . . . . . . . . . . . . . Peter


Dennis Had Inspire LP-2 preamp
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Restored AR 2ax', Omega Super 7 XRS Alnicos
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Re: Pr17LS problem!

Post by admin »

Hi pstrisk,

Interesting issue. The fact that it runs for awhile, then not, then again made me think of an overheating problem as well. You may want to run a large blower fan over the open unit and see if that extends the time that it runs. It may be a faulty component that is heat related which can still cause it to over heat and then turn off. Let us know how this evolves.

PS- I did move this topic to the troubleshooting area as it will get more attention here from people that may be able to help.
-admin
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Main stereo: ART Amplifier and ET7s2. 2nd stereo: PV-14L and MV-55. Previously Owned: PF2 preamp, Evolution 2000 Amp, PV-12AL preamp, D/A-2b Vacuum-Tube Digital Processor.
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pstrisik
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Re: Pr17LS problem!

Post by pstrisik »

Well, it doesn't seem to be a tube. After swapping one pair, it still failed. Swapped the other pair and it still failed. I did notice though, that the tubes go out when this happens. There is power to the unit with the LED's lit, but the tubes go dark. I can change input and they will come back. I can run for hours before it happens. Earlier, it would happen again pretty quickly if I brought it right back. Tonight it's playing again without failing soon after a recovery.

Still hoping to troubleshoot this and avoid sending back to CJ for repair, though I realize I may end up having to do that. Trouble is, it takes so long to show up, I'm afraid they won't be able to find anything wrong.

Admin - What you say makes sense. It does seem like it has to play for hours before it happens. I have a pair of very quiet fans coming from Coolerguys.com. I was going to use them for my amps, but it's worth set them up for the 17LS before giving up.
.
. . . . . . . . . . . . . . . . . . Peter


Dennis Had Inspire LP-2 preamp
Dennis Had Inspire KT150 amp
Thorens TD-145 MkII
Restored AR 2ax', Omega Super 7 XRS Alnicos
Cambridge Audio Stream Magic 6/DAC Magic +
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Ian Millar
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Re: Pr17LS problem!

Post by Ian Millar »

An infrared thermometer can measure component temperatures without touching anything (accuracy depends on colour/emissivity of target - matte black being best suited for most inexpensive thermometers). I do not know your particular pre-amplifier, but I do know that C-J uses thermal cut-off switches in some of its amplifiers (e.g. MF-2500 at the back of the heatsink). It sounds like your 6.3V heater circuit is going open for some reason. Whether that's a protection circuit at work or something else - who knows. A much better pre-amp was the Premier Ten with a basic mechanical input selector dial and manual stepped attanuator volume control. Another guess is that the unneccessary complexity around the push-button (and remote control?) arrangements on that thing could be the cause.
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Re: Pr17LS problem!

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Well, I moved it to sit on top of the console. It seems to be good so far. I had it on a shelf inside with about 7" above and thought it would be good. In fact is was until it started to get into the 80's here in Anchorage. I've never seen temps above the 70's in the 13 years I've been here. So I'm hoping this was it. A couple of more days without problem will be pretty convincing! And, it may be placebo, but I swear I've gotten a smidge more transparency and air with it on top. :mrgreen:
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. . . . . . . . . . . . . . . . . . Peter


Dennis Had Inspire LP-2 preamp
Dennis Had Inspire KT150 amp
Thorens TD-145 MkII
Restored AR 2ax', Omega Super 7 XRS Alnicos
Cambridge Audio Stream Magic 6/DAC Magic +
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Re: Pr17LS problem!

Post by Ian Millar »

I'd go along with that placebo theory.
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Re: Pr17LS problem!

Post by admin »

pstrisik wrote:Well, I moved it to sit on top of the console. It seems to be good so far. I had it on a shelf inside with about 7" above and thought it would be good. In fact is was until it started to get into the 80's here in Anchorage. I've never seen temps above the 70's in the 13 years I've been here. So I'm hoping this was it. A couple of more days without problem will be pretty convincing! And, it may be placebo, but I swear I've gotten a smidge more transparency and air with it on top. :mrgreen:
Hmm, it does sound like a heating problem if simply moving it to a better ventilated area resolved the issue. Glad to hear that it's working well. Let us know how it turns out after some extra time.
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Main stereo: ART Amplifier and ET7s2. 2nd stereo: PV-14L and MV-55. Previously Owned: PF2 preamp, Evolution 2000 Amp, PV-12AL preamp, D/A-2b Vacuum-Tube Digital Processor.
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Re: Pr17LS problem!

Post by pstrisik »

Latest update:

Finally got to talk with Jeff, the main tech at CJ. I described the symptoms and he was immediately confident about what the problem is. He described the situation with the microprocessor that the controls work through and said that it is particularly sensitive to interference from other electronics that might emit stray signals. He did not think heat was the issue. However, since I moved it to the top of the console to keep it cooler, it hasn't failed. So it may be that I moved it away from some interference (good chance it would be the cable box that was on the shelf above it). I will put the 17LS back on the shelf and move the cable box to the top and see how it goes.

He also said that some new smart phones and tablets have IR emitters that are always on. Well, I have both a Samsung S4 phone and a Samsung tablet that have IR emitters. I don't think that's it though as it has failed even when I wasn't using them. But good to know about this.

Hopefully these factors will show up in any search results if anyone ever has similar symptoms with a CJ pre.

So, if no failures through the weekend, I think I'm good and won't have to worry about a problem with the 17LS. :D

Thanks everyone for support during this trying time (oh, such first world problems!).
.
. . . . . . . . . . . . . . . . . . Peter


Dennis Had Inspire LP-2 preamp
Dennis Had Inspire KT150 amp
Thorens TD-145 MkII
Restored AR 2ax', Omega Super 7 XRS Alnicos
Cambridge Audio Stream Magic 6/DAC Magic +
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Re: Pr17LS problem!

Post by Ian Millar »

In other words is he telling you that the thing is not competently shielded? It would not surprise me one bit. The thing should be designed to work in the modern world. All so-called sources of interference must comply with emission standards, so the problem is very unlikely to be those. Reminds me of the TV antenna guy who blamed the birds in my area for bending the rods within two days. Well they're just birds - so light that they float on air. He says "It's a known bird area". I say "You installed it here. If it's a know bird area, it should be bird-proof like every other competent antenna in the street".
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Jim Treanor
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Re: Pr17LS problem!

Post by Jim Treanor »

Peter, sounds similar to the other-component remote emission issue I alluded to elsewhere, so hopefully getting it relatively clear of the cable box will solve the problem. I'd note that my 17LS has about 3" less vertical clearance above it than the 7" you've indicated, and heat generated by the unit has not caused an operational problem in the 11 years I've had it.

In any event, good luck with the placement switch. Keep us posted.
Living Room: Premier 17LS, MF2500, Win10 laptop, TEAC UD501, Paradigm SE-3
Bedroom: Luminous Audio Axiom II, MF2500, Win10 Laptop, TEAC UD501, Paradigm Studio 20 v.5
Home Office: Luminous Audio Axiom II, Sonographe SA250, Paradigm SE-1
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pstrisik
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Re: Pr17LS problem!

Post by pstrisik »

Thanks Jim, will do.

From your "avatar", it looks like an LS17 and a 2500. How's that combo for you? I have a 2250A, though I'm selling it. If I were to stick with solid state, that amp could do me fine.
.
. . . . . . . . . . . . . . . . . . Peter


Dennis Had Inspire LP-2 preamp
Dennis Had Inspire KT150 amp
Thorens TD-145 MkII
Restored AR 2ax', Omega Super 7 XRS Alnicos
Cambridge Audio Stream Magic 6/DAC Magic +
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pstrisik
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Re: Pr17LS problem!

Post by pstrisik »

Ian Millar wrote:In other words is he telling you that the thing is not competently shielded? It would not surprise me one bit. The thing should be designed to work in the modern world.
Well, it was made during the turn of the millennium.

So... it reads like you would know what is good shielding material. It might be worth a layer under the shelf above. What would work?
Last edited by pstrisik on Fri Jul 26, 2013 5:36 pm, edited 1 time in total.
.
. . . . . . . . . . . . . . . . . . Peter


Dennis Had Inspire LP-2 preamp
Dennis Had Inspire KT150 amp
Thorens TD-145 MkII
Restored AR 2ax', Omega Super 7 XRS Alnicos
Cambridge Audio Stream Magic 6/DAC Magic +
[/color]
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Re: Pr17LS problem!

Post by Jim Treanor »

Peter, the 17LS/2500 combination works fine with the Paradigm Se-3's in the current setup (and did so with the previous Maggie 1.6 setup in a dedicated room that I had to give up for other purposes).
Living Room: Premier 17LS, MF2500, Win10 laptop, TEAC UD501, Paradigm SE-3
Bedroom: Luminous Audio Axiom II, MF2500, Win10 Laptop, TEAC UD501, Paradigm Studio 20 v.5
Home Office: Luminous Audio Axiom II, Sonographe SA250, Paradigm SE-1
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pstrisik
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Re: Pr17LS problem!

Post by pstrisik »

Well, the 17LS got through the weekend and beyond without any issues. I'm ready to say "false alarm". If it is interference, I'm guessing that there is good shielding on the bottom of the unit and not on the top, particularly since there has to be vents on the top cover. I moved it from below the cable box to above it. A great relief!
.
. . . . . . . . . . . . . . . . . . Peter


Dennis Had Inspire LP-2 preamp
Dennis Had Inspire KT150 amp
Thorens TD-145 MkII
Restored AR 2ax', Omega Super 7 XRS Alnicos
Cambridge Audio Stream Magic 6/DAC Magic +
[/color]
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