CJ PV10 AL

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bor.greiner
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CJ PV10 AL

Post by bor.greiner » Mon Oct 31, 2016 12:52 pm

Hi all!

After comprehensive online research I bought a CJ PV10 AL on ebay.
If I connect it to my power amp through TAPE OUT it works fine (bypasses volume control), but if I connect it through MAIN OUT only right channel works and there is some static noise occasionaly, but left channel does not work.
Did I bought a faulty unit? :(

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Re: CJ PV10 AL

Post by admin » Mon Oct 31, 2016 1:12 pm

First, welcome to CJO. Nice to have you with us.

As to your question. It may be a faulty unit. I would probably open her up (unplugged) and just look at the connections. Also, test continuity with a multi-meter. Make sure there are no broken circuit paths. Also, can the left channel static be influenced by wiggling the connects or lightly hitting/shaking the unit? If so, it would point me toward a faulty connection. Of course, it could be an outright component failure in the left channel circuit as well.
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Current Conrad Johnson Equipment in System: Evolution 2000, PV-12L, and D/A-2b.

bor.greiner
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Re: CJ PV10 AL

Post by bor.greiner » Mon Oct 31, 2016 1:26 pm

Thank you very much for your speedy answer. Much appreciated.

As I am literally at the door I will open her up upon return.

But I am thinking of taking the matter up with the seller, as unit was described as fully working.
I did connect her to my Adcom GFA-535 via TAPE OUT and I don't mind bypassing volume button as I can remotely adjust volume on DAC. I am just uneasy about being crossed and will demand additional discount on the price.

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Re: CJ PV10 AL

Post by admin » Mon Oct 31, 2016 1:40 pm

If you just got the unit and it was sold as "working perfectly" I would either ask for a return or a significant discount. Although you may have an equitable workaround for use, this would substantially decrease it's value and resale potential.
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Current Conrad Johnson Equipment in System: Evolution 2000, PV-12L, and D/A-2b.

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Re: CJ PV10 AL

Post by bor.greiner » Mon Oct 31, 2016 1:50 pm

Thank you. I understand and agree. Substantial discount would be 25% off?

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Re: CJ PV10 AL

Post by admin » Mon Oct 31, 2016 2:01 pm

I think it depends on how much you paid and what it would cost to fix it (not to mention the inconvenience and time you have to spend on repair issues).
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Current Conrad Johnson Equipment in System: Evolution 2000, PV-12L, and D/A-2b.

bor.greiner
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Re: CJ PV10 AL

Post by bor.greiner » Mon Oct 31, 2016 2:17 pm

Again thank you and I agree. I will haul the unit to local audio repair guru to do the measurements and then try to get the costs for repair reimbursted from the seller.

Maybe any other advice on upgrade while the unit is at doctors?
Shall I get any other components checked while she is at surgery?

I thought about replacing tube sockets with ceramic ones and maybe getting Peatl tube coolers...

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Re: CJ PV10 AL

Post by admin » Mon Oct 31, 2016 2:22 pm

Haven't heard of people upgrading the tube sockets too much. I think the most popular upgrade path is replacing the caps (which may be a good idea considering the age of the unit).
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Current Conrad Johnson Equipment in System: Evolution 2000, PV-12L, and D/A-2b.

bor.greiner
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Re: CJ PV10 AL

Post by bor.greiner » Mon Oct 31, 2016 2:47 pm

Mhm. We are talking about power supply caps, right?
Been reading on CJ offering upgrades, alas PV10 is not on that list.
Would not a teflon cap be an aggressive replacement? I like the way it sounds now and would not like to loose this vintage warmth.
Getting a matched pair of MULLARD CV4003 and
Premium PSVANE MARK II 12AU7-T will be my experimenting area. :)

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Re: CJ PV10 AL

Post by admin » Mon Oct 31, 2016 2:56 pm

If you like the sound I probably would not do too much with it as you may find that you have to spend a lot of money relative to the value of the unit. Spending $500 for upgrades on a $5000 unit is very reasonable, but you typically don't want the upgrades to cost close to the unit price unless you expect a major improvement. IMHO. If you like the sound, get some tubes, fix the channel issue and see how it is. You may be very happy with what you have and then there is no need to spend on upgrades. Also, just because you buy more expensive components does not necessarily mean you'll like the sound any better. Just my 2 cents.
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Current Conrad Johnson Equipment in System: Evolution 2000, PV-12L, and D/A-2b.

bor.greiner
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Re: CJ PV10 AL

Post by bor.greiner » Mon Oct 31, 2016 3:16 pm

Thank you very much. I am glad I found this site. Time to Implement a donate button though. :)

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Re: CJ PV10 AL

Post by Big Dog RJ » Tue Nov 01, 2016 12:51 am

Hey mate, Admin is absolutely right.

The PV10 series, although not in the same league as the PV12 series or CJ's premier series, it is still a wonderful musical instrument!

Having said that, you can spend quite a lot of money to get it upgraded towards a PV12 series or higher, in which case you might as well go for one of the newer models, still has all the warmth that you're looking for.

Buying the item off an online site without even an audition is always risky. I am actually surprised that one channel works... I wouldn't touch eBay or any other site, unless it was a direct sale from a well known owner on well established "audio" forums, such as CJO or WBF. eBay sells everything from a pillow case to a dam tank!

Sounds like you definitely purchased a faulty unit, and I would be burning the sellers house down by now! - well actually don't do that!

Bypassing the level control on the PV10AL would be omitting its linestage circuitry altogether, hence absolutely no value in purchasing a preamp in the first place! Just as Admin has stated, get that channel fixed and have both output channels working perfectly. Make sure you are using the main outs, as these outputs have special FET circuits that improve the overall linestage performance. These are special propriety circuits of CJ's linestage preamps and this is what makes them sound special.

I would focus on having a fully working preamp with all inputs and main outs in perfect condition, then start upgrading the caps as you go along.
Since there are a few caps compared to a series of multiple caps used in their other preamps, upgrading the caps on the PV10AL is not difficult.
There are audio signal caps as well as power supply caps, these can be easily upgraded but will certainly cost you a fair bit. Also the level control potentiometer used for volume makes a huge difference. You can replaced and upgrade that as well- in which case I think you're better off in purchasing a Classic preamp- no as you can see the upgrade path is endless.

Therefore, one step at a time mate...
Cheers, RJ

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Re: CJ PV10 AL

Post by plurn » Wed Nov 02, 2016 10:17 am

bor.greiner wrote:Hi all!

After comprehensive online research I bought a CJ PV10 AL on ebay.
If I connect it to my power amp through TAPE OUT it works fine (bypasses volume control), but if I connect it through MAIN OUT only right channel works and there is some static noise occasionaly, but left channel does not work.
Did I bought a faulty unit? :(
I am not a technician, but looking at the schematic for the PV10a it seems that the TAPE OUT also bypasses the amplification and most of the circuitry, which would include the line stage tubes. It seems the only things in circuit when using TAPE OUT are a switch and a resistor if I am reading it right? Not much can go wrong there. TAPE OUT might even work with the power off?

It could just be that one or more of the tubes is faulty? If you have time to get some replacement 12AU7 tubes to test that would be the first thing to try. Though if they would take a while to arrive it may be better to take this up with the seller first in case the unit is faulty.

As a quicker test you could try swapping the tubes with each other. They are both 12AU7. I am not sure if one tube is used per channel, but if that is the case and you swap them then the left channel may start working and the right may fail. If that happens then it is likely that you just have faulty tubes and the rest may be fine. I am not certain this test will work as I describe because as I said I don't know if it is one tube per channel. My ability to understand the schematic is not good enough to determine that.

If it is 2 x half a tube per channel, then that quicker test might show no change, though that would not rule out the tubes being the issue. It is worth a try since it is so easy, but I think the better test is getting two new 12AU7 tubes to try.

Good luck.
Anthony

edit: added the test of swapping the tubes with each other.

bor.greiner
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Re: CJ PV10 AL

Post by bor.greiner » Wed Nov 02, 2016 5:14 pm

Thank you Big Dog RJ, I will go step by step as you well and valuably advised.
And thank you Anthony for pointing out that TAPE OUT practically bypasses everything. When I write practically I mean literally. Music plays even with CJ preamp off!
Long story short, one of the channels, the right one to be exact now that I looked into it, is not working.
Sadly it is not the lamps, changing them brings no change aka both work in L channel, none when plugged in R.
Also the two identical chips on the board are not faulty, as I mustered the courage to swap them.
I also tried shaking her a bit and played with connectors. Something on board is gone. Hopefully not too complicated.
I will get her to pro tommorow. Will post results. Till then take this as a warning that Ebay is a ground that you shall tread carefully. :)

P.S.: After reading your edit, Anthony... Two 12AU7 RCA cleartops are in the mail, so I may give this a few days before transporting her across town.

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Re: CJ PV10 AL

Post by ronenash » Fri Feb 10, 2017 7:22 am

The PV10 shares the power supply for both channels so that rules out a power supply problem. If you swapped tubes and that did not help it can be one of two things. One of the resistors in the right channel or the muting relay that failed and does not unmute the right channel. A technician should be able to debug this easily. The PV10 circuit is fairly simple.
ronenash
----
Power:CJ LP125m SE, Beard P100, McCormack DNA500, Krell FPB300
Pre:CJ ACT2.1, Pr14, Pr15
Analog:VPI Classic/Falcon/SoundSmith Denon 103R, Lenco L75 rebuild
Digital:J.River-->Chord 2Qude
Speakers:SF Amati Futura

bor.greiner
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Re: CJ PV10 AL

Post by bor.greiner » Sun Feb 12, 2017 6:07 am

A wrap on this story.
A part of circuit unsoldered due to transporation vibrations. After a short procedure, CJ is now well and sings beautifully on both channels.
Thanks all again for your help.

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Re: CJ PV10 AL

Post by ronenash » Sun Feb 12, 2017 7:34 am

Nice work. Enjoy this wonderful preamp.
ronenash
----
Power:CJ LP125m SE, Beard P100, McCormack DNA500, Krell FPB300
Pre:CJ ACT2.1, Pr14, Pr15
Analog:VPI Classic/Falcon/SoundSmith Denon 103R, Lenco L75 rebuild
Digital:J.River-->Chord 2Qude
Speakers:SF Amati Futura

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Re: CJ PV10 AL

Post by plurn » Tue Feb 14, 2017 10:09 am

I'm glad you got it sorted out. Thanks for letting us know. It is alway good to hear about a problem being fixed.

Anthony

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