other new PV-7 caretaker/ owner

The PV-1 to now...
Solyndraloxnda3bears
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other new PV-7 caretaker/ owner

Post by Solyndraloxnda3bears »

Hi everyone and thanks in advance for your tolerance of my problem. Or the explanation of it. I am fairly stupid about algebraic language and reverse-polarities, etc. ?Am I spupposed to put - to + on the speakers and vice-versa..which are pre-amplified David Hafler Acoustat's 2+2's I think, the 8-footers. For the short time I have been acquainted with these components, I always used a 'normal hook-up, +to+, etc. (also, the original problem I was dealing with on the right spkr pre with overheating and blowing fuses gradually seemed to go away all by itself, and the more the spkr's were used, the better they sounded). And next, the next issue is I blew my PV-7 doing something really dumb just after testing everything upstairs after dragging it in from the shop and getting a fantastic result. The whole little house was acting like a giant loudspeaker to the outside world with the C-J at just under half power; and then I wiggled the pre on top of the PS Delta 200, bodies touched..and lightning struck.

So I slept but little all night. Went to church next day believing for a miracle; and then got around to checking it out. I supposed losing the right speaker was due to a power-pop and I can notice a clear polystyrene barrel-shape thing that says 47J on it on the board of the PV-7 which corresponds with the right channel output. So where can I get another one of these, what exact values should I ask for, what brand, and what else aught I to consider besides the obvious visual problem with that one element? I am reading all kinds of stuff online to quick-smart myself up on it, so I can fix this thing and get back rolling again. I really wasted the one opportunity to listen to Concerto For Orchestra instead of the Bee Gees, so now I can only assoc. STAYIN' ALIVE with this awesome, though short-lived, high fidelity listening experience. I never heard vinyl like that. My friend who gave me the speakers and loaned me the amp set-up lives next door so I feel very bad about this. Thanks for any directions with getting back going again (these speakers staring reproachfully at me from the back of this small living space is more than I can take for very much longer).
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Re: other new PV-7 caretaker/ owner

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Welcome to the site. Nice to have you. As to your speaker hookup question, the PV7's line stage is phase inverting, so presuming that no other components are phase inverting in your system, you should hookup your speaker wires from + to -. BTW, the phono stage is phase correct. Luckily we have the PV7 schematics in our database so I would recommending downloading it and you can hopefully identify the malfunctioning component and order a replacement. Here is the link to your database: viewtopic.php?f=17&t=128

Hope that helps. Let us know how it turns out and I would love to see some pictures of your setup if you have 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: other new PV-7 caretaker/ owner

Post by Solyndraloxnda3bears »

So kind of you to welcome me into your community. And thanks for the directions. I am somewhat of a shutter-bug so making some images is not a hassle. However, I do not understand the part about the phase-correct phono stage. Does that alter the plan to reverse hook-ups to the pre-amplified Acoustat's? I am such a slow learner. I can't wait to hear that PV-7 sorting out the sounds of the vinyl again. It was amazing. BTW, I cleaned my friend's chimney for him and he gave me some neat stuff from the garage..a 1940's Magnavox am/ short-wave radio with all the original tubes and ext. antenna and he said it still worked the last time he turned it on. It has that odd tube at the top of the radio face aimed straight out with the undulating light in the shape of a fan opening and closing. I recall seeing them on old reel-to-reel tape recorders. It seems to correspond with signal intensity or waves or something. It also has all the original old tubes on it, YIKES! be talking to you..Again, thanks for the support. -c.
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Re: other new PV-7 caretaker/ owner

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The PV7 will invert the phase once regardless of line source or phono stage. Thus, you will have to invert the speaker wire from the amp to the speaker to correct for this. You do not have to keep switching the speaker wires depending on line input or phono input.
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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: other new PV-7 caretaker/ owner

Post by Solyndraloxnda3bears »

Okay, good, I can understand that. I will try to post a picture of the blown element which I think is a polystyrene film capacitor in line to the right output next to a resistor. The element is labeled 47J and there's about 4 to 6 of them scattered around the board..I mean 'strategically installed' on the board. Nothing else appears fried, so If I replace it I think I'll be back in business, hearing things in vinyl I never dreamed were there. And I will avoid wasting it on Bee Gees records in the future; however, even the crummy disco-beat, heard through the PV-7 with electrostatic speakers is stunning in its effect.
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Re: other new PV-7 caretaker/ owner

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I tried looking at PV-7 schematics and I can't see anything in enough detail to find out what the '47J' things are that burned, they answer the description of polystyrene capacitors..one is under a 12ax7 by the phono inputs and the other is also in line with the same channel (left I think, not sure, though..I did say in a previous post) by the other tube-row. Also I noticed a couple of the tubes on the larboard side are dark..possibly because the cap's are burnt and not necessarily a case of bad tubes? Anyway, I've moved on, opting to enjoy the C-J in a novel mono application, making use of the good channel I still have. I keep the balance knob tossed to the working channel so no demand is made on the bad channel..I assume; and in any case, is that likely to cause further harm using it for just the one channel? So the application is this: I ran the RCA jack from a Seeburg 160 to the C-Johnson, and grounded the jukebox from the C-J phono-grnd connector by sticking it in the front glass cover lock-slot with a long wire from a junked Whirlpool washer, and that made the Liszt single sound way better than it ever did going through the Seeburg amp. But in any case, I was thinking it would be nice to have both. So my question is this: Can I use an RCA splitter to double the audio signal outputs and plug one lead in the Seeburg amp, and the other in the Conrad-Johnson PV-7? Is there any risk of potential bad-stuff happening because of bleed-back by outputting the signal from the record-changer mechanism directly to both amps? And if so, is there a one-way filter thingee that eliminates that kind of scenario. Thanks for your help with this, chris..
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Re: other new PV-7 caretaker/ owner

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Sorry you couldn't get it working. There is a parts list and schematic file for the PV7, so I'm not sure what component you are having difficulty identifying. I just looked at the schematic and yeah, the quality is pretty bad. However, you should be able to figure what component it is from the schematic (ie whether a capacitor or resister, etc.). The other thing I would mention is "47" is often a capacitor or resistor rating, but if you are able to find the corresponding component by trying to trace back the circuit path and comparing it to the schematic, it should be pretty easy to figure out which one it is just by the appearance. You can post a picture of the components that you think are burnt out and we can help you identify it. Testing a resistor is super easy with a $10 multimeter.

As for your setup. I don't think you really need the extra ground. Your RCA cable is already grounded. I guess it wouldn't hurt however. As for your connections, if you truly plan to use the PV7 as a one channel preamp, why not just simply use a RCA splitter on the output of the working channel of the PV7 and then feed the same signal to both channels of the amp?
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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: other new PV-7 caretaker/ owner

Post by Solyndraloxnda3bears »

I hadn't conceptualized splitting the PV-7 output to the power amp, I was thinking to run a straight signal back to the jukebox's integrated amp once that gets fixed (bad 12ax7). In the meanwhile thanks for the suggestion, 2 Acoustat's off the Seeburg are definitely better than one. ~c.
PS:I tried posting a picture of the PV-7 board showing the 47J element, and had a miserable time with that! But the 47J's sit beside blue resistors by the 12ax7's and there's one set for each channel and one by the phono input is bad and one by the output side of the board by the 2nd row of tubes also looks zapped; both to the same channel. I'll try again later, but I have to go fix someone's stacked frigidaire washer/ dryer right now. Thanks again for the assistance. The jukebox sounds 'clean' through the C-J!
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Re: other new PV-7 caretaker/ owner

Post by Solyndraloxnda3bears »

okay, i think i got it. It's so amazing i flunked computer sci 2x! hopefully this will result in an image of the 47j being made viewable
I'm putting something here because i don't know why..like my 7th try, already!
I'm putting something here because i don't know why..like my 7th try, already!
art photos 2016 001.jpg (627.32 KiB) Viewed 832 times
I'm putting something here because i don't know why..like my 7th try, already!
I'm putting something here because i don't know why..like my 7th try, already!
art photos 2016 001.jpg (627.32 KiB) Viewed 832 times
..the other one is to the larboard side by the phono inputs under the shadow of a 12ax7, ~c. (PS: it looks like this will include the photo, abut at this point, all bets are off..I'm clicking SUBMIT)
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Re: other new PV-7 caretaker/ owner

Post by Solyndraloxnda3bears »

oKAY IT WORKED..REDUNDANCIES AND ALL! HOORAY FOR CHOCOLATE!! ~c.
(image the product of a simple Kodak 'easy-share'..plus significant struggle with the technology; leaves me feeling a little of the pride I suppose Lord Nelson may have felt after his victory at Trafalgar, amid the smoke and ruins..same sense of satisfaction, relief)
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Re: other new PV-7 caretaker/ owner

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Those translucent caps (especially the right one) look pretty funky. You may want to replace those. It should be very cheap and relatively easy to do.
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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: other new PV-7 caretaker/ owner

Post by Solyndraloxnda3bears »

Oh, I said blue resistors, but then when I looked, I remember resistors have color code lines, so they are not resistors. Anyway, there's that one 47j in the picture I guess it's in the output stage, and the other in the same channel (no pic) is back by the phono inputs. Now that I know how to do it, I'll put up some pic's of the monaural use of the PV-7 ina while. chow! ~c.
I have to type up some new title-strips for the singles I am adding. If you think about it, the Seeburg jukebox was a kind of early computer for enjoying your favourite music on demand..little different these days, kids and i-pods and all. Analogue is still kind of nice, though.
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Re: other new PV-7 caretaker/ owner

Post by Solyndraloxnda3bears »

I talked to a guy at an electronic's supply called MFARADS I believe, and he got all the info I had about the preamp and the part name and checked it out..he said the value is 47 pF (not the same as ones on e-bay being called .0047 or anything like that, right?) So does that value seem correct? and what brand should I use for replacements? and could those blown cap's be the cause of the two 12ax7's going dark; or in other words, are the tubes maybe alright and likely to light up again once the cap's are replaced? (I can test the tubes anyway) I am thinking about the potential mischief from re-heating the board to do the operation..could I snip the wire ends off the cap's and twist them up w/ the replacements above the board and solder there; rather than inflicting all the heat involved with total removal of the damaged parts? Does that make sense? ~!
PS:Guess I'll have to tool-up, too.
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Re: other new PV-7 caretaker/ owner

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The capacitance rating for any components being replaced should be checked via the schematic and then parts list. Yes, 47 pF is a common value for these. I would be cautious with buying some really cheap caps off of ebay as many are really poor quality sold by Chinese wholesalers. Ordering something from a more reputable site such as digikey will at least make sure you get what your paying for and they will also provide the spec sheets for the components. Of course there are also sellers of "high end" audiophile components that you can choose from as well.

As for soldering, you can buy some really cheap "solder wick" to make removing the components easier. Simple quick soldering should not damage the circuit board. You can cut the terminals and solder directly on there but that is going to be "sloppy" and have a higher chance of failure in the future.
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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: other new PV-7 caretaker/ owner

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Alright, now I'm armed and dangerous! (thanks)
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Re: other new PV-7 caretaker/ owner

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Here is the monaural ap of the PV-7 to power the record-changer output of a Seeburg Select-o-matic 160 seen in 2 cross-views inside the TRHQ (Testosterone Relaxation Headquarters, aka, Mna-cave)..I am trying to find out the voltage value of the polystyrene cap's that need to be replaced with a pF value of 47; also, what brand is best, like Siemens, or Phillips, or --? The parts list seems to indicate there are only 2 47's in there but it looks to me like 2 per channel, left and right. I guess Ill re-check that. Thanks so much, ~c.
PS:I just made the jukebox play me my new RCA 45 EP of Artur Rubinstein's recording of Rhapsody Hungroise #TEN and it was very relaxing, pounding along with it, making believe I am Horowitz - fantastic! (notice the Panasonic 8-Track recorder/ player in foreground, playing Mariachi music as we speak with very nice bass built-in to the recording).
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Re: other new PV-7 caretaker/ owner

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A few more components and it will also double as a time machine!
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Re: other new PV-7 caretaker/ owner

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It does a very nice job playing back 78 rpm records. My kingdom for a talking-cylinder machine! ~c.
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Re: other new PV-7 caretaker/ owner

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Recent development: My friend works at the city dump and got me a couple tube-caddy's full of tubes someone threw (including a nos EL37 Mullard!) and there was a couple RCA 12AT7's brand new i.b. with al the stuff..So I changed those in the PV-7. Didn't think of anything till later, then I thought what the heck, I'll hook up the side i burned and see if it fixed itself at some point; and it did! both sides seem to be working now, and the only thing I did was pull some tubes, test them and put them back, adding the pristine 12AT7's. My question:I have the Hafler electrostatic 2+2's and slave amp and C-J out back in a Mayflower van and it's winter again and temps can drop to ZERO. Is it okay to be storing this stuff in that temperature range? I understand about that it should 'thaw' before turning it on. Thanks, chris
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Re: other new PV-7 caretaker/ owner

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PS: So I did get my miracle - praise G-d!
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