Service Manual with Schematics for PL0171

roccus

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#1
I have a PL400 with what seems to be the PL0171 board in it. I bought a disc off ebay that was supposed to cover all revs of the 400 but this board is not included... Is there a real complete manual out there that really does cover all revs?? More importantly one that covers my board?

 

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#2
The board number is printed on the backside of the PCB. Have you looked on the back of yours?? Nevermind, you don't have it yet...
 

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My manuals contain schematics for the PL400C board, the PL14A board and the PL14B board. I don't think you'll find a manual with a schematic for a PL0171 board in a 400. I have not seen one. I will call Ed tomorrow and confirm this.
 

grapplesaw

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My manuals contain schematics for the PL400C board, the PL14A board and the PL14B board. I don't think you'll find a manual with a schematic for a PL0171 board in a 400. I have not seen one. I will call Ed tomorrow and confirm this.
Here is the board. Someone has added the four veri resistors to it.
 

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#6
My manuals contain schematics for the PL400C board, the PL14A board and the PL14B board. I don't think you'll find a manual with a schematic for a PL0171 board in a 400. I have not seen one. I will call Ed tomorrow and confirm this.
it appears in the 700B service manual
 

oldphaser

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#8
My manuals contain schematics for the PL400C board, the PL14A board and the PL14B board. I don't think you'll find a manual with a schematic for a PL0171 board in a 400. I have not seen one. I will call Ed tomorrow and confirm this.
Lee,

I have just a spare moment and then back to packing for my move to CT.

The PL0171 was never used in the 400 series 1 amplifier. The PL0171 was used only in the original 700's (a.k.a 700A).

In the case of the 400's, there were several revisions to the PL400C. Likewise there were a number of revisions to the PL14/PL14A and PL14 boards. Unfortunately the service manual does not include every revision.

Ed
 

roccus

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Lee,

I have just a spare moment and then back to packing for my move to CT.

The PL0171 was never used in the 400 series 1 amplifier. The PL0171 was used only in the original 700's (a.k.a 700A).

In the case of the 400's, there were several revisions to the PL400C. Likewise there were a number of revisions to the PL14/PL14A and PL14 boards. Unfortunately the service manual does not include every revision.

Ed
OK I do need a manual for the amp to have just a schematic alone does not help me very much I need info on test points and values to set/check bias... so as of now I don't know whether this is a PL0171 or a 400C people here have said it could be either on I guess??? According to tracking it should be here tomorrow I will open it up and look for numbers on the board
 

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Bias is checked just as in the manual, it's set by the added pot and the pot that sits vertical on the left. To set DC offset.....It'll have to be set like the PL0171 board as listed in the 700 Ser I manual.
 

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roccus

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#14
Thanks! After looking them over real quick the animal I have looks like a cross between the 400C and the 700B boards... If this amp checks out ok and runs I think all I will do to it for now is put new power caps in... I'm really thinking I would rather put my time and money into a 700B amp and build it up with WO goodies in it.. if I decide to keep the 400 I will end up putting a WO board in it anyway but it looks like the PL pros here are a bit stumped by the one in my 400... do I get some sort of prize for that??? lol
 

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#15
It's early in the morning.........

Here is a little more information on the PL0171 and PL400C boards.

First off the early Phase Linear 700's are about a 1/2" taller than the later 400's and 700's. Thereby allowing for the larger PL0171 pc board to be installed. A PL0171 will not fit into a 400.

The PL0171's have the bias transistor (MPS5172) mounted on the pc board. All pc boards that followed had the bias transistor (i.e. 2N3403's) mounted on the back on the chassis directly behind or next to the heatsinks.

When Bob Carver was finished designing the 400 series 1 he handed the amplifier off to Terry Phillips to copy and put into production. This was in December 1971. By the way, Terry was known as Mr. Amplifier at the time. (Terry later went off to work for Boeing. I am not sure if Terry is currently in Wichita or back in Seattle.)

These early PL0171 and PL400C's are now exhibiting the following problems; 1.) carbon composition resistors going up in value, 2.) ceramic disc capacitors going down in value, and 3.) electrolytic capacitors failing, etc. These pc boards can be a headache to repair. Later series pc boards replaced many of the carbon composition resistors with carbon film resistors and do not exhibit these problems. They also replaced the electrolytics with other vendors (whose capacitors have turned out to be more reliable over time) and are not as prone to failures. The best electrolytics were probably the Nichicon brand. Phase Linear however did not replace the ceramic disc capacitors.

When I work on the PL0171 and PL400C boards, I remove and test all components individually and replace where necessary. This process can take me up to 8 hours to complete. It seems hardly worth the time doesn't it? Ah but this has been a passion of mine. Not an attempt to make any real money.


Take care!

Ed
 

roccus

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#16
Thanks Ed for taking the time to write this up. First I would like to lay out a bit of my background. I worked for a short time for Lockheed Martian, while there I got mil spec certified for soldering, pc board rework, and repair. I am not exactly new to working on vintage electronics over a period of near 20 years I built a business (The Jukeyard) buying, selling, restoring, and repairing jukeboxes specializing mostly in Seeburg's from the 50's era and all their accessories. I messed my back up and just could not move these old machines anymore some of them weigh up to 500lbs so with deep regret I ended up liquidating the business. I was then approached by an old friend who worked for a company based in MA. called Lexicon. They specialized in digital effects type processors for musicians and recording studios. He ended up becoming the father and head engineer of a revolutionary new product known as the MPX G2, it was a huge success and was used by pro musicians and top recording studios world wide and ended up with a cult like following that exists even to this day. Harmon Kardon ended up buying out Lexicon shut down the plant in MA and moved the offices out to CA. They outsourced all manufacturing to China and dropped most of the Lexicon line including the G2. Even though the G2 was dropped my friend went on to support it for the cult followers developing upgrade ROM chips and new software for it but then shortly ran into a problem. Parts used to build them were becoming obsolete and techs that were repairing them was drying up yet owners who love these vintage units wanted to keep them going. One of his biggest request from owners was where can they send them for repairs. This is where I entered the SMT digital world. We made some agreements and I took the repair work on on all vintage Lexicon products including the G2. After a few years he and I had a falling out so basically I told him to stuff the Lexicon repair work.

A jukebox has several key components of a combination of electrical and mechanical to make it work. The only component in a juke that has nothing to do with the operation of a juke is the amp. The amp in most jukes has nothing to do with the operation of the juke they have only 2 (early seeburg up to 1956) circuits that even touch the juke. They have of course the obvious one that goes to the stylus on the pickup arm to the preamp circuit in the amp and then a second muting circuit that would open the amps output circuit to the speakers when the pickup arm gets to the end of the record. In 1957 Seeburg introduced its first preamp that was mounted on the mech outside of the amp. This preamp was actually one of the first uses of a transistor used in commercial use. Then the other components include the mech, pin bank, selector, receiver (receives signals from the selector), coin mech, and lighting/animation that many of them had. Then of course the cabinet, the glass, the chrome, etc. The point here is I fully understand the importance of being meticulous and thorough especially on customers repair or restore work on vintage electronics.

I think most of us can agree we don't do this for money, in fact when all is said and done we make very little money at restoring vintage electronics considering the the cost of the unit to buy to restore, time, labor, materials, and cost of parts compared to what market value is of the unit. We do it cause we want to preserve these vintage/antique pieces of audio equipment. Our reward at least for me is to bring something back to new or in most cases better than new condition and hear that unit belt out music. I am now retired I am not looking to start another business of buy these things to repair to resell. I just want to end up with a PL amp for my own use, not to say if one fell in my lap I would repair it and pass it on so someone could enjoy it for hopefully many years to come. After all it is about preserving great vintage audio equipment for all to enjoy not for the money.
 

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#18
I have 3 questions for ED and for all :
- 1) Why PL 0171 has two different input for normal and DC operation ?
I don't understand the reason of delay unit .
- 2) Why PL 400c is not DC coupled ?
- 3 Why all the boards of PL 4000 are equipped with 4,7 uF and 5uF as
described in the manual ?
I don't understand the difference between 4,7 and 5 uF for electrolic caps .
They are only my curiosities .
Ciao
Marco
 

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#19
An other question :
Why PL 4000 volume pot is not connected directly to ground ?
It's clearly written but not explained .
Thank you again
Ciao
Marco
 

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#20
I have 3 questions for ED and for all :
- 1) Why PL 0171 has two different input for normal and DC operation ?
I don't understand the reason of delay unit .
- 2) Why PL 400c is not DC coupled ?
- 3 Why all the boards of PL 4000 are equipped with 4,7 uF and 5uF as
described in the manual ?
I don't understand the difference between 4,7 and 5 uF for electrolic caps .
They are only my curiosities .
Ciao
Marco
5uF is not a standard value, 4.7uF is.
 
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