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Phase Linear 400 and 700B

Fhamre

Fhamre

Super Member
Just starting to work on my first PL units. A 400 with the driver board marked 14 and a 700B with a PL 20A driver board. Both units have one output shorted.
My plan is to replace all the outputs in the 700B with MJ21196's (20)and put the outputs from the 700B (XPL909's) in the 400 with new insulators.
I note the 700B burnt the two resistors attached to the right channel connectors. Need a copy of the correct service manual for the 700B. I believe it is the early version. I have read most of the excellent PL posts. Just gets a little confusing with the different versions.
I am no expert so any advice is appreciated.
I have no plans to plug them in anytime soon. I will follow the online advice on start up once I am somewhat confident it will be uneventful.
These pieces are in great cosmetic shape and I am looking forward to making them sing again.
 
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Fhamre said:
Just starting to work on my first PL units. A 400 with the driver board marked 14 and a 700B with a PL 20A driver board. Both units have one output shorted.
My plan is to replace all the outputs in the 700B with MJ21196's (20)and put the outputs from the 700B (XPL909's) in the 400 with new insulators.
I note the 700B burnt the two resistors attached to the right channel connectors. Need a copy of the correct service manual for the 700B. I believe it is the early version. I have read most of the excellent PL posts. Just gets a little confusing with the different versions.
I am no expert so any advice is appreciated.
I have no plans to plug them in anytime soon. I will follow the online advice on start up once I am somewhat confident it will be uneventful.
These pieces are in great cosmetic shape and I am looking forward to making them sing again.
Click to expand...

I can't add much as I don't know a great deal about PL. I acquired an absolutely mint PL 700 (not the "B" model) recently and I'll be watching this thread with a great deal of interest.
:thmbsp:

Best Regards,
TerryO
 
The two resistors burnt on the speaker posts are known as a Zoebel network. Any time a PL amp shorts aN OUTPUT THERE ARE OTHER COMPONENTS THAT HAVE GONE WITH IT. Usually the pre-drivers(Q7, Q10) and their associated diodes. To test these components you have to desolder and remove from the board, they'll be dead shorted or open and pretty eaSY TO DO. i HAVE BEEN ABLE TO TEST THE DIFFERENTIAL INPUT PAIR in place with no problems unless they test bad in which case removal is the only positive way of confirming that.
The 21196's are an excellent choice to replace the XPL 909's, so is the MJ15024. I've repaired 20 of these and have relied heavily on d3imlay when i got Geschtunkenflopped. I'm sure he'll be chiming in shortly. I can help until then.
BTW, the factory service manuals are great diagnostic references.
 
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Thank you for the info.
The two resistors burnt on the speaker posts are known as a Zoebel network. Any time a PL amp shorts aN OUTPUT THERE ARE OTHER COMPONENTS THAT HAVE GONE WITH IT. Usually the pre-drivers(Q7, Q10) and their associated diodes. To test these components you have to desolder and remove from the board, they'll be dead shorted or open and pretty eaSY TO DO. i HAVE BEEN ABLE TO TEST THE DIFFERENTIAL INPUT PAIR in place with no problems unless they test bad in which case removal is the only positive way of confirming that.
The 21196's are an excellent choice to replace the XPL 909's, so is the MJ15024. I've repaired 20 of these and have relied heavily on d3imlay when i got Geschtunkenflopped. I'm sure he'll be chiming in shortly. I can help until then.
BTW, the factory service manuals are great diagnostic references.
Click to expand...
When I get back next week I will do some more troubleshooting and hunt down the service manual for my 700B( PL 20A driver board) and the 400 (PL 14 board).
Will be taking it slow as I don't want to cook expensive parts and living in Canada doesn't make part acquisition cheap or convenient.
 
Most all components can be subbed with modern equivalents, let me know if you want a sub list, i've got it laying around here somewhere.
 
Hey a sub list would come in handy. I will be in the big city(Vancouver) this weekend so I might be able to pick up a few bits.
 
Ok , here we go,
PL 400 PCB14A

Q1,Q2-------- Factory MPS5172(Mot)------------------ Sub TIS97 Fairchild Semi(Mouser, Digi-Key)
Q3-----------Factory 2N5401(Mot)--------------------Sub TIS93 Fairchild Semi(Mouser, Digi-Key)
Q4------------Factory MPSA93(Mot)--------------------Sub MPSA93 Fairchild Se
Also On-Semi (Mouser, Digi-Key)
Q5------------Factory 40327(RCA)----------------------2N3440 ST Microelectronics TO-39 case (Mouser, Digi-Key)
Q6------------Factory 2N3403(various)------------------2N3403 Central Semiconductor TO-92HS case. A sub in a to220 case are---MJF15030G, MJF 3055G (On-Semi) (Mouser, Digi-Key) Central Semiconductor--4-Star Electronics
Q7------------Factory MM4003 ( Mot)-------------------2N5415 ST Microelectronics TO-39 case (Mouser, Digi-Key)
Q8------------Factory 2N1304 ( various TI, RCA, GE)-----Sub NONE Can be had on line auction sites, or me I have a few. TO-39 case
Q9------------Factory 2N1305 ( various-TI, RCA, GE)-----Sub NONE Can be had online auctions, or me. TO-39 case
Q10-----------Factory 40327 (Mot)----------------------Sub 2N3440 ST Microelectronics (MOuser, Digi-Key) TO-39 case.
Q1 thru Q4 TO-92 case 7-8 cents apiece, buy 50 each. I like to match them within 2 ohms, some say not necessary in this day and age, but hard to argue with 0-4MV offset.
Caps- Re-place all electrolytics with Elna Silmic II or Nichicon KZ (Muse) , only 10 per board, great improvement.
Power Supply caps---5600uf 80 volt- alot of subs, your only limitation-size.
I'll do the 700B pl020 in another post.
Thanks, Lee
 
The only difference on the 700B PL020 board is thatv Q5 is an RCA 40412V1, replaced with a 2N3439, by ST Microelectronics, this will need a large heatsink. PS caps are 9200uf @ 100volts. A lot of replacements for these, the sad part? Most are pricey.
 
Thank you for all the great info. I am hunting down a 700B service manual and getting my parts in order. I may tap you for the transistors if they prove elusive. Couldn't get them in the big city.
 
Everything except the 2n1304, 2n1305 and the 2n3403 are available through Mouser and Digi-key. Things had to go real bad for the above to be bad. Manuals can be had at stereomanuals.com. Guys name is Rick Stout. Good man.
 
I sure wish I had known about you guys a few years ago. I had a Phase Linear that was my all time favorite Amp. Thing was a bear to move, but it had enough power to run anything, with room to spare. :music:

It developed some distortion, in the right channel, I believe. Took it to a local guy I knew, old school, grew up working on old equipment like this. He was always busy, so I told him to keep it as long as necessary....was in no hurry. I would drop by the shop now and then, checking on it....always some excuse...but will get around to it.

He kept it a year (literally!). I finally gave up, got it back and traded it off to a friend who dealt with stereo equipment all the time. He paired it with a big PL preamp with problems of it's own, and sold them 'as is'. What I wouldn't give to have it back, along with the Preamp! :sigh:
 
Spent some time on the 400,today. Took me quite awhile to determine my board is revision "N".
Started to check component values and noticed that one pin of diode D9 on the left channel was now loose.Handy to test , it tests fine. I have attached a picture. This is the side with the shorted output. I also note that this side was repaired sometime ago and they did not reinstall a cap. I have attached pictures of the right channel for comparison.
Will continue to check components later in the week.
 

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I hope you're a better solder hand than the last guy to work on that. Where the wires are soldered to the board those blobs are way to close for me. The electro's look stressed they've got to go.
Did you check offset before you tore it down?
If you look at the schematic the left channel has only one cap by the output sockets. That looks correct in the pic. Should be a .0015uf ceramic.
 
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This amp came to me without a user history. Got it from a guy who got it from a guy etc. The guy I got it from said go ahead and plug it in. I said let me look inside first. While I was doing that I noticed a missing fuse cap. Thats all I needed to know. Thus I have never plugged it in. Same for the 700B. Came from the same guy ,said he used it to run his AR 9's and it worked fine. I opted to open it up and spotted the cooked resistors. Thus it has never been plugged in by me.
Certainly plan to recap them. I agree about the solder blobs. I will examine more closely.
Yes,its a .005 cap.Where did you see that on the schematic?I must need a schematic refresher.
I also have one emitter resistor one the left side with a bulge. No signs of heat anywhere.
 
Yes, I use one now. Wish I built one sooner.
Got to spend some time on the 400. Checked all the components,replaced the D9 diode,just because and recapped the board with the exception of C3 as I did not have it on hand. Will complete the recap,later, likely the power caps as well. However they checked out fine at this point.I replaced the outputs with the XPL's from my 700B. The 700 has 20 MJ21196's on the way.
With the outputs removed I powered it up through the bulb limiter and kept adding a pair of outputs until everything checked out. DC offset is a sweet 1.3mv and 2.0mv. I set the bias as well.
Then this morning with the wife away I ran it with a Technics SU 9600 preamp through a pair of L 50 JBL's. OMG it sounds great. I could stare at those big meters for hours.
Now to do some more listening.
I don't own 250 watt dummy loads. Will try to address that.
Got a 700 service manual from Don.
Next opportunity I will start check components on it
Its a bit scarier but the 400 was a good start before the big boy.
I am going to put the 400 on my scope later. Still learning those ropes.
I appreciate all the advice.
 
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