Help fix PL700B with PL-14B board

[snoopy]

Hi guys need help to fix a PL700B i recently acquired serial number 647-003B.When i received it the right channel was working perfectly and the left channel was distorting badly.I discovered that the left channel bottom fuse was missing,so I put in a new fuse and turned it on only to witness the a few resistors flame up and a blown test speaker .Also the switch for the vu meters is missing so somebody in the past has removed it (probably the reason why the meters don't work).
Any way I have removed the main pcb it is the PL-14B ..I would like to restore it back to its original form .I have been looking all over the net to find info on this exact board and have not been able to find the original.Work has been done to the amp previously by during its life,parts have been changed to non original parts also seems like a little circuit board has been added not sure what it does .I have read alot of info on the forum however Im totally confused as to which parts are the originals.So im going to need your help.My knowledge is very limited so please feel free to assist. Does anybody have a PCB diagram or a parts placement diagram of this particular board.Also the transistors on the back of the amp are mixed with up 3 XPL909 ,2 RCA410..something cant see the numbers have erased ..and the rest are MJ15024.
The right channel has the RCA40412V1 but on the blown left channel has been replaced with an M2N 6557(is there an easier to find more common replacement for the RCA40412V1)

Q7 is MJE15031 and Q10 is MJE 15030 on both channels

I will add photos as soon as I can workout how to upload them ...Thanks in advance

 

[Northwinds]

Probably cheaper to put WO boards in it eh? Then you will have a real hotrod

 

[laatsch55]

The PL 14B was probably the most prolific board Pl made. It was used in the 700 as well a the 400. You have some outputs shorted do not replace the fuse and turn it on again you'll just toast more stuff. Do you have a DMM, solder iron, scope,etc??

 

[laatsch55]

Let's get some pics and we'll go from there. There are modern replacements for everything, but if you want to turn it back to factory stock, you've come to the right place, if you want to make it state of the art , you've come to the right place...

 

[laatsch55]

To upload pics, "reply to thread" then scroll down to "manage attachments" then select "Browse" then select from your source then click "upload". Watch the "browse" box until it says "close this window", then, "submit reply"

 

[snoopy]

thanks for replying guys..heres some photos

I have a DMM and solderer no scope as yet.

 

[laatsch55]

Man, that's rough. Ido have a lot of factory boards after doing a lot of White Oak conversions. You an have one. It will be a working board. I need an address. Before you install this board you need to dismount all outputs and check for shorts and opens, be able to lift the sockets enough to look for anything that might be shorting there and check the power supply for proper voltage.

 

[snoopy]

Hi laatsch55 i sent you a PM not sure if you got them ...thanks for your reply

 

[laatsch55]

Yes, I got them..

 

[snoopy]

laatsch 55 thanks for the replies ...im just gonna get the WO kit so dont worry about sending the board ....Thank you kindly for your advice

 

[Northwinds]

laatsch 55 thanks for the replies ...im just gonna get the WO kit so dont worry about sending the board ....Thank you kindly for your advice

Nice, your in for a treat!

 

[snoopy]

hi guys just ordered ordered the WO kit for the 700B

just trying to work out a few things on the rest of the amp and trying to work out how to get everything back to how it left the factory ..this little circuit board(pictures below) doesnt look original and looks its been added on somewhere along its lifetime ..anyone know what it is?...I am goin to remove is it a good idea..
The other thing is the switch for the VU meters has been totaly removed ..

The restoration to return things back to original looks like its gonna be a nightmare..does anyone have info how to wire the whole thing back up ready for the WO install

 

[laatsch55]

That is an added on DC protect relay. Or and on/off muting relay board, hard to tell... As far as rewiring the whole thing, that is a major project. Gander through the PLWO archives section as there is all of Joe's release notes and most of the assembly notes also. Rewiring is a very involved process. It's doable, and long distance help leaves so much to be desired......Keep a good camera at hand.
Now when you say factory orignal you know putting a White Oak board in there pretty well ruins that "restored" statement? There's restored and then there's upgraded.. Decide which one you want because it's a whole different approach...

 

[snoopy]

i will rephrase that..want to rebuild it ready for the WO kit.

 

[laatsch55]

Hookay, you got some studying to do. Look in the PLWO archives section for Joe's wiring instruction for the PL14a boards, that will get you started. Are you going to put a DC protect board in? Do you have a service manual??

 

[snoopy]

i would like to keep it as simple as possible so not DC protecion ...I dont have a copy of the service manual...

right now I am trying to gather all the info and parts i can ..
I have got some parts sofar ..
20 X MJ15024
4X RCA 410 (had to empty out a million boxes in the shed to find them and was lucky to find 4 )

2X SPRAGUe powerlytic 36DX 10000-75DC(not sure if I should use these or keep the originals

 

[Gepetto]

i would like to keep it as simple as possible so not DC protecion ...I dont have a copy of the service manual...

right now I am trying to gather all the info and parts i can ..
I have got some parts sofar ..
20 X MJ15024
4X RCA 410 (had to empty out a million boxes in the shed to find them and was lucky to find 4 )

2X SPRAGUe powerlytic 36DX 10000-75DC(not sure if I should use these or keep the originals

Absolutely NO WAY on the 75V caps please!!!

 

[laatsch55]

A 75 volt Dc rated power supply cap will not work in a 700. Have you measured rail voltage yet?It's going to take a 100 volt rated cap AT THE VERY MINIMUM, and more like a 125.

 

[laatsch55]

WOW, that post brought some immediate attention!!

 

[laatsch55]

The rest of the parts are good parts , no problem there.