orestesp Posted May 20, 2017 Posted May 20, 2017 Hello! This is my first post ever here, and generally I have just started exploring the wonderful world of vinyl records, but not without issues. I've found this old turntable (Pioneeer PL-X77Z) collecting dust in my basement, and wanting to play the records that I happened to have at my disposal, I am trying to repair it. So far, I have managed to hook it up to a power supply, since it used to be powered by an old amplifier that has been thrown away (12V is listed as the appropriate voltage, and although current isn't listed, after a quick google search, I found out that 400-500 mA were plenty for a TT, and I happened to have a 12V/1.2A DC power supply lying around, and it works great, since the surplus current doesn't affect the TT in any way). I bought a new needle, since the old one was broken, only to try it out today to see it wasn't working (the record was spinning, but no sound or anything was coming out of the speakers, although you could hear it playing if I put my ear close to the record). I opened it up only to find out that the tonearm cables had been ripped off (if that's how they're called, they're essentially the cables that connect to the cartridge and then go through the arm to something like a primitive control board, that then connects to the RCA cables). I couldn't find the service manual for my turntable, so I soldered them back on the board the way it seemed they were before they had broken off (I have mediocre soldering skills, but I somehow managed to do a half-decent job of connecting them). I then put it then back together, and although it was working, a really loud humming/buzzing noise was coming out of the speakers along with the music. After trying to ground the amp (by connecting a wire to the power outlet's ground, couldn't figure out a better way to do it), the humming actually became louder (the way I did it isn't probably the best way, but I thought I should give it a shot, feedback on this one's appreciated). I have pretty much narrowed it down to: 1. The tonearm wiring was done wrong? (but could it work with wrong wiring?) Note: There are 5 cables, and one of them is a pair of 2 cables. or 2. I haven't grounded properly the amp. or 3. RCA cables on the TT side need to be changed, they are old after all. I may be way off, that's why I came here to ask for your help. I'm currently at my wits end, any ideas on how to fix it are more than welcome. Final Notes: My amplifier is a Technics SU-V620, and the TT is connected to the Phono input. Thanks in advance!
eltech Posted May 21, 2017 Posted May 21, 2017 I didn't look up your particular turntable. But generally the metal part of the tonearm needs to be grounded to the phono preamp. Your arm has 4 wires for the signal right is red+ green- left is white+ blue- check you've wired the rcas correctly. + Being the centre pin of the RCA, and - being the outer ring. Then there should be a black ground wire which is connected to the metal tonearm, and that should connect to your phono preamp. The ground wire from the power supply should only connect to the motor, though sometimes it might also join the ground wire at the tonearm. 1
eltech Posted May 21, 2017 Posted May 21, 2017 Hello! This is my first post ever here Thanks in advance! As you suspected you will get hum if the ground wire isn't connected, or if the cartridge/ RCA wires are hooked up incorrectly. 1
orestesp Posted May 21, 2017 Author Posted May 21, 2017 7 hours ago, eltech said: I didn't look up your particular turntable. But generally the metal part of the tonearm needs to be grounded to the phono preamp. Your arm has 4 wires for the signal right is red+ green- left is white+ blue- check you've wired the rcas correctly. + Being the centre pin of the RCA, and - being the outer ring. Then there should be a black ground wire which is connected to the metal tonearm, and that should connect to your phono preamp. The ground wire from the power supply should only connect to the motor, though sometimes it might also join the ground wire at the tonearm. 7 hours ago, eltech said: As you suspected you will get hum if the ground wire isn't connected, or if the cartridge/ RCA wires are hooked up incorrectly. First of all, thanks for replying. The wires that you mention are the exact same coming out of the tonearm, the only difference from what you described is that the black wire is also twisted with a yellow one. Could this mean that this isn't the ground wire I've been looking for? (there is no ground wire coming out of the TT, should I just connect the black+yellow wire to the GND on my amp -my amp has phono input, meaning there's no need for an pre-amp). I'll open it right away and maybe post some pictures so you can have a better look on what's going on.
orestesp Posted May 21, 2017 Author Posted May 21, 2017 (edited) Here are the pictures I just took. Under every picture, you will find all the necessary information (hopefully). Spoiler What you pretty much see when you take off the lid. The 2 RCA connectors and the power input (that cable between them) all connect to this small logic board. That black wire screwed on the gear assembly seemed to me to be something related to the grounding circuit of the TT (you can see below were that cable is connected to). Spoiler The back of the board. Those are the cables coming out the tonearm, and I have marked which solder points belong to the RCA cables. Spoiler And back to the front of the board, I've marked where the RCA cables terminate. Note that that the point that I've painted yellow on the second pic is where that ground (?) cable is soldered to. The remaining black & red cables are for power. The cables for Left are: Black and after that White The cables for Right are: Red and after that Red (or pink) Spoiler And the white ones lead to this switch on the back of the gear assembly. How do I know which one is for the outer ring and which one is for the inner pin? My soldering was completely off, everything was screwed up, so no wonder why it doesn't work as intended. EDIT: Soldering them back correctly this time. Figured out the RCA polarity. Will post results soon. Thanks for taking the time, if you need anything explained just ask me. Edited May 21, 2017 by orestesp
orestesp Posted May 21, 2017 Author Posted May 21, 2017 Update: It's working! Re soldered them all in the place were they were supposed to be (w/ the appropriate polarity and such) and now everything works great! Although there is still a hum, the previous one was in a league of its own. What can I do to eliminate completely that hum? It isn't a top-notch TT, but should I further ground it to my amp somehow? (the grounding seems to be taken care by that black cable which connects to the metal part of the gear assemby).
eltech Posted May 21, 2017 Posted May 21, 2017 Oh good! The RCA cable board (PCB) has a marking for ground GND. Just connect that track/ wire to your amp ground post. 1
orestesp Posted May 21, 2017 Author Posted May 21, 2017 It already has a ground cable, which is screwed onto the metal chassis (see the 1st spoiler in my previous post or the first picture below). Should I add a new ground wire that leads to the amp? If so, 1. Should I lead the new ground cable to the amp from here (the point where the original GND cable is located) or 2. from the yellow-painted solder point (see pic): Thanks for bearing with me.
orestesp Posted May 22, 2017 Author Posted May 22, 2017 (edited) 8 hours ago, eltech said: @orestesp please see the attached instructions Soldered and connected to the amp. The TT now produces a crystal-clear sound, no hums no nothing. You're awesome. I wouldn't have fixed if it hadn't been for your help. Thank you again! Edited May 22, 2017 by orestesp
eltech Posted May 23, 2017 Posted May 23, 2017 14 hours ago, orestesp said: Thank you again! You're welcome.
John143 Posted December 23, 2018 Posted December 23, 2018 Hello sir, I had a pioneer Pl-x77z in working condition. But the auto functions not working. will you please take some snaps of the mechanism and send to me? I will be so thankfull to you. I cannot find a service manual anywhere in the web. I saw the details you posted in this forum. it will be very helpfull to me to rejuvenate my turntable. thank you in advance. My email address is: jesekum@yahoo.co.in
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