Splicing RCA cables on Technics SL-1200mkiI (Quartz Lock?!?!)

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PROJECT 2501

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Real quick...

Anyone have an explanation as to why the quartz locked speed of the platter malfunctions when splicing new RCA cables with the OEM cables?
 
That shouldn't be linked. If it is, I'll be dam ed.

I can confirm that this anomaly exists in the realm of non-fiction. After splicing rca cables with OEM cables which were cut back to about 3 inch stubs, my platter suffered a random frequency of "hiccups". The platter would not lock on speed as witnessed through the strobe indicator, it instead would have sporadic pauses.....well, looking back now... I don't quite remember if the speed was being momentarily delayed or if in fact it had been the opposite and they were actually burts of sudden speed... .
But regardless, the splicing of cables had directly caused the quartz locked speed of the platter to malfunction in a way which i observed as sporadically occurring disruptions in speed.
As soon as I severed the connection between the spliced cables, the speed anomalies were immediately remedied.
 
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Is this an easy fix? Are there RCA cable ends on this turntable at this point? Lack of RCAs tends to reduce the musicality.

If there are no RCAs, you may need to inside there a solder some new ones in. There are plenty on the auction site or through folks who specialize in the 1200 MK2.
 
I can confirm that this anomaly exists in the realm of non-fiction. After splicing rca cables with OEM cables which were cut back to about 3 inch stubs, my platter suffered a random frequency of "hiccups". The platter would not lock on speed as witnessed through the strobe indicator, it instead would have sporadic pauses.....well, looking back now... I don't quite remember if the speed was being momentarily delayed or if in fact it had been the opposite and they were actually burts of sudden speed... .
But regardless, the splicing of cables had directly caused the quartz locked speed of the platter to malfunction in a way which i observed as sporadically occurring disruptions in speed.
As soon as I severed the connection between the spliced cables, the speed anomalies were immediately remedied.
Is this an easy fix? Are there RCA cable ends on this turntable at this point? Lack of RCAs tends to reduce the musicality.

If there are no RCAs, you may need to inside there a solder some new ones in. There are plenty on the auction site or through folks who specialize in the 1200 MK2.


Ok,
It seems the whole point of my post has been missed.
My turntable does not need any repairs, I'm not asking for guidance on how to repair anything, im not looking to give pointers on how to repair anything and once again my turntable is fully functional as of about a month ago when I soldered in new rca cables.

Now, if you can slap down a meaty hunk of information pertaining to why the splicing of rca cables effects platter stability.....well, then....we got ourselves a party
 
Let me make sure I have the base info down: you have a set of cables on there from the factory. The RCA male plugs on the ends start crapping the bed or got cut off or whatever, so instead of popping it open and de soldering old ones and putting new ones on, you stripped back the pos insulation and the ground shield and took a second pair of cables, stripped those bare, twisted pos to pos and neg to neg, isolated all four leads nicely and wrapped them in electrical tape. (So far this my preferred method of everything when I was a teenager.)

After everything gets wrapped up you notice the two donor plugs start messing with the pitch? Removing them makes all good, but the connection of two alien lengths of wire screws it up?

I have a guess but want to make sure that's it.
 
Let me make sure I have the base info down: you have a set of cables on there from the factory. The RCA male plugs on the ends start crapping the bed or got cut off or whatever, so instead of popping it open and de soldering old ones and putting new ones on, you stripped back the pos insulation and the ground shield and took a second pair of cables, stripped those bare, twisted pos to pos and neg to neg, isolated all four leads nicely and wrapped them in electrical tape. (So far this my preferred method of everything when I was a teenager.)

After everything gets wrapped up you notice the two donor plugs start messing with the pitch? Removing them makes all good, but the connection of two alien lengths of wire screws it up?

I have a guess but want to make sure that's it.


Affirm, that's a copy..
But rather than electrical tape being used to cover the bare wire splices, wire nuts were screwed over each splice.

I forgot to mention that the original ground wire was intact and connected normally.
 
The only WAG I have is -

Disruption of the cable shielding is allowing some sort of noise/RF ingress that's messing with the control. That's best I got... :dunno:

What sort of cables did you splice on?
 
The only WAG I have is -

Disruption of the cable shielding is allowing some sort of noise/RF ingress that's messing with the control. That's best I got... :dunno:

What sort of cables did you splice on?


I beleive that they were just a standard pair of patch cables..
 
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Hi,

Why not properly replace the cables, rather than some bodge splicing, it cannot be hard.

Proper earthing may be an issue, or not, its hard to say what is causing the effect.

rgds, sreten.
 
I think that the shield thing is a good guess. The other might be the two different cables. The output l and r are in the circuit to some degree, and maybe the resistance is messed up? I'm reaching.
 
Affirm, that's a copy..
But rather than electrical tape being used to cover the bare wire splices, wire nuts were screwed over each splice.

I forgot to mention that the original ground wire was intact and connected normally.

I would have thought it had something to do with grounding. If I'm not mistaken, the signal path should be separate and completely isolated from the rest of the TT, with the possible exception of the ground.

That said, if you're using wire nuts, then there are parts of the signal wire that are not shielded. Maybe that's doing something wonky and disrupting the ground at the table? Even if you get the speed problem worked out, I think you may be subject to a degraded signal. As others have suggested, I'd replace the entire cable. In fact, when the cable on my Sony PSX-55 failed, I installed a set of RCA jacks on the back of the table, so I could use any good pair of RCA cables back to the preamp.

Also, if the signal cable failed, then there is a chance that the ground cable has failed as well, or it could have a bad connection at either end. I'd stick an ohm meter on both ends to make sure it's got continuity, and maybe disconnect and clean the connections at both ends as well.

And finally, try reversing the polarity of the power plug at the receptacle. Maybe that is out of phase with the receiver/preamp?

Curious to know what you find to be the actual problem here.

bs
 
I would have thought it had something to do with grounding. If I'm not mistaken, the signal path should be separate and completely isolated from the rest of the TT, with the possible exception of the ground.

That said, if you're using wire nuts, then there are parts of the signal wire that are not shielded. Maybe that's doing something wonky and disrupting the ground at the table? Even if you get the speed problem worked out, I think you may be subject to a degraded signal. As others have suggested, I'd replace the entire cable. In fact, when the cable on my Sony PSX-55 failed, I installed a set of RCA jacks on the back of the table, so I could use any good pair of RCA cables back to the preamp.

Also, if the signal cable failed, then there is a chance that the ground cable has failed as well, or it could have a bad connection at either end. I'd stick an ohm meter on both ends to make sure it's got continuity, and maybe disconnect and clean the connections at both ends as well.

And finally, try reversing the polarity of the power plug at the receptacle. Maybe that is out of phase with the receiver/preamp?

Curious to know what you find to be the actual problem here.

bs

See, this whole thing that i speak of...its not a problem that I am plagued with or anything of the sort.

Here's how this whole thing went down...

My rca cables began to take a shit on me. I knew what had to be done to fix it..so, i began disassembling my TT to perform the cable swap.....but i never bothered to double check the last roll of solder I had in my workstation drawer.
Upon my rummaging through drawers and cabinets looking for a packing hook to pry open the power cord clip, I happens upon my soldering drawer, so I decided to grab out what I needed while I was there..
Well, remember the whole bit about not checking what I had on tap? Heres why I brought that up... there was in fact a brand new roll of solder at the bottom of the drawer. But if I just had taken a second to glance at the label over the last, .. I dunno year or two that it's been in the drawer... I would have known that what I had was 80/20 tin and lead solder....the kind that goes on copper pipe...not rosin core for electronics...

So, since I had gone as far as I had on the prepping of the TT, and I had every intent to complete the job.....I was at a stand still because it was 10 pm at night and I had to wait until the mornong to pick up the solder.

Can anyone guess what I ended up doing next?
 
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Could you elaborate on some of reasons why they would not be ideal for this application?
Others can explain far better than me, but most cartridges are designed to work at an optimum capacitance. The cables with your SL-1200 originally are the correct capacitance. Adding excess capacitance with regular high capacitance cables will change the load on the cartridge and adversely impact the sound
 
Could you elaborate on some of reasons why they would not be ideal for this application?

No shielding can lead to excess interference which usually translates to noise or hum. Excess capacitance leads to signal loss particularly in the high frequencies.

Remember you are dealing with a very low level signal from a cartridge and it's easily compromised. Any excess noise here gets a lot more amplification than line level signals like your CD player.
 
Having popped open more than a few TTs and having cobbed more than a few RCA cables over the years, I can see how possibly you could pick up hum, or static. But why that would have any effect on the pitch is eluding me. The theory behind the schematics is most often beyond my pay grade, although I can use them to trace issues a lot. I do know that Technics pitch uses a feedback from the platter to correct itself via resistance adjustment, so someone with a good handle on the thing would have to look at the schematic and figure out why the splicing would get in the mix. My pigeon electronics thinks resistance on the wiring is maybe something.
 
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