Vintage HiFi Audio Forum
Audio Discussion => DIY => Topic started by: OldiesButGoodies on October 16, 2011, 11:22:04 AM
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Hi guys..
I have a dual CS-5000 that is loosing signal somewhere between the headshell and the RCA plugs to the receiver. I have ruled out the cartridge and the preamp's phono stage as the cause by swapping components out. Now I need to find where the signal is degrading and fix it.
I have a low level signal coming out of the cart through the headshell into arm down the tube into the base and to the RCA interconnect. I have a VOM meter. I assume I should look for resistance forming somewhere in the path where it should not (I have lower volume in one side - not a complete dropout). The problem could be the corrosion in the terminals connected to the cart in the headshell. If so - is there a chemical way to clean them (soldering new ones is a surgical procedure or just plain impossibility - the unique Dual headshell is designed so that the wires descend into holes in the plastic so I guess they are not user replaceable:
(http://i1122.photobucket.com/albums/l538/namikis/IMG_1017.jpg)
(http://i1122.photobucket.com/albums/l538/namikis/IMG_1019.jpg)
Any ideas - other than procuring a new Dual headshell (it screws in not the standar bayonet - it looks like threaded nylon)? I am trying to avoid opening the base if the headshell is the issue. Any tricks you know to revive bad contacts in a miniature connection like this appreciated!
Thanks,
Pepe/OBG
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Could b e a bad crimp.
I've rewired these tonearms where I do away with the headshell connections and just go straight through to the cartridge.
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Thanks Anders. I may need your help with these one - but will try the DIY approach a bit longer. ???
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Just so you know... Rewiring your tonearm with good litz wire is a stunningly good improvement.
A friend of mine re-wired his cheap Sanyo turntable using strands of litz wire from a speaker cable.
He was stunned at the improvement.
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Stunningly stunned? ;)
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Just so you know... Rewiring your tonearm with good litz wire is a stunningly good improvement.
A friend of mine re-wired his cheap Sanyo turntable using strands of litz wire from a speaker cable.
He was stunned at the improvement.
+1 on rewiring, I did that on my DIY project table and the results were very noticeable.
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It sounds like I that is next on my list of DIY stuff - after I finish the speakers. The issue with doing that in this table is the unique headshell connection. Will not look perfect but will probably sound great.
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A short term solution may be some de-oxit where the arm wire connects to the cart. Remove and reconnect the wire a few times to clean the connection. Be careful to not damage or cause the wire to break away from the little "plugs" There might also be a cold solder joint where the wire is fastened to the RCA jacks.
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Macgeek: I will try that after I replace the interconnects. As you can see in the pictures, the soldering technique was kind of poor (blobs, some too close to each other), and the actual cables were the really cheap kind, and the plugs are old and getting that cloudy haze in the ends that signal oxidation, so will upgrade that as well. Then after testing will try deoxit on the ends if still needed. I am afraid of messing with those super this hair-size signal cables if I can avoid it. :-\
Any other thoughts from what you see in the pictures>
OBG
(http://i1122.photobucket.com/albums/l538/namikis/dual1.jpg)
(http://i1122.photobucket.com/albums/l538/namikis/dual2.jpg)
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Note too that whomever did the first interconnect replacement did not even reattach them to the base using the nylon crimp, so those cables have been hanging loose and mechanically weakened by moving the table around. When I put the replacement cables in I will reuse the clamp top right to keep them in pace. I could wire this to RCS females on the base, that could be a nice upgrade. More decisions. ::)
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What kind of photo gear are you using to get such clear close ups? My camera is great for pics of gear, but not the details.
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OBG,
did you solve the signal loss issue? If not, I would definately resolder the connections to the pc board...
Enjoy the Dual...
I have two, a CS-530 & a 1237 ;)
George
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Hi George!
The good news is that one of the interconnect solders was very weak and almost came off by itself when I touched it with the iron - so that could be the cause of that. I soldered a new set of interconnects and that aspect is good to go.
The bad news is that I am having trouble rebuilding the thing. The she'll that goes around the arm base is a superlative pain to reinstall - and as you know the anti-skate and queuing depend on it, so that is where I am right now, trying to put that back together (effort limited to a few minutes every night because of the work thing). Worse case I will take it with me to the meeting Saturday and ask Tom and Anders for help.
Regards,
OBG
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Replaced the interconnects, rebuilt it and it sounds awesome. I am sure that replacing the arm hair-thin wires would help a lot as well, but one step at a time. One downer: when I was almost done I held the little stan that holds the arm (#53 in the pic below, the little part in the second pic) at rest the wrong way and broke the microscopic piece of plastic that pushes the queueing plunger. So queuing is INOP until I find a spare. If any one runs into one on ebay r elsewhere (or a parts cs-5000), let me know! Not essential (and it is easier to balance the arm without it) but a cool convenience.
Thanks,
OBG
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I measured the resistance between the terminals that clip on to the cartridge (while disconnected from the cart) and the RCA plug tips on the other end that connect to te preamp. I am getting:
Blue - 0.7 ohms
Red - 0.8 ohms
White - 0.7 ohms
Green - 0.6 ohms
Do these values seem right o you all? I was expecting lower - like zero or close to it.
Thanks,
Pepe
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Those measurements are fine.
Sometimes I get higher readings than that and its still ok.
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Thanks A - appreciate the perspective.