Rabco ST-7 questions

scott911sc

scott911sc

Active Member
hi. ive got a Rabco ST-7 that I have used trouble-free for about 12 years.

recently it has developed two problems

1) once tracking speed is set...the next time i turn table on (for example..the next day, 24 hours later or so.....), tracking speed is no longer set. the tracking wheel rubber is fine. all rubber bits look as new, everything is lubricated and free of dust....

2) once the table has been on for a few hours, the on/off-speed touch-control becomes almost unresponsive....like it is dying. when i first turn table on though, it works perfectly

seems like i am developing an electrical problem(s). Any ideas?

Thanks
 
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Clean the metal buttons real good, and your switch problem should disappear. New belt should solve your speed issue. My ST8 did the same thing, and a good cleaning and new belt solved the problem.
Regards,
Jim
 
when you say new belt, are you talking about the platter belt? i just put a new one on

if your talking about the round style belt the runs the tracking wheel...do you have a good source for one, and what is it called?

ill clean the on/off metal buttons with contact cleaner and see what it does

thanks
 
To fix the switch problem, remove the plastic touch switch. The wires plug into the sensors and are likely corroded underneath. Use some deoxit and a q-tip to clean the pins well.
For speed, there are several things you can try. I finaly got mine dialed in by adjusting the small nylon screws on the motor. My belt was running up and down the pulley. Adjusting these fixed the problem of the speed changing slightly on each revolution. I also replaced all the electrolytic caps on the logic board and motor. I think there are 3 and Radioshack had them for about $5 total. And if you are crazy like me, you can then replace the neon bulb with blue leds and veneer the top panel. John
st-7HK1.jpg

st-7HK2.jpg

blue.jpg
 
Yeah it really makes it kick! I should have tried some exotic wood, but made it match my Fisher 800c since i had leftover veneer. John
 
Has anyone every upgraded the headshell wires? mine desperately need to be replaced, as they are brittle and have been repaired several times by my awful soldering

Any advice as to how to replace...(I have not had the actual arm apart to see how the wires travel through the arm)

Where to buy the wires at the proper length?
 
Funny you should say that. I was thinking the same thing. I just installed a new Shure cart last night and one connector fell off. I had to search on the floor for 15 minutes to find it. I'm not sure of a source, but it could be done. I stupidly just glued the connector in the arm end as it was loose. Now it will be much harder to do. I'm happy with it for now. John
 
my end is loose as well...the end of the arm tube that plugs into the rest of the tracking assembly....the black plastic inner part, pulls out of the metal tube

Specifically my concern is the following: sometimes when i remove the arm from the table, the black inner plastic housing (inside of the metal tube) pulls out of the metal tube, as i am disconnecting the arm. The tone arm wires run from the cartridge, through this metal tube and end in the black plastic piece with female metal connectors. when the black plastic piece pulls out of the tube, the wires on that hidden end, attached to the female metal connectors, are getting pulled and stressed. i have no idea what the condition of them on that side are because obviously, you cant see inside the tube.....

Ever have the tube apart? photos? descriptions? i would rather not just start pulling stuff apart. if it breaks, im certain the only way to replace the arm is to buy a for-parts rabco table....
 
My little black plug was also coming out when the arm was removed. I glued it back in place carefully. Hopefully That was not a bad choice. I bet if I needed to I could just crack it free and use new wires. I bet the plastic tip and connectors could be re-used. I re-soldered the connections on the cart, and covered them with thin heat shrink. Hope this will have them hold up. Also when I took off the top plate, I found one of the wires leading to the arm was broken. It was the ground wire. After fixing it , it didn't hum when I touched the arm. John
 
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