I found that there are a few of these for sale on eBay lately. Now 40 years old the grease has thickened into a sticky glue that impedes the motion of the tone arm on the rail and the little belt gets stretched so it often doesn't work. Fortunately the belt is readily available and the grease is pretty easy to clean off following videos on youTube for similar models. I could not find instructions for how to align the tone arm or clock frequencies on the web, so I bought the service manual. As it has no copyright notices anywhere to be found on it, I scanned it and have attached it here. Technics SL-Q5 Service Manual.
I few pictures. There is a nice little screw in the second photo that adjusts the position of the optical interrupt sensor to center the the tone arm position measurement. The servo gain adjustment pot is also on the same assembly. I think it will be interesting to monitor the voltage from the optical sensor output as the table is playing. I found the magnet that spins along with the carriage motor had broken it's plastic spool and was free to slide around. My table spent 41 hours in a truck going end to end on I-90, so I suspect all that vibration may have been more than it could take. A drop of superglue set it back in place.
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A Revox would certainly be worth working on. I sent you an email. I went down the record playback rabbit hole pretty far over the last two months. I'm just about able to start digitally capturing some records and doing some processing to reduce the playback tracing distortion.
I worked through the alignment steps last night. A few things.
1. Page 8, Step 3, Servo Gain. The max voltage with the tone arm pushed to one side was about 2.5 volts, so I adjusted it up to be 3.6 volts as per the instructions. Odd that it could be that far off. It drifted for a few seconds after I made each adjustment.
2. I then followed the steps to adjust the midpoint, tone arm centered voltage. Page 8, Step 4, offset voltage. This was totally futile using the process described in the manual. It turns out the voltage varied with horizontal and vertical movement of the tone arm. So the only way to get it right was to do it with a record playing. I put a piece of painters tape on the carriage to mark where the left side of the tone are would be when centered perfectly. I figured I want it perfectly perpendicular to the rod the tone arm rides on. With the tape there as a guide I can see clearly with a record playing I could see how far off it was. I would stop the record adjust the screw that moves the optical sensor and resume playing. After a few iterations, it was centered while playing. As this is a mechanical adjustment, it is pretty easy to get right.
3. It looks like I didn't follow the clock speed adjustment instructions properly. I will have to try again. I didn't understand the need to connect a jump wire between the pins before making the measurement.
My player seems to work fine. I may pull a few of the capacitors and test them. It could be that leaky capacitors are causing the large variation from the specified values.
1. Page 8, Step 3, Servo Gain. The max voltage with the tone arm pushed to one side was about 2.5 volts, so I adjusted it up to be 3.6 volts as per the instructions. Odd that it could be that far off. It drifted for a few seconds after I made each adjustment.
2. I then followed the steps to adjust the midpoint, tone arm centered voltage. Page 8, Step 4, offset voltage. This was totally futile using the process described in the manual. It turns out the voltage varied with horizontal and vertical movement of the tone arm. So the only way to get it right was to do it with a record playing. I put a piece of painters tape on the carriage to mark where the left side of the tone are would be when centered perfectly. I figured I want it perfectly perpendicular to the rod the tone arm rides on. With the tape there as a guide I can see clearly with a record playing I could see how far off it was. I would stop the record adjust the screw that moves the optical sensor and resume playing. After a few iterations, it was centered while playing. As this is a mechanical adjustment, it is pretty easy to get right.
3. It looks like I didn't follow the clock speed adjustment instructions properly. I will have to try again. I didn't understand the need to connect a jump wire between the pins before making the measurement.
My player seems to work fine. I may pull a few of the capacitors and test them. It could be that leaky capacitors are causing the large variation from the specified values.
A picture showing the painter's tape to help center the tone arm, page 8, step 4 in the manual, while playing. The tape is located to align with the left edge of the tone arm when it is centered. I have yet to test the result. I will look at the delay between the L & R channels while playing some test record mono test tones.
I also posted a pic of my favorite cartridge for use with this table. It has a stylus radius of 0.2 Mil and has the lowest distortion of the cartridges I tested.
I also posted a pic of my favorite cartridge for use with this table. It has a stylus radius of 0.2 Mil and has the lowest distortion of the cartridges I tested.
