Pioneer PL-L800 Linear Tracking Turntable
This is a Linear (Tangential) tracking turntable. This one has faults; the arm moves to the controls, elevation (up/down), left/right, but would not move along tangentially when playing a record. The "arm lamp" had blown - a small lamp shines through a slit in a "flag" that is attached to the arm pivot shaft (hidden away under the arm); the slit covers/uncovers a pair of light dependent resistors that connect to a comparator circuit, the output needs to balance and to keep balance the motor is driven to move the flag, to keep up with the arm which is moving out of parallel due to it playing the record to the centre! Whew. And hence the arm is always very close to parallel to the record grove, less so than a conventional swinging arm.
I replaced the lamp with a LED pair and a current reducing resistor. It's a fiddly and delicate job that requires carefully removing the tonearm, preferably without unsoldering all the wires, and delving into the underside base of the tonearm
(I was concentrating and forgot to take photos; and I'm not taking it all apart again!! surfice it to say it works perfectly after adjusting the balance voltage (the red ringed trim pot in the photo below); if it's unadjusted as per the specs the arm drifts and/or simply returns to the beginning or the end of the record- I'm glad I found a schematic for this turntable.
The quartz lock is a little flaky, it locks well when "warmed up" but seems to be typical of out of spec capacitors, however there are some adjustments for the motor that need to be performed as well. I'll be taking great care with further intrusions into this unit as the proprietary integrated circuit(s) are unobtainable.
The turntable lid needs a clean and polish otherwise this turntable is in pretty good condition and even now is playing very well. Even the original rubber suspension feet are in good condition.
I must mention that working on these would be easier if you had four arms, you need to lift the top plate after removing screws and disconnect two connector plugs while holding the top plate up...then carefully lift the cover over the tonearm while holding and guiding the tone arm through the opening in the top plate; but only after stripping the arm of head shell, counter weight and counterweight stub. Hmm recruit some help!
I replaced the lamp with a LED pair and a current reducing resistor. It's a fiddly and delicate job that requires carefully removing the tonearm, preferably without unsoldering all the wires, and delving into the underside base of the tonearm
(I was concentrating and forgot to take photos; and I'm not taking it all apart again!! surfice it to say it works perfectly after adjusting the balance voltage (the red ringed trim pot in the photo below); if it's unadjusted as per the specs the arm drifts and/or simply returns to the beginning or the end of the record- I'm glad I found a schematic for this turntable.
The quartz lock is a little flaky, it locks well when "warmed up" but seems to be typical of out of spec capacitors, however there are some adjustments for the motor that need to be performed as well. I'll be taking great care with further intrusions into this unit as the proprietary integrated circuit(s) are unobtainable.
The turntable lid needs a clean and polish otherwise this turntable is in pretty good condition and even now is playing very well. Even the original rubber suspension feet are in good condition.
I must mention that working on these would be easier if you had four arms, you need to lift the top plate after removing screws and disconnect two connector plugs while holding the top plate up...then carefully lift the cover over the tonearm while holding and guiding the tone arm through the opening in the top plate; but only after stripping the arm of head shell, counter weight and counterweight stub. Hmm recruit some help!