[bryaudioguy]

Hello Everyone,

This is my first post here so for starters I would just like to introduce myself.
My name is Bryan and I am an electronics technician by means of an ancient degree and have had the great fortune of allowing my career to follow my passion for music, my intrigue by audio and recording equipment and an early interest in electronics to all come together. I think everyone should be so lucky as to be able to follow a hobby into their career.
Along the way I have gained a bit of valuable knowledge and experience in these areas so hopefully I can become not only a friend to many of you, but also a helpful resource and an interesting member of this forum as well. I prefer to not be judgmental or jaded in my opinions as experience has shown me that anything is possible in this world, no two paths are the same, and what you think you know today may be proven wrong tomorrow. With that being said I prefer to keep an open mind and always try to think outside the box and to show respect to everyone's opinion.
   My reason for this post is to reach out for help with a challenging project I have started.
In a recent road trip and audio-goodies treasure hunt I was the lucky finder of an early Goldmund Studio turntable with a T3 tangential arm in pretty ratty shape. However, the cables, platter motor power supply and most importantly, the PL5 Servo unit had all been lost in transit some time ago when the unit was shipped from California to South Carolina. Well to make a long story short, Goldmund has been fantastic with regard to support but I am now faced with the challenge of building, from scratch, the PL5 servo unit as they of course are long ago gone. I have already successfully repaired the Papst platter motor and built a nice fully regulated 24VDC power supply for it so if any members on here need assistance with your non-functioning Papst motors I may be able to help you out with that. So with the platter motor all being in place its now time to move on to the challenge of the arm servo unit. Goldmund provided me a copy of a basic hand-drawn schematic of a PL-6 servo unit that could be adapted to drive the T3 arm but unfortunately there are major differences between the PL5 and PL6 and there are some details in the PL6 schematic that are a mystery. The schematic shows IC4 and IC6 as "boxes" in the schematic that do not conform to standard schematic symbols so an educated guess is the best I can do to identify these devices. IC6 is obviously a voltage regulator as evidenced by its three connections, one being power in, one ground and the other I assume VCC for all the other ICs, but to guess that its a 15VDC regulator could only be my best assumption. IC4 is a real mystery though. The schematic shows two logic inputs to the drawn box, three leads that are directly strapped to VCC, one lead tied to VCC through a resistor and that lead coupled to another lead of the device through a capacitor. The output of the box feeds two paralleled inverters.
If anyone has the PL5 schematic, that would be very helpful because the PL5 servo is obviously a very different design than the PL6 and other than the two drive motors, an opto sensor and a few LEDs mounted in the T3 arm, everything else is a completely different layout. Also, if anyone would be willing to open the top cover of their PL5 or PL6 servo units and snap a shot of the board, that would be very helpful too as I could simply read the IC numbers right off the top of the chips.

Thanks Everyone
Bryan

[neobop]

I saw your post on Audiogon.  Although I never owned the T3, my business partner had one on a Reference.  He knew how to keep it working and despite what they said on Agon, the sound was excellent.  A couple of air bearing linear arms might float the image a little better, but the resolution on the T3 is first rate.   Besides all the reverse engineering, your biggest problem might be getting the ICs.  Many are discontinued.  I have no idea, and my partner isn't around anymore.  Have you tried Audio Asylum?

The suspension on the Studio is set up for the T3 arm.  Goldmund had substitute springs - they had different color markings on the spring.  If you don't have an assortment, or any substitutes, you might have to defeat the suspension if you replace the arm.  Sorbotane pucks are popular for this.  The Studio is a great table and you can get excellent results with a good arm.  I had a Studietto with a Zeta arm.  If you elected for a pivoting arm, Goldmund supplied aluminum armboards for both SME mount and Linn (Zeta) mounts.  The plinth was routed on both sides and the armboards were two piece with the plinth sandwiched in between.   With the height of the platter, you might have to do something similar. 

Oh, one other thing, you don't have to apologize for having a direct drive table (Audiogon).  The Studio is really a great table.  The only reason audiophiles were sold belt drives, is because they're easier to build and the Japanese stopped making DD motors.  The later Goldmunds used JVC motors.  Good luck with the table.
neo

[Toni Rambold]

... the PL5 servo is obviously a very different design than the PL6 and other than the two drive motors, an opto sensor and a few LEDs mounted in the T3 arm, everything else is a completely different layout.

The PL5 was developed by Architecture & Physique Appliquée founded by the Levy brothers in 1978.
It speaks for itself that Reverchon does not have the schematics.

There were actually two Servo PL5 units. The first one has an additional "Impulsion knob":



The second unit only "Speed" and "Delay":




PL6/7 were made by another contractor, maybe Pierre Lurné (not sure).


Good luck with the reengineering

[iperezp]

Hello, here's some images of Goldmund Studio PL6 Servo, the unit does not power on. It has 2 burned resistors right next to the AC mains input as shown on the photo. I'd like to replace them and see what happens, any advice or suggestions will be appreciated.
Thank You, best regards: Ignacio.