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I've been through that thread recently and didn't see anything that suggested such. I would be quite interested to see the comments as well.

You'll find some good information here and here.

Thanks for the comments. The SME is pricey and I'm not sure about the bearings either. The Magnepan looks interesting but the proprietary headshell is a deal breaker. I want to be able to move cartridges between turntables easily. I think both the Grace 940 and the FR-24 are mid mass and...

Looking at acquiring one of these three for a project in progress. Cartridges used are in the 20 - 25 compliance region and run at 1.25 to 1.5g tracking weight. SME at 9.5g effective mass is definitely suitable but most expensive. I know from experience the G-840 at 12g works and is recommended...

I hope the listing of viable component substitutes proves useful for anyone that lands in the same position I found myself with the non-functional drive.

To button it up I replaced the 12v zener with a Vishay BZX85B12-TR and the four mylar caps with MLCC-COG replacements of same value. I ended up replacing all the carbon film resistors, a few were minimally out of spec and one was bad but I had 1% metal film replacements in my parts collection...

Quadraflex QL-410 from the look of it. Apparently the house brand of Pacific Stereo.

With the JFET in circuit the supposed 9.0V reference voltage measured at 3.221V and slowly and steadily climbed by millivolts as the TT spun faster and faster. Might be a workable concept to use a JFET to replace the zener but the execution here was on par with everything else I've found (and...

This particular circuit is a resistor followed by two 10D-05 diodes followed by the Zener and as I understand it, is a voltage regulator intended to provide a constant 9V. The schematic posted by @flavio81 just above is a way to modify the circuit to use an LM7809 regulator or equivalent in...

Per the service manual parts list and schematic I'm replacing an M47 and have just ordered from Digikey the 7V5C along with a variety of other replacement parts for the project. I'm expecting to receive the order by Wednesday and with a bit of luck, may have a functioning TT as a result. The...

Thanks for that very helpful schematic of the changes for @Pio1980's regulator substitution, also for stitching together the SM schematic into a useful form. The two pages of schematic from the 2250 SM don't combine well and miss some information. I've considered making the change to regulators...

Three quick questions for the experts but first an update. Transistors came and I swapped out the SC806A for the first one to arrive. It measures good but low Hfe at just 2 so I'm not sure about it and will swap in the other which has a more appropriate Hfe of 15. Reinstalled the board and...

Seem to be a problematic outfit.

I've been using the TTS-4000 threads as well as the 22xx threads as helpful guidance in the repair of this TTS-2500 because the circuits are are so similar. There are a lot of capable people who have offered assistance to those of us with problematic units, a truly valuable and generous resource.

The 4000 drive transistor Q9 is Q6 on the 22xx/2500 series. Q8, and as you pointed out, Q7 and an alternate Q6, are in the 4000 circuit though not in the 2xxx models. It is that Q6 that is giving me grief.

Yes, Q8 is the culprit; thanks for the explanation. The other differences I've found are in the wiring harness and particularly the terminal blocks for motor and transformer which vary between 5 and 6 terminals. This drive has minor differences from all the published schematics but all the...

The tests I did on the transistor used a Fluke 85 meter for a diode test and showed the following: 3.05V Vf on the C>B junction 0.475V on B>C open on E>B 0.475V on B>E 0.633V on C>E open on E>C. I also used a Mega328 component tester connected to test diode junctions and measured: open on C>B...

That is the first of the two I acquired and runs as it should, a lovely machine. There is no voltage or frequency switch and the 100V is provided by a stepdown transformer. The second one was purchased as the drive only and no switch on it either. I've been going through the 4000, 2250 and 2251...

All three have very similar specs with Vce range between 200 and 400V, Vbe between 400 and 700V, Ic minimum 8A and Pt 125W. 2N6308 has slightly lower Hfe but is in range. I have one of that type coming and it should allow me to at least confirm whether the transistor is the root of my problem.

Making a bit of progress on this. All electrolytics have been replaced with quality 105 degree versions of appropriate values and I replaced tantalums that had been subbed out with electrolytics. Traced and tested every point to point wire, removed and cleaned and reinstalled VR1 and 2 trimmers...

Suit yourself.

No paper required. I was a steel fabricator many years ago and used a press brake to fold steel. Specified finished dimensions of bent or folded material were obtained by calculations using the neutral line as the basis for locating bends. Basing calculations on either inner or outer surfaces of...

The belt has a neutral line somewhere between inside and outside faces; inside that line it compresses around curves and outside it stretches. The effective diameters of the pulleys are the actual diameter plus 2 times the distance between the neutral line and the inside face of the belt.

Thanks flavio, that is helpful and I will follow your guidance. I'm taking my time with this so none of it will happen quickly; I've discovered over the years that taking time to observe and consider and come up with a workable plan leads to much better outcomes. I have wired in a replacement...

Regardless of whether it is started on 33 or 45, the drive is slow to come up to speed, occasionally even needing a push to get going, and according to the strobe, on either speed it overshoots 45 rpm then slows back down to under 33 rpm. It sometimes does this cycle once and sometimes several...