Pink Triangle PT1 - Original Wall wart DC transformer?

limbok

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Hi all m

My PT1 has the original outboard DC transformer which I am thinking of replacing. I have measured the output as 17.63V but no idea what polarity is configured? The transformer uses a 2.5mm microphone/headphone style jack. The outer most ring of the jack will be either positive or negative and the inner one the converse. Does anyone know which way around they are? Image below for visualisation purposes only.
1698247959913.png
 

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Just a suggestion but it might be worth getting in touch with The Funk Firm Arthur Khoubesserian the main designer of the PT turntable is the owner and I would think he has all of the answers that you are looking for .
 

limbok

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Just a suggestion but it might be worth getting in touch with The Funk Firm Arthur Khoubesserian the main designer of the PT turntable is the owner and I would think he has all of the answers that you are looking for .
Do you think he would answer my quite trivial (important to me) question?
 

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As always only one way to find out and get in touch , what's the worse that can happen ,not replying ?
 
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Wine man forthe County

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@limbok .. Truepoint make a direct replacement PSU for the PT1 called the Midas. I did have a version of the Midas on my PT Anni, it was a definite improvement on the original PSU from the early 90's. Since then I have moved up to the 'Midas Plus' which is better still.

https://www.true-point.audio/ Look under 'PT spares and upgrades'.
 
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Beobloke

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Hi all m

My PT1 has the original outboard DC transformer which I am thinking of replacing. I have measured the output as 17.63V but no idea what polarity is configured? The transformer uses a 2.5mm microphone/headphone style jack. The outer most ring of the jack will be either positive or negative and the inner one the converse. Does anyone know which way around they are? Image below for visualisation purposes only.
1698247959913.png
If you’ve measured the output then you must already know the polarity.

If the reading on your meter is a positive number, then the positive probe of the meter is on the positive terminal. If the reading is negative, then your positive meter probe is on the negative terminal.
 
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limbok

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@limbok .. Truepoint make a direct replacement PSU for the PT1 called the Midas. I did have a version of the Midas on my PT Anni, it was a definite improvement on the original PSU from the early 90's. Since then I have moved up to the 'Midas Plus' which is better still.

https://www.true-point.audio/ Look under 'PT spares and upgrades'.
Cheers. Yes I’ve looked at the Midas PSUs but the cost puts me off for now. If I upgrade the motor then perhaps I will revisit. I’m curious just how much better a modern transformer will perform.
If you’ve measured the output then you must already know the polarity.

If the reading on your meter is a positive number, then the positive probe of the meter is on the positive terminal. If the reading is negative, then your positive meter probe is on the negative terminal.
Blimey yes how foolish of me LOL! Okay here goes for anyone interested, Positive is the tip or end of the jack, negative is the inner ring. The weird thing is the voltage from a cold start is now down to 16.4V and creeps up to 16.5V or more. I can't find any info on what it should be apart from a forum with someone saying it was 9V?
 
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Blimey yes how foolish of me LOL! Okay here goes for anyone interested, Positive is the tip or end of the jack, negative is the inner ring. The weird thing is the voltage from a cold start is now down to 16.4V and creeps up to 16.5V or more. I can't find any info on what it should be apart from a forum with someone saying it was 9V?
The voltage will sit high with no load but if you’re seeing 16V or so, I’d expect it to be a nominal 15V or maybe 12V supply.

If it really is 9V and is kicking out 16V with no load then its regulation is very poor!
 
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9v is fine. Positive is the tip. If you want to know whether a new transformer will benefit you, run it from a PP3 battery. You're gonna decide you want a better power supply...
 
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limbok

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9v is fine. Positive is the tip. If you want to know whether a new transformer will benefit you, run it from a PP3 battery. You're gonna decide you want a better power supply...
Thanks for confirming. I think you are right. The motor is also a little noisy for my liking so if I can open it up easily, I'll give it a service. Otherwise, new power supply and motor time. I don't really want to spend too much as I will probably sell the deck at some point and you never get back the money you put in. The Truepoint audio offerings are just too expensive, even Origin stuff is too much for what you get...yes I've read the reviews. Looking for someone not trying to rip off the audiophile community LOL.
 

Pinkie

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Thanks for confirming. I think you are right. The motor is also a little noisy for my liking so if I can open it up easily, I'll give it a service. Otherwise, new power supply and motor time. I don't really want to spend too much as I will probably sell the deck at some point and you never get back the money you put in. The Truepoint audio offerings are just too expensive, even Origin stuff is too much for what you get...yes I've read the reviews. Looking for someone not trying to rip off the audiophile community LOL.
Sell the deck to buy what? Why? It punches a long way above its weight - even stock. A bit of a high pitch purr is normal from an original PT1. Try it with a PP3, but put a cushion under your chin before you do. And try a Houdini trick - loosen the allen bolts that hold on the arm board a bit. It takes a bit of experimentation , but tinker till you get the quietest "needle talk". (Be sure your arm cable is properly dressed first). Oh - and a new belt if you haven't replaced in the last 5 years
I've just done a lube service on mine after the suspension collapsed and have to refit the platter - which is not easy on the 3 pink string vector for someone blind in one eye and with Parkinsons disease. The scariest bit is removing the stylus guard on a cartridge mounted with Houdini. Fingers crossed
 

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limbok

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Sell the deck to buy what? Why? It punches a long way above its weight - even stock. A bit of a high pitch purr is normal from an original PT1. Try it with a PP3, but put a cushion under your chin before you do. And try a Houdini trick - loosen the allen bolts that hold on the arm board a bit. It takes a bit of experimentation , but tinker till you get the quietest "needle talk". (Be sure your arm cable is properly dressed first). Oh - and a new belt if you haven't replaced in the last 5 years
I've just done a lube service on mine after the suspension collapsed and have to refit the platter - which is not easy on the 3 pink string vector for someone blind in one eye and with Parkinsons disease. The scariest bit is removing the stylus guard on a cartridge mounted with Houdini. Fingers crossed
If I can get it quiet and stable its defo a keeper! Btw is the whole sub-chassis meant to move within the plinth, i.e. I can move the move the arm mounting poing slightly to the right and I can see the spindle move too (with the platter removed of course)?
 

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@limbok .. there is a small plastic bush assembly which can be attached to the base of a TT motor. The threaded section is glued to the base of the motor, the bolt section is gently screwed in which raises the spindle height. This often cures motor noise. I'm not sure of the correct name for this accessory, @Pinkie might well remember.
 

Pinkie

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If I can get it quiet and stable its defo a keeper! Btw is the whole sub-chassis meant to move within the plinth, i.e. I can move the move the arm mounting poing slightly to the right and I can see the spindle move too (with the platter removed of course)?
Hmm. Probably. Not sure I understand. The sub-chassis should move LOTS. I'm starting to think you haven't had it from new. Forgive me if this is a stupid question, but you have removed the transit bolt? With the platter fitted it should be bouncing up and down smoothly when tapped with a finger. Although, properly set up, it is MUCH more stable than (say) an LP12 it none-the-less has a fair bit of lateral movement possible.
 

Pinkie

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@limbok .. there is a small plastic bush assembly which can be attached to the base of a TT motor. The threaded section is glued to the base of the motor, the bolt section is gently screwed in which raises the spindle height. This often cures motor noise. I'm not sure of the correct name for this accessory, @Pinkie might well remember.
I think that gizmo was used for AC motors - which PT changed to eventually - but this is a DC motor on a PT1. They were a bit noisy , but not intrusive once a record was playing
 

Pinkie

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If I can get it quiet and stable its defo a keeper! Btw is the whole sub-chassis meant to move within the plinth, i.e. I can move the move the arm mounting poing slightly to the right and I can see the spindle move too (with the platter removed of course)?
How are you getting on with the set-up? Do you need an explanation of how to set a PT1 up or are you familiar with it?
 
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limbok

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How are you getting on with the set-up? Do you need an explanation of how to set a PT1 up or are you familiar with it?
Yep I might need some advice on set up and yes I'm not the original owner. Bought it last year in an auction. I need to find some time to have a look inside to see if everything is fine and dandy.
 

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Yep I might need some advice on set up and yes I'm not the original owner. Bought it last year in an auction. I need to find some time to have a look inside to see if everything is fine and dandy.
There's not a huge amount to find inside. The main thing to be aware of is that there is a transit bolt which holds the sub-chassis tight to the suspension rails - which stabilises it for transit, and for cartridge / arm set up. Next you need to know how to fit the belt (if remotely serious, you are going to need a new one). First , free the suspension by loosening and removing the transit bolt. Fit the belt loose on the inner hub, with the bearing fitted in the platter. Loop a (pink) thread through the belt, and pull it taught so the belt with string through it touches the inner edge of the outer platter. Hold it secure while you fit the platter and bearing over the spindle, and try not to smash the saphire when you seat the bearing (its pretty robust really). Meantime pull the belt which you have been holding taught so it fits over the motor pulley, and then release the thread and pull it out of the belt. Level the suspension with a record on the platter, using the 2 side and one rear adjusters. The rear adjuster uses a screwdriver (pretty sure its a phillips head - I have a different custom arrangement on my modified subchassis with the motor mounted on it and vector pulleys so I can't easily check) and the side adjusters a hex socket - one of which would have been supplied with the deck originally. With the deck level, assuming you have an arm fitted, dress the cable to get a free vertical bounce when you tap the platter directly over the transit screw. This is best achieved by having as supple a cable as possible, and creating a soft loop which sits on the subchassis and then clamping the cable with the P clip.

If you struggle to level it, and/or get a smooth bounce, then check you have the correct weight at the armboard. The suspension is designed so that the centre of mass is at the centre of suspension. To achieve this, compensating for the different mass of arms (weight on the scales, not effective mass), armboards, in addition to being cut to the size of the arm mounts, are supplied with a lead weight fixed to the underside of the armboard with double sided sticky foam tape. With the suspension set up properly I can tap the record quite hard, and provoke a pretty substantial bounce, with a record playing, without causing any skip of jump from the record. If you tell me what arm you have, I can check the amount of lead you need. This is the thing so many people get wrong, and frustrated by. If you have the wrong mass at the armboard, no amount of stretching, pulling, or anchoring is going to have it work properly. One member of another forum ended up abandoning the suspension and screwing the deck rigid to the frame on his Anniversary - which completely defeats the whole concept of the turntable.

Just make sure the cable is loose and as far as possible not constraining the free bounce of the suspension. Any questions , please ask. It's a little gem if you can get it running properly
 
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limbok

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IMG_7922.JPG IMG_7920.JPG There's not a huge amount to find inside. The main thing to be aware of is that there is a transit bolt which holds the sub-chassis tight to the suspension rails - which stabilises it for transit, and for cartridge / arm set up. Next you need to know how to fit the belt (if remotely serious, you are going to need a new one). First , free the suspension by loosening and removing the transit bolt. Fit the belt loose on the inner hub, with the bearing fitted in the platter. Loop a (pink) thread through the belt, and pull it taught so the belt with string through it touches the inner edge of the outer platter. Hold it secure while you fit the platter and bearing over the spindle, and try not to smash the saphire when you seat the bearing (its pretty robust really). Meantime pull the belt which you have been holding taught so it fits over the motor pulley, and then release the thread and pull it out of the belt. Level the suspension with a record on the platter, using the 2 side and one rear adjusters. The rear adjuster uses a screwdriver (pretty sure its a phillips head - I have a different custom arrangement on my modified subchassis with the motor mounted on it and vector pulleys so I can't easily check) and the side adjusters a hex socket - one of which would have been supplied with the deck originally. With the deck level, assuming you have an arm fitted, dress the cable to get a free vertical bounce when you tap the platter directly over the transit screw. This is best achieved by having as supple a cable as possible, and creating a soft loop which sits on the subchassis and then clamping the cable with the P clip.

If you struggle to level it, and/or get a smooth bounce, then check you have the correct weight at the armboard. The suspension is designed so that the centre of mass is at the centre of suspension. To achieve this, compensating for the different mass of arms (weight on the scales, not effective mass), armboards, in addition to being cut to the size of the arm mounts, are supplied with a lead weight fixed to the underside of the armboard with double sided sticky foam tape. With the suspension set up properly I can tap the record quite hard, and provoke a pretty substantial bounce, with a record playing, without causing any skip of jump from the record. If you tell me what arm you have, I can check the amount of lead you need. This is the thing so many people get wrong, and frustrated by. If you have the wrong mass at the armboard, no amount of stretching, pulling, or anchoring is going to have it work properly. One member of another forum ended up abandoning the suspension and screwing the deck rigid to the frame on his Anniversary - which completely defeats the whole concept of the turntable.

Just make sure the cable is loose and as far as possible not constraining the free bounce of the suspension. Any questions , please ask. It's a little gem if you can get it running properly
Many thanks again for the advice. makes me really want to keep the deck. I got really lucky with the courier and the fragile lid is still intact. Yes I watched a vid on how to site the belt using a ribbon. If you haven't guessed already I'm a tapehead but what better source than Vinyl so have an affection for the format too. I am okay with simple electronics issues and have serviced motors before. I have a longstanding Linn LP12 which I would sell if I got the PT1 working to my satisfaction. One thing great about the LP12 is the silent motor but its a pain to set up.

I will add a pic to this post shortly so you can see what arm I have.

kind regards
Ian
 
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