Lpt GTi speed

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Spirantho
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Location: Aberystwyth, Wales

Lpt GTi speed

Post by Spirantho » 14 Sep 2019 11:41

Hi everybody,
I recently bought a very dusty little LPT which needed some TLC but otherwise was in good condition. I was pleased to see that the GTI power supply board is in perfect working order with no scorch marks or anything :)
I've changed the belt with a new Funk Firm one, and I've recapped the PSU with nice new Panasonics (105 degree ones as it can get a bit toasty in there).
The turntable is now sounding fantastic, but a little slow. RPM app on my phone says 33.0rpm, and indeed running Brainwashed simultaneously between the LPT and my CD player shows the LP lags by a few seconds by the end of the 4 minute track 1.
There are two presets in the LPT PSU, and I tried tweaking them a little but no matter what I do, I still get 33.0rpm on the app, and Brainwashed is still a little slow.
I've changed the oil on the main bearing, which is perfect and shows no cracks or anything, and I've cleaned the motor spindle such that there's still some black discolouration, but any gunk from the old belt is removed.

Can anyone help?

Thanks!

--
Ian Gledhill

abril
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Re: Lpt GTi speed

Post by abril » 15 Sep 2019 15:29

Are you sure your app is accurate?
Try a strobe to double check,downloadable from this site-try using a halogen bulb to illuminate it.
There are no speed settings on the LPT-they are voltage settings and are necessary for the smooth running of the motor so you may have screwed them.
If the strobe still shows it as running slow measure the belt thickness and get a thicker belt,even an extra 0.1mm on the thickness will make a difference.

Spirantho
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Posts: 33
Joined: 10 May 2007 14:18
Location: Aberystwyth, Wales

Re: Lpt GTi speed

Post by Spirantho » 17 Sep 2019 12:16

Thanks for the reply!
I'm not sure the app is accurate, but doing back to back comparisons between a digital sourced LP and a CD, it's definitely slow.
I returned the presets back to as they were, and it's behaving the same as it was.
The belt is a brand new Funk Firm one so it should be correct!
I'm going to change the 3.2768MHz Crystal in case it's drifted over the years. Maybe that'll make a difference!

abril
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Georgia
Posts: 2535
Joined: 13 Oct 2002 20:48
Location: Republic of Georgia/Cornwall

Re: Lpt GTi speed

Post by abril » 09 Oct 2019 13:56

And??????

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