Can power LPT with Linn PSU?

avinunca · 29th August 2008, 03:08 PM

As far as I know the Linn uses the same Airpac motor as the Pink LPT.
Does anyone know if the PSU's are interchangeable?
I think they are both supplying two 90 degs out of phase supplies.
The Pink is about 100vac per coil.
I see a lot of Linn PSUs on EBay and I wondered if I could use one
on my LPT

abril · 31st August 2008, 01:37 PM

Providing there is between about 85V and 110V on the two phases and the phases are 90deg apart there is absolutely no reason why you cannot (the motors are after all to all intents and purposes the same).
But you may be stuck with 33rpm only?
LPT PSU gone kaput ?

avinunca · 17th February 2009, 09:30 PM

Well yes and this is the longest repair job in history. I bought a cheap scope and isolating transformer on EBay but I am still put off by the
direct rectified mains of the psu.
Someone is offering a psu on EBay but in my opinion he is asking too much.
There is at least 20v difference between the phases and the motor shudders.
I read somewhere that it could be the phase cap. I remember you saying that the value of mine was wrong at 0.68uF but the one on the EBay psu is the same.
It would be great to have another psu to compare voltages.
Does anyone take on repair jobs on these?
I was looking longingly at my vinyl collection the other day. They haven't been played for 11 years - sob!

abril · 18th February 2009, 07:36 AM

This shuddering with the motor going nowhere and excessive voltage difference between the phases is something you will get if the phase cap value is totally wrong,but I can't understand why this PSU on ebay also has that value-did you ask?

If push comes to shove send me the motor and PSU and I will have a look-NO guarantees.

avinunca · 18th February 2009, 09:24 PM

I didn't ask about the value. I will try the .22uF.
Thank you for your very kind offer of help. I will see what the cap change does first. I need to order one.

abril · 19th February 2009, 07:34 AM

Beware of tiny wire links underneath.
Beware of voltage rating
Good luck

avinunca · 27th February 2009, 06:48 PM

I changed the phase cap as per Abril's advice and also the electrolytics (except 1uf) for good measure.
After varying the preset pot value I got 81v across the directly connected coil and 90v across the cap fed coil. This is the closest I've seen. I needed to adjust the position of the motor plate because it was rubbing on the platter but in the end it worked and started up nicely.
The voltages at 45rpm were 82v and 130v - scary so I will try some more adjustment. It did play a 45rpm disc fine but I only did it briefly in
case one or more transistors expired.
I opened my box of albums that I hadn't heard for over 10 years
and played them all afternoon. There is a Goldring Elektra fitted to the RB250. I played about with tracking weights using trial and error
- no gauge and I am very pleased indeed with the sound especially through my headphones and Heed Canamp. I couldn't stop my feet tapping! Need to sort out a new cartridge and phono amp now
and then fine tune the phase cap - not necessarily in that order.
Many thanks to Abril

abril · 28th February 2009, 07:52 AM

Great stuff

Would recommend you replace the 1mfd caps with 105C rated parts as they are badly affected by the heat (have you got scorch marks on the board under the row of resistors!)

Try dropping the voltage lower starts OK and runs smoother with 70 and 80V,seem to remember I got a crazy voltage reading like that at 45rpm (it has been over 12 months since I had an LPT).

Still got my box of tricks

Better cartridge first I think!

avinunca · 28th February 2009, 09:32 AM

Yes I did intend to change the 1uF caps though on my board they are not near the 2W and above resistors.
My board is very similar to this one (below) albeit with more big caps.

http://cgi.ebay.co.uk/ws/eBayISAPI.d...m=290296402083

Farnell where I bought the rest of the gear only had USA import caps at this value/size with £15 delivery.
Will look at some other sources unless you have a suggestion.

Do you have any suggestions for a new cartridge and do you have an opinion on the s/h market.

I am pleased to hear you saw similar voltages at 45rpm. I will try the lowest settings for good start-up etc.

I'm glad you still have the cap changer. The tuning seemed to make a lot of difference to your LPT performance.

Must check the forums for Vinyl sources and cleaning hints. It's been an age since I cleaned an LP.

abril · 28th February 2009, 10:23 AM

I have a vague recollection they were 100V but you will have to check ,in which case

http://www.maplin.co.uk/Module.aspx?ModuleNo=11992

What phono input have you got?

29th August 2008, 03:08 PM	#1
avinunca diyAudio Member Join Date: Mar 2007	Can power LPT with Linn PSU? As far as I know the Linn uses the same Airpac motor as the Pink LPT. Does anyone know if the PSU's are interchangeable? I think they are both supplying two 90 degs out of phase supplies. The Pink is about 100vac per coil. I see a lot of Linn PSUs on EBay and I wondered if I could use one on my LPT

27th February 2009, 06:48 PM	#7
avinunca diyAudio Member Join Date: Mar 2007	I've got music! I changed the phase cap as per Abril's advice and also the electrolytics (except 1uf) for good measure. After varying the preset pot value I got 81v across the directly connected coil and 90v across the cap fed coil. This is the closest I've seen. I needed to adjust the position of the motor plate because it was rubbing on the platter but in the end it worked and started up nicely. The voltages at 45rpm were 82v and 130v - scary so I will try some more adjustment. It did play a 45rpm disc fine but I only did it briefly in case one or more transistors expired. I opened my box of albums that I hadn't heard for over 10 years and played them all afternoon. There is a Goldring Elektra fitted to the RB250. I played about with tracking weights using trial and error - no gauge and I am very pleased indeed with the sound especially through my headphones and Heed Canamp. I couldn't stop my feet tapping! Need to sort out a new cartridge and phono amp now and then fine tune the phase cap - not necessarily in that order. Many thanks to Abril

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31st August 2008, 01:37 PM	#2
abril diyAudio Member Join Date: Sep 2004 Location: Cornwall	Providing there is between about 85V and 110V on the two phases and the phases are 90deg apart there is absolutely no reason why you cannot (the motors are after all to all intents and purposes the same). But you may be stuck with 33rpm only? LPT PSU gone kaput ?

17th February 2009, 09:30 PM	#3
avinunca diyAudio Member Join Date: Mar 2007	Well yes and this is the longest repair job in history. I bought a cheap scope and isolating transformer on EBay but I am still put off by the direct rectified mains of the psu. Someone is offering a psu on EBay but in my opinion he is asking too much. There is at least 20v difference between the phases and the motor shudders. I read somewhere that it could be the phase cap. I remember you saying that the value of mine was wrong at 0.68uF but the one on the EBay psu is the same. It would be great to have another psu to compare voltages. Does anyone take on repair jobs on these? I was looking longingly at my vinyl collection the other day. They haven't been played for 11 years - sob!

18th February 2009, 07:36 AM	#4
abril diyAudio Member Join Date: Sep 2004 Location: Cornwall	This shuddering with the motor going nowhere and excessive voltage difference between the phases is something you will get if the phase cap value is totally wrong,but I can't understand why this PSU on ebay also has that value-did you ask? If push comes to shove send me the motor and PSU and I will have a look-NO guarantees.

18th February 2009, 09:24 PM	#5
avinunca diyAudio Member Join Date: Mar 2007	I didn't ask about the value. I will try the .22uF. Thank you for your very kind offer of help. I will see what the cap change does first. I need to order one.

19th February 2009, 07:34 AM	#6
abril diyAudio Member Join Date: Sep 2004 Location: Cornwall	Beware of tiny wire links underneath. Beware of voltage rating Good luck

28th February 2009, 07:52 AM	#8
abril diyAudio Member Join Date: Sep 2004 Location: Cornwall	Great stuff Would recommend you replace the 1mfd caps with 105C rated parts as they are badly affected by the heat (have you got scorch marks on the board under the row of resistors!) Try dropping the voltage lower starts OK and runs smoother with 70 and 80V,seem to remember I got a crazy voltage reading like that at 45rpm (it has been over 12 months since I had an LPT). Still got my box of tricks Better cartridge first I think!

28th February 2009, 09:32 AM	#9
avinunca diyAudio Member Join Date: Mar 2007	Yes I did intend to change the 1uF caps though on my board they are not near the 2W and above resistors. My board is very similar to this one (below) albeit with more big caps. http://cgi.ebay.co.uk/ws/eBayISAPI.d...m=290296402083 Farnell where I bought the rest of the gear only had USA import caps at this value/size with £15 delivery. Will look at some other sources unless you have a suggestion. Do you have any suggestions for a new cartridge and do you have an opinion on the s/h market. I am pleased to hear you saw similar voltages at 45rpm. I will try the lowest settings for good start-up etc. I'm glad you still have the cap changer. The tuning seemed to make a lot of difference to your LPT performance. Must check the forums for Vinyl sources and cleaning hints. It's been an age since I cleaned an LP.

28th February 2009, 10:23 AM	#10
abril diyAudio Member Join Date: Sep 2004 Location: Cornwall	I have a vague recollection they were 100V but you will have to check ,in which case http://www.maplin.co.uk/Module.aspx?ModuleNo=11992 What phono input have you got?

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