Nakamichi PA-7 bias trimpots...

tubeornotube · 11th October 2012, 09:20 PM

Could anyone who has any experience with replacing the bias trimpots on the Nak PA-7 please let me know what multi-turn trimpot is best to use.
Essentially need to know the resistance rating..but any further info would help.
The trimpots on my PA-7 are wonky to say the least and I can't get a steady bias setting at 40mV.

Thanks

Matt...........tubeornotube

Old'n'Cranky · 11:36 PM

shoot me your email and i'll send you a scan (tiff's) of service manual...

vr 101 - 4.7k
vr 102 - 150 ohm

tubeornotube · 11th October 2012, 11:48 PM

Hey Old'n'Cranky

I have a copy of the service manual.It shows the bias trimmers to be 150R semi-fixed or something like that..I wouild like to install multi-turn trimpots and want to know what other owners have or had installed.

Matt..........tubeornotube

tubeornotube · 11th October 2012, 11:51 PM

Also mine and another I have inspected internally have no vr101(4.7k) which I assume to be the offset trimmer. It's possible this was a revision as the serial numbers on these two amps were quite far apart.

Matt.....tubeornotube

Old'n'Cranky · 12th October 2012, 12:08 AM

vr 101/201 are dc offset adjustments.

and i do believe their are several 'revisions' of this amp.
manual i have covers "pa7/pa7e"

No mention of 'power ratings' for the trimmers, so id suspect whatever 'bournes' multi turn floats ya boat

Bourns are what i've fitted into my Pass Labs x150.

sorry i can't be of more help.

11th October 2012, 09:20 PM	#1
tubeornotube diyAudio Member Join Date: Dec 2010	Nakamichi PA-7 bias trimpots... Could anyone who has any experience with replacing the bias trimpots on the Nak PA-7 please let me know what multi-turn trimpot is best to use. Essentially need to know the resistance rating..but any further info would help. The trimpots on my PA-7 are wonky to say the least and I can't get a steady bias setting at 40mV. Thanks Matt...........tubeornotube

11th October 2012, 11:33 PM	#2
Old'n'Cranky diyAudio Member Join Date: Aug 2009	shoot me your email and i'll send you a scan (tiff's) of service manual... vr 101 - 4.7k vr 102 - 150 ohm Last edited by Old'n'Cranky; 11th October 2012 at 11:36 PM.

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11th October 2012, 11:48 PM	#3
tubeornotube diyAudio Member Join Date: Dec 2010	Hey Old'n'Cranky I have a copy of the service manual.It shows the bias trimmers to be 150R semi-fixed or something like that..I wouild like to install multi-turn trimpots and want to know what other owners have or had installed. Matt..........tubeornotube

11th October 2012, 11:51 PM	#4
tubeornotube diyAudio Member Join Date: Dec 2010	Also mine and another I have inspected internally have no vr101(4.7k) which I assume to be the offset trimmer. It's possible this was a revision as the serial numbers on these two amps were quite far apart. Matt.....tubeornotube

12th October 2012, 12:08 AM	#5
Old'n'Cranky diyAudio Member Join Date: Aug 2009	vr 101/201 are dc offset adjustments. and i do believe their are several 'revisions' of this amp. manual i have covers "pa7/pa7e" No mention of 'power ratings' for the trimmers, so id suspect whatever 'bournes' multi turn floats ya boat Bourns are what i've fitted into my Pass Labs x150. sorry i can't be of more help.