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johnm 8th July 2011 08:45 PM

Technics SP-10 Mk.II PSU voltages
Hi folks!

Hoping someone out there familiar with these turntables might be able to help.

I have completely recapped the external SH-10E PSU unit, as well as the deck itself.

On the PSU (whilst disconnected from the deck) I have set the two adjustment pots for 5V and 32.5V respectively, as dictated in the service manual. The 140V line has no adjustment pot. I just measured this rail and it reads 159V! Surely this is too high?

Am I supposed to take this reading (and indeed, set the 5V and 32.5V adjustment pots) with the PSU connected to the deck instead?

If not what could be causing the 140V rail to be so high? Our mains is a little high at approx. 248-250V - could that account for it?

Many thanks.

- John

johnm 9th July 2011 11:55 AM

P.S. The 140V line is unregulated, so I assume that once connected to the deck the 159V I am currently getting would likely decrease anyway? The voltage of C417 is 160V, so I'm worried about running that cap at its limit.

The 5V and 32.5V lines are regulated, so I guess it makes no difference if these are measured under load or not?

johnm 9th July 2011 03:50 PM

Just took the voltages again with the external PSU connected to the deck. The 140V rail now measures 149V so I guess (taking into account our high mains here, and the fact that rail is unregulated) all is well with that.

The 5V on the PSU measured 4.9V under load, so I tweaked that up to get 5V. Ditto 32.5V which needed a very slight tweak. I guess the newbie lesson here is to measure under load!

All working well :)

The only bad news is that the strobe has finally met its maker! Was looking at this LED mod (Post 5):

The poster mentions R1=2K11 - however it doesn't appear to be that value from the picture (red/brown/brown/red/black/yellow??!)

- John

jlsem 9th July 2011 11:21 PM

You could increase R422 slightly to get the correct 140 volts.


johnm 10th July 2011 11:28 AM

Thanks for that John - that's great :D

I'll try tacking some other values in there and see what happens. I might abandon the 140V line altogether actually and try one of the LED mods instead (the 140V line is purely for the neon bulb).


MellowFellow 11th July 2011 06:58 AM


My French is not so good - do you know of, or are you able to make an English translation of the LED strobe mod?

johnm 11th July 2011 10:08 AM

Just stick that link into Google translate:

Google Translate

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