SP10 Troubles

Love it or hate it, it just won't stop
Neal
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#16

Post by Neal »

Nick you're the man!

Indeed it was the Phase timings that needed tweaking, phew! Found that slowing the platter down with a finger stabilised and locked the speed. Weird though, as I had checked that the deck was OK just before changing the last few ceramics...the timing must have been right on the edge.

I went back and checked the Phase reference and found it needed a tweak as well, did that and then re-adjusted the Phase timing again.

I also found the master clock was a touch out so adjusted that as well.

There's still some weird noise spikes that I can't figure out but the deck seems to be working OK now.
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Nick
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#17

Post by Nick »

Cool. Well done.
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#18

Post by Mike H »

Image

Image

Image
 
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Neal
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#19

Post by Neal »

Just posting this for reference, theres little info on the web about SP10 servicing so hopefully this may prove useful.

One thing I have noticed and maybe Nick could shed some light on, is C19 on the drive board...it seems to be very value sensitive...on my deck if this cap is replace with a plastic film cap of the correct 56nF value my deck is unable to lock speed....it hunts and no amount of VR101/102 tweaking will bring it into line. Replace it with a 47nF and is works fine. It may just be my deck but there is some sort of curious interaction that I cant pin down.


SP10 MKII Work:

Fault: Platter rotates backwards and is resistant to moving forward by hand. Motor growls. All speeds.
Diagnosis: High levels of ripple found on +5v Line, cap C411 and C412 failed.
Fix: Replace caps and re-cap PSU if original caps. Adjust +5v and +32.5v rails measured from the SP10.

Fault: Platter rotates in normal fashion but fails to start from rest unless pushed or will only self start if placed in a certain position. Occasionally platter will self start normally. All speeds.
Diagnosis: One drive Phase has failed. TR1, 3 or 5 open cct or shorted. Or complimentary TR2, 4 or 6 faulty.
Fix: TR5 found to be short cct. Replace TR1, 3 and 5 with D45H8 and replace complimentary TR2, 4 and 6 with D44H8

Fault: Platter starts and rotates but wont lock speed and `coggs' at all speeds.
Fix: Adjust phase reference T1 for 18uS and set Phase timing correctly for 33.3rpm and 78rpm by adjusting VR101 and VR102 respectively. Alternatively, check C19 (56nF), found this cap can cause above symptoms, replace with like for like or with Wima.

Fault: Platter rotates at `hyperspeed' with no lock or control. All speeds.
Diagnosis: PLL not working correctly, check ceramic capacitors on Control Board. Check C109 for correct value, short or too low will cause uncontrolled platter speed. Also can be caused by high ripple levels on +5 and 32.5v rails
Fix: Replace all ceramics with correct values especially C109. Re-cap PSU.

Other work:
Replace (RS226-1500) and adjust master clock for 3.5795Mhz.
Adjust T1 for 18uS period
Adjust VR101 and VR102 for correct period timing: See manual
Replace all `lytic caps for correct values, use Panasonic FC for C2, 4 and 6
Replace all Ceramic caps for correct values, use WIMA plastic film. C109 value critical and C19 sensitive in value.

Description of motor operation from DIYAudio:

There are 3 sensor coils set 120 degrees apart, each one is magnetically energized by an exciter coil adjacent to it, but not closely magnetically coupled to it.

Machined into the rotor is a sinusoidal shaped metal coupling ring that runs adjacent to the exciter coils and the phase coils. As the motor rotates the reluctance between the exciter coil and the phase coil follows a sinusoidal pattern - as determined by the physical shape of the coupling ring.

The waveform is determined by the physically cut shape of the coupling ring and is thus a VERY good sine wave. This wave - amplified by a linear gain stage - is used to drive the motor.

The use of exciter coils and variable reluctance means that the generated waveforms are of constant amplitude, no matter what the rotational speed...only the frequency changes with speed.

Because the position of the phase coils slightly leads the phase of the actual motor drive coils, the motor always produces torque, at any speed, and will always start.

It *is* a synchronous motor - the only oddity is that the 3-phase drive is generated within the motor itself. It is both a 3-phase synchronous motor and a 3 phase alternator in one.

Because the phase coils are energised in synchronicity with the motor rotation, the setup *behaves* exactly like a DC motor with a mechanical commutator - there is no inherent speed limit as with a conventional synchronous motor.

This is where the velocity feedback (Mk1) comes in and, later on PLL (mk2), which backs off the drive current, increasing the slip.
Neal
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#20

Post by Neal »

Interesting site on DIY electronics for the SP10 plus some other interesting stuff,,,,worth a browse...

http://web.eject.co.za/s8nspawn/hifi/ak/
Neal
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#21

Post by Neal »

Another good site, detailed photos, just needs translation! Anyone?

http://amp8.com/amp-etc/record/technics/sp-mk2.htm

Google version: http://translate.google.co.uk/translate ... sp-mk2.htm
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Nick
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#22

Post by Nick »

Good list of information Neal. I have always wondered just how that motor works. Cunning.

All I can add is how to replace the logic board devices with modern 74LS types. Problem is I can't remember the exact details, mainly its a case of changing the load resistors for the couple of transistor pulse stretchers. Improving the decoupling around the on off switch, and adding a pull up resistor to the single open collector device thats used from the speed selector in the clock divider chain.

I will have a look at the circuit again and see if I remember what I did.
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Paul Barker
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#23

Post by Paul Barker »

Well now it is clear I am only ever going to be capable of troubleshooting a 301.

Does it turn? oil it.

Does it not tun? is idler wheel in good shape and in contact with platten? yes?

Does motor run?

Is power to motor?

Is fuse in plug?


Is fuse intact?

New motor off ebay.

Phew that lot is hard enough for any man.

I don't want a TT that is more complicated than my bicycle even if it does sound nearly as good as a 301.
Neal
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#24

Post by Neal »

Nick wrote:Good list of information Neal. I have always wondered just how that motor works. Cunning.

All I can add is how to replace the logic board devices with modern 74LS types. Problem is I can't remember the exact details, mainly its a case of changing the load resistors for the couple of transistor pulse stretchers. Improving the decoupling around the on off switch, and adding a pull up resistor to the single open collector device thats used from the speed selector in the clock divider chain.

I will have a look at the circuit again and see if I remember what I did.
Thanks Nick, anything you can add would be great, the logic board is the one board that didn't give me any problems! Touch wood.
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Greg
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#25

Post by Greg »

Paul Barker wrote:I don't want a TT that is more complicated than my bicycle even if it does sound nearly as good as a 301.
:lol: :lol: :wink:
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#26

Post by Neal »

As luck would have it I've landed myself another SP10! :P Not wanting a TT that has all the mechanical sophistication and sound of an 1950's push bike it will be interesting to see how this one compares to my existing one.
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#27

Post by cressy »

i wouldnt mind comparing an sp10 with my kenwood kd07
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pre65
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#28

Post by pre65 »

cressy wrote:i wouldnt mind comparing an sp10 with my kenwood kd07
I found out what a KD-07 is

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cressy
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#29

Post by cressy »

that one in the video is the actual one i bought, the seller put that video up to show it all working properly. :D

ive wanted an sp10 for a long time but i was never sure what i needed to buy, ive seen alot with separate psu's and alot without. alot pulled from consoles (radio stations?) with all sorts of other gubbins with them. i might get one eventually :roll: or one of the big denons :D
Neal
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#30

Post by Neal »

Second SP10 arrived today. Cosmetically its better than my current one and its seems to be a later version as well. It works, starts well, speed changes sharp and precise and theres load of torque. Stability seems a bit worse but I suspect its still got all the original caps if the PSU is anything to go by.

Will be interesting to measure this one and see if the anomalies I noted with my original one apply here...
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