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SP10 Mk2 - recap, looking for suitable tech.


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Hi everyone, 

I'm having a bit of trouble finding a tech to recap my Technics SP10 Mk2. It's been put in the too hard basket already by one and I thought I should put it out there for a recommendation. 

My plan is to have the turntable serviced and recapped then sent on to Richard Krebs in NZ for an upgrade to the motor unit. 

I live on the Gold Coast, so ideally local would be good, but I'm prepared to post to whomever if they come highly recommended. 

Thank you for any help you can offer. 

Ian Jackson. 

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Hi, 

I've tried asking Richard to do both but I don't think he is interested. 

Ian.
not sure if anyone here can do the PS recap.

I will ask around my circle of contacts.

The problem with recapping a MK2 is that there is a bunch of them in the
main board inside the TT as well as in the external power supply. This
means that it is not a small job
Anyone in AU that could do this and then send it to me for the upgrade
itself?

 

Hence, I'm looking for either someone in AU or NZ for the recap. 

I've looked at getting Bill in the US to do both, but it's a pricey option. 

 

Cheers, 

Ian. 

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Hey Ian

 

There are quite a few SP10 owners on SNA so hopefully they can chip in with recommendations or at least suggestions for you.  C'mon folks!!

 

With the weight of population on the East coast you'd think someone could help rather than having to send it all the way to NZ 😵

 

But closer than sending it to WA!  According to the interweb....around 2200km GC to Auckland.......around 3600km GC to Perth 

 

2B

 

 

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Recapping the entire SP10 is not something I would recommend.

 

Recap the external PS as these will most likely be toast. There are only 3 caps in the TT that should be replaced and these are C2,4 & 6 on the drive PCB, the rest of the caps on the other PCB's will be fine.

 

I don't know what's involved with the Krebs mod so I won't comment on that.  Upgrades - remove the brake as the plastic surround IMO prevents the motor screws being tightened. The motor rings like a bell, blutack effectively dampens this ringing, don't need a lot just a little spread around the top of the motor flange after it's been bolted down without the brake. I have done baseline measurements but haven't measured the blutack upgrade yet as I'm in the process of machining stainless steel platters. Once finished I plan to measure a raft of upgrades including a new 12mm bearing.

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  • 4 months later...

Hi Ian,

 

I purchased an SP 10 Mk2 just before Christmas 2020. I am in Brisbane.

 

I will be doing a power supply recap, replacing C2. C4, C6 and an LED strobe soon.

 

A power supply recap doesn't appear to me to be a particularly large, difficult or expensive task.

 

I would happy to assist with yours, if I can, after I do mine. 

 

I know it's a couple of months after your initial post but I didn't become an SP10 owner till late December. 

 

I'll send you my contact details so please let me know if I can be of assistance.

 

Cheers,

 

Richard 

 

 

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I'm a retired technician and have 4 SP10's and have a fair amount of experience repairing audio gear so happy to help out if you need advice.

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Hi Warren, 

 

Thank you for your reply. 

Where abouts in Australia are you? 

I see you're using an EPC-205 with your SP10. So am I. I bought one with a crook stylus and fitted a jico SAS/B replacement, and I must say that I'm impressed. 

Cheers, 

Ian Jackson. 

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Hi Ian,

 

I'm in SW Victoria near Warrnambool.

 

Yes I'm using an EPC205 I have 2 a mk2 and mk3U with original stylus the hollow boron pipe job. I also have a Jico SAS/B and a SAS/R the R is better and the B is slightly better than the mk3 stylus. Both are extremely good and I would put them infront of all the high $$ MC's I've had.

 

There is an SP10 thread you post some pics of your SP10 there.

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Good Morning Warren,

 

I've been admiring your work since I recently discovered it whileresearching SP10s and if I may I would like to ask a few questions.

 

With regard to recapping the power supply and with reference to the SP10 recapping list that is going around that was posted above by Ian I note that the list has uprated capacitance for most of the replacement power supply caps by a factor of (x5 - x7).

 

From my basic knowledge of recapping power supplies gleaned from the web it appears to me that the rules of thumb for recapping a power supply are;

 

1) a capacitor replacement voltage of up to (x2) of the original; and

2)a capacitor replacement capacitance of up to (x2) of the original.

 

Q1-

Do you think that uprating the capacitance by (x5 - x7) is appropriate for an SP10 power supply or would it be best to stick closer to within (x1 - x2) of the original capacitances?

 

Q2-

I may be overthinking this and looking for solution to a problem that isn't there but with the consideration that I won't be using the 140V line;

for the 5V and 32V lines do you think a diy power supply based on the LM317 regulator or similar would provide a benefit over the original power supply in terms of regulation, ripple etc?

and;

if so would it be enough to make it a priority? or could I do consider doing it later after the unit is up and running and in a plinth?

 

 

I would appreciate any comments/advice you may be able to provide.

 

 

I am also considering plinth construction and have read your posts on casting with great interest but I will revisit them before I post any queries on that. Being my first turntable that requires a plinth I am thinking of doing one out of ply to start with and then moving on to casting after I get a feel for the dimensions/proportions that I would want long-term.

 

I have also ordered a bearing cap and ball bearing from eBay. The bearing replacement seems to me to be one of those jobs that if it's going to be pulled apart for inspection it might as well be done up while it's apart.

 

 

 

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Only opinion as another SP10 owner - fortunately mine already came recapped from the studio I bought it from. However generally I wouldn’t change capacitor uF values especially in power supplies. They are designed that way for a reason (in high end gear) and not for cost saving. For later value it’s best that like for like is done. The one thing I would upgrade is the temp values ie instead of 85 degree ones use 105 rated, for longevity. 
 

With regards to plinth I started off with the one that came from the studio. Was a large chipboard box arrangement. Did the job but sounded a bit boxy.  Then I built one out of Bunnings oak shelving material. This was clearly better as there was more solid resolved sound and less resonance. Then on advice from Warren I built a cat litter and acrylic plinth. Wow. Without any resonance and complete solidity this made a real improvement to image precision and sound staging. A worthwhile and relatively inexpensive experiment. Just a bit messy and still looks a bit dIY. 
 

In the past I had bought a Moldova plinth off eBay for a Lenco but I feel it dampened the sound too much and lost microdynamics. 
 

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Q1 No upgrading capacitance will do little in the SP10 PS. I would upgrade voltage of C2,4&6 to 100v capacitance 10-12uf 105deg I use Panasonic FC . You can inspect the rest of the electrolytic caps on the electronic PCBs for bulging but I would bet they are all good.

 

Q2 Yes an LM317 regulator is extremely good use the low noise circiry from the datasheet. Also buy quality LM317s NOT from eBay get from RS Components.

 

Then you should check oscillator and phase tracking with a scope to ensure it's operating correctly.

 

Before I got CAD I used to make plinth from MDF or particle board to check dimensions. Then make a mold from form ply to cast a resin bentonite (kitty litter)plinth. When you get here we can be more specific with help.

 

Resin bentonite is about as good as it gets for a plinth. Mine you tap on the plinth with the stylus on a stationary record and there is only very small sound from the speakers.

Edited by Warren Jones
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Thank you Chris and Warren for sharing your experience gained the long way (if I may respectfully put it that way) along with some excellent advice and encouragement.

 

Following that advice, I think I'll conservatively recap the original PS for good measure and also do an LM317 based one using parts from Mouser, element14 or RS.

 

I've already had a look inside the main unit and the caps look ok so I'll stick to C2, 4 & 6. Purchasing the SP10 was the catalyst to get a scope. I bought a 20Mhz 2-channel analogue one in good condition so I'll see how I go with that.

 

By providing your experiences and advice regarding plinths you've both helped me understand where I need to be with that.

 

I'm looking forward to learning more about casting a plinth in due course.

 

Thanks again.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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What I would suggest is to inspect the caps in the PS and if none are bulging plug the PS into the SP10 and check the voltages. If you can adjust them then just recap the PS. If you can't adjust the 5v then build an LM317 regulator.

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Thanks Warren.

 

The power supply caps look pretty good with no bulging, signs of leaks or excess heat on the components or boards.

 

They look to be mostly original except that C410, a 1000uf 16v smoothing cap immediately after the rectifier on the 5v line, has been replaced with a 100uf 250v Jamicon.

 

Testing at C2 and C4 inside the unit and turning the trimpots in the power supply 'lock to lock' after a dash of electrical 'clean and lube' spray I get:

 

32V = 27.1 - 36.4

 

5V = 4.37 - 4.97

 

So the 5V line is still within spec (4.75 - 5.25) but at the maximum range of the pot.

 

 

 

 

 

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Plug the PS into the SP10 and turn it on, start the the TT on 33 and check the 32.5 and 5v lines for ripple.  You can do this with a scope or DMM on AC. I would expect a couple mV RMS ripple.

 

If these are good I would not re-cap the PS plug it in and use the SP10.

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Thanks Warren,

 

I just did a quick set up with my DMM. It's not a true RMS meter.

 

Testing at the output of the power supply circuit board before it goes to the DC output jack for the 5v line I got (5.08v DC / 0.029v AC). For the 32v line the AC was jumping around and I couldn't get a reading.

 

So it might be time to get a true RMS DMM to redo the voltages and also have a look with my analogue scope.

 

I'll try and get it to it this weekend but if not it will probably be the following weekend.

 

This will be my first proper use of a scope and I think I should look at calibrating it as per the manual first. As part of that I need to make a probe to use the 1v calibration voltage output on the front panel.

 

Is it ok to take these noise/ripple measurements on the output of the power supply circuit board just before it goes to the DC power socket output or should I measure at the C2 and C4 test points inside the unit to get more of a 'real world' reading?

 

I appreciate being walked through this as I find that learning and understanding new technical concepts is facilitated when there is a practical situation to immediately apply them to.

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The easiest place to make the DC voltage measurements is in the PS on the output of the PCB.

 

The C2,4&6 test points are NOT DC voltage these are the 3 phase motor drive.

 

The process is

Test and Adjust DC voltage

Adjust T1 on the Logic PCB

Adjust phase tracking

Re-check T1

 

 

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Thanks Warren, once I check the scope calibration and get a new DMM I will be sure to follow that test sequence you have kindly provided and post my results.

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  • 3 weeks later...
On 21/01/2021 at 5:01 PM, Gennett said:

Thanks Warren, once I check the scope calibration and get a new DMM I will be sure to follow that test sequence you have kindly provided and post my results.

Sorry for the late reply, I am approaching the end of a short intensive summer semester for uni.

 

I'll be finishing that assessment in the middle of next week and am looking forward to getting back to the SP10 after that.

 

 

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  • 2 weeks later...

Hi Guo, thank you for posting that photo of your very nicely redone SP10 Logic Board. That is neat work to put in sockets for the ICs.

 

I think I would only do put sockets in if I replaced my ICs. I would be a bit anxious about damaging them when removing them if they are ok to start with. I do use sockets in any new builds of course.

 

My SP10 came from a radio station and at present is not mounted in a plinth. I think because it was in an air-conditioned radio studio and turned on a for most of it's service life it is ok for now.

 

For the short term I would like to focus on getting my SP10 calibrated with an oscilloscope and into a plinth before I think about a full recap. But I will first do C2, C4 and C6 as part of the oscillocope calibration.

 

I am considering building a regulated power supply and would look at maybe doing a recap then too  but for now I would like to get it set up first.

 

Thank you for sharing your photo and advice with me. I do appreciate the help and guidance am receiving from the members of this forum.

 

I hope we can all use our SP10s for ever.

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