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The Incredible Technics SP-10 Thread
The Incredible Technics SP-10 Thread
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Old 28th February 2018, 10:42 PM   #991
Dave Cawley is offline Dave Cawley  United Kingdom
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Quote:
Originally Posted by Algar_emi View Post
I decided to recap both power supplies. Now both are working just fine.
I would also change the bridge rectifiers, I have had to do 2 sets on MK3's in the last 6 months !

Dave
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Old 28th February 2018, 10:43 PM   #992
Algar_emi is offline Algar_emi  Canada
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The Incredible Technics SP-10 Thread
Test digital board using only my lab 5V power supply and found that IC2 is defective, very hot and draining the supply. Removed it, installed an IC socket, and ordered the parts on ebay from the US.

Using other transistors from the board (used for switching duties only), I replaced TR218 & TR219 (3.58Mhz osc) with the correct 2SC828A transistors, and clock is now of the correct amplitude at P1 test point. Ordered the correct transistors.

Waiting for the parts to continue...
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Old 1st March 2018, 04:38 PM   #993
Algar_emi is offline Algar_emi  Canada
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The Incredible Technics SP-10 Thread
Found this interesting page that list BBC engineers recommended maintenance works: Technics SP-10MKII SP-10Mk2 SP-10Mk3 SP-10Mk4 modifications

They mentioned to replace all motor caps (from Drive Circuit PCB) with Panasonic FC caps. They are C2,4,6 (3x 10uF/50V) and C7,8,12-17 (8x 1uF/50V)

They also mentioned on this page that no cap degradation will prevent the table to work, it will only degrade the performance.

Just to be sure I'll replace these small caps as well in both tables.
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Old 1st March 2018, 05:30 PM   #994
Algar_emi is offline Algar_emi  Canada
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The Incredible Technics SP-10 Thread
I continue my test of the Digital PCB. First thing I saw after removing the defective IC2 is that the defective PCB 5V current consumption was much higher than the good pcb, 670ma compare to 270ma. I suspect that this table was connected to a defective supply in its past life, and since the 5V regulator is supplied by 12V, a short pass transistor will certainly send higher voltage than 5V to the digital circuit pcb...

I measured all IC temperature and found some really too hot to be in good condition, or soon to fail. I compare to the good PCB and all PCB are within 28-30C, so anything higher than these value is suspect.

I also realized that these M53 chips are in fact TTL chips, so easy to get by. Here the table of my measurements, and TTL part no equivalent. We can see that IC3, 4, 5 10 and 14 are overheating and need to be replaced.

BTW these PCB are very fragile and I delat with this kind of board in my career. By experience the only way to safely removed the defective IC from the board it to first cut all the IC pin legs with a sharp cutter, then to remove gently each pins from the board using a small tip soldering iron. Then you remove the solder from the pads, and install a good quality IC socket. That insure no damage to the board and easy maintenante afterward.

I'll start installing IC sockets shortly.
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File Type: jpg Digital PCB - IC Testing.JPG (62.3 KB, 236 views)
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Old 1st March 2018, 09:22 PM   #995
Algar_emi is offline Algar_emi  Canada
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The Incredible Technics SP-10 Thread
Well found this incredible site about the SP-10 rebuilding process. Great works:
Technics SP-10 Mk2 Project - mpbarneysources
It is explained how to easily replaced a defective neon strobe using orange leds.

This one also about the recommended maintenance: Technics SP-10MKII SP-10Mk2 SP-10Mk3 SP-10Mk4 modifications

An other great site that has a nice section on the SP-10:
sp10 Gallery

Last edited by Algar_emi; 1st March 2018 at 09:41 PM.
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Old 1st March 2018, 10:33 PM   #996
Algar_emi is offline Algar_emi  Canada
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The Incredible Technics SP-10 Thread
Did you know that the platter screws have a small silicone rubber sleeve over them (see picture), so they fit nicely into the platter holes, I didn't. The bronze color on the screws is not bronze, it is the rubber sleeve...

Found out that I'm missing a few. I measured them to be O.D. 7mm & I.D.5mm. Ordered 1m of silicone rubber tubing from China for a few dollards.
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Old 2nd March 2018, 08:28 AM   #997
Dave Cawley is offline Dave Cawley  United Kingdom
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I use rubber tubing it provides a small shock buffer during start up,

Dave
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Old 4th March 2018, 12:41 AM   #998
Algar_emi is offline Algar_emi  Canada
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The Incredible Technics SP-10 Thread
Yeap, that what I thought.
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Old 2nd May 2018, 10:04 PM   #999
Aleks1 is offline Aleks1  United Kingdom
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Default BBC Rp2/9 Mkii P

I recently got an Ex BBC Rp2/9 P version of the Sp10.

All I got was the motor unit. It was missing the power supply and control unit. Also none of switches were wired up save the speed indication LEDs. Also the switches are missing.

I managed to source an original PSU fairly cheaply as it was defunct. I recapped this and replaced the diodes. Most of the caps were leaking fluid and some were open circuit. That now works fine.

My logic board had no onboard clock source or stop start logic. I've got round this with minimum changes or modifications.

Adding the quartz timing source was simple, all I had to do was fill in the missing components on the logic board and put the redundant half of IC17 into service. See photo I've outlined the area added with a red marker. Also I've marked the circuit diagram up.

This modification is tested and works fine. I can select all three speeds but need to do the VR1 and VR2 cals next as 78rpm is a bit roapy and I can see they are off on my scope.
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File Type: jpg Clock Addition.jpg (501.3 KB, 153 views)
File Type: jpg mk2P Logic Board IC17, Clock Addition.jpg (61.5 KB, 150 views)
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Old 2nd May 2018, 11:13 PM   #1000
Dave Cawley is offline Dave Cawley  United Kingdom
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Well done !
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