Technics SP 10 Speed Problems - Page 2 - diyAudio
Go Back   Home > Forums > Source & Line > Analogue Source

Analogue Source Turntables, Tonearms, Cartridges, Phono Stages, Tuners, Tape Recorders, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 13th February 2004, 09:52 AM   #11
Luke is offline Luke  New Zealand
diyAudio Member
 
Join Date: Sep 2001
Location: Wellington NZ
Send a message via AIM to Luke
Hi rollinr,

i have no idea about the sp10, but I have had a technics turntable that suffered the same symptoms as yours.
Min was caused by a dodgy switch, from memory itr was the speed selector push buttin switch, if you tap it while rotating, does the speed change?
Good luck.

cheers ab
  Reply With Quote
Old 14th February 2004, 01:13 AM   #12
EC8010 is offline EC8010  United Kingdom
diyAudio Moderator Emeritus
 
EC8010's Avatar
 
Join Date: Jan 2003
Location: Near London. UK
Default It's a standard fault.

Years ago, I spent hours chasing round the oscillator and servo to be casually told by a colleague to look at the 5V reservoir capacitor in the power supply. When it dies, spikes upset the dividers etc in the pulse generator.

Edit: All the strobe tells you is that the servo has locked the platter to the pulse generator. It doesn't necessarily confirm correct speed.
__________________
The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...
  Reply With Quote
Old 14th February 2004, 01:49 PM   #13
BrianL is online now BrianL  United States
diyAudio Member
 
Join Date: Mar 2002
Location: USA
If the crystal oscillator is working correctly, the strobe will indicate
whether or not speed is correct. The whole point of the crystal
oscillator is to have a stable frequency source. I, too, have an
SP-10 (Mk IIa) -- purchased off Ebay relatively cheap because
"speed not stable". Haven't dug into it yet, but much of the
electronics are small-scale logic ICs and custom Technics digital
chips. If they fail, it's not likely to work at all. That leaves power
supply, as others have mentioned, some op-amps in the PLL
circuitry and drivers, or --- scary thought -- dead motor windings.
If motor windings, one is really hosed; you then have a parts
unit for the next one you buy to replace this one...

I'm hoping my problem is power supply caps. $20 to Digi-key and
I'm up and running. They should probably be replaced anyway
on a unit this old. Of course, it'll sound best with Panasonic
caps in it. ;-)
__________________
bel
  Reply With Quote
Old 22nd February 2004, 05:29 PM   #14
rollinr is offline rollinr  United States
diyAudio Member
 
Join Date: Feb 2004
Location: San Antonio
Default SP 10 still running wild

Thanks for all the posts re my SP 10 Mk II. I put all new caps in the power supply and had high hopes. They were dashed. No
change. Let me add now that the power switch has no effect. When you plug the power supply (into the mains, for my Brit friends) and switch it on, the platter starts rotating at a high rate...faster than 78 rpm, and the power switch will not stop it. The speed buttons also have no effect. Still seeking a solution or solace.

Thanks,

rollinr
  Reply With Quote
Old 8th April 2004, 04:10 AM   #15
hnarula is offline hnarula  Indonesia
diyAudio Member
 
Join Date: Apr 2004
Location: Indonesia
I too have a Technics SP10 Mk II which I have had for a few years, and it just went dead also with speed problems. The turntable turns very fast, the speed controls do not work.

I happen do thave the serfice manual and am trying to se if this can be fixed here. The problem is not with the power supply, it is on one of the 3 boards (the 4th board just conects the 3 together).

My symptoms are: turns on and off from the start button, but spins very fast, the speed change buttons have no effect on the speed. A technician friedn has found some voltage anomolies, but has yet to trace the source of the problem.

If anyone can help on this, I would apreciate hearing from you, and if I can get this fixed here, I will post the solution here once it is done.
__________________
H. S. Narula
  Reply With Quote
Old 9th April 2004, 10:23 AM   #16
EC8010 is offline EC8010  United Kingdom
diyAudio Moderator Emeritus
 
EC8010's Avatar
 
Join Date: Jan 2003
Location: Near London. UK
Default Servo loop?

Hmmm, tricky. Still, there are a few things that you can discount. From memory, the three-phase motor is driven by three power amplifiers and some timing logic. All of that must be working correctly, otherwise the platter would sit there and quiver. I suspect that the servo control loop has been broken and that feedback pulses are not getting back from the platter tacho, causing the control electronics to drive the motor harder.
__________________
The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...
  Reply With Quote
Old 10th April 2004, 03:01 PM   #17
hnarula is offline hnarula  Indonesia
diyAudio Member
 
Join Date: Apr 2004
Location: Indonesia
Thanks for the suggestion, I'll check this. What you say seems logical, I just hope the exact problem is easy to isolate.

While I have you, perhaps you can give me some suggestions on my SP25's fault. In this, when the control is set to neutral, the turntable quivers, but when the pitch control is engaged, either plus or minus, the turntable works fine. What could be causing this?

I never realized turntables had such complicated electronics. Whatever happened to the simple motor, pulley and belt?

Rgds
__________________
H. S. Narula
  Reply With Quote
Old 10th April 2004, 06:22 PM   #18
EC8010 is offline EC8010  United Kingdom
diyAudio Moderator Emeritus
 
EC8010's Avatar
 
Join Date: Jan 2003
Location: Near London. UK
Direct drive turntables are complex, and best thought of as a complicated bit of electronics with a motor hanging on the end!

Regarding your SP25, the drive amplifiers are definitely fine, but there's a problem with the feed to them. In variable pitch mode, the turntable may use a completely different servo system to fixed speed mode. In fixed speed, it almost certainly compares the frequency of pulses from an internal quartz refernce with tachometer pulses from the platter. In variable pitch mode, it might not be able to do this. The clue will be in the way that the variable pitch control works. If it adjusts speed in steps, then it is changing the division ratio of the digital system. I would be prepared to bet, however, that in your turntable, the variable pitch control is continuously variable, indicating an analogue control system.

I would check that the dividers from the quartz oscillator are operating correctly and producing a low frequency square wave that can be compared with the corresponding square wave generated by tacho pulses from the platter. Good luck.
__________________
The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...
  Reply With Quote
Old 6th May 2004, 11:04 PM   #19
lectec is offline lectec  United States
diyAudio Member
 
Join Date: May 2004
Location: san antonio texas
Default sp10mII

i have just repaired this turntable with speed control loss. i found the square wave breaking down at ic5, ic6 on the speed control board. im not looking at the scematic and may have these chip numbers wrong. i will look tomorrow at work and make any corrections. i also found these chips to be getting near hot. (pretty warm ). these chips are not available from panasonic but are as generics. i will try to get back to you with the correct chip id numbers.

lectec.
  Reply With Quote
Old 7th May 2004, 05:18 AM   #20
hnarula is offline hnarula  Indonesia
diyAudio Member
 
Join Date: Apr 2004
Location: Indonesia
Hi. Thanks for the suggestions. I will have someone look at this and hopefully I can get this resolved.

Were your symptoms the same? My turntable runs only in 1 speed, and that is FAST. There is no speed control via the speed selector switches, but the turntable starts and stops as per normal, and the brakes work fine also.

I have a service manual, but fat good that is doing me, with the local technicians hardly able to understand the operation and logic. Most have never worked on a turntable before, so its greek to them.

Any suggestions you can provide would be most useful. Otherwise it will be trying to change one component at a time to arrive at the one which is defective, and that could take a long long time to resolve.

Thanks/ Rgds
__________________
H. S. Narula
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Technics SL-1210MK2 - weird speed problem mnsh Analogue Source 67 20th October 2013 05:50 PM
Technics SP-10 speed problems Stefanoo Analogue Source 3 17th August 2008 10:05 PM
Technics SL1200 / 1210 Speed Fluctuation Problem rob110101010001 Analogue Source 1 31st May 2008 03:52 AM
Thorens TD 125 speed problems singinghairdo Analogue Source 22 27th February 2008 08:11 PM
33 speed problem on a Technics SL-QL1 mattjk Analogue Source 3 21st January 2005 05:48 PM


New To Site? Need Help?

All times are GMT. The time now is 01:36 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2