Thorens TD 125 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 25th June 2007, 07:26 PM   #11
diyAudio Member
 
Join Date: Aug 2006
Location: Berkshire UK
Default TD125 speed

Hi Ed,
The toothbrush idea is perfect, I use them for the same thing also stencil brushes for cleaning PCBs with IPA .
I don't know about tweaking it for 78RPm, when I next get one in for repair I will have a look

John
  Reply With Quote
Old 25th June 2007, 10:16 PM   #12
diyAudio Member
 
Join Date: Jun 2007
Thanks John


Ed
  Reply With Quote
Old 26th June 2007, 01:50 AM   #13
diyAudio Member
 
Join Date: Feb 2006
Location: Willy, VIC
Quote:
Originally posted by singinghairdo

I have heard rumours that the 16 rpm setting can be tweaked to run at 78 RPM, is this true, or ill advised?
The frequency of the Wien bridge can easily be changed - try changing R18 to around 22k, R19 to around 10k and C11 to around 0.47 uF. Whether you can develop enough voltage to run the motor at 78 rpm and how it copes with this I don't know.
  Reply With Quote
Old 27th June 2007, 04:41 PM   #14
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Quote:
Originally posted by Mark Kelly


The frequency of the Wien bridge can easily be changed - try changing R18 to around 22k, R19 to around 10k and C11 to around 0.47 uF. Whether you can develop enough voltage to run the motor at 78 rpm and how it copes with this I don't know.

You'll also need to replace the 250uF phase shifting capacitor normally used for 16rpm with something like 33uF + 10uF in parallel to get the right phase shift on the motor winding.

Set the voltage to 8Vrms as per 45rpm operation or more if adjustment range is sufficient.

I can't say whether or not any of this is a good idea, and possible problems with the power amplifier and motor could ensue. Use at own risk!
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan
  Reply With Quote
Old 27th June 2007, 11:43 PM   #15
diyAudio Member
 
Join Date: Feb 2006
Location: Willy, VIC
Thanks Kevin, I'd overlooked the need to change the phase shift capacitance.
  Reply With Quote
Old 27th October 2007, 11:26 AM   #16
600LPs is offline 600LPs  Thailand
diyAudio Member
 
Join Date: Oct 2007
Using a KAB Speedstrobe, I'm noticing an apparent drift in speed with my TD 125 MKII. It's also hard to get the speed right in the first place, as if the speed control seems to be sticking and letting go (so fine tuning is more of a slingshot operation! ). ;-)

I've also noticed that after I get the speed apparently right, and record (to digital) an album or two, the speed seems to have changed - test is always without a record or other weight on the platter.

I'm learning about stylus drag, etc., but I didn't think such a thing was an issue with my MkII's 16 pole motor. Ah, learning curves.

I'm following up on this thread to ask:

1. What can I do about an apparently unresponsive speed control - clean, replace?

2. Is a motor problem causing drift? If not, what's the most likely cause?

I've been using a KAB Speedstrobe for a while now, but only recently noticed problems with setting and keeping the speed.

I've changed arms on my table, but I don't do well with soldering, etc., so advice on the practicality of fix attempts vs turn table replacement would be appreciated. What's a good choice if necessary, when considering the cost on 500 recording sessions or so.

Thanks
  Reply With Quote
Old 27th October 2007, 03:04 PM   #17
diyAudio Member
 
ashok's Avatar
 
Join Date: Jun 2002
Location: 3RS
Default Service manual

Service manual downloadable from here :

http://www.vinylengine.com/library_m...ed_model=TD125
__________________
AM
  Reply With Quote
Old 27th October 2007, 04:49 PM   #18
600LPs is offline 600LPs  Thailand
diyAudio Member
 
Join Date: Oct 2007
ashok, thanks for your reply and the link.

My TT is the TD125 MK II, though, and I couldn't find it there.
  Reply With Quote
Old 28th October 2007, 02:04 AM   #19
diyAudio Member
 
ashok's Avatar
 
Join Date: Jun 2002
Location: 3RS
How could you miss it ?
It's listed at the bottom of the Downloads list as " mkII service manual (en) "
Cheers.
__________________
AM
  Reply With Quote
Old 28th October 2007, 12:25 PM   #20
diyAudio Member
 
Join Date: Aug 2006
Location: Berkshire UK
Default TD125 speed change

Hi 600
I think the first thing you should do is either clean with IPA or replace the speed adjustment pots on the motor drive board. The main problem appears to be the silver wiper track becomes black with Silver Sulphide so cleaning it with IPA and putting a very light smear of silicone grease on them will help.
If you mark the position of the wipers with an indelible pen, as I have said before, it is pretty easy to get back to square one.
To set the Wein bridge pots you really need a 'scope to look at the waveform.

John Caswell
  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
thorens td 180 in ....high speed east electronics Analogue Source 0 7th October 2008 08:29 PM
Technics SP-10 speed problems Stefanoo Analogue Source 3 17th August 2008 10:05 PM
Thorens TD 125MKII speed inconsistent? 600LPs Analogue Source 0 26th October 2007 05:32 PM
Technics SP 10 Speed Problems rollinr Analogue Source 26 21st June 2004 06:44 AM


New To Site? Need Help?

All times are GMT. The time now is 10:17 PM.


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