Just replaced the 6 electrolytic capacitors, cleaned the pots with de-oxit and set voltages. A week later 33rpm and 16 rpm are holding speed fine and strobe is stationary. However 45 rpm is bouncing around on the strobe and I cannot get it to stay as still as with the other speeds. I have also noticed that when trying to get 45rpm still on the strobe I am having to turn the red wheel further to the right. This is after centring the strobe when I set the voltages. Could this be an issue with the 45 rpm pots, shall I try changing them? Thanks.
Certainly sounds likely, I'd try "deoxiting" the 45 pots again, also giving them a few tweaks each side of the original spot. If you do end up changing the pots cermet ones are worth the little extra; I used 10 turn ones on my mk2 td125.
Good luck
Good luck
The trim pots rarely go off.A cleaning is generally adequate. I also had the same trouble recently; replacing the 0.2,0.1 & 0.075 caps solved the problem.Some were well outside tolerance,and one was generating a lot of noise Also check all of the carbon composition resistors for tolerance. Some of mine were so bad that the trimmers did not have enough range to dial in the adjustments.
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Thanks for the advice. Which resistors were causing problems for the speed adjustments? Are some of them specific to each speed? I can also see some other silver coloured capacitors on the board next to the ones you mentioned. Are these worth looking at too? Many thanks!
You will have to post a pic of your board,or give me the board number,as there are two variants that were used in the MKI.I can't be specific without knowing which board we're dealing with.This information is in the service manual.
As for the components themselves,Thoren's had some weird build practices;They seemed to use whatever they had in the bin😕
They often used Phillips carbon film resistors (really good) in some locations,and much lower quality carbon composition types (made by who knows!) in others.
The Phillips types rarely cause trouble,it's the carbon comps (brown body with really square ends) that drift all over the place.If you're not sure,just use google images for each type to see what they look like.
As for the components themselves,Thoren's had some weird build practices;They seemed to use whatever they had in the bin😕
They often used Phillips carbon film resistors (really good) in some locations,and much lower quality carbon composition types (made by who knows!) in others.
The Phillips types rarely cause trouble,it's the carbon comps (brown body with really square ends) that drift all over the place.If you're not sure,just use google images for each type to see what they look like.
Ok,the board number you gave me did not help,but now that I see which board you have,we're in business.The actual board number is B 830-225.
On the version you have,the 45rpm speed is established by the two 0.075 caps,which are call-outs C10 & C13. These are two of the mustard coloured caps located along the bottom edge of the board.These are the exact same types I had problems with,so I would recommend changing all of them at the same time in the interests of future reliability.The silver ones have been reliable,so far,but so long as you are in there,you might as well do those as well.
So all together,that would be: C8,C9,C10,C11,C12,C13.
Oddly enough,in all my years in the electronics industry,I have seen many of those so-called ''mustard caps''.They were made by Phillips,and up until recently with my own TD-125,and now your's,I have never seen one fail😕
On the version you have,the 45rpm speed is established by the two 0.075 caps,which are call-outs C10 & C13. These are two of the mustard coloured caps located along the bottom edge of the board.These are the exact same types I had problems with,so I would recommend changing all of them at the same time in the interests of future reliability.The silver ones have been reliable,so far,but so long as you are in there,you might as well do those as well.
So all together,that would be: C8,C9,C10,C11,C12,C13.
Oddly enough,in all my years in the electronics industry,I have seen many of those so-called ''mustard caps''.They were made by Phillips,and up until recently with my own TD-125,and now your's,I have never seen one fail😕
So, changed all the capacitors as suggested and same problem remains. At 45rpm, the strobe is bouncing around left and right and this can be heard on some records, particularly with piano. I have cleaned the pots again and reset voltages. I can get the voltages right for 45rpm but when playing records the strobe seems to bounce around. I have not yet replaced any resistors, could these be a cause of the problem? Maybe a replacement belt would help. Also, it may be worth mentioning when I originally replaced the C6 electrolytic capacitor pair, my unit had two 50uf capacitors rather than a 50uf and a 25uf as stated on the circuit diagram. When I replaced these I went for the 50uf and 25uf as on the diagram. I don't know if this would have had a detrimental effect. Thanks.
Update: Just listening to a 45 and fiddled with red speed control wheel and speed is now more stationary. So will see what transpires.
Sorry to hear that things aren't going well!
While it is possible for the belt to cause speed issues (especially on 45 as the motor is generating more torque at the higher speed) I would think it would show up at lower speeds as well.It could be that the belt is marginal,and still ''good enough'' for the lower speeds.
Did you clean the speed control? If its ''noisy'' the speed variations will be more noticeable at high speeds. Mine was erratic at all speeds and cleaning resolved this.
The only resistors that are dedicated to individual speeds are the trim pots; all of the others are shared for all speeds. I'm wondering if perhaps one of the ''45'' trimmers is defective?
As they look original in your pic,the use of two 50uf caps was either an assembly error or production expediency.Replacing them with the proper values was appropriate,and will cause no problems.
Art
While it is possible for the belt to cause speed issues (especially on 45 as the motor is generating more torque at the higher speed) I would think it would show up at lower speeds as well.It could be that the belt is marginal,and still ''good enough'' for the lower speeds.
Did you clean the speed control? If its ''noisy'' the speed variations will be more noticeable at high speeds. Mine was erratic at all speeds and cleaning resolved this.
The only resistors that are dedicated to individual speeds are the trim pots; all of the others are shared for all speeds. I'm wondering if perhaps one of the ''45'' trimmers is defective?
As they look original in your pic,the use of two 50uf caps was either an assembly error or production expediency.Replacing them with the proper values was appropriate,and will cause no problems.
Art
Thanks for the help! What I have noticed is that when I flick the speed selector switch quickly between 33rpm and 45rpm and then leave it on 45rpm the speed stabilises better. When I bought the turntable 16rpm would just wobble back and forth so I cleaned the contacts on the speed selector switch which were black with oxidisation. I could not remove all of it but 16rpm worked after I had finished. I will go back and clean it again paying attention to the contact for 45rpm.
Can you tell me how to access the speed control so I can clean it properly? I have squirted contact cleaner down the slit on the front but guess that this probably isn’t good enough. I have noticed that when moving the red wheel the strobe can jump all over the place and sometimes in the opposite direction I want it to go. Thanks for the advice, I will get this working!
Can you tell me how to access the speed control so I can clean it properly? I have squirted contact cleaner down the slit on the front but guess that this probably isn’t good enough. I have noticed that when moving the red wheel the strobe can jump all over the place and sometimes in the opposite direction I want it to go. Thanks for the advice, I will get this working!
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I cleaned my speed control the same way,just try to spritz it around inside the best that you can. Also,the speed selector switch can be a real pain in the a**; believe me,I know!
For cleaning purposes,the absolute best is the DeOxit brand. I generally start with their D5 for initial cleaning (especially when the control/switch is heavily oxidized) followed by their ''Gold'' to finish up and provide long-term protection.
As the circuit board traces for the switch are gold plated,the application of this latter product is well worth the effort.
You'll get it eventually,these aren't the simplest or easiest tables to work on!
For cleaning purposes,the absolute best is the DeOxit brand. I generally start with their D5 for initial cleaning (especially when the control/switch is heavily oxidized) followed by their ''Gold'' to finish up and provide long-term protection.
As the circuit board traces for the switch are gold plated,the application of this latter product is well worth the effort.
You'll get it eventually,these aren't the simplest or easiest tables to work on!
OK, so cleaned the speed selector contacts with Silvo and DeOxit D5 until it was gleaming and will treat it further with the Gold spray when I get some. 45rpm is now more or less stable. Takes about 10mins after turn on to get there though. I have noticed that on 33rpm and 45rpm the strobe occasionally wanders very slowly and then will stop. Not enough that you can hear it however.
Got the belt about a year ago from a French seller in a kit which included bearing oil, known as Joel's kit. You might know it. However, when I got the belt I gave it a good stretch because I read somewhere this is what you should do! Now thinking I maybe should not have done this, or maybe it hasn't made much difference.
Well,I have heard of Joel's kit,but I have NEVER heard of this ''stretching'' practice.
It seems to me that this would impart an uneven wear to the belt,as there is no way you could ever perform this stretching uniformly throughout the length of the belt. This lack of uniformity will impart speed variations and possibly cause slippage in the most worn areas.
To my mind,belts are designed and manufactured to be of a specific,uniform length,and after X number of hours use,will have elongated to the point of being non-serviceable.
In the TD-125,the belt functions as part of a synergic system due to the floating deck;
Too tight and you wear the motor bearing and offset the deck.
Too loose and you have slippage.
Basically what I'm trying to say (hey,I'll get there eventually🙂) is that you really do need the correct length belt for the table.
Seeing as you've addressed every other possibility (and please don't consider this as wasted time.At this point every TD-125 needs these things done,and now your deck is ready for another lifetime of service.) you might as well spring for a new belt.
And only use the genuine Thorens type,which has the name printed on the belt itself.
It seems to me that this would impart an uneven wear to the belt,as there is no way you could ever perform this stretching uniformly throughout the length of the belt. This lack of uniformity will impart speed variations and possibly cause slippage in the most worn areas.
To my mind,belts are designed and manufactured to be of a specific,uniform length,and after X number of hours use,will have elongated to the point of being non-serviceable.
In the TD-125,the belt functions as part of a synergic system due to the floating deck;
Too tight and you wear the motor bearing and offset the deck.
Too loose and you have slippage.
Basically what I'm trying to say (hey,I'll get there eventually🙂) is that you really do need the correct length belt for the table.
Seeing as you've addressed every other possibility (and please don't consider this as wasted time.At this point every TD-125 needs these things done,and now your deck is ready for another lifetime of service.) you might as well spring for a new belt.
And only use the genuine Thorens type,which has the name printed on the belt itself.
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