Hi guys
I am really hoping that someone on here can help me identify a problem with a Thorens TD 125 mk II TT I recently bought.
I am so keen to get this fixed as this was my fantasy TT in my teens.
There is absolutely no sign of an power on the TT, essentially it's as if the TT was not plugged into the mains.
I have a basic multimeter and basic knowledge of electronics.
I can get AC on both sides of the fuse under the black plastic cover.
Both poles of the micro switch mounted under the chassis are working.
I have read a similar thread on here but that person had power going to the strobe.
Thank you in advance of an help
Graham
(UK)
I am really hoping that someone on here can help me identify a problem with a Thorens TD 125 mk II TT I recently bought.
I am so keen to get this fixed as this was my fantasy TT in my teens.
There is absolutely no sign of an power on the TT, essentially it's as if the TT was not plugged into the mains.
I have a basic multimeter and basic knowledge of electronics.
I can get AC on both sides of the fuse under the black plastic cover.
Both poles of the micro switch mounted under the chassis are working.
I have read a similar thread on here but that person had power going to the strobe.
Thank you in advance of an help
Graham
(UK)
You may also be getting power to the strobe, but it may be dead.
Check secondary AC voltages on the transformer and DC voltage. If that's ok it's either the motor or the oscillator/driver. Or one of the switches. It will be much easier if you have a scope, or are able to connect your PC sound card to the motor terminals.
Check secondary AC voltages on the transformer and DC voltage. If that's ok it's either the motor or the oscillator/driver. Or one of the switches. It will be much easier if you have a scope, or are able to connect your PC sound card to the motor terminals.
Many thanks for tips, any more please ?
Wow, that's great fast feedback, impressed here indeed
I notice that the secondary winding on the transformer has 3 leads out, and am confused about how to check its output. Any suggestions please ?
Unfortunately I do not have access to a scope, and I fear that would be outside the limits of my knowledge. I have been trying to find a simple step by step guide to take you through servicing but no luck.
I have been trying to get at the slide switches but not sure how to do this or what to clean the contacts with.
Any help at all would be fantastic
Many thanks
Graham
Wow, that's great fast feedback, impressed here indeed
I notice that the secondary winding on the transformer has 3 leads out, and am confused about how to check its output. Any suggestions please ?
Unfortunately I do not have access to a scope, and I fear that would be outside the limits of my knowledge. I have been trying to find a simple step by step guide to take you through servicing but no luck.
I have been trying to get at the slide switches but not sure how to do this or what to clean the contacts with.
Any help at all would be fantastic
Many thanks
Graham
TD 125 fault continues
Hello all,
I hope Christmas went well for everyone. I am continuing to try and fix my Thorens TD125 mk ii TT, after several months of failed attempts.
I have again attempted to re calibrate the speeds on the TT by following the TD 125 mk ii service manual on Vinyl engine, as follows;
Connect meter (dmm) to test points ge and rt (phase 1) and adjust:
45rpm set R10 for 6V
33rpm set R9 for 5V
16rpm set R8 for 3.2V
connect meter to test points ge and bl (phase 2) and adjust:
45rpm set R13 for 6V
33rpm set R12 for 5V
16rpm set R11 for 3.2V
Speed adjust:
set pitch control to centre position and adjust:
45rpm set R18 for stationary display on strobe ring
33rpm set R20 for stationary display on strobe ring
16rpm set R22 for stationary display on strobe ring
Repeat until no further change noted.
16 rpm and 45 rpm are setting perfectly, but despite repeatedly measuring the voltages and re setting the PCB pots over several months, I am still unable to set the 33 speed so that the strobe is stationary. I am wondering if one of the components, which are specific to the 33 speed (R21 and C12) might be at fault. I am assuming that the TT has been mostly used on 33 over the years and therefore components are likely to at fault when in this speed setting ?
Any help would be really appreciated.
Happy New Year everyone.
Graham
Hello all,
I hope Christmas went well for everyone. I am continuing to try and fix my Thorens TD125 mk ii TT, after several months of failed attempts.
I have again attempted to re calibrate the speeds on the TT by following the TD 125 mk ii service manual on Vinyl engine, as follows;
Connect meter (dmm) to test points ge and rt (phase 1) and adjust:
45rpm set R10 for 6V
33rpm set R9 for 5V
16rpm set R8 for 3.2V
connect meter to test points ge and bl (phase 2) and adjust:
45rpm set R13 for 6V
33rpm set R12 for 5V
16rpm set R11 for 3.2V
Speed adjust:
set pitch control to centre position and adjust:
45rpm set R18 for stationary display on strobe ring
33rpm set R20 for stationary display on strobe ring
16rpm set R22 for stationary display on strobe ring
Repeat until no further change noted.
16 rpm and 45 rpm are setting perfectly, but despite repeatedly measuring the voltages and re setting the PCB pots over several months, I am still unable to set the 33 speed so that the strobe is stationary. I am wondering if one of the components, which are specific to the 33 speed (R21 and C12) might be at fault. I am assuming that the TT has been mostly used on 33 over the years and therefore components are likely to at fault when in this speed setting ?
Any help would be really appreciated.
Happy New Year everyone.
Graham
Problem solved.....Very stange brain teaser
Happy New Year guys
Ok this one is very strange indeed.* After months of trying to fix my Thorens TD 125 mk II, I have solved the problem, but have no cle how this works.
After finding an App called iRPM for my IPhone, I thought I'd experiment with it on my Thorens.
A complete a complete failure* to set the strobe properly on 33 speed I used the iRPM app to measure tge platter speed on each speed setting.
Whilst adjusting the speed control pot (20) for 33 speed and observing tge patter speed I have managed to lock all 3 speeds. Tge strobe is stationary on 16 and 45 rpm. But I still can't set 33 to be still, even though tge iRPM app gives the speed as 33.3.* Weird ?* *Makes me wonder how accurate these turntable strobes are.*
So to summarise, the 33 speed is now stable according to the iRPM app but not on the TT strobe
Any clues to explain this guys ?* *
Sitting here listening to the Thorens with Shure V15 iii and the improvement over my previously used AT 95e and Shure M75ED ii is staggering.
One happy bunny here
Any clues guys ?
Graham
Happy New Year guys
Ok this one is very strange indeed.* After months of trying to fix my Thorens TD 125 mk II, I have solved the problem, but have no cle how this works.
After finding an App called iRPM for my IPhone, I thought I'd experiment with it on my Thorens.
A complete a complete failure* to set the strobe properly on 33 speed I used the iRPM app to measure tge platter speed on each speed setting.
Whilst adjusting the speed control pot (20) for 33 speed and observing tge patter speed I have managed to lock all 3 speeds. Tge strobe is stationary on 16 and 45 rpm. But I still can't set 33 to be still, even though tge iRPM app gives the speed as 33.3.* Weird ?* *Makes me wonder how accurate these turntable strobes are.*
So to summarise, the 33 speed is now stable according to the iRPM app but not on the TT strobe
Any clues to explain this guys ?* *
Sitting here listening to the Thorens with Shure V15 iii and the improvement over my previously used AT 95e and Shure M75ED ii is staggering.
One happy bunny here
Any clues guys ?
Graham
The 16 2/3 rpm and 33 1/3 rpm speeds generally use the same strobe pattern and if you look at your TD-125 you will see this the case, and it is relatively accurate as well. (Something better than 1% IIRC) I would be suspicious that something is still wrong with your table if you cannot set the speed accurately using the internal strobe - otherwise all other speeds would be off as well. I would suspect the iPhone app has a long integration time constant and might be hiding the issue as a result.
Hopefully you have replaced all of the electrolytics in your turntable as they are ticking time bombs. I had an early TD-125 and was very surprised at the large improvement in performance that resulted from replacing all of the capacitors in it. The ripple on the supply lines dropped by nearly an order of magnitude with replacement capacitors of the closest standard value to the originals. (Went from several volts of ripple to a couple of hundred mV IIRC. I no longer have this TT so not possible to check.) Starting torque increased considerably and the motor ran more quietly as well. Your controller board is different from the one in my early table, but the caveats still apply.
Hopefully you have replaced all of the electrolytics in your turntable as they are ticking time bombs. I had an early TD-125 and was very surprised at the large improvement in performance that resulted from replacing all of the capacitors in it. The ripple on the supply lines dropped by nearly an order of magnitude with replacement capacitors of the closest standard value to the originals. (Went from several volts of ripple to a couple of hundred mV IIRC. I no longer have this TT so not possible to check.) Starting torque increased considerably and the motor ran more quietly as well. Your controller board is different from the one in my early table, but the caveats still apply.
Confused much I am !
Thanks for the great feedback Kevin
I'm in the process of replacing all the caps. But I'm really confused
I'll used the iRPM app on several other turntables and it seems really accurate
33 is accurate on a Technics SL 1500 and several Lencos
Surely if it's accurate on other TT,s then it should be on the Thorens too ?
The response rate of the app is very quick too
Also, this is the second restored and cleaned motor control board I've tried with exactly the same problem.
Out of interest what's the most thorough method of cleaning the on board pots ?
It's a strange one !
Cheers again
Graham
Thanks for the great feedback Kevin
I'm in the process of replacing all the caps. But I'm really confused
I'll used the iRPM app on several other turntables and it seems really accurate
33 is accurate on a Technics SL 1500 and several Lencos
Surely if it's accurate on other TT,s then it should be on the Thorens too ?
The response rate of the app is very quick too
Also, this is the second restored and cleaned motor control board I've tried with exactly the same problem.
Out of interest what's the most thorough method of cleaning the on board pots ?
It's a strange one !
Cheers again
Graham
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I've never really had much success cleaning those style pots, I either leave them completely alone other than setting them or I replace them with modern pots.
Mine was the original TD-125 with the later version of the original control electronics - all discrete, and different motor too. I never had any problems with speed stability in that table even when it was performing under par. (I've worked on several of them, but not the MKII..)
Mine was the original TD-125 with the later version of the original control electronics - all discrete, and different motor too. I never had any problems with speed stability in that table even when it was performing under par. (I've worked on several of them, but not the MKII..)
Hi Graham,
I joined the forum to ask you if you could tell me what you did to solve your problem. I seem to have a similar problem, in that, I have a td 125 mk II that was given to me by a friend who knows I like this stuff. He had not used the table in years but says it worked when he used it. Now, when I turn it on, nothing happens. The motor tries to move a little, maybe a five degrees rotation, not even a whole rotation, and then stops. The light on the circuit board does not come on and the readings I get are around 3.75 VAC between bl & f and bl & e and about twice that between e and f. This is much lower than what other members have suggested it should be and I don't know if I have a problem with the transformer, the circuit board, both or perhaps with one of the input leads into the transformer not being soldered well and draining voltage or something totally different. Not knowing how to get a handle on this, I'm asking the path you took that led you to your solution and of course any help or suggestion that any other member may be kind enough to give me.
I joined the forum to ask you if you could tell me what you did to solve your problem. I seem to have a similar problem, in that, I have a td 125 mk II that was given to me by a friend who knows I like this stuff. He had not used the table in years but says it worked when he used it. Now, when I turn it on, nothing happens. The motor tries to move a little, maybe a five degrees rotation, not even a whole rotation, and then stops. The light on the circuit board does not come on and the readings I get are around 3.75 VAC between bl & f and bl & e and about twice that between e and f. This is much lower than what other members have suggested it should be and I don't know if I have a problem with the transformer, the circuit board, both or perhaps with one of the input leads into the transformer not being soldered well and draining voltage or something totally different. Not knowing how to get a handle on this, I'm asking the path you took that led you to your solution and of course any help or suggestion that any other member may be kind enough to give me.
Thank you Kevin for your reply. My prime suspects are in fact the electrolytic caps, c2 and c4. One of them even looks sick as it has changed color from silver to almost purple-grey. The rectifier diodes you're referring to, are they the four that come as part of one piece labeled Gr1 in the circuit diagram? How do I check them? And do I check them on the board or off the board? Another question, which might have an obvious answer and if so please pardon my ignorance, is that the low potentials that I read off the output from the transformer, I read them at the board where the lines from the transformer connect to the board at points bl, e, and f. And I read them while the lines are still soldered to the board; my question is if board circuit is defective could it cause for the potential drop at those points? Or, they should always show the voltage that comes out of the transformer. In other words, I have not disconnected the transformer from the board to measure its output. Does it matter? Thanks.
Yes, it matters if the bridge rectifier or one of those capacitors is bad.. Run it long enough and the transformer will probably fail.
Replace all of the electrolytics though, not just the two in the supply filter.
In terms of checking the bridge rectifier for shorts if it is shorted it should be pretty unambiguous with a good DVM. Here is something to help you understand how to test diodes: Testing Diodes (Much easier than me trying to explain it all..
)
Replace all of the electrolytics though, not just the two in the supply filter.
In terms of checking the bridge rectifier for shorts if it is shorted it should be pretty unambiguous with a good DVM. Here is something to help you understand how to test diodes: Testing Diodes (Much easier than me trying to explain it all..
)Hi Kevin. First I'd like to say I'm very thankful to you for having posted your advice on this forum. I'm quite a novice in these matters and since I don't know anybody nearby to help me with this I'm resorting to a DIY solution. However, I'm optimistic that I'd eventually solve the problem. But I certainly need help.
The rectifier diodes, as you had suspected, show on my meter to be all shorted. Is it likely that all four are shorted or am I doing something wrong? If they are, where would I obtain a substitute for it? The part number on the circuit for the rectifier is B60C800Si AEG. AEG is the manufacturer. Giving that part number on the google search, it can be located at some distributers but they are all wholesalers and sell them in bunch after giving you a quote. Does it have to be changed with that very same rectifier or are there other ones that can be substituted? My problem seems to be escalating a bit!!! Should I proceed with changing all these elements or give up? Was there a cause for these to be shorted? I mean, do I face the possibility that get shorted again if and when I change it? These are the question that run in my mind now. Thanks.
The rectifier diodes, as you had suspected, show on my meter to be all shorted. Is it likely that all four are shorted or am I doing something wrong? If they are, where would I obtain a substitute for it? The part number on the circuit for the rectifier is B60C800Si AEG. AEG is the manufacturer. Giving that part number on the google search, it can be located at some distributers but they are all wholesalers and sell them in bunch after giving you a quote. Does it have to be changed with that very same rectifier or are there other ones that can be substituted? My problem seems to be escalating a bit!!! Should I proceed with changing all these elements or give up? Was there a cause for these to be shorted? I mean, do I face the possibility that get shorted again if and when I change it? These are the question that run in my mind now. Thanks.
go to here for general thorens resources:
Thorens Dept.
The next bit is my contribution to the magnificent td125
TD125 MKII circuitry
As kevin says change out the bridge and the electrolytic caps
then I bet one of your power transistors is bunkum, Change them
Here is a list of components
http://www.theanalogdept.com/images...5II circuit board pics/thorens parts list.xls
Change the opamp (put it a dil socket first then put the opamp into the socket)
Then change out t1 to t4.. My deck stopped where the platter kind of wiggled a bit even though strobe was on.
Short of your motor being cactus this is a very rebuildable deck. I have done pcb design that i used to fix one of my 125's with a smashed circuit board.. it works.
Once you change out the caps and the opamp/t1 to t4 then do the calibration procedure. The adjustment pots are pretty reliable they shouldnt need changing at all.
Oh one other thing.. there is a neon lamp on the circuit board.. dont damage that as it is important in loading the circuit... I dont knoe if you can replace these easily as they have a specific voltage and current draw,
Welcome to the dungeon of owning a classic and beautiful bit of gear
Nick
Thorens Dept.
The next bit is my contribution to the magnificent td125
TD125 MKII circuitry
As kevin says change out the bridge and the electrolytic caps
then I bet one of your power transistors is bunkum, Change them
Here is a list of components
http://www.theanalogdept.com/images...5II circuit board pics/thorens parts list.xls
Change the opamp (put it a dil socket first then put the opamp into the socket)
Then change out t1 to t4.. My deck stopped where the platter kind of wiggled a bit even though strobe was on.
Short of your motor being cactus this is a very rebuildable deck. I have done pcb design that i used to fix one of my 125's with a smashed circuit board.. it works.
Once you change out the caps and the opamp/t1 to t4 then do the calibration procedure. The adjustment pots are pretty reliable they shouldnt need changing at all.
Oh one other thing.. there is a neon lamp on the circuit board.. dont damage that as it is important in loading the circuit... I dont knoe if you can replace these easily as they have a specific voltage and current draw,
Welcome to the dungeon of owning a classic and beautiful bit of gear
Nick
duderduderini,
I'm familiar with those sites and they help and I know that there are only a finite number of pieces on that board and that number is small - excluding the resistors, there are no more than 12 to 16 pieces and I know that if I don't know which piece is faulty I can always try changing them all. But that is the path I was trying to avoid. I would like to be able to pinpoint the problem. But I don't know how to do that. So, at the end, I might do it by brute logic which is to change everything or as much as I can. But even in trying to do so I have a problem, that is I don't know where to get these pieces. Are they commonplace? If you read my previous message you know that I have a hard time finding the rectifier bridge because I can't find the original and I don't know what to substitute it with. All I have ordered are the two caps c2 and c4. Those I could find easily. The lamp is also easy to find. RadioShack has a mini 6V 250mA lamp which should work although I'm not sure what the life on it will be. Better choices are EIKO lamps such as EIKO 7381 at least here in the US. The life of that is 20000 hours.
I think I should have started my own thread of needing help with my td125. This is grahamwales thread who has already solved his problem so for most people who look at this thread they think the problem is solved. And I came in precisely to ask grahamwales what he did to solve his problem and he has not answered.
At this point I'm waiting for the caps to arrive; a thinner solder tip I've ordered to arrive; finding a source for all the other pieces including the rectifier bridge which I've not been able to locate. And I'm not even sure if my rectifier is bad. The check I did which said it was bad was with it still on the board and you know that can't be a valid test. It has to come off the board to be tested.
I know that this an old circuit but still it shouldn't have all, except for the electrolytic caps, gone bad in this time. Also, Kevin talks about some other electrolytic caps on this beside c2, c4. Which ones are they?
Thanks all.
I'm familiar with those sites and they help and I know that there are only a finite number of pieces on that board and that number is small - excluding the resistors, there are no more than 12 to 16 pieces and I know that if I don't know which piece is faulty I can always try changing them all. But that is the path I was trying to avoid. I would like to be able to pinpoint the problem. But I don't know how to do that. So, at the end, I might do it by brute logic which is to change everything or as much as I can. But even in trying to do so I have a problem, that is I don't know where to get these pieces. Are they commonplace? If you read my previous message you know that I have a hard time finding the rectifier bridge because I can't find the original and I don't know what to substitute it with. All I have ordered are the two caps c2 and c4. Those I could find easily. The lamp is also easy to find. RadioShack has a mini 6V 250mA lamp which should work although I'm not sure what the life on it will be. Better choices are EIKO lamps such as EIKO 7381 at least here in the US. The life of that is 20000 hours.
I think I should have started my own thread of needing help with my td125. This is grahamwales thread who has already solved his problem so for most people who look at this thread they think the problem is solved. And I came in precisely to ask grahamwales what he did to solve his problem and he has not answered.
At this point I'm waiting for the caps to arrive; a thinner solder tip I've ordered to arrive; finding a source for all the other pieces including the rectifier bridge which I've not been able to locate. And I'm not even sure if my rectifier is bad. The check I did which said it was bad was with it still on the board and you know that can't be a valid test. It has to come off the board to be tested.
I know that this an old circuit but still it shouldn't have all, except for the electrolytic caps, gone bad in this time. Also, Kevin talks about some other electrolytic caps on this beside c2, c4. Which ones are they?
Thanks all.