Hi All,
This is my coat check and 1st post rolled into one. I have been reading up on a few post on this forum for help with a problem I am faced with regards to my Logitech Z680 speaker/amp unit.
The unit was working fine one day and just all of a sudden stopped powering on. I initially thought it was the fuse but have confirmed with a spare one and a multimeter continuance test that it's not the problem.
There were no signs of failure prior to the unit actually not powering up at all. I have opened it up and confirmed that there is no burnt capacitors, resistors, IC's e.t.c and it appears that all the LM chip amps are still in fine working order.
I have tried to do some troubleshooting with my limited knowledge and I have come down to what I think is the problem causing part.........The TOROIDAL TRANSFORMER. Although, I am not 100% sure as I'm not very certain on how to test it properly to see if there is a short in the windings.
Before I go any further the specs of the toroid are as follows:
The transformer is a Tenpao Model # TOU543005F0
The diagram on the side shows the Primary as 240v brown 0v black and Secondarys with a 26.2v orange, 0v black, 26.2v yellow, and then a 14.5v blue and 0v blue.
I have tried using the multimeter to test the secondary rails with red probe on orange and black probe on the 0v black but don't seem to get a very clear reading.
What i would really like your much appreciated help with is either how to 100% confirm if it is the transformer that needs replacing or method to test the unit so I get a clear more definitive answer.
If possible I would also like some advice on whether the Toroidal's I found at these sites below will be a suitable replacement for my unit. If so then which one would you recommend.
https://secure.vividcluster.crox.ne....asp?ID=MT2114&CATID=19&form=CAT&SUBCATID=539
OR
160VA Toroid Transformer
Sorry to make it such a long post but if you still feel like it is not enough details then please let me know and I will try to answer them to the best of my ability.
Thank you kindly in advance for you help and any sort of assistance/advice will be greatly appreciated.
This is my coat check and 1st post rolled into one. I have been reading up on a few post on this forum for help with a problem I am faced with regards to my Logitech Z680 speaker/amp unit.
The unit was working fine one day and just all of a sudden stopped powering on. I initially thought it was the fuse but have confirmed with a spare one and a multimeter continuance test that it's not the problem.
There were no signs of failure prior to the unit actually not powering up at all. I have opened it up and confirmed that there is no burnt capacitors, resistors, IC's e.t.c and it appears that all the LM chip amps are still in fine working order.
I have tried to do some troubleshooting with my limited knowledge and I have come down to what I think is the problem causing part.........The TOROIDAL TRANSFORMER. Although, I am not 100% sure as I'm not very certain on how to test it properly to see if there is a short in the windings.
Before I go any further the specs of the toroid are as follows:
The transformer is a Tenpao Model # TOU543005F0
The diagram on the side shows the Primary as 240v brown 0v black and Secondarys with a 26.2v orange, 0v black, 26.2v yellow, and then a 14.5v blue and 0v blue.
I have tried using the multimeter to test the secondary rails with red probe on orange and black probe on the 0v black but don't seem to get a very clear reading.
What i would really like your much appreciated help with is either how to 100% confirm if it is the transformer that needs replacing or method to test the unit so I get a clear more definitive answer.
If possible I would also like some advice on whether the Toroidal's I found at these sites below will be a suitable replacement for my unit. If so then which one would you recommend.
https://secure.vividcluster.crox.ne....asp?ID=MT2114&CATID=19&form=CAT&SUBCATID=539
OR
160VA Toroid Transformer
Sorry to make it such a long post but if you still feel like it is not enough details then please let me know and I will try to answer them to the best of my ability.
Thank you kindly in advance for you help and any sort of assistance/advice will be greatly appreciated.
Thanks for your reply and advice.
I have tried testing the unit with the power in the following ways.
probes red--->orange--->yellow but don't get any reading | multimeter set at 200/500 Volts ~
probes red--->orange + black--->black but don't get any reading | multimeter set at 200/500 Volts ~
probes red--->blue + black-->blue but don't get any reading | multimeter set at set at 200/500 Volts ~
I have also tried with the power off but get similar results. I have only been able to test the secondary rails so far as the primaries are still solder in. I didn't want to unsolder or remove anything just yet in case it wasn't the power transformer. I have also tried setting the multimeter to resistance and I do get continuance. But I have a feeling I am doing something wrong or have set the meter at the incorrect mode.
Am I setting the multimeter correctly and should be I setting it to 20 Volts AC or DC?
One more bit of detail I would like to provide is I gone out to buy a non touch AC voltage tester (the one's that beep when a current is detected). The really weird thing is when I use it to test the unit it seems to detect a current from the mains cable all the way to the fuse but then it seems to stop close to the power switch??? Could this possibly mean that the power switch is faulty or dead? But it looks perfectly fine and I have checked the soldered connections that connect it to the fuse then to the mains as well and they all appear to be fine.
Any help is greatly appreciated and thank you kindly in advanced.
Thank you for your help once again.
I have retested again with the multimeter set to 200V~ and to make sure I have used another multimeter to perform the same test as well but that also shows the same result.
If it is the switch that is faulty then would it be advisable to unsolder the primaries from the switch/fuse and connect another one? I'm just scared that if I do unsolder it and it doesn't end up being the switch which is faulty then I've screwed things up.
Or can I somehow test the switch itself with the multimeter to find out if it is actually faulty or not?
I have retested again with the multimeter set to 200V~ and to make sure I have used another multimeter to perform the same test as well but that also shows the same result.
If it is the switch that is faulty then would it be advisable to unsolder the primaries from the switch/fuse and connect another one? I'm just scared that if I do unsolder it and it doesn't end up being the switch which is faulty then I've screwed things up.
Or can I somehow test the switch itself with the multimeter to find out if it is actually faulty or not?
Unfortunately, the plug is not removable as it is soldered on so I guess the only way to get it off to check is to unsolder it.
I have taken it to a repair tech for a professional quote and he will let me know how much it would cost to fix it. If the quote is too expensive then I will just try to unsolder a few things and try my luck.
Redshift187, thank you kindly for all of your advice and assistance so far. I will surely post an update after a couple of days with how things went.
If I'm not able to fix the unit then I might just use the TDA's and other parts I can salvage off it to build my very first custom amp project.
I have taken it to a repair tech for a professional quote and he will let me know how much it would cost to fix it. If the quote is too expensive then I will just try to unsolder a few things and try my luck.
Redshift187, thank you kindly for all of your advice and assistance so far. I will surely post an update after a couple of days with how things went.
If I'm not able to fix the unit then I might just use the TDA's and other parts I can salvage off it to build my very first custom amp project.
Just got the unit back from the so called professional electronic repair man and he reckons that there is more than one problem with it. Apparently, there is a problem with the input and output of the unit??? (I'm not sure how he was able to test that without being able to get any power to it.)
Also, he thinks that there may also be a problem with the power supply which is sort of confirming my concerns. I had to leave the unit with him overnight so could not see what was happening hence not able to say exactly how he troubleshooted it. He apparently tested the power switch as well and that was fine according to him. However, due to his lack of or should I say incoherent english skills I was not able to get a clear and concise answers or diagnosis out of him. He said that it is unrepairable and even if it was he wouldn't be able to locate the required parts for it. I somehow find that hard to accept as in this day and age you can pretty much find any part with help of the internet. Also, I don't believe that this unit is damaged beyond repair as there are no burnt parts or signs of damage anywhere.
May I ask if there is anybody from around Australia reading this post may be able to recommend a local repair shop/man close to the Lidcombe/Bankstown/Fairfield area of Sydney NSW so I can take it to for a 2nd opinion?
Or alternatively, if there are any Pro's or experienced McGuyvers reading this post and are local then please PM me. I am a Professional IT Technical Analyst with 10years+ experience so can offer help and assistance with any IT (Hardware or software) assistance in return for your help or maybe even offer a gift of a cartoon of beer, mobile phone or cash to anybody who is able to fix this for me.
Also, he thinks that there may also be a problem with the power supply which is sort of confirming my concerns. I had to leave the unit with him overnight so could not see what was happening hence not able to say exactly how he troubleshooted it. He apparently tested the power switch as well and that was fine according to him. However, due to his lack of or should I say incoherent english skills I was not able to get a clear and concise answers or diagnosis out of him. He said that it is unrepairable and even if it was he wouldn't be able to locate the required parts for it. I somehow find that hard to accept as in this day and age you can pretty much find any part with help of the internet. Also, I don't believe that this unit is damaged beyond repair as there are no burnt parts or signs of damage anywhere.
May I ask if there is anybody from around Australia reading this post may be able to recommend a local repair shop/man close to the Lidcombe/Bankstown/Fairfield area of Sydney NSW so I can take it to for a 2nd opinion?
Or alternatively, if there are any Pro's or experienced McGuyvers reading this post and are local then please PM me. I am a Professional IT Technical Analyst with 10years+ experience so can offer help and assistance with any IT (Hardware or software) assistance in return for your help or maybe even offer a gift of a cartoon of beer, mobile phone or cash to anybody who is able to fix this for me.
Yes, cut 'em apart and see if there are any problems. It seems like a loose wire to me, nothing else... Anyway you're lucky that your transformer is accessible, i had to replace a trafo with shorted turns in a Z-5300, and i basically had to smash open the subwoofer box to get at it then build it a new box. They used so much glue that the box was impossible to open without breaking.
I have just retested the unit as you have advised. I managed to pull back the sheathing where the primaries connect to the power cable--->fuse--->switch and test with the DMM set to 700V~ with the power running but I don't get any sort of reading at all??? The DMM reading was 0 when the power was off and after I switch the power on the reading is still 0. I also tested the switch for continuity and when in the ON position there is continuity and none in the OFF position. I guess my theory about the switch being faulty just went out the door. I then tested the primaries for continuity and there appears to be none either with the power switch on or off.
I also spoke to the repair guy again (or tried too converse anyway) and he told me that the part which is faulty is a SMD on the board which controls the Rear Left and Front Left channels. He reckons that the fault was caused by a shorting of speaker wires or turning the volume up too loud. I find that unbelievable because I just pulled the whole amp apart by unscrewing the board from the heatsinks and could not find any SMD's on the board. at all. Also, correct me if I'm wrong but isn't the output controlled by the 7x TDA chip amps that are connected to the heatsinks? I double checked these TDA chips and they all look like they are in good working order (no obvious marks/burnt/blown on the chips). I was thinking as a next step to try connecting a little EI transformer that I have pulled from another faulty el cheapo brand 5.1 speaker/sub/amp unit which I know is working 100% to see if the unit will power on. Before I do that though I would like to know if that is safe to do, meaning would I be stuffing more components up by doing so? I know that this little EI will probably not have sufficient power to run the Z680's properly but I was just hoping to confirm if the transformer was the only obstacle/problem I am faced with. I think the other faulty sub I pulled the EI from was only 50RMS so it probably just has 2x 12volt primaries.
Any further assistance with this would be greatly appreciated and I would like to take the chance here to thank Redshift187 for all his help and valuable advice thus far.
I also spoke to the repair guy again (or tried too converse anyway) and he told me that the part which is faulty is a SMD on the board which controls the Rear Left and Front Left channels. He reckons that the fault was caused by a shorting of speaker wires or turning the volume up too loud. I find that unbelievable because I just pulled the whole amp apart by unscrewing the board from the heatsinks and could not find any SMD's on the board. at all. Also, correct me if I'm wrong but isn't the output controlled by the 7x TDA chip amps that are connected to the heatsinks? I double checked these TDA chips and they all look like they are in good working order (no obvious marks/burnt/blown on the chips). I was thinking as a next step to try connecting a little EI transformer that I have pulled from another faulty el cheapo brand 5.1 speaker/sub/amp unit which I know is working 100% to see if the unit will power on. Before I do that though I would like to know if that is safe to do, meaning would I be stuffing more components up by doing so? I know that this little EI will probably not have sufficient power to run the Z680's properly but I was just hoping to confirm if the transformer was the only obstacle/problem I am faced with. I think the other faulty sub I pulled the EI from was only 50RMS so it probably just has 2x 12volt primaries.
Any further assistance with this would be greatly appreciated and I would like to take the chance here to thank Redshift187 for all his help and valuable advice thus far.
RavenPhoenix, you can see if the power switch and toroidal transformer are all OK by testing continuity with your multimeter on the resistance range. Disconnect the power cable from the 240v mains, and measure across the active and neutral of the power cable with the power switch turned on you should be able to see the primary side of the the power transformer, my guess is you should see something like 20 - ohms on the primary side of the transformer. Set your multimeter to the ohms range or resistance. If you cannot see this and you are sure the fuse is OK then you have confirmed that the toroid has gone open circuit. It could also be the power switch which has failed or a poorly soldered joint which has finally gone completely open.
Note this kind of testing must only be done while the unit is disconnected from Mains power.
Look for filter components on the primary (mains) side of the transformer which may also have gone open circuit. These could be smaller coils or thermal fuses for protection circuits.
Let me know how you go when you get the unit back I am in Adelaide but have a friend in Sydney who may be able to help.
Note this kind of testing must only be done while the unit is disconnected from Mains power.
Look for filter components on the primary (mains) side of the transformer which may also have gone open circuit. These could be smaller coils or thermal fuses for protection circuits.
Let me know how you go when you get the unit back I am in Adelaide but have a friend in Sydney who may be able to help.
RavenPhoenix, you can see if the power switch and toroidal transformer are all OK by testing continuity with your multimeter on the resistance range. Disconnect the power cable from the 240v mains, and measure across the active and neutral of the power cable with the power switch turned on you should be able to see the primary side of the the power transformer, my guess is you should see something like 20 - ohms on the primary side of the transformer. Set your multimeter to the ohms range or resistance. If you cannot see this and you are sure the fuse is OK then you have confirmed that the toroid has gone open circuit. It could also be the power switch which has failed or a poorly soldered joint which has finally gone completely open.
Note this kind of testing must only be done while the unit is disconnected from Mains power.
Look for filter components on the primary (mains) side of the transformer which may also have gone open circuit. These could be smaller coils or thermal fuses for protection circuits.
Let me know how you go when you get the unit back I am in Adelaide but have a friend in Sydney who may be able to help.
Note this kind of testing must only be done while the unit is disconnected from Mains power.
Look for filter components on the primary (mains) side of the transformer which may also have gone open circuit. These could be smaller coils or thermal fuses for protection circuits.
Let me know how you go when you get the unit back I am in Adelaide but have a friend in Sydney who may be able to help.
I have retested the unit as per Peter's instructions and here are my results:
With DMM set to resistance and power switch on.
Get a reading of 8 on one DMM and 6 from secondary cheaper DMM from probing the active and neutral primary cables behind the power switch and mains cable.
With the power switched off.
I get a reading of infinity (or at least I thin it is infinity) on both as on one DMM it is a 1 and the other it is a -0.
Does that mean the trafo is OK? I didn't get a reading of 20 but I did get some sort of reading at least. I have checked around for the "filters" and "thermal fuses" and could not see any of them. Maybe it's cause I'm a noob and don't really know what I'm looking for.
I can make a video or take photos of while I'm testing the unit if that is of any help to you guys providing further assistance?
Peter, I would really appreciate it if your friend in Sydney is able to help and I promise to make it worth his time. Even if he can't fix the damn thing at least I can make a new friend.
Thanks heaps for all your help guys, I'm loosing too much sleep over this and really would like to get to the bottom of things.
With DMM set to resistance and power switch on.
Get a reading of 8 on one DMM and 6 from secondary cheaper DMM from probing the active and neutral primary cables behind the power switch and mains cable.
With the power switched off.
I get a reading of infinity (or at least I thin it is infinity) on both as on one DMM it is a 1 and the other it is a -0.
Does that mean the trafo is OK? I didn't get a reading of 20 but I did get some sort of reading at least. I have checked around for the "filters" and "thermal fuses" and could not see any of them. Maybe it's cause I'm a noob and don't really know what I'm looking for.
I can make a video or take photos of while I'm testing the unit if that is of any help to you guys providing further assistance?
Peter, I would really appreciate it if your friend in Sydney is able to help and I promise to make it worth his time. Even if he can't fix the damn thing at least I can make a new friend.
Thanks heaps for all your help guys, I'm loosing too much sleep over this and really would like to get to the bottom of things.
Thanks for your concern AndrewT.
I know it is very dangerous to do so and that 240 mains electricity can kill me instantly if I don't do it properly. However, I have studied a little bit of electronics in my high school days and have enough common sense (I think
) to know how to not get myself killed while trying to tackle this issue.Before testing, I always made sure that I checked there were no breakages in the probe wires and that I was well insulated with a pair or plastic gloves/rubber thongs.
I'm really loosing too much sleep over this as you can see from the time of this posting (nearly 1am in the morning checking if anybody has replied with more advice). I would really like to be able to resolve this issue and use it as a means of a stepping stone to getting myself prep'ed with basic knowledge on building my first custom amp.
what does the cheap DMM read when the probes are open circuit in the air?
What is the reading when the probes are touching each other and still in the air?
Now do the same for the less cheap DMM.
Compare your "in circuit" readings to those "in air" readings.
Always, i mean always, i'm a little tipsy but by no means wrong, use the resistance measurement on a piece of equipment that is not plugged into its power source.
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