Topping d70s MQA dac troubleshooting.

[Andy74]

HI, I am new to the forum. Seeking some advice and help please.

I brought a Topping d70 dac from the USA to home in the UK. I plugged the unit into the socket at 230v. Apparently there is a voltage selection switch in the unit, which I did not realise. The unit for selected for 115v. I did to realise my mistake until after the damage wad done.

The unit powered on with a buzzing noise and the word “PROTECT” displayed in the panel for few minutes and it died. I opened the unit and found the big blue round possibles a toroidal transformer bulged on two sides. It looks like its burnt. Where can I find a replacement.? Any advice and help please. Its soldered on to the PCB. Please see pic. Thanks

 

[Sokel]

I don't think it will be as easy as changing the toroidal unless you're very lucky and the fire (yes,fire did that) haven't damaged PCB.
And with a multilayered pcb like this you can't be sure unless you measure everything and it's ok.

Better take it to a repair shop,it's a long shot,but...

 

[DVDdoug]

The bad news is that the toroidal transformer, buy itself, would almost have certainly survived. Something else probably "blew" and shorted, drawing excess current and then burning the transformer. .

Although... Doubling the voltage is 4-times the power (assuming nothing else changes/happens). That might overheat the transformer but I wouldn't expect that to happen right away, and DACs don't use a whole lot of power.

And/or that blue housing looks like a heatsink so maybe the whole power supply (or most of it) is in there.

 

[Sokel]

Is that dirt/flux or burned?

 

[Andy74]

It’s not burnt. Rest of the PCB and the components looks fine on inspection. Only the blue TT has bulges.

 

[Andy74]

I have written to the Topping to see if they will sell me a similar replacement transformer. The Local Hifi repair guys (who deals with really high end stuff) has agreed to replace that transformer (if i can get it) and also check other components. Hoping that every thing will work.

 

[Roland68]

HI, I am new to the forum. Seeking some advice and help please.

I brought a Topping d70 dac from the USA to home in the UK. I plugged the unit into the socket at 230v. Apparently there is a voltage selection switch in the unit, which I did not realise. The unit for selected for 115v. I did to realise my mistake until after the damage wad done.

The unit powered on with a buzzing noise and the word “PROTECT” displayed in the panel for few minutes and it died. I opened the unit and found the big blue round possibles a toroidal transformer bulged on two sides. It looks like its burnt. Where can I find a replacement.? Any advice and help please. Its soldered on to the PCB. Please see pic. Thanks

You have a chance that nothing has happened to the device.
The transformer received twice the voltage, the primary current also doubled, and four times the power suddenly caused it to boil.
Since after the transformer there are rectifier diodes, capacitors and voltage regulators, it is possible that these components have survived. All components in front of the transformer, i.e. all on the power grid side, especially the filter choke, should be checked.

But the transformer is not a standard part. In the picture you can see which pins belong to the transformer. According to the pin assignment, the primary side is 2 x 0-110V and on the secondary side there are 3 voltages. Probably +/- ?? with center tap for the analog side and + ?V for the digital side.
If you don't get a replacement transformer, I would simply put 2 transformers in an external housing, alternatively 2 switching power supplies with filters. That doesn't make the device any worse.
However, you would have to find out the 3 output voltages of the transformer.
Maybe a forum member will be so kind and measure the 3 voltages before and after the rectifiers on his device.

Good luck and don't take it so hard

 

[Andy74]

You have a chance that nothing has happened to the device.
The transformer received twice the voltage, the primary current also doubled, and four times the power suddenly caused it to boil.
Since after the transformer there are rectifier diodes, capacitors and voltage regulators, it is possible that these components have survived. All components in front of the transformer, i.e. all on the power grid side, especially the filter choke, should be checked.

But the transformer is not a standard part. In the picture you can see which pins belong to the transformer. According to the pin assignment, the primary side is 2 x 0-110V and on the secondary side there are 3 voltages. Probably +/- ?? with center tap for the analog side and + ?V for the digital side.
If you don't get a replacement transformer, I would simply put 2 transformers in an external housing, alternatively 2 switching power supplies with filters. That doesn't make the device any worse.
However, you would have to find out the 3 output voltages of the transformer.
Maybe a forum member will be so kind and measure the 3 voltages before and after the rectifiers on his device.

Good luck and don't take it so hard

View attachment 326997

You assessment is very knowledgeable. I written to Topping , China, to see if they will sell me a replacement transformer. Yet to hear from them. The other components before the transformer namely the filter chose , 2 small capacitors and voltage selection switch all appears ok visually on closer inspection. Anyway, I don’t have equipment to check them. I need to take it to a professional. Also the output voltage of the transformer is not know.

Thank you for your input.

 

[Roland68]

You assessment is very knowledgeable. I written to Topping , China, to see if they will sell me a replacement transformer. Yet to hear from them. The other components before the transformer namely the filter chose , 2 small capacitors and voltage selection switch all appears ok visually on closer inspection. Anyway, I don’t have equipment to check them. I need to take it to a professional. Also the output voltage of the transformer is not know.

Thank you for your input.

A resourceful technician should be able to figure out what voltages are needed based on the components on the board in case Topping doesn't want to help. The analog voltage (+/-) will be approximately 2 x 7-15V AC and the digital one will be 5-9V AC. If a technician has an adjustable transformer, he can just try it out.

Unfortunately, you can't tell from the outside of the components whether there is a defect. In such a case I would replace all parts (except the voltage selector) because the components are cheap and it takes less time than checking everything. I would swap the filter choke for a higher quality one, e.g. TDK, with the same values but a higher current load.

 

[Andy74]

A resourceful technician should be able to figure out what voltages are needed based on the components on the board in case Topping doesn't want to help. The analog voltage (+/-) will be approximately 2 x 7-15V AC and the digital one will be 5-9V AC. If a technician has an adjustable transformer, he can just try it out.

Unfortunately, you can't tell from the outside of the components whether there is a defect. In such a case I would replace all parts (except the voltage selector) because the components are cheap and it takes less time than checking everything. I would swap the filter choke for a higher quality one, e.g. TDK, with the same values but a higher current load.

View attachment 327149

How do i find the value of the capacitors which are located before the transformer? There are 2 of them. Also the filter choke, can i buy any make and expect it to fit into the existing slots?

Thank you for your help.

 

[Andy74]

You have a chance that nothing has happened to the device.
The transformer received twice the voltage, the primary current also doubled, and four times the power suddenly caused it to boil.
Since after the transformer there are rectifier diodes, capacitors and voltage regulators, it is possible that these components have survived. All components in front of the transformer, i.e. all on the power grid side, especially the filter choke, should be checked.

But the transformer is not a standard part. In the picture you can see which pins belong to the transformer. According to the pin assignment, the primary side is 2 x 0-110V and on the secondary side there are 3 voltages. Probably +/- ?? with center tap for the analog side and + ?V for the digital side.
If you don't get a replacement transformer, I would simply put 2 transformers in an external housing, alternatively 2 switching power supplies with filters. That doesn't make the device any worse.
However, you would have to find out the 3 output voltages of the transformer.
Maybe a forum member will be so kind and measure the 3 voltages before and after the rectifiers on his device.

Good luck and don't take it so hard

View attachment 326997

Hi, what sort of external transformers are you talking about, Pleae educate me . Thanks.

 

[Roland68]

Hi, what sort of external transformers are you talking about, Pleae educate me . Thanks.

The values should be on the capacitors, but they can also be varistors or something else. The size of the filter throttle must be appropriate and the legs must be able to be aligned. But everything I write should be done by a technician or experienced DIYer.

If you don't get the original transformer, it would make sense to use 2 separate and higher quality transformers for analog and digital. They don't fit into the device and therefore have to be in an external housing.
You may also find a transformer with the appropriate 3 voltages, but you have to see whether it fits into the housing.

 

[Andy74]

The values should be on the capacitors, but they can also be varistors or something else. The size of the filter throttle must be appropriate and the legs must be able to be aligned. But everything I write should be done by a technician or experienced DIYer.

If you don't get the original transformer, it would make sense to use 2 separate and higher quality transformers for analog and digital. They don't fit into the device and therefore have to be in an external housing.
You may also find a transformer with the appropriate 3 voltages, but you have to see whether it fits into the housing.

HI, could you please interpret these close up shots Of the capacitors. Thanks.

 

[Andy74]

Also if you could advise where i can purchase these capacitor and the choke filter please that will be of help. My plan is to purchase all the components and take it to the local hifi repair shop and get it done there. Thanks.

 

[Sokel]

These and the choke are probably fine,they are before the 120/240V switch and they can take a lot higher voltage (you can see it on them,400V).

It's best to take it to the repair shop and let the people there order what it needs and may be more components down the road (the reason that so much current was sucked is still unknown)

 

[Andy74]

These and the choke are probably fine,they are before the 120/240V switch and they can take a lot higher voltage (you can see it on them,400V).

It's best to take it to the repair shop and let the people there order what it needs and may be more components down the road (the reason that so much current was sucked is still unknown)

The reason so much current was sucked was because i plugged it to 230V outlet while the unit was selected for 115v. I didn’t realise i had to change the volt from 115 to 230v before plugging it in UK socket.

 

[MaxwellsEq]

The reason so much current was sucked was because i plugged it to 230V outlet while the unit was selected for 115v. I didn’t realise i had to change the volt from 115 to 230v before plugging it in UK socket.

Yes, that is the initial error, but no-one here can deduce the actual current path and what was involved.

 

[trl]

Just change the transformer and let us know after that how are thing going with your Topping device. Better off would be to make this repair in a local repair shop, if possible, as they have several tools to do proper check after the repair and prior to plug the device back into the power outlet.

 

[Andy74]

Just change the transformer and let us know after that how are thing going with your Topping device. Better off would be to make this repair in a local repair shop, if possible, as they have several tools to do proper check after the repair and prior to plug the device back into the power outlet.

I wrote to Topping , China and they advised me to ship the unit to them for service and repair. I did email the photos to them and they were happy to send the replacement transformer. However, they recommended that i send the unit to them to check other components too. I think that would be the sensible thing for me to do as they would be in a far better place to replace other parts if found broken. Will keep the forum posted how things go. Thanks to everyone who advised.

 

[Count Arthur]

Looks very similar to Talema: https://talema.com/products/low-profile-pcb-mount-toroidal-transformers/

If you can match the pin layout and find out the VA and output voltage, they're not overly expensive: https://uk.rs-online.com/web/c/power-supplies-transformers/transformers/toroidal-transformers/?applied-dimensions=4294329366,4294874607