Following up on my original thread posted back in 2022 : thread
Context:
I got a Rega DAC-R second-hand from someone i trust didn't have, or at least didn't notice, any issues with the device prior to shipping it. It turns out it looks (and sounds) like it has significant channel imbalance (see measurements below).
My Goal:
I'm trying to find an obvious issue with this DAC, as i suspect it might be a poor connection or faulty passive component that could've happened during transit or due to age. If it is not, I will send it for repair, but i figured i'd try to give it a try before i do so as it will be costly to the point where i'd rather replace the DAC considering a chip replacement might be more than what i paid for the DAC.
What could help me:
Any guidance in terms of diagnosing possible issues without sophisticated testing equipment. Any knowledge on this particular device or DACs in general (if it is a common issue etc.) as it will be my first attempt at fixing or at least diagnosing a DAC.
Note: I have no expectations, and will provide any and all necessary pictures or measurements I can take as I would be grateful for any help 🙂. I see this as a learning experience if nothing comes out of it.
Thank you to anyone taking the time to reply to this, I'm taking it apart and looking for any visible issues tonight and will update with anything I find worth noting.
Measurements:
Dac-r + brio-r :
Left: 2.88v
Right: 1.99v
Difference: -0.89v / ~ -31%
Dac-r + linn:
Left: 2.84v
Right: 0.94v
Difference: -1.9v / ~ -67%
(Measured at amp speaker output. Issue persists with various amps. Amps are fine with a different DAC.)
Context:
I got a Rega DAC-R second-hand from someone i trust didn't have, or at least didn't notice, any issues with the device prior to shipping it. It turns out it looks (and sounds) like it has significant channel imbalance (see measurements below).
My Goal:
I'm trying to find an obvious issue with this DAC, as i suspect it might be a poor connection or faulty passive component that could've happened during transit or due to age. If it is not, I will send it for repair, but i figured i'd try to give it a try before i do so as it will be costly to the point where i'd rather replace the DAC considering a chip replacement might be more than what i paid for the DAC.
What could help me:
Any guidance in terms of diagnosing possible issues without sophisticated testing equipment. Any knowledge on this particular device or DACs in general (if it is a common issue etc.) as it will be my first attempt at fixing or at least diagnosing a DAC.
Note: I have no expectations, and will provide any and all necessary pictures or measurements I can take as I would be grateful for any help 🙂. I see this as a learning experience if nothing comes out of it.
Thank you to anyone taking the time to reply to this, I'm taking it apart and looking for any visible issues tonight and will update with anything I find worth noting.
Measurements:
Dac-r + brio-r :
Left: 2.88v
Right: 1.99v
Difference: -0.89v / ~ -31%
Dac-r + linn:
Left: 2.84v
Right: 0.94v
Difference: -1.9v / ~ -67%
(Measured at amp speaker output. Issue persists with various amps. Amps are fine with a different DAC.)
2 X WM8742. Do you have an oscilloscope for measuring? I would focus on measuring after the DAC chips and at the outputs. It could be a muting relay that is faulty.
I unfortunately do not have an oscilloscope for now. I can get my hands on a Leader LS8022 quickly though, would that be enough?
Sure. If you measure the outputs of the DAC chip to be OK you can be glad. Then you will need to work to the outputs as something will be wrong there.
Try to find the points where to measure and write them down. Maybe you could find the service manual?! Makes it more easy.
A CD or file of a continuous sinusoidal tone would be handy. Works better than a music CD.
A CD or file of a continuous sinusoidal tone would be handy. Works better than a music CD.
The user manual has "some" information in it : https://www.rega.co.uk/download/dac-r-user-manual-english.pdf
No you need a schematic to do things more focussed. It can be done without it.
Ask Rega by email.
Ask Rega by email.
In absence of instrumentation as oscilloscope, I hope you have any polymeter you can measure resistance and diodes.
Well, in the PCB, you can measure all resistances and semiconductors from the two WM8742 until the two reds capacitors. If you see, in the PCB is serigraphied Left and Right, and the two channels circuits are equals. You have to find any difference that lead you to find the cause of the missequal in output signal. You can check DC voltages, maybe you find anything.
Well, in the PCB, you can measure all resistances and semiconductors from the two WM8742 until the two reds capacitors. If you see, in the PCB is serigraphied Left and Right, and the two channels circuits are equals. You have to find any difference that lead you to find the cause of the missequal in output signal. You can check DC voltages, maybe you find anything.