It's likely you've an issue with the negative supply.
Could you post a picture of the label on the transformer ? and measure, in AC, the voltage across the yellow and brown cable located on the opposite side of the green connector. (not the center one !)
Could you post a picture of the label on the transformer ? and measure, in AC, the voltage across the yellow and brown cable located on the opposite side of the green connector. (not the center one !)
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Here is the picture of the transformer: Shared album - Mykhailo M - Google Photos and I will take the measurement in a moment
I`m not sure if I measured correctly. I placed the multimeter - one pin on the transformer Black pin and another pin on the opposite contacts. I got 0.3, 0.3 and 0.2, 0.2 on the brown and yellow. Shared album - Mykhailo M - Google Photos
I`m not sure if I measured correctly. I placed the multimeter - one pin on the transformer Black pin and another pin on the opposite contacts. I got 0.3, 0.3 and 0.2, 0.2 on the brown and yellow. Shared album - Mykhailo M - Google Photos
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The pair of white & blue: 10.8V and Yellow & Brown 18.7V Here is the picture: Shared album - Mykhailo M - Google Photos
Maybe you are pushing button too quickly and it isn't getting time to switch on ?
Have you tried holding down button and waiting for light to come on ?
Have you tried holding down button and waiting for light to come on ?
With the DMM in AC. Place one probe on the brown cable attached to the 3 screws connector then other probe of the DMM on the yellow cable also attached to the 3 screws connectors, you should either Close 0 either close 36V.
Hi Mykhailo,
It seems to me that you've inserted your op-amps wrong. On metal can packages the notch is on pin 8 and as I see it on your images it is inserted in pin 1 socket position.
Regards,
Oleg
It seems to me that you've inserted your op-amps wrong. On metal can packages the notch is on pin 8 and as I see it on your images it is inserted in pin 1 socket position.
Regards,
Oleg
Hi Oleg, by inserting this way ( which is wrong) it works or at least allows the signal go through if I would insert it in the correct way the sound will be blocked on both channels. If I remove the op-amps ( both) the sound still goes on both channels even with NO op-amps in there - strange. something around op-amps is wrong.
If you applied power to the op-amps while they were inserted the wrong way you may have killed them. To troubleshoot I would insert a suitable opamp in DIP package and see how it goes.
If I place multimeter points on both sides of the 3 points connection (not the middle with both wires) for brown and yellow I get 02.8V Shared album - Mykhailo M - Google Photos
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BTW, it looks like some resistors have been changed on the PCB since they don't fit the footprints and soldering job is not super clean. Was it you who did that or the board came with the modes?
The DAC board came non functioning. I have changed some resistors to rise the output signal or volume out of the DAC which didn`t help.
yes the op-amps were inserted when the DAC board arrived. And didn`t work. I though I have got faulty op-amps, then I have changed to MUSES mono and Analogue devices Mono - didn`t work. I have tried dual - didn`t work either.
Do you remember which op-amps (make/model) were inserted as received? Also "trying" duals in place of singles is not so good idea...
I would suggest to make close-up photos of the op-amp socket and its surrounding (top and bottom of the board). This may help to understand what goes wrong with the op-amps. The presence of audio output without the op-amps suggests that the DAC output works. Since the only active part between the DAC and the line output is op-amp then we should concentrate on troubleshooting this part of the circuit.
Original op-amps that came with the DAC: Shared album - Mykhailo M - Google Photos
1). Op-Amp Photo sarrounding Shared album - Mykhailo M - Google Photos
2). DASC underneath Shared album - Mykhailo M - Google Photos
Thanks
1). Op-Amp Photo sarrounding Shared album - Mykhailo M - Google Photos
2). DASC underneath Shared album - Mykhailo M - Google Photos
Thanks
OK, some observations:
1. The board came with single op-amps which excludes using duals.
2. Four resistors have dry joints or no solder at all. I would expect bad or no electrical connection there. You should definitely resolder those joints.
3. The op-amps are still inserted wrong way around.
1. The board came with single op-amps which excludes using duals.
2. Four resistors have dry joints or no solder at all. I would expect bad or no electrical connection there. You should definitely resolder those joints.
3. The op-amps are still inserted wrong way around.
OK, on the 3 screws connector you should swap the 2 brown cable or the 2 yellow in order to get correct full wave rectifier setup. But it shouldn't solve the supply issue, you now should check the stabilizer.
I'm currently in the train arriving at the station, I should find some time later the get back in the thread
rgds
2. I have left those resistors unsoldered just in case I will need to change them again (didn`t effect the sound or change anything from removing previous).
3. I removed resistors completely now - didn`t change the sound or volume output. If I was to insert them correctly I will have no sound as the sound will be blocked.
3. I removed resistors completely now - didn`t change the sound or volume output. If I was to insert them correctly I will have no sound as the sound will be blocked.