I just assembled and tried the DAC for the first time.
Unfortunately it’s a no go, so I need some help.
I noticed that one of the DACs was warmer than the other so I immediately cut the power.
I carefully checked for shorts. First - between the rails, then - the caps. Nothing. Finally, after a long time I started checking the DAC pins. I noticed a short on one of the (colder one) DACs between pin 1 and 2.
I pulled it out of the socket to make sure it’s the DAC and not the rest of the PCB. I’t s the DAC.
I guess I’m open to a) suggestions and b) if someone is selling another pair of 1862s.
In the meantime, since I still seem to have one chip, I’ll keep digging and will try to make at lest one of the channels work.
On a totally separate note, I realized I have bought a while ago some 4627. I have at least 6 soldered on single brown dog adapters.
If someone is interested, I’ll part with a couple for now - I bought a pair of 627s for this project and I may part with the rest of the 4627 if you guys insist
It seems I also have some 49990 - at least 2 unsoldered and at least 4 more on 2 dual brown dog adapters.
Send me PMs if interested - I’m not eager to part with them, but would be willing to help fellow enthusiasts and save them from evil bay.
All these parts were acquired from Mouser, so 100% legit.
It’s alive!
Well, half of it. Can anyone measure the resistance between pin 1 and 2 on a normal chip?
As I said above, I assumed the chip with the short between pins 1 and 2 was the bad one. That was the “cold” one.
So I reassembled the DAC and put the “hot” one in. There was a faint sound - very faint.
So in Hail Mary attempt, I decided to try the “broken” one in the other channel. It was all perfect.
So, it seems short between 1 and 2 is OK.
I will sacrifice the remaining good chip and will put it in the other position to see if both of the channels are OK. I did measure everything before testing again and I don’t see any differences between the channels: everything is symmetrical.
I am being sent two more chips, so if the swap works, I’ll just put them in and case closed.
bummer.
Maybe Happylistening has one spare of Rochester left in a next group buy as they are sold by 5 units packaging ???
If someone has a single from Rochester and I don’t fry the remaining chip, I’ll be happy to get it. Please let me know.
Mouser BOM
Here is my BOM if anyone needs some help in picking parts. Mind you that I used Panasonic FC which are 6,5 mm diameter so it will be tight so look for Vunce or others posts for alternative capasitor placement.
And there is no op-amps included in this BOM.
I am also open to suggestions for some better parts.
View attachment AD1862_DAC.pdf
Here is my BOM if anyone needs some help in picking parts. Mind you that I used Panasonic FC which are 6,5 mm diameter so it will be tight so look for Vunce or others posts for alternative capasitor placement.
And there is no op-amps included in this BOM.I am also open to suggestions for some better parts.
View attachment AD1862_DAC.pdf
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Hi diyiggy, I know first build I used Nichicon audio grade so thats why now I am adding Panasonic I also put in my basket suggested Tantalum SMD Capacitors for C15, C16, C25 and C26. To do some comparison. And test diferent capasitors on the second board while using first board for reference...
Thanks will try first without soldering
Thanks will try first without soldering
Sacrifice went as per a Hollywood script: all was good in the end. The good chip works fine in the “bad” channel.
So I’m waiting for the new chips to arrive and will start rolling opamps, compare and report.
I’m thinking of desoldering the 49990 from one of the dual adapters and testing with it as well as 4627, 627 and some others I have laying around.
Question: is there a list (or a link to messages) where OpAmps are compared for this setup? I’m especially interested whether we know which are stable. I have an oscilloscope and can measure oscillations, but I need a start... the search engine is quote bad with 3-digit search terms, so it’s tricky to search for “627” etc...
Thanks for all the help guys!
Be sure to let a few hours "burn-in" for the new AD1862 DACs, then start testing.
There is not such a list or a collection of links. There aren't many testers yet. A few fellows built this DAC and they are mentioned in the first post. In the end you will probably search post by post anyway - try ctrl+f on each page.
There is not such a list or a collection of links. There aren't many testers yet. A few fellows built this DAC and they are mentioned in the first post. In the end you will probably search post by post anyway
- try ctrl+f on each page.
Hi,
Andrea Mori opened his GB (GB section) for his master clock we all wait for almost 20 years now.
There is a not expensive bare board power supply which is Gnd - +3.3V or +5V or +6v : called TWRPS-pp micro PCB
I don't know yet if two boards of it according the embeded reg and caps arrengments could provide a -6v-gnd-+6v. Anyway 8 euros the bare pcb.
There is another board more expensibe around 20 euros that can provide GND-+10 to +16V , if the same is possible, two boards could make a good supply for the oap stage for the non 5V oaps !
To be checked as these boards are single poer supply and not +/gnd/- needed for the Miro's ad1862 pcb
.
Anyway Andrea and his co-dev made + the help of some great engineers diy enthusiasts a great and long work and it is giving a wonderfull opportunity to have a sota masterclock for all your dac boards projects.
Andrea Mori opened his GB (GB section) for his master clock we all wait for almost 20 years now
.There is a not expensive bare board power supply which is Gnd - +3.3V or +5V or +6v : called TWRPS-pp micro PCB
I don't know yet if two boards of it according the embeded reg and caps arrengments could provide a -6v-gnd-+6v. Anyway 8 euros the bare pcb.
There is another board more expensibe around 20 euros that can provide GND-+10 to +16V , if the same is possible, two boards could make a good supply for the oap stage for the non 5V oaps !
To be checked as these boards are single poer supply and not +/gnd/- needed for the Miro's ad1862 pcb
.Anyway Andrea and his co-dev made + the help of some great engineers diy enthusiasts a great and long work and it is giving a wonderfull opportunity to have a sota masterclock for all your dac boards projects.
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Hi diyiggy, your idea is great if the supplies could work on miros dac. [emoji106][emoji106][emoji106][emoji6]Hi,
Andrea Mori opened his GB (GB section) for his master clock we all wait for almost 20 years now
There is a not expensive bare board power supply which is Gnd - +3.3V or +5V or +6v : called TWRPS-pp micro PCB
I don't know yet if two boards of it according the embeded reg and caps arrengments could provide a -6v-gnd-+6v. Anyway 8 euros the bare pcb.
There is another board more expensibe around 20 euros that can provide GND-+10 to +16V , if the same is possible, two boards could make a good supply for the oap stage for the non 5V oaps !
To be checked as these boards are single poer supply and not +/gnd/- needed for the Miro's ad1862 pcb
Anyway Andrea and his co-dev made + the help of some great engineers diy enthusiasts a great and long work and it is giving a wonderfull opportunity to have a sota masterclock for all your dac boards projects.
look at here : The Well Regulated Power Supply
And also one always need. PS for the source (streamer , RPI, USB to I2S board and so on)
And also one always need. PS for the source (streamer , RPI, USB to I2S board and so on)
Separate PSU grounds
I correstponded with @Paddy Garcia and thougt I should ask in the main thread too.
I have an old PSU from Adcom GDA-700 DAC that I recapped and replaced the regulator chips, etc, but then failed when trying to replace the DAC chips.
So I canibalazied the PSU. It provides Analog +/-12, +-16, +/-5 and Digital +/-5.
The Digital uses the LM317 and a separate trafo, while the Analog is using a beefier trafo and 78xx/79xx regs. The grounds are not connected. I measured some minor potential between them.
Since the DAC PCB GND is common, what do you think I should do: use only the Analog outs (which I’m doing right now) or use the Digital for the +/-5V and Analog - for the +/-12V?
I have other options - many other - but this is an interesting qiestion that would help mine and hopefully other members education.
I correstponded with @Paddy Garcia and thougt I should ask in the main thread too.
I have an old PSU from Adcom GDA-700 DAC that I recapped and replaced the regulator chips, etc, but then failed when trying to replace the DAC chips.
So I canibalazied the PSU. It provides Analog +/-12, +-16, +/-5 and Digital +/-5.
The Digital uses the LM317 and a separate trafo, while the Analog is using a beefier trafo and 78xx/79xx regs. The grounds are not connected. I measured some minor potential between them.
Since the DAC PCB GND is common, what do you think I should do: use only the Analog outs (which I’m doing right now) or use the Digital for the +/-5V and Analog - for the +/-12V?
I have other options - many other - but this is an interesting qiestion that would help mine and hopefully other members education.
Separating the power supplies/trafo/winding for digital (+-5V) and analog (+-12V) is suitable.
As you connect both grounds together, the potential becomes null (common).
The best connection should be one place, where the conversion from digital to analog occurs, it is the DAC PCB in our case.
In a case of independent regulators for each channel (2x +-5V, 2x +-12), you can connect them separately for each channel (instead of J1-J13).
As you connect both grounds together, the potential becomes null (common).
The best connection should be one place, where the conversion from digital to analog occurs, it is the DAC PCB in our case.
In a case of independent regulators for each channel (2x +-5V, 2x +-12), you can connect them separately for each channel (instead of J1-J13).
Side: last call for a group buy of AD1862 from Rochester: Another Rochester AD1862N group buy?
When you say common ground is the DAC PCB, do you mean to use the output channels grounds to connect to the chassis? Like take the output grounds connect them together and then use a wire to the chassis star ground or take from one of the output channels ground to the chassis? I have a separate transformer for +/-12vdc and also another separate transformer for (+/-5vdc and +3.3vdc for the I2S dac). Right now I used the +/-12vdc ground to connect to the chassis star ground. Whenever the DAC is powered up I see a slight thump on my setup as the USB is connected to a raspberry pi running Roon transport.
Thanks
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Hi Maniraj,
If you use three wires main power cable and your local rules about electricity and security needs that, you can connect the Earth wire of the cable on your metal enclosure.
That means the rca connectord gnd must be isolated from the metal cabinet to avoid huge ground loops. That is the purpose of the nylon round layets tjat are provided with rca socket.
The gnd of the pcb is connected to the orhers devices via the gnd wires of the rca cables.
So the dac pcb must be isolated from the metal enclosure. In some countries, there are no earth main connector for these low power devices. In some countries I believe you must be earthed.
I use wound cabinet for dac as my flat electrical circuitry has diferential switching that prevent shorts that can fire your place.
If you use three wires main power cable and your local rules about electricity and security needs that, you can connect the Earth wire of the cable on your metal enclosure.
That means the rca connectord gnd must be isolated from the metal cabinet to avoid huge ground loops. That is the purpose of the nylon round layets tjat are provided with rca socket.
The gnd of the pcb is connected to the orhers devices via the gnd wires of the rca cables.
So the dac pcb must be isolated from the metal enclosure. In some countries, there are no earth main connector for these low power devices. In some countries I believe you must be earthed.
I use wound cabinet for dac as my flat electrical circuitry has diferential switching that prevent shorts that can fire your place.
Ok thanks, I will use only one ground wire from the +/-12vdc PSU to the star ground on the chassis and not connect the +/-5vdc ground to the same point. I will see which makes better as currently I do not have any hum or hiss issues with this star ground connection as the RCA jacks are isolated from the cabinet and that is the only one ground connection point from the psu to the chassis via a thermistor and then from that point to the IEC safety earth per electrical rules.