Hello all,
Got a AMR DP-777 SE and has issue with Volume control - always at max - changing attenuation does nothing on Analog Preamp in. Sounds distorted at max vol...
I have read that the SE upgrade has issues with Volume Control chip...
Have not yet checked the DAC part...
Anyone work on one of these before? Let meknow.
Be good, and safe out there.
Got a AMR DP-777 SE and has issue with Volume control - always at max - changing attenuation does nothing on Analog Preamp in. Sounds distorted at max vol...
I have read that the SE upgrade has issues with Volume Control chip...
Have not yet checked the DAC part...
Anyone work on one of these before? Let meknow.
Be good, and safe out there.
DAC portion working fine - just preamp of Digital / analog is not functioning - very distorted...apparently there is an issue on the Volume control chip - its a JRC 1159 8011c.
Anyone have any insight? I resoldered all the connections on that little IC smd, but no luck getting volume to work when attenuated and very distorted....
Currently in Preamp Bypass mode - Dac sounds pretty sweet!
Anyone have any insight? I resoldered all the connections on that little IC smd, but no luck getting volume to work when attenuated and very distorted....
Currently in Preamp Bypass mode - Dac sounds pretty sweet!
You might be able to sketch out a schematic of the volume control circuitry. Look at the signals going in and coming out of the volume control chip. Look at its power supply pins to make sure it is receiving correct power.
If all power pins look good, incoming audio looks good, only audio coming out of the volume chip looks bad, then starting to look like the chip has failed, no?
If all power pins look good, incoming audio looks good, only audio coming out of the volume chip looks bad, then starting to look like the chip has failed, no?
Chip
Hello thanks for reply...trouble is this chip is under another board - cannot check the power to the chip terminals as it needs this top board to operate...
See pic... I should just clean up the soldering...not very clean...
Hello thanks for reply...trouble is this chip is under another board - cannot check the power to the chip terminals as it needs this top board to operate...
See pic... I should just clean up the soldering...not very clean...
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You could solder some thin wire leads to input and output pins, then reassemble it with the test leads sticking out and secured so they can't short out to anything. Power on testing might be possible then.
However, solder to the top side of R12 does look funky in the pic. Don't know what it looks like from other angles. Re-soldering it for good luck might not be unreasonable. Same for other questionable joints. Any evidence of cracked solder or SMD components? Hairline cracks can be hard to see sometimes. Cleaning with flux solvent might help if flux residue is an issue.
Ringing out connections with a ohmmeter might help too.
However, solder to the top side of R12 does look funky in the pic. Don't know what it looks like from other angles. Re-soldering it for good luck might not be unreasonable. Same for other questionable joints. Any evidence of cracked solder or SMD components? Hairline cracks can be hard to see sometimes. Cleaning with flux solvent might help if flux residue is an issue.
Ringing out connections with a ohmmeter might help too.
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You don't have enough wire, or you are worried about causing some new problem?
I see some holes in the PCB, it is 2 layer or more? Wire wrap wire might pass though existing holes, or new ones (if only 2 layers and you can see what is on both sides).
I see some holes in the PCB, it is 2 layer or more? Wire wrap wire might pass though existing holes, or new ones (if only 2 layers and you can see what is on both sides).
Why not two long wires, one to look at analog in, one to look at analog out for a channel that has the symptom. I guess the power rails could be rung out with power off.
Or, replace the chip if you want to go with a hunch. Never know, you might guess right first time.
Or, replace the chip if you want to go with a hunch. Never know, you might guess right first time.
If grounds are common you only need signal wires. And proving one channel is distorting inside the chip is probably enough to declare the chip bad (assuming power is okay). So, one input signal wire, and one output signal wire, no?
R12 - I will hit it quick. may be the power...but if R12 was not properly connected only one channel would be off...hmmm
I think the R11/R12 are the inputs...need to get at it again...
I think the R11/R12 are the inputs...need to get at it again...
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could it be a lead or a resistor shorted to gnd, caps that have bounded (x7r smd) not showing its cold joint to the ground... around that chip, trimpot somewhere, relay ? Not a tech I am, just guessing... had a sort of that issue on the analog domain on an amp... though not on both channel, hence the chip as you guessed perhaps ?!
Since issue on both channels, either chip or + or - voltage to chip...methinks...
There are a few other connections not power or voltage /ground connections that could also be culprit (chip control)...
There are a few other connections not power or voltage /ground connections that could also be culprit (chip control)...
rapid resoldering of passive parts joint around ? AMR uses also 4 poles resistors a lot... and indeed a 4 layers boards would be a mess to fix..
Yes the AMR has problems with the volume control IC. Just replace it and 99% sure you're good to go. We had 1 customer having the issue several times, but don't know what IC was used as a substitute (thinking different brand or type instead of the standard fitted on the board.
Either way, it beats looking for errors, as it's the only issue I know these boards have.
Either way, it beats looking for errors, as it's the only issue I know these boards have.
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OK, ordered two JRC NJW1159 chips ($2.33 each and $8 ship).
I would rather not try messing with unit to get existing chip working if the fault may lie (99%) with chip... as I was initially thinking...
I would rather not try messing with unit to get existing chip working if the fault may lie (99%) with chip... as I was initially thinking...
Well I tried to remove the mini volume board and was not coming loose - so I de-soldered the 1159 chip and put in a new one. I did get volume control back on the left channel but right channel had static...went back in a resoldered all connection a few more times, but still couldn't get that right channel working. After messing with it until late, I ended up buggering the whole board. Well at least the unit works great as a DAC with preamp Bypassed, but no volume control....
I bought a couple of those 1159 chips, and considering buying a ssop16 board, to mount the chip and then wire them to direct main board, but can only make out a couple of those connections. There appear to be 5 connections on left side, and 7 on the right...I wish I took a pic of the tracing under the chip...
5 on left going down
#1 - ?
#2 - +7v
#3 - ?
#4 - GRND
#5 - ?
7 on right going down
#1 - ?
#2 - CLK, CE1, CE2
#3 - ?
#4 - INL
#5 - GRND
#6 - ?
#7 - GRND
I bought a couple of those 1159 chips, and considering buying a ssop16 board, to mount the chip and then wire them to direct main board, but can only make out a couple of those connections. There appear to be 5 connections on left side, and 7 on the right...I wish I took a pic of the tracing under the chip...
5 on left going down
#1 - ?
#2 - +7v
#3 - ?
#4 - GRND
#5 - ?
7 on right going down
#1 - ?
#2 - CLK, CE1, CE2
#3 - ?
#4 - INL
#5 - GRND
#6 - ?
#7 - GRND
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