Hey,
NAIM CD5 SX no analog output (RCA or DIN) setting is set correctly. S/PDIF is working.
Anyone have had similar problems and any tips what could cause this?
Anyone have done reverse engineering to draw schematic of this analog board?
NAIM CD5 SX no analog output (RCA or DIN) setting is set correctly. S/PDIF is working.
Anyone have had similar problems and any tips what could cause this?
Anyone have done reverse engineering to draw schematic of this analog board?
Just very quickly.... scope around all those opamps to see if audio is actual present and check those two relays (which are probably for muting) are in the correct state. Audio may be there but muted for some reason.
It seems that at least two OPA604 are faulty. Is OPA134 good replacement?
There is not so many anymore in DIL package.
Relays seems to be ok.
There is not so many anymore in DIL package.
Relays seems to be ok.
It would be very unusual for an opamp to actually be faulty, more so for two to be suspect. The OPA134 probably would be OK as long as the supply voltage is within limits (OPA604 is -/+24 volt rated) and also as long as the offset null terminals are not used (they don't appear to be) as they are configured differently.
What are you seeing that makes you suspect them?
What are you seeing that makes you suspect them?
See measured results (OPA1/2 1st stage of filter, OPA3/4 2nd stage of filter)
Seems that OPA3/4 are faulty ones
Seems that OPA3/4 are faulty ones
| Pin | Pin name | OPA1 | OPA2 | OPA3 | OPA4 | |
| 1 | offset trim | 0.64 | 0.62 | 1.25 | 14.74 | V |
| 2 | -in | 9.3 | 9.28 | 0.06 | 14.63 | V |
| 3 | +in | 9.2 | 9.2 | 9.31 | 13.97 | V |
| 4 | -vs | 0 | 0 | 0 | 0 | V |
| 5 | offset trim | 0.64 | 0.62 | 0.05 | 14.7 | V |
| 6 | out | 9.31 | 9.26 | 0.07 | 14.6 | V |
| 7 | +vs | 18.64 | 18.62 | 18.52 | 18.52 | V |
| 8 | NC | 0 | 0 | 0 | 0 | V |
I'll tell you what I find strange in all those readings... is it really a single rail design running on 18 volts? Is pin 4 of the chips really connected to ground or is a rail missing, maybe with a shorted tantalum cap as the cause.
You have the advantage in having the board to spin around and look at, I don't 🙂
I see four T0220 devices. Voltage regulators?
You have the advantage in having the board to spin around and look at, I don't 🙂
I see four T0220 devices. Voltage regulators?
Something else unusual, for three of those opamps you have pin 2 as being at a higher voltage than pin 3 (normally in linear circuitry both would be the same voltage) and that means they should be behaving like comparators.
If pin 2 (inverting input) is the higher then the output should swing low and yours are not.
OPA3 readings are an odd one out I agree but that would only be one channel. Worth rechecking that result.
If pin 2 (inverting input) is the higher then the output should swing low and yours are not.
OPA3 readings are an odd one out I agree but that would only be one channel. Worth rechecking that result.
Measurements checked, new results below. I think OPAs 3/4 are faulty.
Board has four regulators, two for OPAs (one for OPA1/2 and 2nd for OPA3/4). Two other regulators are not for OPAs.
Board has four regulators, two for OPAs (one for OPA1/2 and 2nd for OPA3/4). Two other regulators are not for OPAs.
| Pin | Pin name | OPA1 | OPA2 | OPA3 | OPA4 | |
| 1 | offset trim | 0.64 | 0.62 | 1.25 | 14.74 | V |
| 2 | -in | 9.25 | 9.27 | 0.06 | 14.71 | V |
| 3 | +in | 9.25 | 9.27 | 9.31 | 14.07 | V |
| 4 | -vs | 0 | 0 | 0 | 0 | V |
| 5 | offset trim | 0.64 | 0.62 | 0.05 | 14.7 | V |
| 6 | out | 9.25 | 9.27 | 0.06 | 14.71 | V |
| 7 | +vs | 18.62 | 18.62 | 18.52 | 18.52 | V |
| 8 | NC | 0 | 0 | 0 | 0 | V |
| pin 4 is connected to GND (single rail supply power) |
Fair enough 🙂 it's very very unusual to see single rail though... however...
So for 18v single rail seeing 9 volt at the opamp output would be expected. So OPA1 and OPA2 fall into that scenario. Can you see audio on these outputs?
OPA3 and 4 seem to have one with the output stuck at + supply and one at near 0 volts. Opamps are super super reliable and to have two with a fault... it just doesn't happen unless something catastrophic has happened to kill them.
For test purposes you should be able to fit pretty much any unity gain stable opamp, a TL071, even a 741.
Questions I always ask. Has this player got a hidden history? Is it yours or have you acquired it from somewhere?
Indulge me with a couple of questions 😉
Are all those voltage regulators 'positive' types?
Have you looked to see that pin 4 really does physically go to ground?
So for 18v single rail seeing 9 volt at the opamp output would be expected. So OPA1 and OPA2 fall into that scenario. Can you see audio on these outputs?
OPA3 and 4 seem to have one with the output stuck at + supply and one at near 0 volts. Opamps are super super reliable and to have two with a fault... it just doesn't happen unless something catastrophic has happened to kill them.
For test purposes you should be able to fit pretty much any unity gain stable opamp, a TL071, even a 741.
Questions I always ask. Has this player got a hidden history? Is it yours or have you acquired it from somewhere?
Indulge me with a couple of questions 😉
Are all those voltage regulators 'positive' types?
Have you looked to see that pin 4 really does physically go to ground?
Lets just pursue this a bit more...
Given that I say opamps are super reliable (and they really are) lets work on the basis they are not faulty.
Look at OPA3 with pin 3 at 9 volts positive and pin 2 near 0 volts. The output should be swinging to the positive rail. Working on the premise the opamp is good you need to look at where pin 6 goes.
Is anything pulling that pin down?
Is OPA3 warmer than the rest indicating a short?
Could there be a break in the print anywhere that has broken (removed) the feedback.
OPA4 results obviously don't compute with both inputs stuck high.
Which opamp is which on the board? Are the two incorrect ones in the same channel or one in each channel?
Given that I say opamps are super reliable (and they really are) lets work on the basis they are not faulty.
Look at OPA3 with pin 3 at 9 volts positive and pin 2 near 0 volts. The output should be swinging to the positive rail. Working on the premise the opamp is good you need to look at where pin 6 goes.
Is anything pulling that pin down?
Is OPA3 warmer than the rest indicating a short?
Could there be a break in the print anywhere that has broken (removed) the feedback.
OPA4 results obviously don't compute with both inputs stuck high.
Which opamp is which on the board? Are the two incorrect ones in the same channel or one in each channel?
Thanks for qood reply and questions!
Some answers below,
OPA1/2: these are L/R-ch 1st stage filter
OPA3/4: these are L/R-ch 2nd stage filter
1 LM317T: this is delivering power for OPA1/2
2 LM317T: this is delivering power for OPA3/4
OPAs pin4 is going to board GND.
Audio can be seen output of OPA1/2.
The device is one of the friend and no one has been repaired it before.
I have removed OPA3/4 and those will be replaced when I get J-FET OPAs.
Some answers below,
OPA1/2: these are L/R-ch 1st stage filter
OPA3/4: these are L/R-ch 2nd stage filter
1 LM317T: this is delivering power for OPA1/2
2 LM317T: this is delivering power for OPA3/4
OPAs pin4 is going to board GND.
Audio can be seen output of OPA1/2.
The device is one of the friend and no one has been repaired it before.
I have removed OPA3/4 and those will be replaced when I get J-FET OPAs.
Thanks 🙂
So curious and curiouser then with both output OPA's showing problems.
Could your friend have 'hot plugged' anything into the outputs while it (and anything else) was turned on?
Equipment using switching power supplies can be prone to 'leakage' meaning some equipment can have quite a high potential on it if it is just floating and not connected to anything. Something like that could be a possibility.
It was possible to get quite unpleasant 'shocks' from TV's and recorders while coupling them all up if they happened to be on at the time. You could easily draw an arc from an aerial plug to the aerial socket for example... all because of leakage from switching supplies and non earthed (double insulated) equipment.
It is worth you checking and asking.
Also valve audio gear can sometimes have high voltage residual voltage on inputs and outputs if the circuitry isn't terminated correctly internally. All worth asking 🙂
I'll be interested to see if the OPA's are an instant fix. If they are then something external (I would think) has killed them.
So curious and curiouser then with both output OPA's showing problems.
Could your friend have 'hot plugged' anything into the outputs while it (and anything else) was turned on?
Equipment using switching power supplies can be prone to 'leakage' meaning some equipment can have quite a high potential on it if it is just floating and not connected to anything. Something like that could be a possibility.
It was possible to get quite unpleasant 'shocks' from TV's and recorders while coupling them all up if they happened to be on at the time. You could easily draw an arc from an aerial plug to the aerial socket for example... all because of leakage from switching supplies and non earthed (double insulated) equipment.
It is worth you checking and asking.
Also valve audio gear can sometimes have high voltage residual voltage on inputs and outputs if the circuitry isn't terminated correctly internally. All worth asking 🙂
I'll be interested to see if the OPA's are an instant fix. If they are then something external (I would think) has killed them.
No 'hot plugged' was done regarding my friend.
OPA3/4 are replaced with TL071 (for trial) and device is working normally.
So weird that both OPAs failed on same time as you wrote.
OPA3/4 are replaced with TL071 (for trial) and device is working normally.
So weird that both OPAs failed on same time as you wrote.
👍 I'm pleased its working and I can't begin to imagine what has happened to cause two to fail. It might be worth checking for any dries on the stand up regulators but beyond that it is a real mystery.
Possible that the unit was powered on when the output switch was used. Apparently the unit should be off before doing the switching.
This is just my conjecture as to how both OPAs to fail…per seeing Naim forum post.
https://community.naimaudio.com/t/naim-cd5-xs-problem/26586/7
This is just my conjecture as to how both OPAs to fail…per seeing Naim forum post.
https://community.naimaudio.com/t/naim-cd5-xs-problem/26586/7
You would have to study the circuitry details. Once an opamp is correctly configured and with the correct supplies present it is next to impossible for them to fail in normal use. Something really obscure has to occur to take out two opamps such as a major supply issue reversing in polarity or a massive over voltage spike or a spike at the inputs perhaps reverse biasing them.
Obviously whatever it is has happened though.
Obviously whatever it is has happened though.
