hello there.
I got a Linn CD12 CD player and inside of that there were 4 PCM1704 DAC chip,3 of them are broken and i thinking of replacing them, but on the internet i can only found pxm1704u.but the original one are marked PCM1704 with 2 white dot on it.
What is the diffence between them?
thanks all
tablekwan
I got a Linn CD12 CD player and inside of that there were 4 PCM1704 DAC chip,3 of them are broken and i thinking of replacing them, but on the internet i can only found pxm1704u.but the original one are marked PCM1704 with 2 white dot on it.
What is the diffence between them?
thanks all
tablekwan
The two dots mean that this is the K grade of the IC. At that level of engineering this is an important thing to take into consideration, there was a long thread about the PCM63 and grades, even within the grade there are differences.
My Muse Erato II uses 4 chips as well and the funny thing was that three were from the same batch( manufacturing date is on the chip), the fourth was very different. I spoke with the guys at Muse and they said that they measured each chip and chose 4 that were really close. Otherwise it is a good idea to buy chips with the same codes on it, the chance is that they will measure close.
BTW I just sent you a PM.
My Muse Erato II uses 4 chips as well and the funny thing was that three were from the same batch( manufacturing date is on the chip), the fourth was very different. I spoke with the guys at Muse and they said that they measured each chip and chose 4 that were really close. Otherwise it is a good idea to buy chips with the same codes on it, the chance is that they will measure close.
BTW I just sent you a PM.
2 PCM1704s just failed consecutively on my DAC. They all died on right channel. I don't know what happened. Perhaps the 1000uf servo decoupling cap is the culprit. However, the same setup has been working well with PCM63PK without any problem. I got a feeling that PCM1704 is quite fragile.
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I repeat my above question, how do you know the DAC chip has failed? I'm not defending the PCM1704, just wondering how you isolated it as having failed.
Have you verified the presence of the correct digital input signals to the chip with a scope?
How did you verify the presumed absence of the chip's analog current output signal? If feeding an typical active virtual-ground I/V amplifier input node the current output pin will show a just that, a virtual ground and no signal voltage when operating properly or improperly.
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because i just de solder the one that have output after the I-V opamp stage to the place of other 3 place then i found out there are 3 of the dac chip are dead
someone said it need to remove the output cable after remove the power cable? maybe the pcm63 have same problem?
about my way to test, i test all 4 ic data input,clock,voltage and 4 of them are the same, then i test the output after 4 of the IV opamp output,and i just got one output are working, then i swapped the one working opamp with the one without output.and the IV stage seem OK for me ,
so i swapped the DAC chip and found out the other 3 of them are not working.
Definitely not the cable. We're talking about circuits here, and my 1st 1704 died during the operation. I heard some of the expensive DACs also have faulty 1704 after few years of usage. I will try to find the cause. The first step would be following the recommended value for those decoupling caps.
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