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Old 3rd February 2013, 07:04 AM   #151
Coris is offline Coris  Norway
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Sorry, I have mixed up about negative regulator. There is place for component on the board, but is not planted.
Anyway that situation when 12v from Molex is regulated with an 12v regulator it still exist, but for +12v rail (as you can see on the picture here - 7812).
The negative rail it have no regulation more than what is done in the inverter.
I have marked up on the picture the points where is to be cut or lift up the component`s pin.
There is no problem when the regulator have the output in the air. You can of course cut both or all its terminals, but is more easy to cut one... If you cut the input only, then when you put your external PSU on that it`s output pin, is not just what the regulator likes... BTW, if you cut out it`s output pin, that regulator do not work any more... for the purpose it is there. You have to use another PSU in that point...

This picture here is an old one. There is not my last modification here, but one of the many...

Last edited by Coris; 3rd February 2013 at 07:06 AM.
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Old 3rd February 2013, 07:32 AM   #152
Coris is offline Coris  Norway
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This is a part of the board with the actual functioning/last mods.
An 8v regulator it were used to minimise the heat dissipation in the power system.

Last edited by Coris; 3rd February 2013 at 07:43 AM.
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Old 3rd February 2013, 09:32 AM   #153
Corvus5 is offline Corvus5  Poland
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Quote:
Originally Posted by andreudze View Post
frog993, let me explain how power supply is arranged. Strart with molex +12V and + 5V
1.) +12V thru three 3.3 Ohm resistors feeds the 7805, that in his turn supplies analog part of DAC and auxilary consumers (ADC and relays)
2) +5V is converted by the HF invertor into +15V, that feeds the 7812 and into -12V (in fact, it would be better to have -15V and 7912 then, while there is place for 7909 on the PCB). Thus, we have splitted power supply (+/-12V) for I/U and output stage as well as for the headamp.

+3.3V comes directly from the PCI and feeds digital part of PCM as well as DSP.

The picture belows shows the power paths.
That's a little strange. The reason was probably to support regulators with higher voltage to make them work properly. So some 5V filtering are still before being converted to +/-12V and not being used in the 5V DAC analogue stage anymore. More, some 12V
filtering is only being used for 5V DAC analouge stage and not the opamps.

I'm trying different settings for the digital stage. Ceramics are the must. The 47uF oscon is too soft while bypassed with 100nF MLCC is little clearer. Still 2x47uF + 1uF MLCC was better but sounded unnatural. Moving to the SMD is probably unavoidable. Stack of a few >10uF MLCC may sound good
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Old 3rd February 2013, 09:41 AM   #154
Corvus5 is offline Corvus5  Poland
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From this I see that the 12V molex will affect the 5V on board after regulation. I read the 78xx application note. The GND is floating:

Quote:
If a GND pin is made floating in an operating mode, an unstabilized input voltage is outputted. In this case, a
thermal protection circuit inside the IC does not normally operate. In this state, if the load is short-circuited or
overloaded, it is likely to damage the IC.
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Old 3rd February 2013, 11:00 AM   #155
Corvus5 is offline Corvus5  Poland
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I'll take a look at the path near the 7805. If the 2 capacitors near it are a little hot, then maybe one of them is at the input and the other is at the output. One closer to the output pin and any placed in the parallel are mediocre hot. One closer to the input pin is little hot. 12V filtering oscon near the 7805 is also little hot.

Still I try to figure out proper digital decoupling. I leaved only 1uF MLCC, the card wasn't recognized and relays didn't switch. Then I added 22uF tantal. Still the same. So I placed 470uF electrolitic with probably quite high ESR and 1uF MLCC. Worked. Each configuration produces very different sound. According to the appliction note the 10uF should be sufficent but even 22uF wasn't.

Are the intern filter caps for the VcomL and VcomR DAC input? There's also the Vcc1 input in the datasheet.
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Old 3rd February 2013, 12:05 PM   #156
Corvus5 is offline Corvus5  Poland
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I leaved the digital at 470uF Nichicon HV + 100nF MLCC as the compromise. Now I'll try to figure out from which the hot comes. It seems it's the high frequency. The further from the source, the low ESR/ESL caps only gets hot like oscon yes but elna RJH not. Closer the source and all caps starts to get hot. The original track seems like this: 330uF oscon, 330uF oscon, 7805, 47uF (or 100uF) FG, 47uF (or 100uF) FG. It's most hot at the caps closest to the 7805. If both 5V filtering caps gets the 5V (I was adding 1000uF/6.3V even before), then there's probably no filtering at the 7805 input which is sugested for longer tracks. Let's say it is short ;-)

So I added 100nF MLCC to the hotter 330uF cap. There are also 1000uF RJH caps but they are cold, they are slow also ;-) Sound slightly become natural but just slighty. This reminded me my first whole card decoupling changes:
- decoupling +/-12V made the sound clearer and removed harshness
- decoupling +5V made the sound more natural and very pleasant to hear
- decoupling +3.3V made the reverberation more present.
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Old 3rd February 2013, 12:23 PM   #157
Corvus5 is offline Corvus5  Poland
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There's a possibility that the 2 input filtering oscon caps are for 5V and 12V. That would make the sense. Also It's possible that the 7805 is oscillating. Some people made it stable by adding 100nF and the input/gnd and 100nF at the ouput/gnd. If only I could measure voltages easily on the working board or see what happens at the oscilloscope it would be easier.
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Old 3rd February 2013, 04:31 PM   #158
Corvus5 is offline Corvus5  Poland
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I tried to figure out connecting between filtering caps but I failed. However I removed 12V filtering 2x1000uF caps and didn't notice difference now except slightly quieter bass. I added another 100nF MLCC. The soundstage got wider. Distant sounds are clearer, with beter granularity/resulution: it's more pleasant to listen to them. Close sounds are however too soft with low resolution. The digital stage is at fault. Still this distant sounds resolutions is sometimes amazing: lot of high frequencies may play and still snares has their own tone and are clear.
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Old 3rd February 2013, 09:27 PM   #159
Corvus5 is offline Corvus5  Poland
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I was listening to the music a lot now. So much difference. In the end I added 4 100nF MLCC caps near the 12V -> 5V regulation. Then I went to the 7812 caps. I added also 100nF for each.of them. The whole 1k-10kHz got great speed up. The 1k-3kHz was slightyly muddy before. Now it's clear. The dropdown is that the 6k-8kHz got louder. The sound has now lightning speed and some sounds are like the natural one. There is no mud at all. What I miss the most is making the sound much more in front of listener. It's very hard for me to achieve.
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Old 4th February 2013, 09:01 AM   #160
Corvus5 is offline Corvus5  Poland
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There's a mistake on our assumption: the 2 330uF/16V oscons near the molex both filter 5V, not the 12V. I measured the voltage and there was 4.96V on both and 4.95V after releays switched in.
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