Panasonic UB9000 - discussions, mods, improvements

Definitely, this it not looks like an possible DIY installation. I guess the LPS connection wires are soldered directly to the boards... As it looks to me, it were made new holes into the chassis bottom to make possible the installation of this LPS approach.
 
Gidday and hello from down under to all the diyAudio worldwide members,
and as a new member can you please PM Coris as I would like your help to find out the shipping and all costs and difference of the simple versus the advanced LPS mod for my UB9000 USA 2019 version and in the near future I will be placing a rattlebyte modchip as I have worldwide BDs and DVDs. I also thank you for your clear youtube videos on the dissasembly and placing of your LPS mod inside the Pana UB9000. Cheers Valozy
 
My ub9000 can not output hdmi signal. other functions working.
can someone help me which chipset error can cause this issue?
thanks
Gidday djtwxj,

Well taking a wild guess have you used new 4K or 8K good quality cables? As we don't know your setup I recommend you just first connect the HDMI Audio+Video port directly to your TV/Projector and then secondly connect the HDMI Audio only port to your AVR, amplifier/soudbar.

Then you will be able to test if either your cables are faulty/old or perhaps your other device are causing issues or perhaps finally the audio/video HDMI port is somehow damaged as the video signal travels via certain HDMI pins. I don't think the chipset is faulty as the HDMI ports are a wear and tear item and if not treated with care then it will fail in time and that goes for the HDMI cables of a poor quality. Cheers cobber
 
I have been looking at impedance matching with my pre-amp and started to look again at the small analogue board in the 9000, my unit with different coupling caps and power supply filter caps is great, as have spare 9000 player I have looked again at this board and have a few questions

  1. The output impedance is quoted at <500 Ohms, I can see there are two resistors of 100 Ohms in series one small (tiny board mount) and one through the hole, seems odd I some ways but there is a small three leg 'device' surface mounted named BBV 36 and have no clue what it's doing. The tracks go from the output pins on the Op amp NJ2114.
  2. Assume the 200 Ohms is to stop a signal short damaging the opamp ? looking at the spec sheet. I dropped my 100 Ohm board mount to 27 Ohm to reduce the output impedance and all has been fine for 3 years
  3. I still have no clue why the signal coupling caps are 470uf as the stereo channels use 47uf and 470uf seems crazy so assume it was just cost as these caps are used elsewhere on the board for the power supply. Perhaps the 47uf 'higher quality' caps were too expensive to fit ? There are no decent Panny caps in a decent penny unit !
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https://docs.rs-online.com/074b/0900766b8002ad5f.pdf
 
1 - The mentioned three pins components (BBV 36), are transistors used for the mute function. In my opinion, the transistor mute approach is not just right to be placed into the audio signal path, but it have some advantages (much smaller footprint, lower power consumption, and lower costs), comparing with the classical mute relay circuits.
The SMD 100 ohm resistors are part of the transistor mute circuits, while the big 100 ohm resistor (through hole) are mounted serial on the signal path. These resistors it adapt/balance the audio output impedances for the connected cables and the further input (amplifier) devices. When such transistor mute circuits are used, the AC coupling caps are interposed to galvanically separate the stages. For relay mute circuits, and if the output DC offset is closer zero volt, such AC coupling caps are not necessary.

2 - These through hole resistors value it can indeed be lowered to 20-30 ohm, for better performances.

3 - The mentioned caps are AC coupling caps. For the signal input (into opamp) the AC coupling caps value is relatively low, and it is right so. For the output signal (lower impedance), the AC coupling caps value should be much larger, and most important such caps should be bipolar (or nonpolar). Value over 1000µ it is allright, if the available space it allow the caps physical dimensions. The DC voltage rating of the AC coupling caps should be approx. two times the AC voltages such caps it are exposed into the given circuits. All AC caps (input/output) it should be paralleled with good quality film caps for better signal pas through. The larger AC coupling cap value it provide lower impedance and better signal passthrough for lower spectre of the audio signal, while relative lower value film caps (into 1µ) it provide better passthrough for high end of the audio spectre signals. Using nonpolar caps is a must in this respect (usual electrolytic caps are only "good enough") .
 
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Coris, hi

Many thanks, I think I understand point 3. so regarding these output coupling caps, I guess I can go quite a bit lower as my pre-amp input impedance is 100k. 470uf seems crazy there is 47uf on the XLR and stereo (which I dont use) I suspect 10uf or single figures would still be fine regarding bass cut off ?

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These caps you show in the picture, is better heaving higher capacity value, as it are placed in a low impedance signal path (the output of the opamps). The AC coupling caps placed in an high impedance signal path (as usual signal input paths), it should be of a lower capacity value (usual into an 100µ). For the mentioned caps on the UB9000 audio board, I will suggest using 1000µ nonpolar caps, 10 - 16v rating is also good in this case.
 
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Just thinking again this is my input buffer circuit that the 9000 feeds into for each channel, (Using input 1) so a 100k to GND then a 10uf cap. Could I remove the AC coupling caps on the 9000 if I only use this set up ? as the DC is blocked by the 10uf tantalum cap in the preamp. I can check the DC leakage but believe it's very low ?

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You cannot remove the AC coupling caps on UB9000 audio board, as that caps are placed in between the opamp outputs and the mute transistor circuit, which is right before the XLR/RCA connectors on the rear panel. When transistor mute is used, then the input of this circuit it have to be DC separated by the final opamp output (the AC coupling caps function in this case).
You can remove that AC coupling caps on the audio final output (on audio board), then take the signal from the opamp outputs (measure the opamp outputs and confirm the DC offset is only few mV or zero), and apply that signal directly to your further device (preamp/amp). Well, connecting the opamps output pin directly to the XLR/RCA connectors (bypassing the transistor mute circuits). In such case you will not have any mute circuit on audio outputs, and so you may hear clicks and pops when power up/down the UB9000.
Another alternative is replacing the transistor mute circuits (dismissing it), with mute relays. This alternative is quite complicated, because a control circuit for that relays should be in place for that all to function properly.
Yet another alternative is replacing the 10µ AC coupling caps (your above schematic), with 47µ or even 100µ (non polar) caps, and parallel these new caps with some 1-2µ good film caps. I will also want to replace the 470pF cap with an good 100pF film cap (eventual two serial 270pF caps). However, the 10µ cap placed on the above circuit output, I would like it to be 100µ or even more, also paralleled with some µ value film caps.
 
I have experimented a bit with the naim buffer and gain boards and ended up with film bypass caps on the majority of caps. I did try the later naim buffer boards but preferred the modded earlier boards. I'll have. look at the values suggested as I can use a pair of boards from one of the other pre amps (I have 4 in operation) to A-B

I guess if I leave the Panasonic on stand it will only 'pop' or click if the audio circuit is on and the 9000 is powered off. I normally boot up the Panasonic before turning on the power amps, so perhaps bypassing the AC coupling and linkng in with the Opamps might be an interesting experiment I could remove the Couling caps and wire in from the Opamp cap input (direct to the coupling cap I think) and bypass the rest of the circuit by lifting the resistors as well. the output impedance will drop too. I'll check the DC from the Opamps and see if this is low or near zero

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However, it is better heaving an 20-30 ohm connected in between the last opamp output and the RCA connector pin (after removing the AC coupling caps). The coupling caps have to be in fact removed from the board, and the connection of the RCA pins should be cut it out somehow from the transistor mute circuits as well. Then a direct wire it will do the job... Also the DC offset should be very low or zero on RCA outputs in this setup. As usual, the DC offset there it vary in a range of +/- volts when the device is powered on or off, and it stabilise itself after a short while. Therefore the mute circuit is designed/used. You should power up the preamp or amp, after a short while the player is powered up, and power off the preamp/amp before powering off the Panasonic.
 
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Coris, thanks, Is there a way of leaving the 12V circuit on for the analogue board, I guess the unit will power down the analog board is the device is left on and it goes through it's timed power down ?

I leave the player permanently wired in to the mains, like most and from memory the digital circuit is permanently on ?

I wonder how noisy the power off might be when the other units are on, perhaps not terrible ?!
 
However, it is better heaving an 20-30 ohm connected in between the last opamp output and the RCA connector pin (after removing the AC coupling caps).

Figures 19 and 20 (Small-Signal Overshoot vs Capacitive Load) on page 10 of the OPA1612 spec sheet show why: opamps are unhappy with capacitive loads directly on their outputs, and a resistor around that value tames down instabilities considerably. Note the capacitances in question are not far from what one would find from a length of interconnect and a preamp input.
 
I think this wold be the easiest way to implement, remove the final 100 Ohm resistors then no relay in contact with the output, remove the AC coupling caps and link the +in (which is direct from the OpAmp output) to the back of the RCA's with a 20-30 Ohm resistor.

Remove all red items and add green to each channel

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