Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems G68D No audio on digital outputs

Thanks, so I am getting it even without the main L/R digital outs. That is good news for me, at least I can use the G68D as connection between a TV optical output and the speakers. The problem with the Zone outputs is that it didn't offer any kind of speaker adjustments, but it's better than nothing.

That is what I have thought.

Thanks, Ron.
In the weekend I will disassemble the unit, check for visual failures and clean everything. Apart from the non digital audio output, the units performs normally. One thing that I might had forgot to mention is that this unit is the D version, so there is only digital outputs except those 2 for subwoofers and the ones for the Zone 2 and Zone 3, but the ones that are for the subs aren't working as well.

Is there a point in the digital output board that I can make some read to see if there is any energy going in to that board? If there is no energy entering the board, my problem could be before it, if there is power entering, the problem could be before and after the digital out board.

About the PSU, I already so the technical explanation on Duncan's page, it seems a pretty easy change and also not an expensive one.

Did you install the XP POWER ECM60UT31 as your new PSU?

Cheers,
Jorge

I wouldn’t know how to check that digital board, maybe someone else here could help with that?
That is the power supply that I used. Just make sure to change the order of wires that connect to the new PSU and adjust output voltage to 5.2, it’s covered in the instructions.
Cheers

Thanks, Ron.

First I need to that a deep look in all the parts and board to check for other serious problem.

I would like to fix the other problems before replacing the PSU, because there is a chance of not being able to fix it, in this case I think is better to sell my units for parts or to do not invest more money to fix it.

Cheers,
Jorge

It looked like your G68 has an older Umec power supply. If this is true, along with changing the order of the wires on the connector, you will need a new case for the power supply as the XP power supply does not fit in the case for the Umec. You may also need to drill a mounting hole or two to mount the new case to the G68 chassis.

Thanks for the help.

Does someone have the G68D service manual?

I find an assistance in Brazil that is very good, but they didn’t have the service manual to do a proper inspection of my problem.

Thanks!

Yesterday I decided to give the G68D another try and for the first time I got some sound from the digital speaker’s output. It as brief, but the display of the speakers showed MHR 48k.

The G68D was being configured with Mconfig and I was only able to make some noise when I ask the software to do a room calibration.

After I start the room calibration in Mconfig, I could hear a relay click from the G68D and then it starts to make pink noise.

I didn’t performed any kind of maintenance in the unit, maybe some can help me if some ideia of what’s needed know that I know it can output “sound” to the speakers.

Could the power supply replacement fix it?

Thanks!

power supply issues are common on the G68 as far as I know.
replace it, and check for any bulging caps on the pcb boards.

The following repair guides should help :
https://www.Meridian-audio.info/pub...4017,P5d.pdf.pagespeed.ce.xOn_FaqFWq.pdf
https://www.Meridian-audio.info/public/technote_tn20_3_-_g_series_psu_exchange%5b4003%5d.pdf
https://www.Meridian-audio.info/pub...oting_surround_controllers%5b4029%5d.pdf


Hope this helps..

If you do get some sound, then I suspect the cards are making intermittent contact.

The card edge connectors need to be really clean, bright gold, and you need to spray plenty of deoxit on the backplane connectors and agitate using a toothbrush.
Each card needs to be cleaned on both sides and you may need to insert and pull out a few times for really good contact.

The digital output card looks to have been very poorly repaired with cheap capacitors, although if you're not using the analogue outputs on the card, I wouldn't worry too much about it.

Check that the PSU is outputting +5.1 volts on the red wires - there should be a trim potentiometer in the PSU that can adjust the voltage - be careful though! - 5.0v is too little, 5.2v is too much!!
Ideally, the voltage should be measured from the regulator on the comms board (top, middle board)

Have a read of Meridian's TN32 - Repairing a G68 following a PSU failure - that should help.

Remember faulty cards can pull the entire bus down and prevent the entire unit working, start with a basic configuration (as per TN32) and build up slowly.

Good luck,

Steve

You can also use an eraser that is a bit rougher intended for ink to clean the contacts on the cards, and as Steve says use plenty oxide clean spray.

Eraser

Thanks a lot for the links, Flores. I will use it.



The only way I was able to make some noise with the digital outs are when connected to the Mconfig and start the Room Correction. When I click start the speaker’s display changes from PCM NL to Data 48K and after a brief second to MHR 48k.

I was able to repeat this and every time it works, I could hear a relay click and I press start and then the sound starts to come.

BUT I am not able to make any sound when trying to Calibrate the level of the speakers (using Mconfig or the front panel). When I tried it, the speaker’s display never changed from PCM NL and there is no relay click. It seems that the Room Correction are sending some commando “to open/start” the outputs, at least is what it seems because of the relay click.




I will do it again and inspect visually.



Yes, I totally agree with that, it was done by the first owner and if the G68D starts to work I will try to replace it with better parts.




Tonight I will try to do that. Can you point me to where to connect the ground of the multimeter? I will connect one end to the +5.1 red wire and the other I don’t know here to safely connect.

About the comms board reading, it seems to be easier to read.



Thanks for the tip, Gemeni. I will buy an eraser today to help in the process.


Best Regards,

Jorge

I read the technical notes and read the voltage in the indicated spot.

The main central board is receiving 5.042 volts and the board with the digital outputs is reading 4.980 volts.

Initially the main was reading near 4.98 v and the other was reading near 4.890 volts, so I increased the PSU output a little.

Even after this small adjustment, nothing has changed.

It seems that the processor are not sending a signal to “start/open” the digital output connection.

Is there a relay that “opens” the sound output? I ask because I can hear it when I turn on the Zone 2 output and also when I try to perform a Room Calibration. No other situation made the processor click the relay. When I hear the relay clicking it is like the speakers and the processor are “handshaking”, after that it starts to display PCM 96k or MHR 48k.

Best Regards,

Jorge

The relays control the analogue outputs. As they click into action, that should be seen as a positive step forwards.

As you can generate test tones, I would say that the output card works, along with the DSP cards and FICL card.
It sounds like the input cards may still have problems...

Strip the unit so you only have the digital output card, DSP C/D, DSP E/F, FICL and CPU card.
Add the digital input card and test, then add each card back in turn.

I've had a unit where the tuner card kills all sound, so could be a single card that pulls the entire bus down.

Good luck, a logical approach should produce results.

Once you've isolated the faulty card(s), you can start to source replacements.

Cheers,

Steve