Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Thread Like Summary - G68D No audio on digital outputs

Hello everyone!

I am trying to install a G68D to use with a pair of DSP7000, but I am facing some possible problems.

The processor is already using the latest firmware, I used Mconfig to assign everything, I can confirm that the processor is receiving sound from the source because the processor are outputting the sound in the Zone 2 output (both digital and analogues out), cable are also working as they should, the processor are able to turn on and control the speaker and the digital audio cable that doesn't work when connected to the Main L/R digital output works perfectly with the zone 2 digital out.

To further investigate the problem, I removed the digital out board and noticed 3 suspicious details, they are the following:
1. Signs of something melted;
2. Signs of black dust on the top of a resistor;
3. A CapXon capacitor tha doesn't fit the quality of Meridian product's as well what seems to be signs of soldering.

The following images are from the board, if someone know what are the melted component and its specs, please let me know:







Does some one with more experience in electronics believe that this could be the cause of the ZERO sound output from this board?

I tried the analogues out presented in this board, configured in Mconfig a sub, set the DSP7000 to small in order to make it send sound to the sub, but the sub didn't receive any kind of sound from it, not even noise.

I really want to find the problem and fix it believing that even after some many years the combo G68 + DSP7000 can produce a really awesome sound.

All the best,

Jorge

Hi Jorge,

It is quite common when the PSUs fail within G-series, that a number of other cards are taken out. It could have been the case with your unit and a poor repair effected.

The components replaced look to only be within the analogue output section of the card, so there must be a more fundamental issue with the G68.
Usually, the FICL card fails - this will result in no digital output (you may still get on zone 2 as that is effectively a direct 'tape out') - a good indicator of this is if the volume control is 'laggy' when a digital source is selected.

Clean and re-seat all cards and try again. Check the capacitors on the backplane - they'll probably be bulging (or should have been replaced) - there is definitely an 'art' to keeping these units running!

Spare cards may still be available, but will probably cost more than the unit cost 2nd hand...

Good luck - you'll need it!

Cheers,

Steve

Hi Jorge,

Looks like an early unit as that is the older LPT42 PSU.

Make sure that all the cards have their edges cleaned, that may help as they do oxidize and that causes intermittent contact.

The FICL card is one hidden in the first stack either between the Digital and Analogue output cards or between the analogue output card and the video output card.
You'll have a hidden DSP card in the stack too.
In the middle stack, under the comms card, there will be the other DSP card.

Check the capacitors on the backplane for any ones bulging - they should be replaced as they look original.

You may need to ask MrTechGuy to find out prices for a replacement FICL card and maybe a replacement digital out card (if still available)...

Also, it may be worth keeping an eye out for a donor unit.

Good luck,

Steve

1. Signs of something melted; That's a small capacitor, will be the same value as the one next to it, was probably melted by the soldering iron when the capacitor was swapped out.
2. Signs of black dust on the top of a resistor; will be heat related, may be open circuit now.
3. A CapXon capacitor that doesn't fit the quality of Meridian product's as well what seems to be signs of soldering.not sure what that is, it's not on the original board?

The large capacitor was changed by cutting the legs of the old one and soldering the replacement to it, this is where I'd guess the damage was done to the other small capacitor.



In the above, there is a cable running from the USB maintenance port to the display, that shouldn't be there.

It seems the G68D you have has been badly repaired in the past, do you know the history of the unit?

All the best,

Steve

It may be worth getting another G68 and using the one you have for spares / as a donor unit...

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.

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..

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

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