Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems G68 Failed power supply ?

My G68D just started acting weird today, switching off after a few seconds, then back on, then off, emitting clicks, clicks, clicks.

I'm suspecting a failed power supply, as it seems fairly common on those units after a few treads I've read on the forum.

I couldn't find anything on the Wiki, so what would you replace the original power supply with today? Has anybody come up with a conclusion?

Thanks again

The PSU failed on my G68 recently too and I replaced it myself. It was reasonably easy to do and it's been working fine since I did it, which was about six weeks ago. If you look at the following post you'll get an idea of what to do: G68 PSU Problems - Again

Provided you're out of warranty it's a lot cheaper to DIY than send it back to Meridian - cost me less than �50. Quicker too.

Cheers, Roger.

First thing I would do is check the output voltage. Apparently the supplier set 5.0V is at the ragged edge. Adjust it to 5.2V and see if your probs go away. Not sure where this adjustment is made though. Probably via a trim pot somewhere on the PS. Maybe someone has a pic they can post.

What do you expect with "adjust the voltage to 5.2V"?
The old tome with TTL logic are gone whre thin wires "eating" the voltage and PCB far away get then "low" voltages.
Can you explain that please ?

Robert

I'm going by what Meridian USA told me after they replaced the PS. When I got the unit back from service it worked perfectly for a month and then started to go into standby on its own. It would do this intermittently and usually within the first 5 mins of operation. I returned the G68 to Meridian and thats what they said they did to correct the problem. Its been fine for the past 6 months.

Thank you for the responses. I'll open my G68D tonight and try to take a few photos inside.

Otherwise, the replacement power supply is XP POWER ECM40UT31, right? Will I need to order anything else?

I was told about the 5.2V also. Why this is critical I have no idea.

Marc Koval replied about the 5.0V vs 5.2V question.

Apparently, the adjustment to 5.2V is only possible with the XP power supply. If you have a UMEC power supply - as most M processors older than 2 1/2 years - there is no adjustment.

Jerome,

If you pm me your email address I'll send you some instructions on how to change the PSU.

M also recommend you change some capacitors on the motherboard as well as on one or two of the cards. I did this because it was obvious in my case that some had failed but it's a fiddly job because you have to strip the G68 chassis right down to get to them. It is possible your PSU hasn't dragged any other components down yet so you may get away without doing this. However, if any capacitors are showing signs of bulging then you will need to change them.

Whilst 5.2V is the voltage M specify I'd be surprised if it were critical to within 0.2V, it is nonetheless desirable to get it as close as possible. The replacement PSU should come preset at 5.0V though you can't guarantee this. You adjust it by way of a trimpot next to the voltage out connector. Do this (taking great care as mains voltage is present) with the PSU powered up but disconnected from the motherboard.

One last tip, if you haven't already got one, get an ESD wrist band and earth yourself to the chassis while working on the unit (which obviously should not be connected to the mains at the time). You don't want stray electrostatic voltages knocking any components out.

Cheers, Roger.

So would I, that would be an operating tolerance of <5% - very worrying if true.

Well couldn't this account for why so many G68 PSs 'seem' to go bad? If a slight drop off in performance is all thats needed to precipitate a problem you'd expect to see many PSs being replaced as is the case with this particular product line. I can't believe the PS themselves are inherently the cause of the failures here. There are just too many.

I'd like to know the failure rate of the newer XP PSUs in comparison to the older version.

I had the original PSU fail about 2 years ago and Meridian service fitted the new type FOC.

I had the new replacement fail about 6 months ago and this was replaced by my dealer as a chargeable repair.