Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems C61R Power Supply replacement

Just bought a C61R from eBay and when I plugged it in I was greeted with the smell of burning electronic components - may be I should have sent it back!

Thanks to this site I purchased a replacement PSU (I went for the ECM60UT31). Fitted according to the instructions in the wiki (no wire changes needed as it had a ECM40UT31 originally)

Everything powers up ok, but I've now come to set the voltage. Out of the box the PSU measured 5.00V at the PSU terminals but 4.97V at the regulator on the COM PCB.

There are many references in numerous topics to various voltages (5.0V, 5.1V and 5.2V) for the various G series/800 series components, but they tend not to say where the voltage is being measured.

Referring to TN32 it states "It is important that the voltage measures exactly 5.0V on the PCB carrying the main processor chip."

I assume this applies to all G series components and therefore equally to the C61R.

I also assume that the "PCB carrying the main processor chip" is the middle board at the top in this image

For the moment I have set it as per the Tech Note - am I wrong to do this, as most other people have gone for other voltages?

Hi Tarik

The 800 series is 5.2V, and we all assumed that this figure applied to everything with an SMPS, but Meridian later noted that G units should be set to 5.0V. I'm sure the relevant post will still be here somewhere....

Cheers

George

I'll leave it set at 5.0V and see what happens and report back.

Update

When the voltage is set to 5.0V as per the tech note, I get strange behaviour.

When playing a two channel CD source, the unit is sluggish when doing anything such as changing volume or DSP, and I get no sound out.

If I increase the voltage to 5.2V CD sources play fine, but movies do not.

I currently have it set to 5.05V and it seems to be working ok.

I appreciate that my multi meter is not calibrated, but I have tried two different models that I have and they both read the same voltage.

It's a bit frustrating that the voltage in the tech note did not work.

I'll continue to monitor and report back.

If you look up Technical Note TN20.3 it shows you the exact chip to measure the voltage. I've replace my C61R psu few years ago and set the voltage over the chip as indicated in TN20.3 to slightly over 5V. No issues ever since. As I recall I replaced it with the ECM40UT31 (original)

If you can't get to the test point then can you set the output at the PSU between red and black wires (either of them) at 5.1 Volts DC

Thanks. I have been measuring it as per Tech note 20.3

Your experience seems to be the same as mine.

Have to be honest that I dont hang around here much these days, but the G61R died a couple of days before xmas eve, and this thread saved it for me so thanks for that.

Had the G61R (what truly awful design) and the HD621 apart, even more shocking was the use of some really low grade components.
Including not the least the very poorly plated edge contacts for the cards to the backplane - these can be wiped clean fairly easily with IPA and the lightest touch of contact oil should help prevent future contact issues (really do this if you have your G61R apart), especially as the backplane connectors do not provide a reassuringly tight fit suggesting these too are poor quality.

Both units got new PSUs and electrolytic caps, the G61R got a little 40mm fan on the PSU as the local cooling is clearly hopelessly unsatisfactory (already changed the PSU already once before and should have done this last time).

So why bother to bump an old thread? Well as reported above 5.05V (on the processor PCBA regulator per TN20) is clearly significant for reasons I can't be bothered to work out.
5.0V and not working, 5.15V and not working. Not related to the processor PCBA itself I think, but other parts of the product.

hth helps someone in the same situation in future.
happy xmas all.

Hi

My G61R SL seems to be in need of a new psu - bad timing dying just before xmas as cannot play new albums :-(

I am trying to find the repair instructions on the wiki but am not being successful... Can someone point me to the correct page(s) so that I can have a read and see if it is a repair I can undertake or whether I need to contact Mr Tech Guy

Thanks

Hi,

You'll need to replace the PSU with an ECM60UT31 (assuming that's what is already fitted)

You should also check all the electrolytic capacitors on both the backplane and on the cards (to check if any are bulging) - if any look suspect, they should be replaced otherwise the new PSU won't last very long!

Whilst the PSU replacement is fairly easy - just need to remove the lid of the unit and then locate the PSU cage, remove PSU in cage, extract PSU, swap out for new PSU module and re-assemble. If you need to change the capacitors, then you'll need to use a soldering iron and completely disassemble the unit.

If you need any further details or help, feel free to drop me a PM as I've repaired a number of G-Series.

Cheers,

Steve

Hi Steve

I would like to PM you and get as much help/advice as possible but attempting to do so results in a "We Encountered A Problem
swpnt is over their Private Topic limit."

My very first question is: How to check outputs on suspect psu? - an ECM40UT31 with a light coating of dust in a few places especially around the large brown capacitor.
Using a multimeter I have found 2 x 5v, 1 x 11.93v and 1 x 12.23v outputs - presuming the multimeter is reasonably accurate. Are those values for the 12v outputs within tolerance?

If "No" where do I find an ECM40UT31 (or ECM60UT31 if that is a replacement)?

If "Yes" what else would cause a G61R in standby mode to start flashing the "Boothroyd Stuart Meridian" startup logo?
I tried power off, left it for about 15 minutes then powered on: the startup logo is displayed and nothing else happens - system fails to boot?

A quick visual inspection does not show anything obviously amiss ... except for some uncertainty over a capacitor on the backplane which looks a little "domed" on the top - I probably should move power lead out of the way and have a really good look. It is the lowest capacitor on the backplane situated behind the mains power input/switch area. Is it meant to be slightly domed?

Thanks

Hi,

Apologies - mailbox was full - now sorted!

Just checking the voltages on the PSU is not sufficient - they may well be well within tolerances but it is the current that is the important part. When the G-Series starts up, there is quite a draw on the +5v rail. Some failing PSUs can't handle the initial inrush of current and momentarily blip... It is almost impossible to see this unless you have a good 'scope. Your issue is that the G61R is not completing the initialisation - most likely that the PSU is failing.

The standard fitment is the ECM40UT31 (which is a 40watt PSU) - these run pretty hot and ventilation is not a G-Series strong point! I always tend to install the ECM60UT31 (which is 60watt) as it runs a bit cooler...

If you search for XP Power ECM60UT31, then you should find various suppliers (CPC, Farnell, RS, DigiKey, etc.) - Find a supplier with stock at a good price and order one.

Most importantly - do check the capacitors on the backplane (these are not easy to see as they are the board side of the backplane, near the power inlet - see if any are bulging (i.e. top looks domed outwards) - if there are any that look suspect - they need to be replaced as they will be presenting an additional load to the new PSU and will cause it to prematurely fail. If one is suspect, it is best practice to replace all of them. At the same time, it is worth checking for any issues with the cards.

Feel free to drop me a PM if you would like any further info.

Cheers,

Steve