Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Thread Like Summary - 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?

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,

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