La Marzocco GS3 - clock jumps to 14:53 while brewing

Equipment doesn't work? Troubleshooting? If you're handy, members can help.

#1: Post by KVC »

Hi, Recently my clock starts to jump while brewing. It jumps to 14:53 (always 14:53), then back to the real time, back to 14:53, back to the real time. When not brewing the clock works fine. The problem persists after unplugging the machine. Does anyone have any idea how to fix this? Thanks, Kees

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#2: Post by Peppersass »

It's likely that something is wrong with the RTC (real-time clock) on the logic board. It could be that the IC is bad and needs to be replaced. I believe it's a surface-mount chip (SMD), which requires certain tools and skills to replace.

Another, and more worrisome, possibility is that there's water contamination on your logic board. This can happen if there's a leak in the machine or if you have the old-style vacuum breaker that vents inside the machine. Water tends to flow along the cable bundle into the brain box, and thence to the logic board. Minerals in the water can short traces on the board, causing all sorts of unpredictable behavior. Often this can be remedied by removing the board, cleaning it with 99% isopropyl alcohol, and allowing it to dry completely. However, in some cases the contamination can be bad enough to destroy the logic board, which is expensive to replace.

Several GS/3 owners have reported problems with the RTC after such contamination, and in one case I know of the RTC was shorted, didn't work at all, and had to be replaced. The owner had the tools and skills to do that.

My advice is to remove the side and top covers, and carefully inspect the inside of the machine for signs of leaks. If you see any drops of water on the chassis floor or any mineral deposits, it's likely that water has gotten into the brain box. In that case, the source of the leak needs to be fixed and the logic board needs to be inspected and, if necessary, cleaned.

If the source of the leak is the old-style vacuum breaker, there's a new version of the valve that vents into the drain box. LM sells a kit to do that replacement. They recently came out with a completely different vacuum breaker that should require much less frequent servicing, so I'd recommend making sure you get that one.

Even if you don't find any signs of a leak, you may still want to inspect the logic board. If you find no contamination, you should be OK if you don't replace the RTC. The behavior isn't particularly bad. At least it works when you're not pulling a shot.

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KVC (original poster)

#3: Post by KVC (original poster) »

Hi Dick, Thanks a lot for your advise. Despite my GS3 being one of the early models (2008), it has undergone several modifications during some service intervals (rebuilt kit steam pipe in 2015 and 2018, new pump in 2018, etc.). I removed all panels and checked for signs of leaks, including in the brain box. I haven't found anything. Since the back of the pump looks a bit shiny (the brown in images 8 and 9) I thought I noticed some moisture. That appeared not to be the case. Guess that this is a good sign. Unfortunately the jumping time still persists. Since I don't have the tools / skills to replace the IC, I will contact my supplier. Thanks, Kees

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#4: Post by Peppersass »

You've posted a photo of the front-panel display board, but that's not the logic board. The "brain box" is much larger, and is located underneath the machine in the back. To get at it, you remove the rear panel, carefully pull the plastic box out, and remove the cover. The logic board is on the left. You may be able to see signs of water contamination on top of the board or on the floor of the box around the perimeter of the board, but the only way to be sure is to remove the board, which requires unplugging a bunch of cables (photograph and/or label the cables so you know where to re-plug them.)

If doing that worries you, then by all means contact your supplier and ask them to do it.

The good news is that your machine was made before the infamous "fire sale" machines (roughly, s/n 500-700), and has the "newer" style vacuum breaker that vents into the drain box. The inside of the machine looks pretty good, but you haven't shown all the places a leak might occur or show. Check around the triangular plates on the ends of both boilers. If the seals are failing, you'll see evidence of water. Check both when the machine is warm (max pressure) and cooled off (the seals contract when cold.)

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#5: Post by KVC (original poster) »

Thanks again for your response. I will have a look later this week and share my photos again.

KVC (original poster)

#6: Post by KVC (original poster) »

I have checked again for signs of leakage, with a cold (photos 1-7) and warm machine (8-15), specially at the triangular boiler plates and the cover of the brain box. I haven't found anything. I leave the inside of the brain box to my supplier.