rdcrich Senior Member Joined: 8 Feb 2013 Posts: 12 Location: Denver Expertise: I love coffee
Posted Fri Feb 8, 2013, 11:54am Subject: PID Silvia short/overheat
Hello,
I've read this forum many times while working on my Silvia, but have never posted in it. My current problems have me a bit stumped though and I appreciate any help that I may find here.
I have a 9-year old Silvia that I have modified to have the new over-pressure valve and steam valve/wand. It also has an Auber PID with pre-infusion. It had been working great until last month. I finished steaming milk and suddenly smelled electronics burning. I unplugged the machine and took it outside and hadn't had time to work on it until this week.
Searching for the cause of the problem, I disassembled the whole machine, cleaned everything, and rebuilt it. I figured I would find a boiler full of scale as my problem, but nothing but very light scale that would have come out with my next descaling. I descale monthly. After reassembly, I started it up plugged into a portable GFI at my workbench and immediately smelled the burning again. Turned it off, disconnected the boiler leads, and started it again and it worked fine. One more time with boiler connected and I found the source of the smoke. The PID relay mounted on the bottom of the machine was melting where the boiler leads connect to it.
I then proceeded to disconnect all PID components and to run the machine in it's original configuration. It seems to run ok and doesn't trip the GFI, but the brew water comes out as steam, even without engaging steam. I realize that the brew thermostat could have gone bad in the years without use, but is it possible that my boiler is the source, given the PID problem? Wouldn't the brew thermostat kick off an overheating boiler?
My current plan is to buy a boiler rebuild kit and new thermostats as well as a replacement relay for the PID. I want to get the machine working in default configuration first and then switch back to PID. I don't want to waste money on a boiler, if unnecessary though. Does this seem like the correct approach to repairing Silvia? Could there be something else that I haven't considered?
Since it is heating well enough to create steam, I doubt the heating element is the problem. Sounds like a shorted/high resistance SSR. The brew thermostat is easy enough to check off the machine using a heat gun and ohm meter. Check the wiring as well. I have a color wiring diagram for Silvia on my website. Check the panel witches as the steam switch may be closed internally.
Thanks for your reply. I just got off the phone with support at Auber. They were excellent. They are sending me a new SSR at a discount and the tech had me check the resistance across the posts and he thinks mine is correct.
I should have stated that I am not getting full steam in brew mode, just too hot. I can run the pump a bit and get water, but more steam than I ever remember comes out of the brew head.
I'll see how the new SSR does and post the results here for anyone else who may have this problem.
While I agree that the problem is likely to be a failed SSR, another possibility is that the connection of one or both of the boiler leads to the terminals of the SSR is/are loose. A loose connection would have too much resistance, which in turn would generate considerable heat.
More likely, though, is that the solid state switch (a silicon device) inside the SSR has developed too much "on" resistance. It would not take much resistance to generate plenty of heat with the 7A load drawn by the Silvia.
rdcrich Senior Member Joined: 8 Feb 2013 Posts: 12 Location: Denver Expertise: I love coffee
Posted Sat Feb 9, 2013, 10:45am Subject: Re: PID Silvia short/overheat
With the PID uninstalled, I've checked all connections and switches. The machine works, both brew and steam, it is just that brew seems too hot. The brew thermostat is turning off the boiler, just at too high a temp making for steam at the group and from the wand until the pump runs a bit to bring it down. Perhaps it was always like this. I know I used to do the temperature surfing thing before I installed the PID. At this point, I'm just going to wait for the new SSR to arrive and see how it goes. I'm relatively certain that the problem is the SSR and not the boiler.
If I recall correctly, these original Silvias had a higher cutoff brew thermostat than the newer ones. I just don't remember so much overheating before the PID.
Thanks for your input. I'll update here when I get the new SSR.
rdcrich Senior Member Joined: 8 Feb 2013 Posts: 12 Location: Denver Expertise: I love coffee
Posted Sat Feb 9, 2013, 11:48am Subject: Re: PID Silvia short/overheat
Randy, your wiring diagrams are awesome. Thanks for pointing me to them.
While I'm working on this machine, I have a couple of other questions for the group.
I reassembled the boiler with the original gasket. I put some high-heat grease on it (very little) and it seems in good shape. It is flattened on the top and bottom and is not leaking now. Should I order a new one and replace it before I close the machine up?
I've now disconnected and reconnected the teflon tube from the pump to the boiler twice and I don't like the look of the end of it, although it is not leaking. I know I can order a replacement, but it also looks like I can get the new braided hose if I also order a new right-angle connector to the pump. Am I right in that, or will I need a new pump too?
Given that machine is 9 years old, but well cared for, should I replace anything proactively while I'm working on it? I already upgraded the overpressure valve and the steam valve. Can this 9-year old heating element have much life left in it? The pump, etc.?
Posted Sat Feb 9, 2013, 12:06pm Subject: Re: PID Silvia short/overheat
The older Silvias has a hotter brew thermostat than later models. People complained about the steam during the brew cycle, so Rancilio dropped its temp by 10C. iirc. So then it gave people something else to complain about- low brew temperatures. Sounds like you are definitely on the right track with replacing the SSR. I think you will be fine after that.
coffeeee Senior Member Joined: 30 May 2011 Posts: 52 Location: over the rainbow Expertise: I love coffee
Posted Sat Feb 9, 2013, 10:35pm Subject: Re: PID Silvia short/overheat
hey Rich
it seems you are so used to the PID that you forgot how it was before... ;-) As you wrote, previous (orig) setup was too high causing some steam and requiring temperature-surf.
I also had such issue few weeks ago and was amazed to find that SSR failed so quickly. I thought those high cost SSRs are much more reliable but unfortunately found it is not so.
good luck and please report the outcome if you need more diagrams including the original wiring one you can find it here and here.
Good luck
Coffee is not a drink...it is an adventure... Author of Rancilio Silvia Mega-Mod and Rocky Timer Mod (see my website)
It seems that I did forget because Silvia is working fine in her original configuration as long as a do the temperature surfing thing. In fact, between new burrs in the Rocky, a new brew screen and group head gasket in Silvia, it is pulling some great shots right now. Lots of steam if I don't surf first though.
Still waiting for the SSR from Auber, but I'm sure everything will be fine when I put it back in.
I'll probably only have her for another month or so, since I am waiting for a La Spaziale Dream, but at least I can sell both Silvia and Rocky knowing that both just had a full overhaul from this process.
I'll give a final confirmation here when I get the SSR.
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