Replacing Solid State Relay on Profitec Pro 500

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

#1: Post by tmorville »

Hi Baristas!

I bought a used Profitec Pro 500 for a good price as the previous owner had some issues with the machine not heating up once in a while. He would keep it on all day which I've read in several places will put strain on the already over-performing SSR.

Got the machine and it had all of the symptoms that have been described in several other posts about malfunctioning SSRs in Profitec 500s. I bought a new SSR from a parts retailer (this one ( ... 0vac-25a-/) as it says it would fit Profitec and was available in Denmark where I reside.

To my demise, when I opened the machine, I found that the wires have spade connectors and not fork connectors :x

Beware that I know next to nothing about electronics, so I found a video that shows a similar SSR. Here each wire has a small U-shaped fin that fits under the metal screen on the screw.

What should I do? As I see it, I have these three options.

a) Get a new SSR that fits - Return the SSR and try to get one with the small square fins. I have not been able to find one like this in Europe. Does anyone know where I can get one of these?

b) Make the one I got work - Replace the spade connectors on the wire with fork connectors one like in the video. I am assuming that just taking the naked wire and wrapping it around the screw on the new SSR is a big nono?

c) Give up - Hand over my machine to a tech and pay 200 EUR for getting it done :shock:

I promise that I will update the post with a guide on how to do this once I am done.


#2: Post by JRising »

I would cut off the crimped connectors that are there and crimp on forks. Any local electrical hobby store has them, or just get them from Amazon.


#3: Post by Bluenoser »

I think you are in 240v land, so you likely don't need to relocate the relay. But when I remount, I'd add a thin layer of heatsink compound between the metal of the SSR and the metal bracket.. Will make a huge difference in cooling the relay.

I would not wrap bare wires.. but I think you could also just cut the leads, strip and tin the leads with solder and then clean well with isopropyl alcohol (to remove burnt rosin).. 99% preferred, but 70% likely fine.. and then screw down well.

A note when removing insulation from stranded wire.. It is super easy to nick strands and then they will break off over time.. try to cut around the insulation, but not all the way thru. Then you twist insulation with fingers and pull and the insulation removes without damaging the wires.. . I can't tell the exact mechanism of the contact, but if you might want to form wire into a J after tinning and insert. Screw tight. Or you can crimp a fork on. Just get a proper crimp for that gauge wire.

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#4: Post by Nunas »

Cut off the connectors, bare the wire back enough to fit under the clip, twist the wire a little, being careful to include all the strands, put the wire under the clip and turn the screw down firmly. My recommendation, especially if you are inexperienced in electronics and do not have a quality ratchet crimper, eliminates the possibility that you'll have a bad crimp joint. A bad crimp joint will lead to early failure of the connector. I suggest not tinning the leads, which can gradually migrate and loosen the joint. The connectors on your SSR are designed to accommodate bare wires.

Incidentally, be sure to mount the new SSR using a heat-conducting compound. Although the SSR is rated at a given maximum current, this is contingent on it being mounted to an acceptable heat sink. If the original SSR failed, it is possible that it was not adequately mounted for heat transfer. Chances are, it was merely mounted to the chassis with heat conducting compound. If the chassis is stainless, which isn't a particularly good heat conductor, you can greatly reduce the probability of the SSR failure by bending a square-U-shaped piece of aluminum, or buying a purpose-built heat sink. Use compound between the chassis and the heat sink and between the heat sink and the SSR. I recommend you have a read here Does relocated Profitec Pro 500 SSR require thermal paste?


#5: Post by canatto »

perhaps try to find adapter like this? ... w-4-3mm-45 for the side having bigger screws, and ... currency=2 for the side having the small screws.

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#6: Post by cafeIKE »

DO NOT tin the wire and place under the terminals.
DO NOT twist the wire and place under the terminals.

IF the terminals come off the new SSR, crimp with a proper crimp tool or solder RING terminals of the appropriate size for the wire gauge and screw diameter.

If the terminals don't come off, as above, but use fork terminals.

Likely insulation colors: RED for control and BLUE for power.


#7: Post by Bluenoser »

Yes.. I was not aware of the creep of solder under a compression as I read now.. it was something we used to do on low current prototypes several years ago. The fork or ring connector as suggested above is great advice. You need a good crimp as you want a good gas-tight seal that won't oxidize. My Pro500 SSR also failed and I think it was mostly do to the lack of thermal paste .. But when mine went I relocated it to the bottom of the chassis and near the back and it has been fine for over 2 years; and because I am in North Am, it is handling double the current. Be careful when you strip the insulation.

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#8: Post by BaristaBoy E61 »

canatto wrote:perhaps try to find adapter like this? ... w-4-3mm-45 for the side having bigger screws, and ... currency=2 for the side having the small screws.
+1 That's the ticket!
"You didn't buy an Espresso Machine - You bought a Chemistry Set!"