Case #1954 Sherlock?

Case #1954

Unit: Jet-Tech F18dp

Paying attention is important in this job. It's a bit like playing Sherlock Holmes and trying to find who done it. Or what done it in this case.

Often the smallest detail is important. In this case the answer was right there in front of my eyes. All I had to do was look and listen.

The machine is a Jet-Tech model F-18dp under-counter dishwasher. The F-18 is a good Italian machine. In Europe it carries the model name CF50. It is made by Adler near Milan. The place was a nice Italian restaurant. I received a call from the chemical distributor. They were in a bit of a pickle. They were afraid of losing the account if the dishwasher could not be fixed. They had sent another technician and he failed to find the problem. The problem reported was the unit's wash pump was defective, and a new one was needed.

Whenever someone sends me after another technician, I do what I always do. I start from the beginning. When they told me the wash pump needed to be replaced I was a bit skeptical. Adler (Jet-Tech) uses one of the best pumps on the market. It is made by FIR  and short of dipping it in water or have a chemical spill on it, it's going to outlast the rest of the machine. Almost.

Anyway, when questioning the operator, he told me the unit would wash occasionally. So it was an intermittent problem. I needed to hear this thing run. By the sound the motor of the wash pump would make I could determine if the pump was indeed defective.

I started by draining the machine. Going through all the sequence of the unit will help determine if I was dealing with one or more problems. I let the machine fill up. The heat kicked in properly. I pressed the start button to get the wash pump to work and it did. The sound was a solid, continuous pumping action. That pump was good. Then the sound changed. I stopped it right away. I took the top cover off and put my amp probe on the wash pump line. Tried it again and the amps went way up. I was thinking a bad capacitor might be the cause. I changed it but the problem remains. It was getting late, 8 pm or so. I was not convinced the pump was bad but right then I couldn't prove it. I took the decision to take it out and bring it to the shop for closer inspection. When I took the rear panel out, I noticed what the last technician did. Reconnect the detergent bulkhead fitting.

In the morning, I put the motor on the bench and tried it. It purred. There was nothing wrong with this pump. I went back to the restaurant and put the pump back, totally convince the problem was elsewhere. It was and not that far. I paid a closer look at the repair the other tech did. Before the operator noticed the chemical fitting was broken a generous amount of detergent had leaked down on the wires. Yes, the wires had been covered with dried detergent. I should have spotted that the previous night but I missed it. I had seen this before. Chemicals will destroy the insulation on the wires and on occasion break the connection. It's exactly what happened with the wire for the capacitor which would be touching sometime. The best course of action is to change the entire wire harness. The next best thing is to clean the wires thoroughly and re-insulated them, repaired the broken connection.

This was done and the machine worked very nicely.

Conclusion: It’s not always good to work too long hours. As a general rule, I stop around 5pm. I mean, what’s the point of working late if you're going to make mistake and have to return. And I am not Sherlock Holmes.