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rebuilding carbs
exvalvesetdabbler:
I have been distracted the last couple of days trying to get my ultrasonic bath working after 15 years sitting in the loft. It's an old industrial one dating from the 90s that decided to start popping fuses coupled with a leaky heating element which is why it was thrown out at work many years ago. Heater perminateley disconnected and the fault on the transducer board now fixed. It frequency sweeps so I didn't want to give up on it because I would never afford a new one having these specs. After 20 minutes running the water is up to 40 Deg without the heater any way. Lots of bits to degrease now including the carb bodies before they go off for wet blasting. No doubt there will be a few watch straps and jewellery joining the queue.
In between fixing this and other jobs I had a look at the pivot pins that locate the floats, none were particularly great so I set about making some new ones. 2 mm diameter brass rod, 23mm in length and chamfered at both ends.
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The two at the top are old ones.
Regards
Dave
AshimotoK0:
**********TECH OVERLOAD WARNING! ALERT FOR ODDJOB, ETC. ;D*********
I got my ultrasonic cleaner out of the skip at work and fixed it ...made by Ultrawave.
It worked great for a while then BANG ! popping all fuses. Managed to fix it but after a few months BANG ! again.
When I looked at the bank of output transistors they all had a number hand written on them. I found out that they matched all of the transistors at the factory and I don't have a clue how to do that. I don't think it's just a matter of gain matching... If you don't perfectly match them, then they don't share the current correctly and eventually go BANG! Problem is with the design of these things they are switching high voltages at high frequency into a highly capacitive load.
Ultrawave is similar design to this one.
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I do have another smaller one that is of the same era and that seems less fragile. Made by Decon Scientific. Pic is of 300B model but mine is a 400B so larger. Got given it as being 'BER... (Beyond Economic Repair).
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exvalvesetdabbler:
Ash , the one I have is a ex lab Decon model like the beige one in your pics , a 200w version.The QC sticker inside is dated 1990. The problem that I found was with a triac bolted to the earthed chassis. Someone didn't deburr the hole properly and the burr had penetrated the insulator to give an intermittent short. Luckily I had some more insulator pads to fix it after deburring the mounting hole. There's no real chance of getting at the heating element without de bonding the tank from the enclosure. It was electrically leaky sufficiently to fail a PAT test and that's why it was on its way to a skip before I rescued it.
It's amazing the amount of stuff that gets tossed in a skip when a lab closes or no longer needed. My boss would routinely lecture me on hoarding stuff that might come in handy one day, Apparently it costs money to store stuff you no longer need.
Regards
Dave
AshimotoK0:
--- Quote from: exvalvesetdabbler on February 13, 2026, 04:54:26 PM ---Ash , the one I have is a ex lab Decon model like the beige one in your pics , a 200w version.The QC sticker inside is dated 1990. The problem that I found was with a triac bolted to the earthed chassis. Someone didn't deburr the hole properly and the burr had penetrated the insulator to give an intermittent short. Luckily I had some more insulator pads to fix it after deburring the mounting hole. There's no real chance of getting at the heating element without de bonding the tank from the enclosure. It was electrically leaky sufficiently to fail a PAT test and that's why it was on its way to a skip before I rescued it.
It's amazing the amount of stuff that gets tossed in a skip when a lab closes or no longer needed. My boss would routinely lecture me on hoarding stuff that might come in handy one day, Apparently it costs money to store stuff you no longer need.
Regards
Dave
--- End quote ---
The Decon ones are much easier to fix apart from the bonded on heater pads. I find the Decon one heats up pretty good anyway without the heater on. The Decon ones have a proper toroidal mains transformer but the Utrawave has just mains rectified power and an output transformer, which drives the bobbin shaped ultrasonic transmitters and provides mains isolation . My Decon one has flat bonded on transmitters .
The modern Utrawave cleaners have a PIC micro that drives the power module and if that goes pop you are stuffed as they would never share the code and I bet the PCB costs more than the cleaner is worth. Built in obsolescence eh !
Oddjob:
Still got my blown Ultrasonic Ash. Never got round to fixing it. If I sent you the PCB do you think you could fix it?
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