On Friday I went to my local electronics store, and while I was there looked through the sale items. Hidden in the back were 3 ultrasonic cleaners, customer returns, in boxes, marked down from $70 ( R645) to $15 ( R150), so I bought all 3, thinking at least one can be made from the parts.
Looks nice, all the interior baskets and stuff in all 3, and one copy of the Chinglish manual as well ( not terribly helpful, but it did describe that when working they go ZI!ZI! sound) and at the price I was going to take a chance, even if all 3 were faulty I could build one, or at least have enough to do a teardown.
No1, works off the bat, no problems at all, so went to number 2.
Front panel defaults to 3 minutes, but you can change that by pressing the buttons. No 2 had a display, but pressing the button display went slightly dimmer and counted down, but otherwise nothing doing. Opened it up and after some work getting the power supply out into DaveCad I had an idea of the way it worked. Did some cold measurements then plugged it in and measured again ( capacitive dropper supply here so it is live) to see voltage. 12V internal rail for the control was at 5V, and dropped to 4V when the control turned on. Checked relay, and it is a 12V unit. main capacitor of 1.5uF 280VAC class X2 ( with UL stamp, VDE and other standards stamped on it, embossed on the top SR.CAP) measures 554.2nF, so definitely not happy. Replaced with a WIMA 1.5uF 400V unit I had in the spares box. Turn it on after assembly and a second working one.
Today I went to number 3.........
Does not bode well, dead and on removing from plastic bag smells a little crispy.
Mounting for the board inside does look well done in places.
Very well done board bottom, it did run rather hot it seems.
fried silicon Crispy is best to describe this, there are little balls of solder inside the case, and the heatsinks are loose. Not going to be easy to fix this well toasted unit.
naked control Front panel after removing the sticker.
bare front The bare panel front.
controlback The back, complete with ground off part numbers. Probably a Microchip unit there anyway.
cooked ceramic Found the transducer has cooked itself, probably this was the cause for the cremation on the main board along with it being run for extended periods.
cracked transducer by
SeanB_ZA, on Flickr
The transducer itself is cracked, so no longer a repairable unit.
All in all I did get 2 for the price of 3/4 of one, so overall I can say it was a success. Not the best of units, case is polystyrene, so only solvent I can use is water, no alcohols or anything else more agressive as a cleaning agent other than water and detergent. Lid is clear ABS as well. But as I do not have a good ultrasonic cleaner and now have one and a spare it will do. Tried it out and it does clean, removes dirt from watch bands using only water, and is faster than using a toothbrush and alcohol ( normal method), just have to remember to unplug after use, and do not use for more than 5 minutes at a time.
