Anyone own an Utrawave Ultrasonic cleaner?

[AshimotoK0]

Fixed a really big one of these for use at home ... it was out of the skip at work.
It packed up on me though a couple of nights ago. Utrawave are very cagey about the repair of these, they basically want you to send it back for a refurb and charge a lot of money to do so.

I have fixed it again but I have repaired a few of these in the past. They all seem to have a common power oscillator board in them with some parts being highly stressed and hence they overheat.
Got a few repair  tips to share  if anyone else has one. The ones I have seen sometimes have fancy timers and 'front' ends but the basic power PCB is the same (the board that usually goes pop).

[JamesH]

Mine's broken ash - awaiting your magic :-)...

[AshimotoK0]

Mine's broken ash - awaiting your magic :-)...

Yes I know about yours James. Can you let me have the model number please, photo of it  so I can guestimate the parts needed to fix it.

Cheers ... Ash

[mike the bike]

I'm forever fixing touch lamps.  When the bulb blows, it takes out the triac.   I put a higher spec one in that has a higher forward current, but still the same TO220 package.  One they've been modified they stay fixed.
Perhaps you need to do something similar with those power supplies.

[AshimotoK0]

I'm forever fixing touch lamps.  When the bulb blows, it takes out the triac.   I put a higher spec one in that has a higher forward current, but still the same TO220 package.  One they've been modified they stay fixed.
Perhaps you need to do something similar with those power supplies.

The transistors are pretty high spec 1200v and ample current  but there are 4-matched to one another for current sharing. The main problem is power resistors getting hot and burning the PCB, then dry joints, so no longer load sharing. Not much room to fit higher wattage ones. I am modding the one I have to fan cooling the PCB and as high wattage parts as I can comfortably fit.

[mike the bike]

How about mounting the resistors remotely on a heatsink?

[AshimotoK0]

How about mounting the resistors remotely on a heatsink?

Yes I can do that in fact I am mounting the PCB in a separate enclosure for the time being.
My main point is that they flogged the same PCB assembly, same basic design,  in various machines for quite a number of years with overstressed components. It's OK for the likes of you and me Mike who understand how to fix/re-engineer but for the average guy, they could buy one say S/H, for quite a bit of money, and it may not  last for long. The other main issue is there is a ferrite output transformer that is glued in a frame with an air gap between the cores. The adhesive de-bonds after a while, the gap changes/varies and  it upsets the oscillator and buzzes away but doesn't ultrasonically clean properly. I have two of these US cleaners and they have both suffered PCB burn and ferrite transformer de-bonding. Ultrawave charge a f'kin fortune to fix 'em. Apart from that they work really well for US cleaning.

The tank alone without the US is great for hot tanking parts.

For anyone who don't know, you test the US action by putting a strip of cooking foil in the tank / liquid and it should develop tiny holes within a short time.

[mike the bike]

No, I didn't know that.

[RGP750]

That's a good tip thanks.
As far as me and electrics you may as well have
been talking Punjabi

[mike the bike]

ਜੇਕਰ ਤੁਹਾਡੇ ਕੋਲ ਇੱਕ ਹਥੌੜੇ ਨਾਲ ਇਸ ਨੂੰ ਠੀਕ ਨਾ ਕਰ ਸਕਦਾ ਹੈ , ਜੇ ਤੁਹਾਨੂੰ ਇੱਕ ਬਿਜਲੀ ਸਮੱਸਿਆ ਹੈ

[RGP750]

  now i can understand that

[royhall]

Not a clue what they just said. Is it English? Sounds bloody impressive though, bet they have to fight the women off with technical talk like that.

[Chris400F]

Thought I'd try Google translate, which comes up with:
'If you can not fix it with a hammer , if you have a power problem'.
Not a clue if this is right, and doesn't really make much more sense than the Punjabi. Is it even close?

[mike the bike]

It's supposed to be. If you can't fix it with a hammer you've got an electrical problem' but it's close enough.