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Old 8th Nov 2018, 6:00 pm   #21
Ed_Dinning
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Default Re: Dead Ultrasonic cleaner.

Hi Les, the welds are not usually very deep, only about 2mm, and the lams can then be knocked apart. A slight clean up and the lams are reusable. Not the lowest lost lam material available but should be OK for your purposes.

Ed
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Old 8th Nov 2018, 6:26 pm   #22
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Default Re: Dead Ultrasonic cleaner.

Off topic some what and not on ultrasonic cleaners.I have been following the story and read with interest about laminations being welded up. Recently a friend had an MEN electric motor starter which made a loud annoying buzzing sound, he has cleaned the pole faces aligned ever thing up and the sound hasn't completely gone away. I would like readers views on Tig or Mig welding the lamination as in cheap stick welders, stopping the lamination movement and noise. I have never seen it done but maybe worth a try. Ted
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Old 8th Nov 2018, 6:37 pm   #23
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Default Re: Dead Ultrasonic cleaner.

It looks like good news after all. I braved it out to the shed this afternoon, removed the jumper (which is in fact now a 200mA meter fitted last year to improve tuning the coil). Plugged in, switched on, and neon lit up, fan started and nothing untoward followed. Obviously not a dead short on the transformer primary. I checked C3 with my megger, no leakage there, and then checked C2, which seemed OK with megger, though it does seem to have leaked a little more oil. Nonetheless I replaced that with a new porcelain version I had off Ed last year, but had not yet changed. A few more checks including C3 capacitance before I try it again, but looking good.
Les.
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Old 8th Nov 2018, 8:05 pm   #24
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Default Re: Dead Ultrasonic cleaner.

Apart from the laminations being welded up, the core might have an air gap or an additional magnetic shunt. I've seen a few MW transformers while doing repairs but I never took one apart so I don't know whether the details are always the same.
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Old 9th Nov 2018, 9:17 pm   #25
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Default Re: Dead Ultrasonic cleaner.

Success. I ventured out again to the shed, and prepared to test it out. But, looking at the Zaerix TY2-125, it looked as if there was a clean crack around the top. Difficult to assess, and I vaguely recall seeing it previously. I could feel what felt like a crack with a finger nail, but then again, could not be sure. No sign of whiteness anywhere. I have a second valve, Mullard, but it was definitely the lower emission of the two.(Not "tested", but concluded from the anode current meter I had fitted in place of the "jumper"). I decided to fit that, and everything started and ran OK, the water surface in the tank showing something was happening. Switched off, and refitted the Zaerix. ran for a few seconds, nothing on the Ia meter, then the fuse blew.
Fitted the dubious Mullard, replaced fuse, hung in the carburettor requiring cleaning, with a kettle of boiling water and a few drops of Fairy. Will try it on the bike asap.

A few further comments to be made. I think I am getting higher Ia with the Mullard than previously, probably a result of fitting the replacement C2 capacitor. Now I assume by changing C2, that will alter the tuning. How should it be tuned from scratch? My thinking is as follows.
Set the ferrite "tuning disc" to the 45 degree position. Check Ia. One at a time, change the coil connectors to 3 or 4 (lead to heater CT), again noting Ia. Next try the output feed from 8, 9 and 10. Select the best of these permutations, and hope that rotating the ferrite disc will tune even more output. Is this logical, Ed perhaps?
I looked up the TY2-125 data today. I knew it was 6.3v on heater, but was amazed to see it ran 5.4 amps. Would a MW transformer source that if asked to?
Max figures for Va and Ia are 2,500v and 250mA (shown as Ik not Ia, i assume interchangeable in this case? Most unlikely to exceed the former, but must be cautious about possibly exceeding the 250mA current.
Of course if the Carb came out clean where it matter on test, I may just put it aside. Meanwhile, pray the old Mullard valve does not go the way of the Zaerix, I don't think I could afford one of those.
Les.
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Old 10th Nov 2018, 12:51 am   #26
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Default Re: Dead Ultrasonic cleaner.

The heater power is about 35W. That's not a lot compared with the 900W or so rating for the MW TX.

I'd be surprised if the maggie it originally drove took much less!
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Old 10th Nov 2018, 9:03 pm   #27
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Default Re: Dead Ultrasonic cleaner.

I must confess to knowing nothing about microwave ovens, though I did have one about 35 years ago, before I got my first Rayburn cooker, and had PROPER heating and cooking facilities ever since. I remember maybe 10 years ago, modifying one for use in a film. I rendered the MW side inoperative, but fitted an internal lamp and separate power to turntable. I have dismantled at least one (hence this transformer) but never gone searching for the magnetron. I don't really know how they work, but did read something a few years ago.
Perhaps I should dismantle another one day and look, but as mentioned previously I know to treat with respect, so will NOT play about with mains anywhere close.
From the point of view of my U/S generator, I would like to know more.I have a single replacement item for ALL components, except transformer and valve, so on the basis of stuff learned here, I only need another TY2-125 for future security of the unit.
Les.
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Old 10th Nov 2018, 9:17 pm   #28
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Default Re: Dead Ultrasonic cleaner.

Hi Les, frequency determining components are the transducers. The osc/ amp is pulled into tune with them as they are in the feedback path.
Absolute minimum smoothing on the HT so amplitude of ultrasonics rattles about at 50Hz. This is quite intentional as it prevents dead spots in the tank.

Ed
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Old 10th Nov 2018, 11:48 pm   #29
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Default Re: Dead Ultrasonic cleaner.

I have a smaller cleaner with a piezo transducer about 4 inches across.
The HT is fed at AC and it relies on the valve to do the rectifying.
It just feeds the workload with 50 bursts of power per second.
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Old 14th Nov 2018, 7:20 pm   #30
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Default Re: Dead Ultrasonic cleaner.

I am trying to properly understand the method of working, but will need a bit of help. I have re-drawn the circuit, which is helping me a bit (attached). It seems the rectified HV from the valve appears across taps 4 and 16 (earthy) of the coil. The grid feed is between taps 0 and 4, and in anti-phase to the main valve current.
As Ed says, the piezo blocks fix the frequency. However the magnitude of valve current is determined by the characteristics of the coil. The info on the receiving tank advises "tuning" with the control knob. This is of course the ferrite disc, FD1 on my circuit. Obviously one expects to tune through a maximum, but I found that the maximum is with FD1 in the position shown on my circuit, i.e.,separating (or is that coupling) the two halves of the coil. (My ignorance showing now). I assume the ideal is to pass through the maximum with FD1 in the 45 degree position. Do I bring about this condition by moving the lead on terminal 4 to terminal 3, or alternatively the earthy feed from terminal 16 to terminal 15.
Best suggestions please.
Note. The coil as drawn lacks terminals 1,2, 5,6, 11 and 12, which appeared on the previous circuit. That was the coil from the dismantled unit (dead transformer) but as now shown has the one fitted in this unit. I suspect the other unit was an earlier model, subsequently "simplified" as well as different mains transformer.
Les.
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File Type: pdf Ultrasonic generator.pdf (82.6 KB, 83 views)
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Old 14th Nov 2018, 10:55 pm   #31
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Default Re: Dead Ultrasonic cleaner.

It's a simple enough oscillator circuit. C3 and the inductors constitute a tank circuit. The piezo transducers are higher Q and are coupled to the tank, but the valve sees a resonant tank circuit driving its grid WRT ground. THe anode is at RF ground, decoupled by C1
THe cathode (heater centre tap) sees a lowish valueresistor and drives a lower tapping on the inductor of the tank.

It's basically a Hartley.

David
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Old 15th Nov 2018, 11:09 pm   #32
MotorBikeLes
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Default Re: Dead Ultrasonic cleaner.

Thanks for the explanation David. I still want to optimise it if I can (not having FD1 as fully across the coil, or fully inline).
I dug out the coil from the dismantled unit, and the "tell tale"snipped off wires.
The cathode feed was tag 3 not tag 4, the output from tag 8 not tag 10, and the earthy end at tag 15 not tag 16. I will feel a bit happier trying some of those alternatives.
Les.
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Old 16th Nov 2018, 12:17 am   #33
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Default Re: Dead Ultrasonic cleaner.

They probably muck around with the tapping choices to firstly get the L-C resonance in close-ish agreement with the piezo-electric view of what would be a nice frequency to oscillate on, and to accommodate the amount of activity of the piezo resonance associated with a full tank. to get the power level about where intended.

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Old 24th Mar 2019, 10:56 pm   #34
MotorBikeLes
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Default Re: Dead Ultrasonic cleaner.

Time for an update I think. You will recall that I found the dead machine was the Z&I valve had a clean break in the glass, so in went the mullard that had previously seemed rather low output. I had also replaced an oily cap with one supplied by Ed, and hoped for great things. I found it would still not tune to a max so went away to think then of course got side tracked by all the other tasks SWMBO provides.I had fitted a milliameter, but it was near to its FSD, so I dug out another moving coil meter and shunted it for 500mA.
Last week I tried tuning, moving three of the coil connections, finally getting a tuneable maximum with FD1 at an angle.
However, I was now getting only about 90mA anode current. I disconnected the meter and used a testmeter, and sure enough, 95mA. I think my other meter was badly shunted (by me of course), but it is a moving iron type. Do they shunt the same as an MC type, or did I just do it wrong?
Anyway, the upshot of this is that I think I need a new/better valve. Type TY2-125. Before I go searching online, I will put a request here.
The circuit with re-positioned tappings is shown.
Les
Attached Files
File Type: pdf Ultrasonic generator.pdf (102.2 KB, 61 views)

Last edited by MotorBikeLes; 24th Mar 2019 at 10:58 pm. Reason: Circuit failed to appear
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Old 31st Mar 2019, 9:36 pm   #35
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Default Re: Dead Ultrasonic cleaner.

Hi!

Is this over your budget?

https://www.ebay.co.uk/itm/Mullard-C...8AAOSwYj9cE4t9

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Old 1st Apr 2019, 9:21 pm   #36
MotorBikeLes
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Default Re: Dead Ultrasonic cleaner.

Chris that must be new. I looked a few times, but bought one from a member here. Unfortunately, it is barely better than the one I have. I now have a decent 250mA meter, previously I had a (badly shunted I assume - - ME) moving iron meter which was obviously over reading. Before it died, my Z&I valve was better (30% +) than the Mullard. Not something I can test easily, and I guess I don't know what current the valve should take in this apparatus.
If I had seen this last week, perhaps I should have got it, but now ? . How much do I spend before before I should have just bought a new one?
If anybody (Ed, RW0 cares to suggest what anode current a new valve would pass, please do so.
Les.
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Old 1st Apr 2019, 11:25 pm   #37
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Default Re: Dead Ultrasonic cleaner.

The data sheet makes it look like 2kV and 150-200mA would not be silly, but it's running from rectified 50Hz

If the valves fed AC HT then real current indications will be halved

ditto for halfwave rectifiers.

David
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Old 2nd Apr 2019, 8:26 pm   #38
Ed_Dinning
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Default Re: Dead Ultrasonic cleaner.

Hi Gents, poorly smoothed HT was often used in ultrasonic generators as it helped sweep the frequency and amplitude a bit and get rid of dead spots in the tank

Ed
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Old 2nd Apr 2019, 8:40 pm   #39
MotorBikeLes
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Default Re: Dead Ultrasonic cleaner.

It is a pity I did not get a proper mA reading before the Z&I valve decided to fail, as it certainly was better than the old Mullard. Yes, in view of that 200mA and 2KV on the transformer (=600W) I expected more.
I am busy with other stuff (a planning application, and don't know what I am doing) but I will get a carburettor in there and see just how much gunge it can remove now.
Thanks for comments.
Les.
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Old 3rd Apr 2019, 12:14 am   #40
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Default Re: Dead Ultrasonic cleaner.

I have got an ultrasonic cleaner that just has a line output valve oscillator fed with AC so that it just conducts and works on half cycles.
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