Was given a fridge with a 3 flash code, meaning locked rotor or too high head pressure. After some investigation decided the fault was in the compressor. I then cut the compressor apart to see why?. Found the compressor was free to turn (not locked) & still gave a 3 flash code. Decided to test the windings for resistance, didn't look too bad, but the inductance of the windings was lower on 2 of the windings (Good compressor they are 5.5mH). So I suspect the 2 windings may have shorted windings causing it to not run & give 3 flash code. Also pict of the Wave form on one set of windings on a good compressor.
Great post, just one thing when you measured the AC inductance of the windings did you disconnect the other two windings that are series with your winding that your are trying to measure. These windings may have a infuence on you meter.I was always taught to disconnect all outside inductance/resistance off the inductor that your are trying to measure. Same as when checking flyback transformers from crt televisions, even to the point of taking the flyback transformer off the printed cct board so as to make certain that there is no other loading of the transformer/ or inductor.
DeBe said
09:13 AM Dec 10, 2015
Interesting point. will try that later. Was realy after a test that didn't require cutting a compressor apart, that then becomes a point of no return.
KFT said
09:41 AM Dec 10, 2015
DeBe were you thinking that comp is already at the point of no return anyway?
I can see one winding that looks a bit cooked
Frank
DeBe said
09:56 AM Dec 10, 2015
Its not cooked Frank its just diferent coloured enamel coating.
KFT said
11:11 AM Dec 10, 2015
Ok thanks
unusual to see different coloured enamel. usually all the same.
so will you get this one going again?
DeBe said
12:56 PM Dec 10, 2015
No its beyond repair Frank. Have since discovered the windings aren't Delta but Star wound. Theres a shorting link that creates the center of the star winding, so I removed it & checked the resistance & inductance of each individual winding. They were closer to the same values. But on re connecting the shorting link now find the compressor will actualy run. So the only thing I have disturbed are the internal conections. Thanks for your input guys, makes you re asses what you have done or missed.
-- Edited by DeBe on Thursday 10th of December 2015 01:12:36 PM
G'day DeBe, "Thanks for your input guys, makes you re asses what you have done or missed."
I have often found that to be helpful. someone else may see things different to you or I and you wonder how did I not see that????
learn something new every day mate and you could live to become an "Old Techo" sort of fella.
hehe
Frank
03_Troopy said
08:06 AM Dec 11, 2015
Darryl, years ago I built a tester that gives a ringing waveform for different coils, which was mainly used for LOPT transformers, but the output can be selected for other sized coils. You could consecutively ping across each of the coil pairs at the inputs and compare the resultant waveform on a CRO. You could use the waveforms from a known good motor to determine whether the one under test is stuffed or not.
You would get something similar to this (this is a pic I pulled of the net just as an example)
I used to download the waveforms to a computer, as well as waveforms of the new replacement LOPTs, and save them for comparison with other LOPTs I suspected as being bad.
I have a shorted turns tester but it only works on LOPT transformers. Need one that you can alter the frequency.
dorian said
08:27 AM Dec 11, 2015
Bob Parker designed an FBT tester as a kit for Electronics Australia. This kit was sold by DSE and others. I expect that one could modify the frequency in his design. Alternatively you could replace IC1a with a 555 timer.
-- Edited by dorian on Friday 11th of December 2015 08:32:27 AM
03_Troopy said
08:37 AM Dec 11, 2015
Yeah, the one I built has 3 different selections, can't remember the frequencies now, I haven't used it in years. It was an old EA or SC project, without the LEDs (not the K7025). I have used it on stator plate coils for a motorbike and various other transformers and coils. Even if you only get a few oscillations per phase displayed (maybe half a dozen), at least it can give a comparison.
I just went looking for the Schematic or kit info, but it seems I may have lost (probably chucked out ) it.
-- Edited by 03_Troopy on Friday 11th of December 2015 08:49:38 AM
DeBe said
09:02 AM Dec 11, 2015
03 if you find the circuit I would be most interested.
I found it and opened it up, but now I remember that it wasn't a kit, but one I got details from somewhere? and built on a vero board. I'll trace out the circuit when I get a chance and try some tests on a couple of different coils. The other thing I realised while searching for it was that I no longer have the desktop computer I used to use to save the waveforms to, and none of my laptops have a serial port. Except for a very old Toshiba notebook that I almost threw out a couple of weeks ago. And I had to download software from the Tektronix website because I might have lost the original software I had. I haven't used the DSO in over 10 years now.
DeBe said
12:39 PM Dec 14, 2015
Be mutch appreciated 03_Troopy.
03_Troopy said
02:01 AM Dec 17, 2015
OK, I have been playing around with the coil tester on a couple of motor windings, and these are the results.
I had 2 different motors, both 240VAC, but different constructions. I tried them both at the different switch settings on the tester and viewed them on a DSO.
The tester, I'm pretty sure, I built from a schematic that was in a pommy TV servicing magazine that I sometimes got when I had my electronics repair business back in the mid 90's. I haven't traced out the circuit yet, because the way I built it (rough and ready) I have to unsolder the pot and switch and sockets to remove it from the box.
The tester.
The tester puts out a series of pulses or different shapes (selected by the 3 position switch) at a frequency of between 66Hz and 124Hz (adjusted by the pot) roughly when not loaded by a device under test. The pulses are between 60mV p-p and 80mV p-p also depending on the switch position, and also when no device under test connected.
Here are the un-loaded pulse trains using switch positions 1 to 3 respectively:
Here are the motors I used for testing:
Here is what happens when the photocopier motor is connected across the tester, leaving the the time base the same for each position, to show the differences in waveforms produced:
Here's what they look like when you adjust the display for a usable waveform:
As you can see, you can get a decent enough ringing pattern to be able to see if you have shorted turns, especially if you have known good waveforms to compare them with.
Here is what the other motor looked like on the tester:
These waveforms are also pretty good for the purpose of looking for shorted turns. Especially in position 3 in the last pic, where you can see a nice symmetric waveform, with a smooth amplitude decay.
Hopefully I'll get some free time to pull the tester apart so I can trace it out. there are only about 8 components in total, but the way I put it together, it isn't easy to get at.
Hi all;
I to built that LOT tester many many years ago, and was also used as a teaching aid. Troopy that pommy magazine that you are talking about was a magazine called ' Television ' and was a good read in those days, and a lot of very usefull information was their to be had. Remember the very first video recorder that we had in Australia ( Philips N1700 ). Pommy land had a earlyer version ( N1500 ) and Television had a series on how to modify it to the longer play version of the N1700 model.
Some of the articals were pure gold in those days. It's a shame that the magazine hads stopped being printed.
03_Troopy said
08:10 AM Dec 17, 2015
We bought a NV-2000 when we were in Malaysia back in 1981, from memory they cost about $1,500.00 in Aus at the time. We also bought a VHS Video Camera like this one, Which were well in excess of $2,000 in Aus at the time.
DeBe said
11:24 AM Dec 18, 2015
Definitly interested in building that. My LOPT tester I built in the late 70s but only works at line freq. I used to get that magazine, but unfortunately I threw them out when I stoped repairing TVs & VCRs as with all the work shop manuals.
valiant81 said
05:48 PM Dec 18, 2015
Hi 03 Troopy;
Yeah great recorders of the day, only down side was they were very heavy in weight and the rechargable battery only lasted about 30 Min's. Old school recorders and now aeirloom material. Had a clean out of my store room ( 2nd bedroom ) the other day and one of the things that went to the local tip was a hitachi vhs (c) camcorder still worked, last time i used it but the way of how things are this days beening a throw away society, now one wants 'old school' same as the do do bird.
And me to had a big clean out of trade mag's etc a couple of years ago. You name it, if it wasn't used or out of date, out it went, a couple of valve school PA amplifiers ( Pararell push pull 807 valves ((4 )) and about 500 volts on the plates ) good for a couple of 100 watts Weighed a ton , but again old school, serperate power supply and serperate radio tuner, built to last and last all in a steel case and made by AWA i remember these things, ran all day 5 days a week. Not like the rubbish that is forced on to the industry these days.
Sorry you guys for getting off topic, once i get on my soap box, their is no stopping me
-- Edited by valiant81 on Friday 18th of December 2015 05:49:59 PM
03_Troopy said
01:10 PM Dec 22, 2015
OK, firstly the waveform I showed in a previous post of the tester outputs on each switch position with nothing connected across the test terminals is pretty useless as it has nothing for the output waveform to be developed across. So I have done another one with a 2K resistor across the output terminals to give a better idea of the outputs.
I had a couple of goes at racing the circuit, but because it's such a crappy job I did of putting it together (was hastily built for use at the time), it was a PITA. So I did the next best thing and made up some diagrams of the board with component layout.
Hope you can work it out from this Darryl, but if you find any problems let me know and I'll try and sort it out. The components aren't critical in their voltage values as you might have guessed, but that's what I had on hand at the time. Capacitor C2 was mounted on the back of the board to allow me to fit it al in the tiny box I used at the time.
Cheers Bob
-- Edited by 03_Troopy on Tuesday 22nd of December 2015 01:13:14 PM
Thanks for that. Have printed it all of & will build it, only part I will have to buy is the IC. Will eventualy get back to you.
DeBe said
10:47 PM Feb 14, 2016
Hi 03_Troopy. Have built the project but cant get it working at this stage. But whilst looking for something else, came across an old Television article I filed back in Sept 1998 issue, it was a LOPT tester. But it made reference to A LOPT tester using a CD4001 IC in Sept 1993 issue by Ian Rees. I suspect this is the one you built. I might try a couple of Electronic Forums to see if some one still has the article.
03_Troopy said
08:08 AM Feb 15, 2016
Hi Darryl, do you get any output at all, using a resistor across the output?
DeBe said
09:35 AM Feb 15, 2016
I would expect a wave form at least on the base of the transistor. As there is none I suspect the oscillator stage is not working.
03_Troopy said
09:16 PM Feb 15, 2016
I'll sit down and trace it out when I get a chance Darryl, incase I've stuffed up somewhere.
Was given a fridge with a 3 flash code, meaning locked rotor or too high head pressure. After some investigation decided the fault was in the compressor. I then cut the compressor apart to see why?. Found the compressor was free to turn (not locked) & still gave a 3 flash code. Decided to test the windings for resistance, didn't look too bad, but the inductance of the windings was lower on 2 of the windings (Good compressor they are 5.5mH). So I suspect the 2 windings may have shorted windings causing it to not run & give 3 flash code. Also pict of the Wave form on one set of windings on a good compressor.
Hi DeBe;
Great post, just one thing when you measured the AC inductance of the windings did you disconnect the other two windings that are series with your winding that your are trying to measure. These windings may have a infuence on you meter.I was always taught to disconnect all outside inductance/resistance off the inductor that your are trying to measure. Same as when checking flyback transformers from crt televisions, even to the point of taking the flyback transformer off the printed cct board so as to make certain that there is no other loading of the transformer/ or inductor.
Interesting point. will try that later. Was realy after a test that didn't require cutting a compressor apart, that then becomes a point of no return.
I can see one winding that looks a bit cooked
Frank
Its not cooked Frank its just diferent coloured enamel coating.
unusual to see different coloured enamel. usually all the same.
so will you get this one going again?
-- Edited by DeBe on Thursday 10th of December 2015 01:12:36 PM
I have often found that to be helpful. someone else may see things different to you or I and you wonder how did I not see that????
learn something new every day mate and you could live to become an "Old Techo" sort of fella.
hehe
Frank
Darryl, years ago I built a tester that gives a ringing waveform for different coils, which was mainly used for LOPT transformers, but the output can be selected for other sized coils. You could consecutively ping across each of the coil pairs at the inputs and compare the resultant waveform on a CRO. You could use the waveforms from a known good motor to determine whether the one under test is stuffed or not.
You would get something similar to this (this is a pic I pulled of the net just as an example)
I used to download the waveforms to a computer, as well as waveforms of the new replacement LOPTs, and save them for comparison with other LOPTs I suspected as being bad.
I have a shorted turns tester but it only works on LOPT transformers. Need one that you can alter the frequency.
Bob Parker designed an FBT tester as a kit for Electronics Australia. This kit was sold by DSE and others. I expect that one could modify the frequency in his design. Alternatively you could replace IC1a with a 555 timer.
http://members.ozemail.com.au/~bobpar/fbt.htm
http://members.ozemail.com.au/~bobpar/k7205.pdf
-- Edited by dorian on Friday 11th of December 2015 08:32:27 AM
Yeah, the one I built has 3 different selections, can't remember the frequencies now, I haven't used it in years. It was an old EA or SC project, without the LEDs (not the K7025). I have used it on stator plate coils for a motorbike and various other transformers and coils. Even if you only get a few oscillations per phase displayed (maybe half a dozen), at least it can give a comparison.
I just went looking for the Schematic or kit info, but it seems I may have lost (probably chucked out
) it.
-- Edited by 03_Troopy on Friday 11th of December 2015 08:49:38 AM
03 if you find the circuit I would be most interested.
Is it in these project lists?
http://www.siliconchip.com.au/Static/EA Projects
http://www.siliconchip.com.au/Static/SC Projects
http://www.siliconchip.com.au/Static/ETI Index
Be mutch appreciated 03_Troopy.
OK, I have been playing around with the coil tester on a couple of motor windings, and these are the results.
I had 2 different motors, both 240VAC, but different constructions. I tried them both at the different switch settings on the tester and viewed them on a DSO.
The tester, I'm pretty sure, I built from a schematic that was in a pommy TV servicing magazine that I sometimes got when I had my electronics repair business back in the mid 90's. I haven't traced out the circuit yet, because the way I built it (rough and ready) I have to unsolder the pot and switch and sockets to remove it from the box.
The tester.
The tester puts out a series of pulses or different shapes (selected by the 3 position switch) at a frequency of between 66Hz and 124Hz (adjusted by the pot) roughly when not loaded by a device under test. The pulses are between 60mV p-p and 80mV p-p also depending on the switch position, and also when no device under test connected.
Here are the un-loaded pulse trains using switch positions 1 to 3 respectively:
Here are the motors I used for testing:
Here is what happens when the photocopier motor is connected across the tester, leaving the the time base the same for each position, to show the differences in waveforms produced:
Here's what they look like when you adjust the display for a usable waveform:
As you can see, you can get a decent enough ringing pattern to be able to see if you have shorted turns, especially if you have known good waveforms to compare them with.
Here is what the other motor looked like on the tester:
These waveforms are also pretty good for the purpose of looking for shorted turns. Especially in position 3 in the last pic, where you can see a nice symmetric waveform, with a smooth amplitude decay.
Hopefully I'll get some free time to pull the tester apart so I can trace it out. there are only about 8 components in total, but the way I put it together, it isn't easy to get at.
I to built that LOT tester many many years ago, and was also used as a teaching aid. Troopy that pommy magazine that you are talking about was a magazine called ' Television ' and was a good read in those days, and a lot of very usefull information was their to be had. Remember the very first video recorder that we had in Australia ( Philips N1700 ). Pommy land had a earlyer version ( N1500 ) and Television had a series on how to modify it to the longer play version of the N1700 model.
Some of the articals were pure gold in those days. It's a shame that the magazine hads stopped being printed.
We bought a NV-2000 when we were in Malaysia back in 1981, from memory they cost about $1,500.00 in Aus at the time. We also bought a VHS Video Camera like this one, Which were well in excess of $2,000 in Aus at the time.
Definitly interested in building that. My LOPT tester I built in the late 70s but only works at line freq. I used to get that magazine, but unfortunately I threw them out when I stoped repairing TVs & VCRs as with all the work shop manuals.
Hi 03 Troopy;
Yeah great recorders of the day, only down side was they were very heavy in weight and the rechargable battery only lasted about 30 Min's. Old school recorders and now aeirloom material. Had a clean out of my store room ( 2nd bedroom ) the other day and one of the things that went to the local tip was a hitachi vhs (c) camcorder still worked, last time i used it but the way of how things are this days beening a throw away society, now one wants 'old school' same as the do do bird.
And me to had a big clean out of trade mag's etc a couple of years ago. You name it, if it wasn't used or out of date, out it went, a couple of valve school PA amplifiers ( Pararell push pull 807 valves ((4 )) and about 500 volts on the plates ) good for a couple of 100 watts Weighed a ton , but again old school, serperate power supply and serperate radio tuner, built to last and last all in a steel case and made by AWA i remember these things, ran all day 5 days a week. Not like the rubbish that is forced on to the industry these days.
Sorry you guys for getting off topic, once i get on my soap box, their is no stopping me
-- Edited by valiant81 on Friday 18th of December 2015 05:49:59 PM
OK, firstly the waveform I showed in a previous post of the tester outputs on each switch position with nothing connected across the test terminals is pretty useless as it has nothing for the output waveform to be developed across. So I have done another one with a 2K resistor across the output terminals to give a better idea of the outputs.
I had a couple of goes at racing the circuit, but because it's such a crappy job I did of putting it together (was hastily built for use at the time), it was a PITA. So I did the next best thing and made up some diagrams of the board with component layout.
Hope you can work it out from this Darryl, but if you find any problems let me know and I'll try and sort it out. The components aren't critical in their voltage values as you might have guessed, but that's what I had on hand at the time. Capacitor C2 was mounted on the back of the board to allow me to fit it al in the tiny box I used at the time.
Cheers Bob
-- Edited by 03_Troopy on Tuesday 22nd of December 2015 01:13:14 PM
Hi 03_Troopy. Have built the project but cant get it working at this stage. But whilst looking for something else, came across an old Television article I filed back in Sept 1998 issue, it was a LOPT tester. But it made reference to A LOPT tester using a CD4001 IC in Sept 1993 issue by Ian Rees. I suspect this is the one you built. I might try a couple of Electronic Forums to see if some one still has the article.
I would expect a wave form at least on the base of the transistor. As there is none I suspect the oscillator stage is not working.