# Sometimes you get a break



## black85vette (Dec 31, 2009)

Had my X2 mill motor stop running. Got to checking and the motor would start and stop as I tapped on the speed control board. In the process of checking for cold solder joints the motor went to full speed and stayed there. Fortunately when I replaced the mosfets on the lathe I ordered spare parts. So swap them out and it is back and running again. Yes, sometimes things actually go your way. Think it is time to order a couple more mosfets. ;D


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## cfellows (Dec 31, 2009)

You speak of replacing a couple of MOSFETS as if it were as simple as swapping out a belt. I wouldn't of known that was even the problem, although I probably could have replaced them once I figured out where to get them!   I understand the theory of most electronics, but the practical application just seems to elude me. Glad you got your problem fixed.

Chuck


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## Powder keg (Dec 31, 2009)

Don't worry Chuck. I to have never been schooled in the ways of the electron.


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## black85vette (Dec 31, 2009)

cfellows  said:
			
		

> You speak of replacing a couple of MOSFETS as if it were as simple as swapping out a belt. I wouldn't of known that was even the problem, although I probably could have replaced them once I figured out where to get them!  I understand the theory of most electronics, but the practical application just seems to elude me. Glad you got your problem fixed.
> 
> Chuck



Not that hard Chuck. Little Machine Shop has troubleshooting instructions in their resource area and then you can buy the transistors from them.  Most of the time it is the Mosfets because they carry all the power. LMS has a chart and you just take resistance reading and compare to the chart.

They do not have info on the diode pack on the board but it is easy to replace as well.  Its symptoms are simple: the fuse blows every time you apply power.

I would guess that the vast majority of failures is one of these two components and replacing them yourself costs less than $10. So I keep 1 diode pack and 2 transistors in stock.


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## Twmaster (Dec 31, 2009)

The shame of it all is you have to even have the parts to keep your machine running. I had a little red lathe from H-F. The failure of the speed control board was the Final Straw.


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## Tin Falcon (Dec 31, 2009)

I had a power surge take out both the board for the mill and lathe. a diode on one and the bridge rectifier on the other less than 10$ in parts. I think the mos fets are the next to go. 
tin


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## Troutsqueezer (Jan 1, 2010)

MOSFETS have found their way into many appliances and tools these days. I have a fairly new front-loading washing machine and what do you know, the MOSFETS blew with a loud snap the other day. Made me long for the days when motors didn't need such control but I suppose it makes for a more sophisticated product. Once you understand the basic circuitry, it's pretty easy to troubleshoot most things that use them. Start by looking for the scorch marks.


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## Deanofid (Jan 1, 2010)

Glad you caught a break, 'Vette!




			
				Powder keg  said:
			
		

> Don't worry Chuck. I to have never been schooled in the ways of the electron.



Huh. Me either, but as a welder of some many years, was well schooled in electrocution..
; )

Dean


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## Tin Falcon (Jan 1, 2010)

> but as a welder of some many years, was well schooled in electrocution..



I learned a long time ago not to make yourself part of the circuit. 
but I have seen it happen a couple times.
Tin


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## Jadecy (Jan 1, 2010)

Sometimes it is a love hate relationship with technology. At least it is for me. It is annoying that some things have become over complicated but on the other hand I love my VFD for 3 phase power to run my milling machine as well as many other pieces of technology. I guess it is just part of progress! ;D


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## websterz (Jan 1, 2010)

I found several cold solder joints on my x2 control board. They revealed themselves when a large resistor fell off the board and shut me down!! The other large resistor had 1 leg soldered correctly and that was all that held it in place. In addition to that, the cooling fan had never run because of several bad joints on it's power board. Go thru it with a magnifying glass 'vette...there are other gremlins hiding in there!! ???


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## Twmaster (Jan 1, 2010)

Or better yet. Take the time to carefully go over each joint with a good soldering iron.


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## vlmarshall (Jan 1, 2010)

Tin Falcon  said:
			
		

> I learned a long time ago not to make yourself part of the circuit.
> but I have seen it happen a couple times.
> Tin


Ah yes... reminds me of my first day with a TIG welder. The learning curve was... shocking.


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## websterz (Jan 1, 2010)

Twmaster  said:
			
		

> Or better yet. Take the time to carefully go over each joint with a good soldering iron.



That too. :big:


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## black85vette (Jan 1, 2010)

Twmaster  said:
			
		

> Or better yet. Take the time to carefully go over each joint with a good soldering iron.



Yep. Did that.  I have a handheld microscope that I use for checking solder connections. Used to be able to do it with my eyes, but, oh well!  Didn't see anything that looked bad so I just hit them all with the tip of the iron until the solder started to flow. Added a little solder to a couple of them. You are right and it never hurts.


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## Twmaster (Jan 2, 2010)

Vernon  said:
			
		

> Ah yes... reminds me of my first day with a TIG welder. The learning curve was... shocking.



Yanno... That explains a lot Vernon....
 :


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## Twmaster (Jan 2, 2010)

black85vette  said:
			
		

> Yep. Did that.  I have a handheld microscope that I use for checking solder connections. Used to be able to do it with my eyes, but, oh well!  Didn't see anything that looked bad so I just hit them all with the tip of the iron until the solder started to flow. Added a little solder to a couple of them. You are right and it never hurts.



There was a time that now seems like forever-ago that I could read the print on an IC chip without glasses....

Now I'm happy to be somewhat blind cuz I don't like half of what I see anymore!


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## Deanofid (Jan 2, 2010)

Tin Falcon  said:
			
		

> I learned a long time ago not to make yourself part of the circuit.
> but I have seen it happen a couple times.
> Tin



Do it for 25 years and you're gonna get bit now and then, Tin. Sometimes you have to use mirrors to see what you're welding and you stick the rod in the wrong place. Other welders, hole in a glove or cable. It happens.

Dean


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## Seanol (Jan 2, 2010)

Here in the desert it gets hot. You sweat. Sometimes you wear short sleeves even though you know better. Sometimes you rest a bare wrist against the metal work table and strike an arc.

After that there is no sometimes. You just don't do it! DAMHIK....


Sean


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## jack.39 (Jan 3, 2010)

Deanofid  said:
			
		

> Do it for 25 years and you're gonna ...._*go blind anyway!*_
> 
> jack


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## jack.39 (Jan 3, 2010)

Could 'ya put in a _CMOS_ chip to watch over yer MOSFET's condition?  ;D

jack


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## black85vette (Jan 3, 2010)

jack.39  said:
			
		

> Could 'ya put in a _CMOS_ chip to watch over yer MOSFET's condition? ;D jack



OK Jack, you have me pinned in. I know enough electronics that I know what CMOS is but not enough to know how to go about doing what you suggest and even worse, not enough to know if you are pulling my leg or not.  ??? ???

What I have done is to buy MOSFETS with a higher rating than the stock ones. Have not had one of these fail yet. Did the same thing with the rectifier pack. I think they just put in devices without enough of a performance margin.


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## jack.39 (Jan 3, 2010)

black85vette  said:
			
		

> OK Jack, you have me pinned in. I know enough electronics that I know what CMOS is but not enough to know how to go about doing what you suggest and even worse, not enough to know if you are pulling my leg or not. ??? ???...



Now you are making me uncomfortable; it was a _joke_..., but, to loosen the tentacles a bit: I only THINK a CMOS chip was the break-through device about 1990 or so which takes a signal consisting of an input of light, like seen through a viewfinder, and does it's magic by converting that signal to a composite video waveform, IOW, a T-V signal. This made small, hand-held video recorders possible, as it eliminated the unwieldy old technology "image orthicon". I think.

So, a CMOS could keep you continuously aware of the appearance of your MOSFETS.

Now, WTH are MOSFETS??  jack


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## websterz (Jan 3, 2010)

Hey 'vette, did you get the new MOSFET's at Radio Shack? I have a board that is in need of new ones and I might as well go with something a little beefier. Got the part number handy for them?


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## black85vette (Jan 3, 2010)

jack.39  said:
			
		

> So, a CMOS could keep you continuously aware of the appearance of your MOSFETS.
> 
> Now, WTH are MOSFETS?? jack



OK. Sometimes I am a little slow catching the humor. Makes perfect sense now that I put the modern video use of CMOS together with watching the MOSFET. :big: I didn't jump on that thought train quick enough and it left me at the station. I spent a lot of time with digital CMOS chips in logic circuits and I was trying to work that into the post.  oh:

MOSFETS are fast, high current, solid state switches.


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## zeeprogrammer (Jan 3, 2010)

websterz  said:
			
		

> Hey 'vette, did you get the new MOSFET's at Radio Shack? I have a board that is in need of new ones and I might as well go with something a little beefier. Got the part number handy for them?



'vette' mentioned these from Mouser...511-STW20NK50ZN-Ch 500 Volt 17 Amp...replace in pairs. No idea if RS has them..I'd be surprised if they do. I've not looked at Mouser or the data sheets on them yet.

I expect to order a few myself.

I remember when CMOS came out...have to admit I was a little tweaked by them..I was happy with LS parts. But I'm the kind of guy you have to pull kicking and screaming into the future. ;D


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## black85vette (Jan 3, 2010)

websterz  said:
			
		

> Hey 'vette, did you get the new MOSFET's at Radio Shack? I have a board that is in need of new ones and I might as well go with something a little beefier. Got the part number handy for them?



As Zee said, you can get them from Mouser Electronics. I also got a rectifier pack from them. I could not cross reference the one on the control board exactly so I went a little bigger. Still fits on the board OK.

512-GBPC1210W 12A Bridge Rectifier $2.45ea 
A little bigger than the orignal but fits fine.

511-STW20NK50Z N-Ch 500 Volt 17 Amp $3.60ea
Mosfet for motor control board. Replace in pairs. 

As cheap as these are and the failure rate that they have, I think everyone who can solder should keep them in stock.


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## jack.39 (Jan 3, 2010)

black85vette  said:
			
		

> MOSFETS are fast, high current, solid state switches.



I attempt humor so rarely, that the results are usually poor; forgive me. Going back, I seem to recall fairly new devices back 'when, which may have preceded MOSFETS, were they called "TRIACS"? There was also another high-current switching device, the name eludes me (NOT a relay!). jack


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## ksouers (Jan 3, 2010)

I'm still trying to figure out tubes ??? :


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## black85vette (Jan 3, 2010)

ksouers  said:
			
		

> I'm still trying to figure out tubes ??? :



Aren't tubes just transistors with the filament removed?? :big:


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## black85vette (Jan 3, 2010)

jack.39  said:
			
		

> There was also another high-current switching device, the name eludes me (NOT a relay!). jack



SCR maybe??


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## shred (Jan 3, 2010)

jack.39  said:
			
		

> Now you are making me uncomfortable; it was a _joke_..., but, to loosen the tentacles a bit: I only THINK a CMOS chip was the break-through device about 1990 or so which takes a signal consisting of an input of light, like seen through a viewfinder, and does it's magic by converting that signal to a composite video waveform, IOW, a T-V signal. This made small, hand-held video recorders possible, as it eliminated the unwieldy old technology "image orthicon". I think.
> 
> So, a CMOS could keep you continuously aware of the appearance of your MOSFETS.
> 
> Now, WTH are MOSFETS??  jack



CMOS image sensors for digital cameras and the like is probably what you're thinking of. They were a price/performance increase over the old CCD image sensors.

Plain old "CMOS" has been around for ages as it's the abbreviation for the type of silicon chip manufacturing process 99% of the chips in the world are made of today.


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## websterz (Jan 3, 2010)

black85vette  said:
			
		

> As Zee said, you can get them from Mouser Electronics. I also got a rectifier pack from them. I could not cross reference the one on the control board exactly so I went a little bigger. Still fits on the board OK.
> 
> 512-GBPC1210W 12A Bridge Rectifier $2.45ea
> A little bigger than the orignal but fits fine.
> ...



Thanks 'vette! I just ordered 4 'FETS and a pair of rectifiers so I can repair one dead board and have spares on hand. :bow:


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## jack.39 (Jan 4, 2010)

black85vette  said:
			
		

> Aren't tubes just transistors with the filament removed?? :big:



Nah! They're the things that leak in my boiler! Seriously, now guys, knocking tubes is OK by me, but keep in mind, I don't think they have economically come up with a solid-state replacement for the Magnetron _tubes_ in our indispensable microwave ovens.......or have they?  jack


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## jack.39 (Jan 4, 2010)

black85vette  said:
			
		

> SCR maybe??



That's it! Gosh, getting old and having to hunt for words that you know are still in the old "bank" is getting to be a drag. My wife always says, "Consider the alternative". Wonder what she's thinking just then??  jack


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## black85vette (Jan 4, 2010)

jack.39  said:
			
		

> Nah! They're the things that leak in my boiler! Seriously, now guys, knocking tubes is OK by me, but keep in mind, I don't think they have economically come up with a solid-state replacement for the Magnetron _tubes_ in our indispensable microwave ovens.......or have they? jack



Just noticed I got my joke backwards. It would be transistors are tubes without a filament. :wall:

I have not heard of a magnetron replacement.  However in the music world tubes have come back. There is just not anything solid state or digital that can replicate the curve of a preamp tube being over driven. A lot of guitar players have gone back to tube pre amps with solid state power amps and there is a good market for rebuilding classic guitar amps with the old spring type reverb / delay.  So maybe we are not as outdated as we thought. Unfortunately I found out about this about a year too late and had thrown out my old RCA tube reference manual thinking I would never need it again. oh:

I ended up building a tube preamp for my youngest son for a bass guitar.


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## ozzie46 (Jan 4, 2010)

Where in blue blazes do you still get tubes? I didn't think they even made them anymore.

 Of course I am electrically illiterate too. :big: :big: :big:

  Ron


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## black85vette (Jan 4, 2010)

ozzie46  said:
			
		

> Where in blue blazes do you still get tubes? I didn't think they even made them anymore.
> 
> Of course I am electrically illiterate too. :big: :big: :big:  Ron



They are out there. You can get them to fix old radios. A lot of them come from Russia (don't ask me why). There is New Old Stock available on eBay and web sites like this one:

http://thetubestore.com/nos-12av6.html

Up until a few years ago my Ham radio transmitter used tubes and many of the higher power RF amps still use tubes in the final stage.  So for the die hard electronics geeks tubes live on.

But then again a lot of people probably wonder; "Why in the world would you mess with steam engines?? I didn't know they even made them anymore."  :big:


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## ozzie46 (Jan 4, 2010)

Getting way off topic here but I was given a "Electrohome" am/fm stereo radio record player. It is a large console unit and the sound is wonderful so I am glad you posted the site for tubes. This thing was made in the 60s or 70s. Immaculate finish on it too.
 Made of REAL wood. Heavy thing too.

 Thanks for the link.


 Ron


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## Kermit (Jan 4, 2010)

The Russians 'perfected' small tubes, because they didn't have the industrial infrastructure to start up manufacture of transistors. They STILL have lots of tubes in use in all kinds of equipment currently.  Their space shots and most of the satellites used them as well. They went into space without a single transistorized device back in the day(60's to 80's)


I watch to much documentary TV, ;D
Kermit


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## Troutsqueezer (Jan 4, 2010)

OK, more than you ever wanted to know about tubes vs. transistors when it comes to audio. 

Many musicians and music lovers prefer the tube sound because the harmonic distortion that tubes generate consists primarily of first and second order harmonics which are close to the frequency they are supposed to reproduce. So a 1 KHz signal from a tube amp has a fairly large 2 KHz distortion component being produced with it. This has the effect of warming the sound so that it sounds fuller than it would if it were being reproduced by a transistor circuit. Over-driving a tube circuit produces even more of these lower order harmonics so some folks really love the result. The distortion from a transistor, because it consists mostly of higher order harmonics where a 1 KHz signal will also produce 4 KHz and 8 KHz harmonic tones is more easily detected by the ear even though the amount of distortion (amplitude) is far less than tube circuit distortion. These higher harmonics are separated from the 1 KHz tone by a larger gap and your ear can distinguish them easily. This can give a harsh sound if the amp is over-driven. 

The downside to tube audio stages (besides the larger distortion component) is that they must be transformer-coupled and so low frequency response suffers. What is a transformer? It is a choke (coil of wire) and chokes are more inefficient at passing low frequencies. 

Told'ja. More than you needed or wanted to know.


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## vlmarshall (Jan 4, 2010)

ozzie46  said:
			
		

> Where in blue blazes do you still get tubes? I didn't think they even made them anymore.





[ame]http://www.dailymotion.com/video/x3wrzo_fabrication-dune-lampe-triode_tech[/ame]


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## jack.39 (Jan 4, 2010)

Do you 'spose those harmonics they talk about in rifle barrels are sum'pin differnt than in them tubes & transitors?

jack


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## websterz (Jan 6, 2010)

websterz  said:
			
		

> Thanks 'vette! I just ordered 4 'FETS and a pair of rectifiers so I can repair one dead board and have spares on hand. :bow:



My parts from Mouser arrived today. Those folks ship FAST!! :bow:


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