Hi John,
Anyway, 99% Isopropyl Alcohol is what is used when conditioning contacts and jacks in the lab just before performing a calibration. Especially when you are dealing with thermocouples. The same applies to cleaning very light oxides off contacts and switches. You can't use this in a potentiometer because the alcohol will attack the lubricants and sleeve bearings in those.
As for PCB cleaning, several people have discovered that alcohol can wick up into components like capacitors and some transistors. Alcohol also attacks rubber (the seal on the bottom of some electrolytic capacitors).
Hi TubeMack,
One thing you don't know perhaps is that Fiberglass is also used for switch wafers. Problem is, Fiberglass is far more porous than Phenolic is, and Phenolic performs better at higher frequencies than Fiberglass. That is unless things have changed since I studied this stuff. I wonder if glass is used in any switches? I'm not talking about reed switches or similar devices. I should refresh my memory on these things I guess, but what Ive said was correct at one point in time. The basics are still accurate as far as how to approach cleaning these switches.
If you want to go ahead and soak your switches - go for it. All I can do is pass on what I've learned over the years. The information I have passed on agrees from a number of sources, but that doesn't mean you have to accept that. My only suggestion to you would be to dig up some information on your own from manufacturers of these type of switches. Other sources of guidance will have other interests, so I don't trust them as completely.
Have fun, Chris
Probably a lot. Still, what you suggested was not correct. This has little to do with who you are, but rather how well you were taught to do these things. Besides, what you suggested might work for now as long as you didn't get into a trimmer capacitor. It's later when the bearings in pots are sloppy and things like that. Rest assured that you are by no means alone when it comes to making an error.
Since you can get 70% Isopropyl more easily, you have to specify the 99% variety. Also, keep it capped because it is hygroscopic.
Anyway, 99% Isopropyl Alcohol is what is used when conditioning contacts and jacks in the lab just before performing a calibration. Especially when you are dealing with thermocouples. The same applies to cleaning very light oxides off contacts and switches. You can't use this in a potentiometer because the alcohol will attack the lubricants and sleeve bearings in those.
As for PCB cleaning, several people have discovered that alcohol can wick up into components like capacitors and some transistors. Alcohol also attacks rubber (the seal on the bottom of some electrolytic capacitors).
Hi TubeMack,
Who ever said the wafers are porous? They can be porous. There are other materials you could make these wafers out of. Things like Ceramic and Teflon seem to work fine - that's if you want the costs of equipment to go through the roof. In fact you will find these materials in use at high frequencies and when dealing with nA or nV. Once you identify the instruments that use these materials, you will then notice the price of these.
One thing you don't know perhaps is that Fiberglass is also used for switch wafers. Problem is, Fiberglass is far more porous than Phenolic is, and Phenolic performs better at higher frequencies than Fiberglass. That is unless things have changed since I studied this stuff. I wonder if glass is used in any switches? I'm not talking about reed switches or similar devices. I should refresh my memory on these things I guess, but what Ive said was correct at one point in time. The basics are still accurate as far as how to approach cleaning these switches.
If you want to go ahead and soak your switches - go for it. All I can do is pass on what I've learned over the years. The information I have passed on agrees from a number of sources, but that doesn't mean you have to accept that. My only suggestion to you would be to dig up some information on your own from manufacturers of these type of switches. Other sources of guidance will have other interests, so I don't trust them as completely.
Have fun, Chris
Try a local chemical supplier/distributor. VWR and Fischer Scientific are two national suppliers that will probably have a nearby distribution warehouse. Suppliers will often sell "safe" chemicals to the public. Their catalogs are online.
Isopropyl alcohol will be listed as isopropanol or 2-propanol. If you want the really good stuff, I would recommend ACS Grade which is >=99.5% pure and leaves less than 0.001% residue after evaporation. (We never used better than ACS grade solvents in our lab for our critical cleaning/rinsing applications.) 99.9% purity is available if you want to go over the top, and is often sold as HPLC grade. However, it will probably cost you more than you want to pay.
Looney
Hi TubeMack,
Hi John,
-Chris
No, but that seems to be a majority view of the advice you are being offered. On top of that, there is a component in your posts that appears to be happy with a short-cut. I have to say that there isn't much left to say beyond whether you have it working or not. I can't give you much more in the way of advice beyond what has been said already.
How about your local drug store? If they don't have stock, it should take less than a week for them to fill your order. BTW, the price will be much lower at the drug store.
Hi John,
Sorry, yes you did. That was in an earlier post that I didn't consider when I replied. As for your other comment on purity, yes. Completely agree.
-Chris
dont mean to butt in on a thread, but hopefully i"m on topic 
I am setting up a bench and wonder if you folks think an old 3562A would be a decent idea to anchor measurements (distortion, freq response) as i set out on rekindling my love for DIY amp-building ? Thanks kindly for the advice...
I am setting up a bench and wonder if you folks think an old 3562A would be a decent idea to anchor measurements (distortion, freq response) as i set out on rekindling my love for DIY amp-building ? Thanks kindly for the advice...
Agilent / HP 3562A Dual-Channel, Dynamic Signal Analyzer, Refurbished HP Agilent Hewlett Packard - Used Test Equipment at Test Equipment Depot ... refurbished = $2000
Agilent / HP 3562A - Price, We Stock Used and New! =
"Agilent / HP 3562A Datasheet (pdf)
Agilent / HP 3562A Manual (pdf)
Agilent / HP 3562A Service Manual (pdf)
Agilent / HP 3562A Programming Manual (pdf)
Link to Agilent Website " ...
Probably quite useful ... at minimum, 25 years old ... so don't pay $2K for it.
Agilent / HP 3562A - Price, We Stock Used and New! =
"Agilent / HP 3562A Datasheet (pdf)
Agilent / HP 3562A Manual (pdf)
Agilent / HP 3562A Service Manual (pdf)
Agilent / HP 3562A Programming Manual (pdf)
Link to Agilent Website " ...
Probably quite useful ... at minimum, 25 years old ... so don't pay $2K for it.
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dont mean to butt in on a thread, but hopefully i"m on topic
It is a *great* instrument. There is an incredible amount of capability packed into that box. The limiting factor is dynamic range in FFT mode, about 80dB.
Unique features are the curve fitter, extracting poles and zeros from a frequency response measurement, true differential inputs, and swept sine mode. The weak point service wise is the vector display - make absolutely sure it works well before buying. The are expensive to replace as they are not a raster type screen, work more like an old analog scope with a digital driver.
It does not drive a printer directly, but HP plotters are supported. You can save data to floppy with an old HP HP-IB disc drive (9122D or combo hard drive/floppy like 9153), and with the right software (SDF utilities), transfer it to a PC for display/printing.
I used to sell these for HP in the 80's. It was so hot and popular when new, it was the #1 volume selling instrument, for HP for many years. Price was $25K new.
Hi kasey197,
Other great HP instruments: 3585A/B, 3577A, even the 3580A! It only gets better with newer HP gear. They just released a brand new audio test system.
What we experimenters really need is a great paying job!
Now, if you don't like older instruments, send it on to me. I can assure you I'll give it a good home and all the respect it deserves.
-Chris
Are you kidding?? I would love to have one of those! You can extend the range by hanging it on the output of a THD meter like an HP 339A.
Other great HP instruments: 3585A/B, 3577A, even the 3580A! It only gets better with newer HP gear. They just released a brand new audio test system.
What we experimenters really need is a great paying job!
Now, if you don't like older instruments, send it on to me. I can assure you I'll give it a good home and all the respect it deserves.
-Chris
Ok got the switches clean using liquid deoxit 100% and a long fine tip artist brush. It seems to have fixed any issues. The OSC waveforms are now stable on the scope with switch turns. Time to test a little more. I guess the next basic thing to do will be to loop the OSC back into the unit to test for overall residual Dist.? what should this figure be? I read it somewhere, but forgot the level.
Anatech, check me out here:
Using the settings in the manual for the RES noise test
Freq = 20K
Input range = 1V
Distortion level = .01
Dist. input shorted (But I have no load)
Meter reading is .05v x .01(Dist Level) = .0004?
So this unit is really kicking butt, or is not quite right? Or do i need to make a proper load?
Using the settings in the manual for the RES noise test
Freq = 20K
Input range = 1V
Distortion level = .01
Dist. input shorted (But I have no load)
Meter reading is .05v x .01(Dist Level) = .0004?
So this unit is really kicking butt, or is not quite right? Or do i need to make a proper load?
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Hi TubeMack,
I guess I'll have to try this out and let you know. If you loop the osc. output into the analyzer input, read the residual distortion (of the oscillator). Do this at 1 KHz and you should come up with the figure I gave you. A shorted input for testing the analyzer is the way to go. There are too many other variables otherwise.
-Chris
I guess I'll have to try this out and let you know. If you loop the osc. output into the analyzer input, read the residual distortion (of the oscillator). Do this at 1 KHz and you should come up with the figure I gave you. A shorted input for testing the analyzer is the way to go. There are too many other variables otherwise.
-Chris
Anatech, thanks for all the help!
Just to be clear I did the first test without the OSC external looped. Strange that a freq setting was required by the manual for this test. Is the oscillator also internally connected to the meter when the Dist input is shorted? The meter does jump as the freq is changed like they are connected internally?
I will also do the test with an external loop from OSC tto Dist input as you suggest. Waiting on BNC to Banana adaptor to arrive!
Lastly, Should the meter reading bounce around any during Distortion measurements? Mine does, and bounces more at lower imput range settings
Just to be clear I did the first test without the OSC external looped. Strange that a freq setting was required by the manual for this test. Is the oscillator also internally connected to the meter when the Dist input is shorted? The meter does jump as the freq is changed like they are connected internally?
I will also do the test with an external loop from OSC tto Dist input as you suggest. Waiting on BNC to Banana adaptor to arrive!
Lastly, Should the meter reading bounce around any during Distortion measurements? Mine does, and bounces more at lower imput range settings
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