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Re: Replacing Electrolytics in a 465/465B
Another method that works well is to use individual adapter
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boards for each cap. The boards are roughly the same diameter as the original caps and allow a modern snap cap to be used. You can make the patterns up in any drawing program if you want to etch your own, gerbers are floating around the web and they are available on ebay once in a while. The boards work out to be around $1 or less each if you use one of the cheap board houses. If you use long leads on those, you can thread the cap in without having to disassemble the scope. That method seems to have been independently invented four or five times that I'm aware of (and probably many more). Paul -----Original Message------- Paul Amaranth, GCIH | Rochester MI, USA Aurora Group, Inc. | Security, Systems & Software paul@... | Unix & Windows |
Re: Desoldering Iron vacuum
The flux fumes will go right through the fiber disk.
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I use a Pace desoldering system with a cotton like plug in the solder capture cylinder and a fiber filter at the end of the tubing just before it goes into the vacuum pump. The fiber filter catches a lot but not all of the vapor. A lot of the flux vapor condenses out onto the inside wall of the tubing connecting the iron to the vacuum pump. The installed vacuum pump here is a rotary vane pump. About once a year, I have to disassemble the pump and clean the carbon vanes and the carbon wear plates to remove the condensed flux vapor. The amount of flux vapor ingested by the system is based on the amount of residual flux left on the solder being removed and the length of time that you are sucking the solder in one session. The hotter the air through the system the more vaporized flux gets to the pump. If you only remove a few parts then let the system rest and the solder capture cylinder cool down there is less flux vapor than if you desolder a large quantity of parts at one time. I do the latter and have recovered over 20 pounds of solder from boards. Glenn On 7/29/2018 10:51 AM, John Griessen wrote:
On 07/29/2018 06:18 AM, Mark Wendt wrote:The Hakko desoldering station I have has two sets of inline filters. One, a kind of springy thingy for stopping the solder bits and pieces from flowing into the pump, and the other a fiber disc for stopping the smokey stuff from getting through.? Perhaps on John's system the fiber disc isn't in place to stop that from happening?It's in place.? It's not enough though. --
----------------------------------------------------------------------- Glenn Little ARRL Technical Specialist QCWA LM 28417 Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178 QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR "It is not the class of license that the Amateur holds but the class of the Amateur that holds the license" |
Re: Looking for Power Cord for 400-series Scope
That's what I ended up doing. If your feet are in good condition you can
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just tuck the plug end between the cord windings and it will stay put. Paul On Thu, Jul 26, 2018 at 11:00:38AM -0400, n4buq wrote:
I've considered cutting an IEC cord (hopefully finding a thinner version since, as you point out, the more common styles are thicker) and just using a common velcro wrap as a "keeper". The clip would be nice but having that ground connection is more important to me. --
Paul Amaranth, GCIH | Rochester MI, USA Aurora Group, Inc. | Security, Systems & Software paul@... | Unix & Windows |
Re: Desoldering Iron vacuum
I also have a Metcal system, absolutely love it.
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I use a $39 HF compressor for it. I bought it because it was cheaper to buy the whole compressor from HF than individual compoenents to add on to an existing, quieter compressor. I stuffed it into a cabinet in my bench which makes it tolerable. That airless compressor makes a huge racket. I like the refrig. compressor idea. One thing to keep in mind is that many recent compressors are 3 phase and use a solid state inverter. If you're scavenging the compressor, don't forget the inverter as well. I ran across a good deal on Metcal power supplies and scavenged ebay for low priced supplies, but if you like to roll your own a fellow has a design for a Metcal power supply on eevblog. Looked quite nice. Paul On Sun, Jul 29, 2018 at 07:58:50AM -0500, EricJ via Groups.Io wrote:
The Metcal has a cotton or felt cube that filters this also. I'd imagine after years of use it might be wise to either clean or replace the venturi (IIRC it can be popped out and a new one slotted in). Personally I would far rather leave the system be and use it under its original guise rather than try to convert it to a vacuum only setup. Not too worried about the efficiency of the venturi generated vacuum setup as it's not used for very long time periods, just a burst for every joint. I use my "silent" compressor as an air source as well, so it comes in handy for more than just desoldering.? --
Paul Amaranth, GCIH | Rochester MI, USA Aurora Group, Inc. | Security, Systems & Software paul@... | Unix & Windows |
Re: Desoldering Iron vacuum
On Sun, 29 Jul 2018 09:51:22 -0500, you wrote:
On 07/29/2018 06:18 AM, Mark Wendt wrote:Perhaps an automotive fuel filter?The Hakko desoldering station I have has two sets of inline filters. One, a kind of springy thingy for stopping the solder bitsIt's in place. It's not enough though. Harvey |
Re: Desoldering Iron vacuum
John Griessen
On 07/29/2018 06:18 AM, Mark Wendt wrote:
The Hakko desoldering station I have has two sets of inline filters. One, a kind of springy thingy for stopping the solder bits and pieces from flowing into the pump, and the other a fiber disc for stopping the smokey stuff from getting through.? Perhaps on John's system the fiber disc isn't in place to stop that from happening?It's in place. It's not enough though. |
Re: Desoldering Iron vacuum
The Metcal has a cotton or felt cube that filters this also. I'd imagine after years of use it might be wise to either clean or replace the venturi (IIRC it can be popped out and a new one slotted in). Personally I would far rather leave the system be and use it under its original guise rather than try to convert it to a vacuum only setup. Not too worried about the efficiency of the venturi generated vacuum setup as it's not used for very long time periods, just a burst for every joint. I use my "silent" compressor as an air source as well, so it comes in handy for more than just desoldering.?
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I used a couple refrigerant compressors in parallel to get a little more CFM and plumbed them into a portable 5 gallon air tank with a check valve, pressure/unloading switch, regulator and filter/drier. The tank already had a pop-off valve and drain. The compressor is quiet enough to be used in my basement workshop while small children are sleeping in the bedroom directly above without waking them. --Eric Sent from my Samsung Galaxy smartphone. -------- Original message --------From: Mark Wendt <wendt.mark@...> Date: 7/29/18 6:18 AM (GMT-06:00) To: [email protected] Subject: Re: [TekScopes] Desoldering Iron vacuum
On 07/28/2018 08:21 PM, Ed Breya via Groups.Io wrote: John wroteThe Hakko desoldering station I have has two sets of inline filters.? One, a kind of springy thingy for stopping the solder bits and pieces from flowing into the pump, and the other a fiber disc for stopping the smokey stuff from getting through.? Perhaps on John's system the fiber disc isn't in place to stop that from happening? Mark |
Re: 7704A Z-Axis Problem
I said the CRT cable (thinking of where the cable leaves the HV unit) but Harvey said it straight forward: in the vicinity of the HV unit .
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This way you measure the HV transformer switching frequency (which simply is the SMPS switching frequency in the 7704A) *regardless* whether you see a dot pattern or not in the trace. The probe picks up the strong alternating EM field and not (or not in the first place) a small AC ripple on the DC HV. In self-oscillating HV situations this is a handy way to verify that the HV unit is oscillating. You can almost sure exclude now hat there was some strange (external? oscillations?) signal entering the Z-axis amplifier causing a dot pattern since in that case you would at the same time have noticed also a running dot pattern (perhaps of different amplitude than the synchronized pattern). Still it's not sure what causes the dot pattern, a badly decoupled LV somewhere in the Z-axis amplifier, or a badly filtered HV voltage. I would first check the Z-axis output TP41120 for 25 kHz ripple. Just to be sure, are all shields (SMPS box and HV unit) present? I don't remember if removing the HV shield causes intensity ripple in a 7704A. Albert On Sun, Jul 29, 2018 at 12:07 AM, Tomas Alori wrote:
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Re: Desoldering Iron vacuum
On 07/28/2018 08:21 PM, Ed Breya via Groups.Io wrote:
John wroteThe Hakko desoldering station I have has two sets of inline filters.? One, a kind of springy thingy for stopping the solder bits and pieces from flowing into the pump, and the other a fiber disc for stopping the smokey stuff from getting through.? Perhaps on John's system the fiber disc isn't in place to stop that from happening? Mark |
Re: Slightly OT - Bourns trimmer pot failure
The failures I saw with the Beckman pots were in telemetry receivers being built for NASA. They were the ones in use when we lost that last shuttle. The media was waiting for information, but when you had built the equipment for the earth stations, with dual diversity at every tracking site I knew as soon as they stated, We have a loss of telemetry' that we had lost another shuttle. It was like a kick in the gut, hoping for the impossible in that six complete systems had failed at the same instant instead of the loss of the shuttle.
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We couldn't wait for Beckman to decide that we were right, because our products were used by many Aerospace companies where failures could cost hundreds or thousands of lives. They forced us to make the change, and only by removing a company from the master Approved Vendor List could we make sure that no one substituted anything else. Purchasing was then forced to state 'NO SUBSTITUTIONS ALLOWED ON THIS ORDER'. As an example, a distributor offered purchasing some tighter tolerance molded inductors for a lower price than the approved part. Purchasing bought them and patted themselves on the back for sving almost 50%, but the new 5% parts caused problems that we had never had with the specified 10% parts. No one bothered to compare the SRF, and the new, unapproved vendor line was about 20% lower, across the range that we needed. Purchasing got their asses chewed out by the head of engineering and one of the Corporate VPs, over that blunder. Michael A. Terrell -----Original Message-----
From: Adrian <Adrian@...> |
Re: Slightly OT - Bourns trimmer pot failure
The silver was a very thin film that was applied to the substrate before the resistive element was printed on top of the substrate. The the terminals were crimped over the other end of the silver film. I saw a lot of failed foreign made versions back in the '80s where the silver had turned into black flakes that curled up and opened the pots. Just like the oxides on good silverware damage the surface with sulphates and other contaminants in the air.
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See if you can uncrimp the terminal on one ind of the bad pot. Then you can see how much remains where it wasn't exposed to contaminants. It's possible that the board cleaning process started the failure mode, and it took years to finally fail. Michael A. Terrell -----Original Message-----
From: Adrian <Adrian@...> |
Re: Slightly OT - Bourns trimmer pot failure
Yup, you could be right, I just looked at a copy of the datasheet I found on the web. The strap line in the sheet is "Now you can specify Bourns for cost-sensitive applications" the sheet is marked 1977 but it is over-stamped with "Obsolete" dated 79 so this design wasn't around long, that may say something about the design? Certainly compared with the lifetime of products like the 3386 which I also used in large numbers at one point in my life with no issues.
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I agree, why do people have such an issue with owning up to a problem? I spent a fair part of my life in aerospace world and there the culture is different - Problem? 'share early, share often' - was the mantra in Boeing and it worked, genuine 'no blame' culture. S**t happens, what matters is you truly understand root cause and fix it, that way we don't kill a bunch of folks (which could include our family members, as we were oft reminded) sitting in a tube at 35,000 ft! On 7/29/2018 8:47 AM, M Yachad wrote:
So, crap like that happens every so often - I haven't boycotted Bourns over that - their quality is usually excellent - and it would be nice if the manufacturer would 'fess up, without dancing around an issue which is plain as day for anyone to see. |
Re: Slightly OT - Bourns trimmer pot failure
Hi Michael,
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You know, I've just been looking at that and you could be right, but I *really* can't tell how those connections were made! Comparing it with the apparently identical one on the old board I would say there is a bit missing entirely! Without taking the second one apart I can't be 100% sure, but it looks to have a fairly solid silvery/gold film extending to the pcb pins that are staked through the paxolin with what could be a varnish of some sort applied over the top. There is not the faintest trace of anything like that on the failed part, nor the slightest trace of any residue whatsoever, it looks like pristine paxolin substrate with an intact resisistive film applied to it and no means of connection at all - very, very odd! If it was open circuit all along why did things only go berserk when I turned the pot? Floaty HF at several kV with assorted capacitors around went unstable when screwdriver approached perhaps? Not convinced! I have some Piher parts on the way that look like they'll fit nicely and we'll see what happens when they arrive. Best, Adrian On 7/28/2018 11:32 PM, Michael A. Terrell wrote:
Did that pot have a short trace of silver between the end of the resistor to the terminals? |
Re: Slightly OT - Bourns trimmer pot failure
About 6-7 years ago, I used Bourns 3352 Cermet open-frame potis as a standard for replacements on amplifiers.
I figured that open-frame would dissipate heat better. After about 2 years, I started getting returns with amplifier failure. Turns out that these particular 3352's had mechanical separation of the adjustable disc from the base unit. The 3352 looks disturbingly similar to the 3555. I'm still in contact with Bourns, trying to get some nominal type of compensation. I switched immediately to Bourns 3386 and Piher PTC10 Cermet sealed units, and have never had a problem since. So, crap like that happens every so often - I haven't boycotted Bourns over that - their quality is usually excellent - and it would be nice if the manufacturer would 'fess up, without dancing around an issue which is plain as day for anyone to see. |
Re: Desoldering Iron vacuum
stefan_trethan
The compressor itself sits in an oil bath, under atmospheric pressure
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(the compressor shell is the inlet side), so no drain there. You do need to drain the receiver tank, as with any compressor. Ed is not wrong, if you _only_ need vacuum it is better to just use the suction side directly, a venturi generator is very inefficient. ST On Sat, Jul 28, 2018 at 8:31 PM, John Griessen <john@...> wrote:
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Re: Slightly OT - Bourns trimmer pot failure
I have never seen a bad Bourns trimpot that wasn't physically damaged, but I had Beckman removed from out approved vendor's list at Microdyne because they were damaged in the board cleaning process.
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Beckman refused to admit a problem, but I ran a test board through the cleaning process several times and I had over a 5% failure rate. Another problem was that a slight mechanical shock would change the calibration of the circuit they were being used in. Beckman called us about a year later and admitted that they had been using out of spec O-ring seals that allowed the citrus based cleaner to get into the pots, but by that time we had switched to Bourns for everything. It was worth the slightly higher price for much better quality. Beckman calls themselves BI, these days. Michael A. Terrell -----Original Message-----
From: "petertech99h via Groups.Io" <petertech99h@...> |
Re: Slightly OT - Bourns trimmer pot failure
Thank god it was not the quality enclosed Bourns pots - I use them all the time!
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Replace the pot and hopefully you'll be back up and running! I don't trust open frame pots over 1M! Cheers! Pete On Saturday, July 28, 2018, 6:32:24 PM EDT, Michael A. Terrell <mike.terrell@...> wrote:
Did that pot have a short trace of silver between the end of the resistor to the terminals? It can oxidize, and open. I've seen a lot of that type that failed, but they were mostly other brands. I don't like open frame pots, but they are cheap so a lot of companies used them in non-critical applications. Michael A. Terrell -----Original Message----- From: Adrian <Adrian@...> |
Re: Desoldering Iron vacuum
Insulin bottles are easy to remove the seals. The aluminum cap is crimped on, but it is so soft that a small screwdriver under the edge will pull it away from the glass, and then it will peel off the top of the bottle. I have about 45 empties, right now, and I have seen them for sale on Ebay as well.
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The Lantus insulin that I'm on right now are the same diameter, but longer than the old Novalin bottles. Th O.D. is 20mm and the total length is 62 mm with the aluminum seal. The top of the bottle has a lip that should fir into soft hose and stay without a clamp. Here is a photo of the bottle. I had no idea that I'm using over $600 a month in insulin. :( <> Michael A. Terrell -----Original Message-----
From: ¸é±ð²Ô¨¦±ð <k6fsb.1@...> |
Re: Desoldering Iron vacuum
The box would be steel, and just enough foam to reduce the noise. When I'm not using the bench, the power is shut off with the lights. Even the wall warts for chargers are powered down when I turn out the lights and lock the door. A power failure will cause a contactor to drop out, as well.
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I'm from the old school where every workbench had a disconnect switch at the end, where all power could be shut down in an emergency. I had a breaker box catch fire in my home. I had to beat the flames out with my bare hands before I could flip the main breaker. Its contacts to the bussbar had failed, and the heat had set that breaker on fire. It burnt the end off the bussbars. A thermal switch is simple to put into an enclosed box, and you need an opening to get rid of the air it collects so it won't be 100% silent. Michael A. Terrell -----Original Message-----
From: John Griessen <john@...> |
Re: Desoldering Iron vacuum
For a filter I used two small pill bottles one nested inside the other, hose from de-soldering head in large one with a? tube from the top to near the bottom, Cotton balls fill the smaller, which has holes in the side near the bottom, the Vacuum from its top to the vacuum source. used O rings to seal bottles, and Silicone rubber to seal the metal connecting tubes that go to the outside. Use small bottles as feasible because the large ones take longer to build vacuum. debris fills large one and cotton keeps the "air" cleaner for the venturi.
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works great, BTW it is an old antique Weller ds100, which has a glass tube with fiberglass ball in the head to collect the most of the hot stuff. I have been making my own tips from copper and brass on my small lathe...length and mass changes temperature. I mounted the Air compressor ( 150 psi Harbour Freight ) in the garage about 75 feet away and ran 3/8 air line from garage through the attic (PE) to my work area so noise is elsewhere, also allow me compressed air in the "shop".....little 1/2 inch hole is easy to fix when/ if i ever move. I like the idea of the insulin or B12 bottle it is even smaller! now to get an empty....hmmm I know someone who uses....Thanks for the idea Michael! ¸é±ð²Ô¨¦±ð On 2018-07-28 05:03 PM, Michael A. Terrell wrote:
I've seen an inline filter with a cotton ball in a glass sleeve so you could see when it needed changed. I've save a bunch of my empty insulin bottles, to see if I can cut the bottom off to use like this. |
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