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 .
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
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On Sun, Jul 29, 2018 at 12:07 AM, Tomas Alori wrote:
Oh I am an idiot, I dont think you meant the CRT cable right? The CRT cable
signal would always match the dotting frequency for obvious reasons.
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Re: Desoldering Iron vacuum
On 07/28/2018 08:21 PM, Ed Breya via Groups.Io wrote: John wrote
"Another thing to consider is the smoky output of desoldering. I recently repaired a Hakko 470, that has
an on-demand vacuum pump, and found the smoke had gummed up the rubber flap reed valves of the pump.
It's a good idea to have some kind of receiver container up stream of the solenoid you use, since it
would be in line to get rosin smoke. Maybe a pipe fitting container with wads of TP in it?"
Good point John. The filter wadding usually built into the desoldering head traps the chunks and some condensates, but it's inevitable that some fumes will go through the vacuum system, causing maintenance issues with heavy use.
Ed 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? Mark
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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.
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
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-----Original Message----- From: Adrian <Adrian@...>
Sent: Jul 29, 2018 4:54 AM
To: [email protected]
Subject: Re: [TekScopes] 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.
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.
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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.
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
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-----Original Message----- From: Adrian <Adrian@...>
Hi Michael,
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 resistive 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
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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.
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!
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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.
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Re: Slightly OT - Bourns trimmer pot failure
Hi Michael,
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
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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?
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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.
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Re: Desoldering Iron vacuum
The compressor itself sits in an oil bath, under atmospheric pressure
(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
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On Sat, Jul 28, 2018 at 8:31 PM, John Griessen <john@...> wrote:
How about a condensate drain valve? Do you have that to let water out the
bottom of the
compressor shell/tank? A small refrigeration compressor from a water
cooler might be a good size
for venturi vacuum generating.
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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.
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
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-----Original Message----- From: "petertech99h via Groups.Io" <petertech99h@...>
Sent: Jul 28, 2018 11:02 PM
To: [email protected]
Subject: Re: [TekScopes] Slightly OT - Bourns trimmer pot failure
Thank god it was not the quality enclosed Bourns pots - I use them all the time!
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
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Re: Slightly OT - Bourns trimmer pot failure
Thank god it was not the quality enclosed Bourns pots - I use them all the time!
Replace the pot and hopefully you'll be back up and running! I don't trust open frame pots over 1M!
Cheers!
Pete
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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@...>
Sent: Jul 28, 2018 4:43 PM
To: [email protected]
Subject: [TekScopes] Slightly OT - Bourns trimmer pot failure
I finally succeeded in breathing life? back into my Tek 634 display today but, as it turned out, only briefly.
Thanks to google, an expired ebay link and a really helpful chap in the US of A I got my hands on a spare A4 HV Multiplier board and also tracked down a failed transistor and diode on the A6 interface board and all came back to life. I ran it for about an hour keeping an eye on the current drawn by the HV board and everything was fine.
The contrast was a bit horrid and the display seemed slightly dimmer than I remembered but as the HV board was a NOS replacement I figured it would need setting up.
I ran through the procedure which worked fine up to the point of setting the cut-off level to make the background raster just invisible. This is a? bias applied to Grid (2?) of the CRT and is derived from a separate winding on the HV transformer with a 5M Bourns 3355 series trim pot as part of a divider network. These pots are a PCB vertical 'skeletal' type with a blue molded plastic thumbwheel type adjuster.
At first it responded as I expected but then the screen suddenly started getting very bright and the current to the HV board started climbing so I switched of sharpish! Investigation revealed the trimmer was open end-to-end and neither end was connected to the wiper. I opened it up - with extreme prejudice - and cannot see any evidence of over-heating or flash-over and the resistive track seems intact and continuous but is just no longer connected to the solder tag stake at either end.
On that basis I will find something to replace it and try again, but for reassurance I'm just wondering if these trimmers were used widely by Tek and if so if anyone has seen this sort of (mechanical?) failure mode before?
Thanks,
Adrian
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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.
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
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-----Original Message----- From: ¸é±ð²Ô¨¦±ð <k6fsb.1@...>
Sent: Jul 28, 2018 9:27 PM
To: [email protected]
Subject: Re: [TekScopes] 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.
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.
Somewhere I have a box of spares from a Pace desoldering system from a vocational school. Spare tips, fuses and other items that were supplied to each new student. If they quit the course, it went into a box for spares. The instructor was thinning his herd when I stopped by to visit and they followed me home.
Michael A. Terrell
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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.
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
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-----Original Message----- From: John Griessen <john@...>
Sent: Jul 28, 2018 9:16 PM
To: "[email protected]" <[email protected]>
Subject: Re: [TekScopes] Desoldering Iron vacuum
On 07/28/2018 07:56 PM, Michael A. Terrell wrote:
I would put the compressor in a foam lined box That could have fire safety problems. If it is too silent, and set to run via a vacuum switch,
either continuous sucking, or a failed switch could let it run continuously and heat up
inside the insulated (sound AND heat) box.
|
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.
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
toggle quoted message
Show quoted text
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.
Somewhere I have a box of spares from a Pace desoldering system from a vocational school. Spare tips, fuses and other items that were supplied to each new student. If they quit the course, it went into a box for spares. The instructor was thinning his herd when I stopped by to visit and they followed me home.
Michael A. Terrell
-----Original Message-----
From: John Griessen <john@...>
Sent: Jul 28, 2018 7:30 PM
To: [email protected]
Subject: Re: [TekScopes] Desoldering Iron vacuum
On 07/28/2018 06:15 PM, Ed Breya via Groups.Io wrote:
Now, of course, using a vacuum supply changes the way the desoldering unit operates, so it would need re-plumbing to eliminate the venturi and make the solenoid valve work for vacuum. Another thing to consider is the smoky output of desoldering. I recently repaired a Hakko 470, that has
an on-demand vacuum pump, and found the smoke had gummed up the rubber flap reed valves of the pump.
It's a good idea to have some kind of receiver container up stream of the solenoid you use, since it
would be in line to get rosin smoke. Maybe a pipe fitting container with wads of TP in it?
|
Re: Desoldering Iron vacuum
On 07/28/2018 07:56 PM, Michael A. Terrell wrote: I would put the compressor in a foam lined box That could have fire safety problems. If it is too silent, and set to run via a vacuum switch, either continuous sucking, or a failed switch could let it run continuously and heat up inside the insulated (sound AND heat) box.
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Re: Desoldering Iron vacuum
The air conditioners are junk, but the mini fridge still works. If I was desperate, I could always use my vacuum pump made for A/C work.
I would put the compressor in a foam lined box under the back of a workbench, so the size wouldn't matter. :)
Michael A. Terrell
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-----Original Message----- From: "Ed Breya via Groups.Io" <edbreya@...>
Yes Michael, a window AC compressor would work too, but is kind of big for the application. I've found that mini-frig compressors are the handiest size for small dedicated P/V applications.
BTW most AC compressors are scroll type, with really good vacuum, compared to the common swashplate-piston refrigeration ones. Scrolls are the preferred kind for many DIY medium high vacuum uses, but still not as good as a two-stage vane pump - the workhorse of roughing,
Ed
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Re: 495P A54 Memory Board Troubleshooting: continued
On Sat, 28 Jul 2018 19:57:48 -0400 (GMT-04:00), you wrote: Rick, if I have a long message to post, I type it into something like Open Office Writer, or whatever word processing software you prefer. Once I'm happy with it, and have checked it for spelling errors, I copy and paste it into the new message. It helps me because of poor vision, because I can use a large font size while editing and the mistakes are easier to spot. I have nerve damage in one hand and Carpal Tunnel in the other hand so I find a lot of transposed character errors. This might help you, as well. I did some technical writing at my last job, and I didn't want to release any poorly written documents to the production floor. :) I've also had the email program fail at times, and REALLY hate to re-type long answers. easier to cut and paste. Harvey
Michael A. Terrell
-----Original Message-----
From: Rick Boswell <frboswell@...>
Sent: Jul 28, 2018 7:23 PM
To: [email protected]
Subject: Re: [TekScopes] 495P A54 Memory Board Troubleshooting: continued
Harvey,
After spending some additional time with the service manual. I see there is a way to cause the microcomputer to cycle through the full range of memory addresses on a repetitive basis. This is done by relocating a jumper on the processor board. Every time the options switch is addressed I should see the tri-state buffer enable line go low and the option switch setting appear on the output of the tri-state buffer/data bus (high for SW4 OPEN, low for SW4 CLOSED). This will repeat approximately every 154ms (if I am reading correctly), making verification much easier than if it is a one-time event with each power up. This should also isolate the problem to either the U3045 decoder or to the tri-state buffer. IOW, no enable to the buffer = decoder problem, incorrect option switch setting on the tri-state output = tri-state buffer problem. Getting closer! (I think!)
PS: Dave, Sorry about the re-editing. Necessary to correct some key typos. Now that I know this causes others problems, I'll try to get it right before posting!
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Re: 495P A54 Memory Board Troubleshooting: continued
On Sat, 28 Jul 2018 16:23:54 -0700, you wrote: Harvey,
After spending some additional time with the service manual. I see there is a way to cause the microcomputer to cycle through the full range of memory addresses on a repetitive basis. This is done by relocating a jumper on the processor board. Every time the options switch is addressed I should see the tri-state buffer enable line go low and the option switch setting appear on the output of the tri-state buffer/data bus (high for SW4 OPEN, low for SW4 CLOSED). This will repeat approximately every 154ms (if I am reading correctly), making verification much easier than if it is a one-time event with each power up. This should also isolate the problem to either the U3045 decoder or to the tri-state buffer. IOW, no enable to the buffer = decoder problem, incorrect option switch setting on the tri-state output = tri-state buffer problem. Getting closer! (I think!) Yes, This is the signature analysis mode. It causes the processor to do no-ops (works on older processors and was in a lot of the TM5000 stuff as well as other scopes of that generation). The no-ops cause the processor to execute an instruction that does nothing, it's one byte, then it goes to the next instruction, which is the same. It functions by hardwiring the return from program memory to the no-op instruction for that processor. Signature analyzers take that pattern that (ought to) "is" at any pin having to do with addressing, and counts up the pulses at that pin, giving you a unique code. Since the hardware is in a fixed response pattern, the signature is constant. Since the addresses are cycling for all possible addresses (reading, that is), you're seeing the read cycle of that switch repeated. and yes, you're getting closer. Modern microcontrollers have all of the ROM and RAM (frequently) inside them, as well as the subsystems. With the exception of a few specialized chips, most of the circuitry not doing unique to Tektronix interfaces (except front panel and IEEE-488) interfaces are now inside a single chip. Much of this (as in the code used in the 468 scopes) actually verifies the processor by making it do certain operations, then trapping the processor in a dead end loop if that operation fails. By looking at the processor address pins, you can identify which processor aspect failed. Only after that would the external parts be tested. With modern processors, most of these tests are not needed, since the reliability is so high. Generally, it'll either work, or not, and doesn't go to try to execute instructions with internal damage. Not impossible, but simply not worth it for most designs. Harvey
PS: Dave, Sorry about the re-editing. Necessary to correct some key typos. Now that I know this causes others problems, I'll try to get it right before posting!
RB
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Re: Desoldering Iron vacuum
Yes Michael, a window AC compressor would work too, but is kind of big for the application. I've found that mini-frig compressors are the handiest size for small dedicated P/V applications.
BTW most AC compressors are scroll type, with really good vacuum, compared to the common swashplate-piston refrigeration ones. Scrolls are the preferred kind for many DIY medium high vacuum uses, but still not as good as a two-stage vane pump - the workhorse of roughing,
Ed
|
Re: Desoldering Iron vacuum
John wrote
"Another thing to consider is the smoky output of desoldering. I recently repaired a Hakko 470, that has
an on-demand vacuum pump, and found the smoke had gummed up the rubber flap reed valves of the pump.
It's a good idea to have some kind of receiver container up stream of the solenoid you use, since it
would be in line to get rosin smoke. Maybe a pipe fitting container with wads of TP in it?"
Good point John. The filter wadding usually built into the desoldering head traps the chunks and some condensates, but it's inevitable that some fumes will go through the vacuum system, causing maintenance issues with heavy use.
Ed
|
Re: Desoldering Iron vacuum
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.
Somewhere I have a box of spares from a Pace desoldering system from a vocational school. Spare tips, fuses and other items that were supplied to each new student. If they quit the course, it went into a box for spares. The instructor was thinning his herd when I stopped by to visit and they followed me home.
Michael A. Terrell
toggle quoted message
Show quoted text
-----Original Message----- From: John Griessen <john@...>
Sent: Jul 28, 2018 7:30 PM
To: [email protected]
Subject: Re: [TekScopes] Desoldering Iron vacuum
On 07/28/2018 06:15 PM, Ed Breya via Groups.Io wrote:
Now, of course, using a vacuum supply changes the way the desoldering unit operates, so it would need re-plumbing to eliminate the venturi and make the solenoid valve work for vacuum. Another thing to consider is the smoky output of desoldering. I recently repaired a Hakko 470, that has
an on-demand vacuum pump, and found the smoke had gummed up the rubber flap reed valves of the pump.
It's a good idea to have some kind of receiver container up stream of the solenoid you use, since it
would be in line to get rosin smoke. Maybe a pipe fitting container with wads of TP in it?
|
Michael A. Terrell