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Help with 24x5B processor board A5 and option 5 timer trigger
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I need help getting a 24x5B processor board running properly. The board came as part of a clean 2445B case I plan to upgrade to a 2465B after its working. But I am unable to get the processor board to work properly. I have already cleaned up the mess from the leaking electrolytics and replaced the resistors calibrating the DAC. I know the DAC is working properly now. My problem is in one of the two demux switches, primarily U2530. U2521 seems to operate properly but U2530 does not. U2530 is a new part, installed when I repaired the DAC. I measured signaling to U2530 and its identical to the signaling for U2521 except for the demux INH lines on pins 6. But the output voltages on U2530 do not change, the ones on U2521 do. So I conclude that the problem is either the demux signal or the package itself. But since U2530 is brand new, I conclude it must be the demux signal INH2. So I need help to diagnose why the INH2 signal is bad. My test scope shows their is logic level activity on INH2 but I am unable to determine if it has the correct timing. Also, I am unable to trace INH2 because I do not have a schematic and layout that corresponds to my version of A5. In particular, I have A5 part number 671-0965-06 and the closest document I have covers A5 part number 671-0965-05. I have verified that these two versions differ in the generation and routing of the INH2 signal.
So, after all these words, I need help and advice to trace and diagnose the INH 2 signal. That help could come in the form of a proper document of my version of A5. Or is it possible that prior removal of CTS and TV options has left the processor in a state where it does not command scanning of the signals on U2530? |
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Chuck Harris
It could also be that the circuit the MUX is driving is stuck,
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not allowing the MUX to change the output voltage on those pins. The capacitors that U2521 and U2530 are driving occasionally can be leaky, or short circuited... and the opamps can occasionally have their inputs shorted too... they are FET input, and are quite sensitive to static electricity. -Chuck Harris machineguy59 via Groups.Io wrote: I need help getting a 24x5B processor board running properly. The board came as part of a clean 2445B case I plan to upgrade to a 2465B after its working. But I am unable to get the processor board to work properly. I have already cleaned up the mess from the leaking electrolytics and replaced the resistors calibrating the DAC. I know the DAC is working properly now. My problem is in one of the two demux switches, primarily U2530. U2521 seems to operate properly but U2530 does not. U2530 is a new part, installed when I repaired the DAC. I measured signaling to U2530 and its identical to the signaling for U2521 except for the demux INH lines on pins 6. But the output voltages on U2530 do not change, the ones on U2521 do. So I conclude that the problem is either the demux signal or the package itself. But since U2530 is brand new, I conclude it must be the demux signal INH2. So I need help to diagnose why the INH2 signal is bad. My test scope shows their is logic level activity on INH2 but I am unable to determine if it has the correct timing. Also, I am unable to trace INH2 because I do not have a schematic and layout that corresponds to my version of A5. In particular, I have A5 part number 671-0965-06 and the closest document I have covers A5 part number 671-0965-05. I have verified that these two versions differ in the generation and routing of the INH2 signal. |
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Thanks for the suggestion. I checked, there are 8 outputs from the mux, only one shows a small amount of activity and that looks more like noise than signal. I checked each output line for shorts to ground and they all show more than 1 meg ohm to ground. I also checked the 3 address lines that are parallel with U2521, they have identical signals. Only the INH signals are different (INH1 is not equal to INH2, of course). Still, there is activity on INH2.
I think I am right, if INH2 is active there MUST be output from U2530. It may be the wrong output, but its some voltage that was on the DAC output at some time. This says that a brand new MUX is bad and I am skeptical of that. I would like to test the circuit a bit more before changing U2530 again but I'm flying blind without a schematic for this particular A5. I appreciate any advice you or anyone else can give. I would especially appreciate a copy of schematic and board layout for A5 part number 671-0965-06. |
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Chuck Harris
First things first, check the pins that provide power and ground,
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for power and ground. You mentioned how hard it is to remove the MUX... which should be dead simple if you have the correct tools... so, it is possible that you damaged the board through your method. Things like pulling out a plated through hole come to mind. Any component removal that involves a manually operated solder sucker, or one of those braided solder wicks is virtually certain to do damage to the board. Solder suckers can be used, but only if you place them on the bottom of the board, and heat the lead from the top of the board. The second thing you need to know about 4051 MUX's, they are entirely without any state storage. So, if the inhibit pins are not in the right state, there will be no signal coming out of the MUX. If the inhibit pins are inactive but for an instant, then the signal will only show up for that instant. That is why the capacitors are there, to store the voltage applied for only an instant, and make it appear continuously. The MUX, capacitors, and the opamp followers make what is called a "Sample and Hold" circuit. Look for damage to the circuit board, or solder bridges, around the inhibit pins, and the selection pins. It is very hard to damage a 4051 through heat... not so hard with static electricity. Do use normal static electricity dissipation practices when working on these boards. You can do a whale of a lot of damage by discharging your body most anywhere on the board. -ChucK Harris machineguy59 via Groups.Io wrote: Thanks for the suggestion. I checked, there are 8 outputs from the mux, only one shows a small amount of activity and that looks more like noise than signal. I checked each output line for shorts to ground and they all show more than 1 meg ohm to ground. I also checked the 3 address lines that are parallel with U2521, they have identical signals. Only the INH signals are different (INH1 is not equal to INH2, of course). Still, there is activity on INH2. |
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Can you swap the two muxes?
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On 4/18/2018 8:00 AM, machineguy59 via Groups.Io wrote:
Thanks for the suggestion. I checked, there are 8 outputs from the mux, only one shows a small amount of activity and that looks more like noise than signal. I checked each output line for shorts to ground and they all show more than 1 meg ohm to ground. I also checked the 3 address lines that are parallel with U2521, they have identical signals. Only the INH signals are different (INH1 is not equal to INH2, of course). Still, there is activity on INH2. |
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Hi, maybe this is the service manual you need?
I uploaded some files to the files section in a folder called : 2465B - 2467 Service Manual /g/TekScopes/files/2465B%20-%202467%20Service%20Manual The 2465b - 2467 file has A5 versions for 2465B with SN < 050000 and >=050000 Un saludo, Leo |
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I apologize for my tardy response, had to leave town for a couple days.? Thank you for your advice. Still no joy.? So I will tell you more.
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I bought this 2445B scope "AS-IS" with the intention of replacing the A1 with the A1 from a 2465B and creating a "frankenscope" 2465B.? After calibration it should be a full member of the 2465B family.? I got the 2445B cheap for a reason.? I found it was missing a power supply, the control board A5 had resistors missing, trace position for CH1 did not function, and options for TV and CTS were partially disconnected but lying inside the case.? I put in a rebuilt power supply, fixed the DAC on the A5 board , and finished removing the CTS and TV option boards.? At this time, it boots nicely except for A1 failure (TEST 05 FAIL 42) of the trigger circuit.? That is not a problem since I plan to replace A1 anyway.? To fix the problem with CH1 trace position I replaced the MUX that controlled the 8 functions that include Ch1 POS (U2530) and the film capacitors (but not the chip capacitors) with new parts from DigiKey.? NOW I have none of them working.? I went backwards and I cant think of anything that I did wrong.? So I started my diagnostics: 1.? Processor diagnostics at power on show a problem with trigger on the A1 board (TEST 05 FAIL 42) which I ignore because I plan to change the A1 anyway.2.? Stepping through the exercise routines to exercise 1 (pots and switches) and continuous loop, I am able to verify that the processor "sees" pot rotation for all of the 8 pots that are connected through U2501.? This is the same 8 variables that must eventually pass through U2530.3.? A bench scope shows that the DAC output changes as each pot is rotated.? Obviously, the processor "sees" the changes and responds with commands to the DAC tracking the new values.4.? The scope CRT never responds to these 8 controls.? There is no processor routine to test the output of U2530 (output mux, mux2) so I look at the 8 output pins of U2530 with a bench scope and see they are all stuck at or near zero. ?5.? I check all pins of U2530, at the junction of the pin to the package body.? I have +5, -5, ground for power, three address lines are active and INH (pin 6) is active.? The address lines measured to be parallel to the address lines on U2521 which is operating correctly.? Only INH2 is unique to U2530.6.? The impedance of each output pin to ground is 1 meg ohm or greater (the hold capacitors are not shorted or leaking), and some of the hold capacitors are new. ?7.? I conclude that either U2530 is bad or the address INH2 combinations on the control lines never gate a signal through U2530.? Said another way, either U2530 is bad or the INH2 commands to it are bad. Questions:1.? Is it possible the CTS option was not properly disconnected and the processor is waiting for the CTS to command outputs for trace position?? Since I have never worked with the CTS option I do not know how it may effect A5 operation if it is removed without informing the processor it is no longer there.2.? Is it possible the TV option was not removed properly and causing unknown issues?3.? Are there option install/remove instructions that will help verify the system is no longer waiting for handshakes from a missing option?4.? What other tests can I perform before removing U2530 and replacing it again? Chuck, Here is why I am loath to replacing U2530.? The part sits immediately adjacent to the large red film capacitors (C2732, C2733) and its difficult for my aging hands to work in the small area.? I use a hot air wand to solder SMD parts like U2530 and the hot air ends up on C2732 and C2733 so I place a damp, not wet, tissue on them for protection.? There are protection traces around each output pin of U2530 to prevent crosstalk between controls.? Its near impossible to use liquid solder in this confined area without also getting some on the guard traces, shorts are a definite threat.? Despite this, I did it once and ohm meter tests say I did it right.? But it doesn't work and replacement is my next try at fixing it. Dave, I can always replace U2530 with a new one.? Swapping with U2521 would be "messy".? Another option is to piggy back a new U2530 to the old one and see if the new one has output.? A scope probe with a capacitor clipped in parallel would make a sample and hold circuit that would be able to test any mux output on U2530 or U2521.? This may be my next step.? OR I could just replace U2530 and hope it fixes the problem. Leo, Thanks for the link.? But I think I already have that document. Again, thank you for any ideas you have. On ?Wednesday?, ?April? ?18?, ?2018? ?11?:?25?:?42? ?AM? ?CDT, Chuck Harris <cfharris@...> wrote:
First things first, check the pins that provide power and ground, for power and ground.? You mentioned how hard it is to remove the MUX... which should be dead simple if you have the correct tools... so, it is possible that you damaged the board through your method. Things like pulling out a plated through hole come to mind. Any component removal that involves a manually operated solder sucker, or one of those braided solder wicks is virtually certain to do damage to the board.? Solder suckers can be used, but only if you place them on the bottom of the board, and heat the lead from the top of the board. The second thing you need to know about 4051 MUX's, they are entirely without any state storage.? So, if the inhibit pins are not in the right state, there will be no signal coming out of the MUX.? If the inhibit pins are inactive but for an instant, then the signal will only show up for that instant.? That is why the capacitors are there, to store the voltage applied for only an instant, and make it appear continuously.? The MUX, capacitors, and the opamp followers make what is called a "Sample and Hold" circuit. Look for damage to the circuit board, or solder bridges, around the inhibit pins, and the selection pins. It is very hard to damage a 4051 through heat... not so hard with static electricity.? Do use normal static electricity dissipation practices when working on these boards.? You can do a whale of a lot of damage by discharging your body most anywhere on the board. -ChucK Harris machineguy59 via Groups.Io wrote: Thanks for the suggestion.? I checked, there are 8 outputs from the mux, only one shows a small amount of activity and that looks more like noise than signal.? I checked each output line for shorts to ground and they all show more than 1 meg ohm to ground.? I also checked the 3 address lines that are parallel with U2521, they have identical signals.? Only the INH signals are different (INH1 is not equal to INH2, of course).? Still, there is activity on INH2. |
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On Sun, Apr 22, 2018 at 20:37 machineguy59 via Groups.Io <machineguy59=
[email protected]> wrote:. Questions:1. Is it possible the CTS option was not properly disconnected I don’t think there’s anything to be configured in software when these options are removed. Note however that the triggers run through options, and so you need to bridge some of the pins in one of the connectors when options are removed. Otherwise you get the 05 error you’re seeing. Otherwise it sounds like the replacement U2530 must be bad; Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth. |
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Chuck Harris
I find I was mixing my metaphors in my advice on using a solder
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sucker.... through hole advice for an SMD board. With an SMD board, if you don't use an underboard preheater, you will cook the parts dead every time. It simply takes way too much heat to get the board, the traces, the solder, and the part hot enough to melt the solder. Underboard preheat to about 100-200C, and then the hot air rework pen will melt the solder in seconds. I think all of the options boards break some circuit loop, or another, in their installation. The loops must be reconnected if the option is removed. There is an options manual available on one of the sites out there. It is for the 2465A, but the cabling still applies. -Chuck Harris machineguy59 via Groups.Io wrote: Questions:1. Is it possible the CTS option was not properly disconnected and the processor is waiting for the CTS to command outputs for trace position? Since I have never worked with the CTS option I do not know how it may effect A5 operation if it is removed without informing the processor it is no longer there.2. Is it possible the TV option was not removed properly and causing unknown issues?3. Are there option install/remove instructions that will help verify the system is no longer waiting for handshakes from a missing option?4. What other tests can I perform before removing U2530 and replacing it again? |
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Hi,
I uploaded two pictures of my A1 with the proper jumper settings for a 2465B without the CTT option. This is the album: /g/TekScopes/album?id=45563 Leo |
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Thank you.? I have the right jumpers in the right place.? I also found a J103 on the schematic and put a jumper on it as shown on the schematic.? The scope now powers on without incident except the trace vertical positions, and intensity knobs do not change trace position or intensity.? I am using the screen bias adjustment as an intensity control. ?
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I am resigned to the idea that my soldering technique cooked the new MUX (U2530) when I installed it.? That has never happened to me before.? So I am planning a new method to hand solder U2530 with a temperature controlled, 1 mm tip soldering iron.? Using 63/37 tin/lead solder and a temperature of 270 degrees.? I am considering high temperature epoxy to coat the guard traces between each pin of U2530.? Ordinarily, this would be overkill but I want to be certain the package is not damaged this time.? Comments? On ?Monday?, ?April? ?23?, ?2018? ?01?:?49?:?48? ?AM? ?CDT, satbeginner <castellcorunas@...> wrote:
[Edited Message Follows] Hi, I uploaded two pictures of my A1 with the proper jumper settings for a 2465B without the CTT option. This is the album:? /g/TekScopes/album?id=45563 Leo |
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Chuck Harris
As I said, you must heat the bottom of the board
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to 100-150C. This is well below the solder melt temperature, and cool enough that it won't damage parts. Then when you use your hot air, you can keep its temperature throttled back to 300-350C, and you will only have to heat the joint for a couple of seconds. When you try to do all the heating and melting with just hot air at the top of the board, you have to way overheat the parts to get the solder to melt. The underboard heater doesn't have to be anything fancy, it could be a hot plate made to warm your coffee cup. I use a commercial product, which cost about $100, and has temperature control. Search: quartz under board heater. I also use a beaker stirrer that has a temperature controlled heater. With that I can even reflow smaller boards. A teflon coated frying pan, or griddle, would work too.. you will have to do something to throttle the heat down, and the sides get in the way. If you must use a soldering iron, use something with a chisel tip, and lots of flux. You can wipe the tip over the leads. -Chuck Harris machineguy59 via Groups.Io wrote: Thank you. I have the right jumpers in the right place. I also found a J103 on the schematic and put a jumper on it as shown on the schematic. The scope now powers on without incident except the trace vertical positions, and intensity knobs do not change trace position or intensity. I am using the screen bias adjustment as an intensity control. |
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Chuck,Thanks for the tip on finding an under board heater.? I will look into it.? I have been using my hot air wand at "low" temperature (200 degrees) to heat the board from the top, then cranking up the heat to solder when its warm.? A temperature controlled hot plate would be much easier and obviously better since it heats from the bottom.
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I don't HAVE to use a soldering iron, its just a method I fall back on.? I am 78 years old and began soldering circuits 65 years ago at age 13.? A temperature controlled soldering iron is my go-to tool.? The only problem I have with it is my hands aren't as steady as they were 65 years ago so I often use kapton to hold the part until its soldered. On ?Monday?, ?April? ?23?, ?2018? ?09?:?02?:?08? ?AM? ?CDT, Chuck Harris <cfharris@...> wrote:
As I said, you must heat the bottom of the board to 100-150C.? This is well below the solder melt temperature, and cool enough that it won't damage parts.? Then when you use your hot air, you can keep its temperature throttled back to 300-350C, and you will only have to heat the joint for a couple of seconds. When you try to do all the heating and melting with just hot air at the top of the board, you have to way overheat the parts to get the solder to melt. The underboard heater doesn't have to be anything fancy, it could be a hot plate made to warm your coffee cup. I use a commercial product, which cost about $100, and has temperature control.? Search: quartz under board heater. I also use a beaker stirrer that has a temperature controlled heater.? With that I can even reflow smaller boards. A teflon coated frying pan, or griddle, would work too.. you will have to do something to throttle the heat down, and the sides get in the way. If you must use a soldering iron, use something with a chisel tip, and lots of flux.? You can wipe the tip over the leads. -Chuck Harris machineguy59 via Groups.Io wrote: ? Thank you.? I have the right jumpers in the right place.? I also found a J103 on the schematic and put a jumper on it as shown on the schematic.? The scope now powers on without incident except the trace vertical positions, and intensity knobs do not change trace position or intensity.? I am using the screen bias adjustment as an intensity control. |
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I plan to replace the MUX (U2530) this weekend and wonder if I can put solder mask on the guard traces between signal pins?? I would use Circuit Works CW2500 epoxy which is good to 350 C.? I cant think of any downside and it would help avoid solder shorts.? The guard traces are very close to the signal pins and shorts mean rework with solder braid.? 14 pins at this pitch are sure to get one that needs touch up.?
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I haven't decided yet whether I will do hand soldering or hot air.? I purchased a griddle at Walmart for $18.00 to act as a preheater and calibrated it with my IR temperature meter.? Its easy to hold the temperature around 170 C.? I will use a hand held fan to cool the board after soldering and before lifting it off the griddle so I don't temperature shock the board.? But I may loose my nerve and just hand solder the new part.? Either way, I think solder mask over the guard traces would help keep the solder from overflowing. On ?Monday?, ?April? ?23?, ?2018? ?09?:?02?:?08? ?AM? ?CDT, Chuck Harris <cfharris@...> wrote:
As I said, you must heat the bottom of the board to 100-150C.? This is well below the solder melt temperature, and cool enough that it won't damage parts.? Then when you use your hot air, you can keep its temperature throttled back to 300-350C, and you will only have to heat the joint for a couple of seconds. When you try to do all the heating and melting with just hot air at the top of the board, you have to way overheat the parts to get the solder to melt. The underboard heater doesn't have to be anything fancy, it could be a hot plate made to warm your coffee cup. I use a commercial product, which cost about $100, and has temperature control.? Search: quartz under board heater. I also use a beaker stirrer that has a temperature controlled heater.? With that I can even reflow smaller boards. A teflon coated frying pan, or griddle, would work too.. you will have to do something to throttle the heat down, and the sides get in the way. If you must use a soldering iron, use something with a chisel tip, and lots of flux.? You can wipe the tip over the leads. -Chuck Harris machineguy59 via Groups.Io wrote: ? Thank you.? I have the right jumpers in the right place.? I also found a J103 on the schematic and put a jumper on it as shown on the schematic.? The scope now powers on without incident except the trace vertical positions, and intensity knobs do not change trace position or intensity.? I am using the screen bias adjustment as an intensity control. |
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Chuck Harris
My question would have to be: did you damage that solder
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mask the last time you worked on the MUX? If not, it should be fine the way it is. It is the flux that allows the solder to pull back into a blob. Without a good flux, it forms oxide stringers that allow bridges. Good flux, and everything works out nicely. I keep the board under preheat the entire time I am working on the topside. When I am done, I just turn it off, and let the board cool down naturally. I find that there are fewer stress problems that way. Let us know how you like working with the preheater. You should see a remarkable difference. -Chuck Harris machineguy59 via Groups.Io wrote: I plan to replace the MUX (U2530) this weekend and wonder if I can put solder mask on the guard traces between signal pins? I would use Circuit Works CW2500 epoxy which is good to 350 C. I cant think of any downside and it would help avoid solder shorts. The guard traces are very close to the signal pins and shorts mean rework with solder braid. 14 pins at this pitch are sure to get one that needs touch up. |
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The original mask is unscathed.? But I am surprised that Tek did not cover the guard traces with mask.? They are just traces after all and covering them with mask would simplify repairs like this.? I understand the need for a good liquid flux, preferably no-clean which I clean after anyway.? But the pitch on these pins is so tight that, in most cases, any trace passing between would be masked.? These are not.? I wonder why. ?
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I don't usually make a big deal of soldering a simple part to a board, done it many times.? But I have never cooked a part with my heat wand before and it has me a bit skittish.? So, I am being extra careful (some might say obsessed) so I know the part isn't damaged.? Then if the MUX doesn't work I can confidently look elsewhere for the problem. Thanks again for your advice and help. On ?Saturday?, ?April? ?28?, ?2018? ?07?:?35?:?35? ?PM? ?CDT, Chuck Harris <cfharris@...> wrote:
My question would have to be: did you damage that solder mask the last time you worked on the MUX? If not, it should be fine the way it is. It is the flux that allows the solder to pull back into a blob.? Without a good flux, it forms oxide stringers that allow bridges.? Good flux, and everything works out nicely. I keep the board under preheat the entire time I am working on the topside.? When I am done, I just turn it off, and let the board cool down naturally.? I find that there are fewer stress problems that way. Let us know how you like working with the preheater.? You should see a remarkable difference. -Chuck Harris machineguy59 via Groups.Io wrote: ? I plan to replace the MUX (U2530) this weekend and wonder if I can put solder mask on the guard traces between signal pins?? I would use Circuit Works CW2500 epoxy which is good to 350 C.? I cant think of any downside and it would help avoid solder shorts.? The guard traces are very close to the signal pins and shorts mean rework with solder braid.? 14 pins at this pitch are sure to get one that needs touch up.? |
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It was the MUX (U2530)!!!? I think Chuck Harris was right when he said I probably cooked the MUX with my hot air wand since I didn't use a preheat system.? I feel like a newbie, lol.? On this second attempt I used my trusty soldering iron and some patience.? First time success at my second attempt.? I still want to try a preheat system as suggested by Chuck Harris.? But prudence says I should try it first on something less important.? Thanks for the help guys, especially Chuck Harris who gave me great advice.
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On ?Saturday?, ?April? ?28?, ?2018? ?08?:?40?:?59? ?PM? ?CDT, machineguy59 via Groups.Io <machineguy59@...> wrote:
The original mask is unscathed.? But I am surprised that Tek did not cover the guard traces with mask.? They are just traces after all and covering them with mask would simplify repairs like this.? I understand the need for a good liquid flux, preferably no-clean which I clean after anyway.? But the pitch on these pins is so tight that, in most cases, any trace passing between would be masked.? These are not.? I wonder why. ? I don't usually make a big deal of soldering a simple part to a board, done it many times.? But I have never cooked a part with my heat wand before and it has me a bit skittish.? So, I am being extra careful (some might say obsessed) so I know the part isn't damaged.? Then if the MUX doesn't work I can confidently look elsewhere for the problem. Thanks again for your advice and help.? ? ? On ?Saturday?, ?April? ?28?, ?2018? ?07?:?35?:?35? ?PM? ?CDT, Chuck Harris <cfharris@...> wrote: My question would have to be: did you damage that solder mask the last time you worked on the MUX? If not, it should be fine the way it is. It is the flux that allows the solder to pull back into a blob.? Without a good flux, it forms oxide stringers that allow bridges.? Good flux, and everything works out nicely. I keep the board under preheat the entire time I am working on the topside.? When I am done, I just turn it off, and let the board cool down naturally.? I find that there are fewer stress problems that way. Let us know how you like working with the preheater.? You should see a remarkable difference. -Chuck Harris machineguy59 via Groups.Io wrote: ? I plan to replace the MUX (U2530) this weekend and wonder if I can put solder mask on the guard traces between signal pins?? I would use Circuit Works CW2500 epoxy which is good to 350 C.? I cant think of any downside and it would help avoid solder shorts.? The guard traces are very close to the signal pins and shorts mean rework with solder braid.? 14 pins at this pitch are sure to get one that needs touch up.? |
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John Griessen
On 04/30/2018 06:30 PM, machineguy59 via Groups.Io wrote:
the pitch on these pins is so tight that, in most cases, any trace passing between would be masked.? These are not.? I wonder why.When the solder mask gets too thin, it will come off. At that point, you just leave it out so that does not happen. Then you cannot have too much solder or solder paste or it will blob short out between some copper. |
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On Tue, 01 May 2018 00:40:52 +0000 (UTC), you wrote:
On 04/30/2018 06:30 PM, machineguy59 via Groups.Io wrote:Adding a LOT of flux can help there, simply because it keeps thethe pitch on these pins is so tight that, in most cases, any trace passing between would be masked.? These are not.? I wonder why.When the solder mask gets too thin, it will come off. At that point, you just leave it out so that does not happen. solder from oxidizing and forming strings between pins. If using solder wick to clean up the pins, flux very well, and it does help. More or less proven on 0.5 mm spacing pins with adequate pads, eutectic solder, and a rather thin tip on a metcal iron. Harvey |
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Well I proved you guys are right.? I put mask (Circuit Works CW2500 epoxy) on the guard traces around U2530.? About half of them survived the hand soldering job.? Didn't need the msk any way because, as you say, lots of flux, careful work and a little braid keeps the solder on the pin and pad with the guard trace clean.? I guess I am learning how to work with tiny spacing on a huge board.
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On ?Monday?, ?April? ?30?, ?2018? ?09?:?00?:?41? ?PM? ?CDT, Harvey White <madyn@...> wrote:
On Tue, 01 May 2018 00:40:52 +0000 (UTC), you wrote: On 04/30/2018 06:30 PM, machineguy59 via Groups.Io wrote:Adding a LOT of flux can help there, simply because it keeps thethe pitch on these pins is so tight that, in most cases, any trace passing between would be masked.? These are not.? I wonder why.When the solder mask gets too thin, it will come off.? At that point, you just leave it out so that does not happen. solder from oxidizing and forming strings between pins. If using solder wick to clean up the pins, flux very well, and it does help. More or less proven on 0.5 mm spacing pins with adequate pads, eutectic solder, and a rather thin tip on a metcal iron. Harvey |
satbeginner
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