Re: [time-nuts] 5370B Input Board Repair [WAS: 5370B Question / help needed]
Hi Don, Yes, my thinking is they may have feared problems and opted for the adhesive, but I'm only guessing. Wouldn't have been my first choice for this piece of kit. I don't think you can get this stuff off one joint at a time, but definitely one component at a time which is what I have done. The adhesive is physically between the component and the pads and unless the component is removed you won't be able to clean up the pad ready for soldering. After all this messing about with these SMD's it is probably better fitting new parts anyway, otherwise you may well be back into the intermittent fault situation fairly quickly. Kind regards, Thomas. Message: 6 Date: Wed, 19 Jul 2017 18:16:42 -0600 From: djl To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] 5370B Input Board Repair [WAS: 5370B Question / help needed] Message-ID: <2138b5104f5a250430c2ed46a755d...@blackfoot.net> Content-Type: text/plain; charset=UTF-8; format=flowed Could it be that someone thought adhesive would be less prone to cracking from stress than solder? Also, do you think that the adhesive could be cleaned one end at a time and replaced with solder? I'm admittedly too lazy to look/try just now. Don ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5370B Input Board Repair [WAS: 5370B Question / help needed]
Thanks! Didier! 73, John K1AE -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Didier Juges Sent: Wednesday, July 19, 2017 1:35 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] 5370B Input Board Repair [WAS: 5370B Question / help needed] That is very good information. I will add your email to the 5370 page on my web site. Didier KO4BB On Jul 18, 2017 4:02 AM, "Thomas Allgeier" wrote: > Hello All Again, > > > > I’ve got my 5370B going now and in the process made a “discovery” which I > thought might be worth sharing: > > The A3 input board is a through-hole PCB with a few SMD capacitors and > resistors on the reverse of the “switch area”. It turns out that on my 5370 > (2410A00777) these components are not soldered, but fitted with conductive > adhesive. I first thought it was solder with a black coating but under a > microscope it is clear that it is not solder at all. Most probably it is a > mixture of epoxy and silver particles, or a similar compound. So no going > over joints with a fine iron… > > Inspecting all this carefully under the microscope I discovered that the > “joints” on 2 resistors (R23 and R56) had cracked. As you know this board > gets heat from the hybrid amplifier IC’s and due to the way the board is > mounted to the front panel I guess it sees thermal stressing when the > instrument warms up and cools down. While this obviously lasts a long time > it looks that on my unit the adhesive has eventually cracked in places. > (Vigorous switch activation and pressing / pulling on the switch handles > also won’t be helpful in this respect…) One of the resistors just fell off > at the slightest touch with fine tweezers. > > > > Anyhow, after removing the offending components, cleaning the pads of the > adhesive, and soldering replacements in place, we have a perfect 99.9x ns > with the 10 MHz on the commoned inputs. Happy days! > > > > So if any of your 5370’s have the kind of intermittent fault I described > (and one or two other people seem to have reported) or instability that > seems to originate from the A3 board – check the joints around the SMD’s. > > > > I wonder why / how it ended up having the adhesive instead of solder – > were earlier / later instruments the same, or was this a build change > introduced at a certain period? > > > > Hope the above is of help to somebody else, > > Thomas. > > > > Message: 1 > Date: Sat, 15 Jul 2017 21:54:47 +0100 > From: Thomas Allgeier > To: Discussion of precise time and frequency measurement > > Subject: Re: [time-nuts] 5370B Question / help needed > Message-ID: > > Content-Type: text/plain; charset="UTF-8" > > Hello Folks, > > I'm coming back to this after a few days of prodding etc. and there has > been some progress. The fault has been tracked down to the A3 input board > and it points at a crack in the board or a joint. Here is the sketch: > After a good clean of the switches and re-seating all boards etc. the 5370 > sprung back into life with almost-in-spec performance of 102.xx ns with > it's own 10 MHz. Trouble is it didn't last - after a while and triggered by > sliding some switches around it went back to the 14 ns. Fiddling with the > BNC's may have the same effect, i.e. there is a mechanical element to it > all. > Turns out that running it with the front panel removed I can make it go > from 14 to 102 ns by slightly bending the A3 board, certainly while it is > cold. After a while this trick doesn't work anymore, my suspicion is > whatever crack/gap is causing the trouble has expanded too far to close it > tight. After cool-down we're back to square one. > I notice there are a few SMD components on that board, right in the middle > where it would bend most - basically on the reverse side of the switches. > Capacitors and resistors I expect. I wonder if it is worth going over the > solder joints of all these carefully. > What has stopped me so far are 2 questions: > Am I the only one with this observation or has anybody come across this > before? > Secondly the solder on these SMD's is coated with a black substance. > Clearly this could be removed somehow but it is probably there for a > reason. Has anybody re-touched joints like these before? > On an instrument like this it is very much a case of "proceed with care" > and I'd hate to do more damage by rushing in. > > On a related subject: last year there was a discussion over redesigning the > input board(s) for the 5370 / 5345. Did this get off the ground? If my A3 > packs up completely... > > Thanks in advance for any suggestions, > > Thoma
Re: [time-nuts] 5370B Input Board Repair [WAS: 5370B Question / help needed]
Could it be that someone thought adhesive would be less prone to cracking from stress than solder? Also, do you think that the adhesive could be cleaned one end at a time and replaced with solder? I'm admittedly too lazy to look/try just now. Don On 2017-07-19 07:09, Gary Neilson wrote: This is very interesting, I have a 5370B that has the same behavior as yours. I will take the input board out again and give it a good inspection. BTW, what did you use to clean the adhesive from the pads ? Thanks Gary On 7/18/2017 2:41 AM, Thomas Allgeier wrote: Hello All Again, I’ve got my 5370B going now and in the process made a “discovery” which I thought might be worth sharing: The A3 input board is a through-hole PCB with a few SMD capacitors and resistors on the reverse of the “switch area”. It turns out that on my 5370 (2410A00777) these components are not soldered, but fitted with conductive adhesive. I first thought it was solder with a black coating but under a microscope it is clear that it is not solder at all. Most probably it is a mixture of epoxy and silver particles, or a similar compound. So no going over joints with a fine iron… Inspecting all this carefully under the microscope I discovered that the “joints” on 2 resistors (R23 and R56) had cracked. As you know this board gets heat from the hybrid amplifier IC’s and due to the way the board is mounted to the front panel I guess it sees thermal stressing when the instrument warms up and cools down. While this obviously lasts a long time it looks that on my unit the adhesive has eventually cracked in places. (Vigorous switch activation and pressing / pulling on the switch handles also won’t be helpful in this respect…) One of the resistors just fell off at the slightest touch with fine tweezers. Anyhow, after removing the offending components, cleaning the pads of the adhesive, and soldering replacements in place, we have a perfect 99.9x ns with the 10 MHz on the commoned inputs. Happy days! So if any of your 5370’s have the kind of intermittent fault I described (and one or two other people seem to have reported) or instability that seems to originate from the A3 board – check the joints around the SMD’s. I wonder why / how it ended up having the adhesive instead of solder – were earlier / later instruments the same, or was this a build change introduced at a certain period? Hope the above is of help to somebody else, Thomas. Message: 1 Date: Sat, 15 Jul 2017 21:54:47 +0100 From: Thomas Allgeier To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] 5370B Question / help needed Message-ID: Content-Type: text/plain; charset="UTF-8" Hello Folks, I'm coming back to this after a few days of prodding etc. and there has been some progress. The fault has been tracked down to the A3 input board and it points at a crack in the board or a joint. Here is the sketch: After a good clean of the switches and re-seating all boards etc. the 5370 sprung back into life with almost-in-spec performance of 102.xx ns with it's own 10 MHz. Trouble is it didn't last - after a while and triggered by sliding some switches around it went back to the 14 ns. Fiddling with the BNC's may have the same effect, i.e. there is a mechanical element to it all. Turns out that running it with the front panel removed I can make it go from 14 to 102 ns by slightly bending the A3 board, certainly while it is cold. After a while this trick doesn't work anymore, my suspicion is whatever crack/gap is causing the trouble has expanded too far to close it tight. After cool-down we're back to square one. I notice there are a few SMD components on that board, right in the middle where it would bend most - basically on the reverse side of the switches. Capacitors and resistors I expect. I wonder if it is worth going over the solder joints of all these carefully. What has stopped me so far are 2 questions: Am I the only one with this observation or has anybody come across this before? Secondly the solder on these SMD's is coated with a black substance. Clearly this could be removed somehow but it is probably there for a reason. Has anybody re-touched joints like these before? On an instrument like this it is very much a case of "proceed with care" and I'd hate to do more damage by rushing in. On a related subject: last year there was a discussion over redesigning the input board(s) for the 5370 / 5345. Did this get off the ground? If my A3 packs up completely... Thanks in advance for any suggestions, Thomas. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and
Re: [time-nuts] 5370B Input Board Repair [WAS: 5370B Question / help needed]
That is very good information. I will add your email to the 5370 page on my web site. Didier KO4BB On Jul 18, 2017 4:02 AM, "Thomas Allgeier" wrote: > Hello All Again, > > > > I’ve got my 5370B going now and in the process made a “discovery” which I > thought might be worth sharing: > > The A3 input board is a through-hole PCB with a few SMD capacitors and > resistors on the reverse of the “switch area”. It turns out that on my 5370 > (2410A00777) these components are not soldered, but fitted with conductive > adhesive. I first thought it was solder with a black coating but under a > microscope it is clear that it is not solder at all. Most probably it is a > mixture of epoxy and silver particles, or a similar compound. So no going > over joints with a fine iron… > > Inspecting all this carefully under the microscope I discovered that the > “joints” on 2 resistors (R23 and R56) had cracked. As you know this board > gets heat from the hybrid amplifier IC’s and due to the way the board is > mounted to the front panel I guess it sees thermal stressing when the > instrument warms up and cools down. While this obviously lasts a long time > it looks that on my unit the adhesive has eventually cracked in places. > (Vigorous switch activation and pressing / pulling on the switch handles > also won’t be helpful in this respect…) One of the resistors just fell off > at the slightest touch with fine tweezers. > > > > Anyhow, after removing the offending components, cleaning the pads of the > adhesive, and soldering replacements in place, we have a perfect 99.9x ns > with the 10 MHz on the commoned inputs. Happy days! > > > > So if any of your 5370’s have the kind of intermittent fault I described > (and one or two other people seem to have reported) or instability that > seems to originate from the A3 board – check the joints around the SMD’s. > > > > I wonder why / how it ended up having the adhesive instead of solder – > were earlier / later instruments the same, or was this a build change > introduced at a certain period? > > > > Hope the above is of help to somebody else, > > Thomas. > > > > Message: 1 > Date: Sat, 15 Jul 2017 21:54:47 +0100 > From: Thomas Allgeier > To: Discussion of precise time and frequency measurement > > Subject: Re: [time-nuts] 5370B Question / help needed > Message-ID: > > Content-Type: text/plain; charset="UTF-8" > > Hello Folks, > > I'm coming back to this after a few days of prodding etc. and there has > been some progress. The fault has been tracked down to the A3 input board > and it points at a crack in the board or a joint. Here is the sketch: > After a good clean of the switches and re-seating all boards etc. the 5370 > sprung back into life with almost-in-spec performance of 102.xx ns with > it's own 10 MHz. Trouble is it didn't last - after a while and triggered by > sliding some switches around it went back to the 14 ns. Fiddling with the > BNC's may have the same effect, i.e. there is a mechanical element to it > all. > Turns out that running it with the front panel removed I can make it go > from 14 to 102 ns by slightly bending the A3 board, certainly while it is > cold. After a while this trick doesn't work anymore, my suspicion is > whatever crack/gap is causing the trouble has expanded too far to close it > tight. After cool-down we're back to square one. > I notice there are a few SMD components on that board, right in the middle > where it would bend most - basically on the reverse side of the switches. > Capacitors and resistors I expect. I wonder if it is worth going over the > solder joints of all these carefully. > What has stopped me so far are 2 questions: > Am I the only one with this observation or has anybody come across this > before? > Secondly the solder on these SMD's is coated with a black substance. > Clearly this could be removed somehow but it is probably there for a > reason. Has anybody re-touched joints like these before? > On an instrument like this it is very much a case of "proceed with care" > and I'd hate to do more damage by rushing in. > > On a related subject: last year there was a discussion over redesigning the > input board(s) for the 5370 / 5345. Did this get off the ground? If my A3 > packs up completely... > > Thanks in advance for any suggestions, > > Thomas. > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5370B Input Board Repair [WAS: 5370B Question / help needed]
Hello Gary, The adhesive doesn't come off with solvent - I am afraid very careful scraping with a pointy scalpel under the microscope was what did it. That's what makes me think it is epoxy-based. Touching it with a hot iron also doesn't seem to have much effect. Once cured it probably can only be mechanically removed. But it is not immensely strong, I guess the metal filler means it can be kind of crumbled off bit by bit. Make sure you really get all the debris removed as of course it is conductive and would easily cause trouble elsewhere. I hope you get yours going! Kind regards, Thomas. Message: 3 Date: Wed, 19 Jul 2017 07:09:58 -0600 From: Gary Neilson To: time-nuts@febo.com Subject: Re: [time-nuts] 5370B Input Board Repair [WAS: 5370B Question / help needed] Message-ID: Content-Type: text/plain; charset=utf-8; format=flowed This is very interesting, I have a 5370B that has the same behavior as yours. I will take the input board out again and give it a good inspection. BTW, what did you use to clean the adhesive from the pads ? Thanks Gary ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5370B Input Board Repair [WAS: 5370B Question / help needed]
This is very interesting, I have a 5370B that has the same behavior as yours. I will take the input board out again and give it a good inspection. BTW, what did you use to clean the adhesive from the pads ? Thanks Gary On 7/18/2017 2:41 AM, Thomas Allgeier wrote: Hello All Again, I’ve got my 5370B going now and in the process made a “discovery” which I thought might be worth sharing: The A3 input board is a through-hole PCB with a few SMD capacitors and resistors on the reverse of the “switch area”. It turns out that on my 5370 (2410A00777) these components are not soldered, but fitted with conductive adhesive. I first thought it was solder with a black coating but under a microscope it is clear that it is not solder at all. Most probably it is a mixture of epoxy and silver particles, or a similar compound. So no going over joints with a fine iron… Inspecting all this carefully under the microscope I discovered that the “joints” on 2 resistors (R23 and R56) had cracked. As you know this board gets heat from the hybrid amplifier IC’s and due to the way the board is mounted to the front panel I guess it sees thermal stressing when the instrument warms up and cools down. While this obviously lasts a long time it looks that on my unit the adhesive has eventually cracked in places. (Vigorous switch activation and pressing / pulling on the switch handles also won’t be helpful in this respect…) One of the resistors just fell off at the slightest touch with fine tweezers. Anyhow, after removing the offending components, cleaning the pads of the adhesive, and soldering replacements in place, we have a perfect 99.9x ns with the 10 MHz on the commoned inputs. Happy days! So if any of your 5370’s have the kind of intermittent fault I described (and one or two other people seem to have reported) or instability that seems to originate from the A3 board – check the joints around the SMD’s. I wonder why / how it ended up having the adhesive instead of solder – were earlier / later instruments the same, or was this a build change introduced at a certain period? Hope the above is of help to somebody else, Thomas. Message: 1 Date: Sat, 15 Jul 2017 21:54:47 +0100 From: Thomas Allgeier To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] 5370B Question / help needed Message-ID: Content-Type: text/plain; charset="UTF-8" Hello Folks, I'm coming back to this after a few days of prodding etc. and there has been some progress. The fault has been tracked down to the A3 input board and it points at a crack in the board or a joint. Here is the sketch: After a good clean of the switches and re-seating all boards etc. the 5370 sprung back into life with almost-in-spec performance of 102.xx ns with it's own 10 MHz. Trouble is it didn't last - after a while and triggered by sliding some switches around it went back to the 14 ns. Fiddling with the BNC's may have the same effect, i.e. there is a mechanical element to it all. Turns out that running it with the front panel removed I can make it go from 14 to 102 ns by slightly bending the A3 board, certainly while it is cold. After a while this trick doesn't work anymore, my suspicion is whatever crack/gap is causing the trouble has expanded too far to close it tight. After cool-down we're back to square one. I notice there are a few SMD components on that board, right in the middle where it would bend most - basically on the reverse side of the switches. Capacitors and resistors I expect. I wonder if it is worth going over the solder joints of all these carefully. What has stopped me so far are 2 questions: Am I the only one with this observation or has anybody come across this before? Secondly the solder on these SMD's is coated with a black substance. Clearly this could be removed somehow but it is probably there for a reason. Has anybody re-touched joints like these before? On an instrument like this it is very much a case of "proceed with care" and I'd hate to do more damage by rushing in. On a related subject: last year there was a discussion over redesigning the input board(s) for the 5370 / 5345. Did this get off the ground? If my A3 packs up completely... Thanks in advance for any suggestions, Thomas. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] 5370B Input Board Repair [WAS: 5370B Question / help needed]
Hello All Again, I’ve got my 5370B going now and in the process made a “discovery” which I thought might be worth sharing: The A3 input board is a through-hole PCB with a few SMD capacitors and resistors on the reverse of the “switch area”. It turns out that on my 5370 (2410A00777) these components are not soldered, but fitted with conductive adhesive. I first thought it was solder with a black coating but under a microscope it is clear that it is not solder at all. Most probably it is a mixture of epoxy and silver particles, or a similar compound. So no going over joints with a fine iron… Inspecting all this carefully under the microscope I discovered that the “joints” on 2 resistors (R23 and R56) had cracked. As you know this board gets heat from the hybrid amplifier IC’s and due to the way the board is mounted to the front panel I guess it sees thermal stressing when the instrument warms up and cools down. While this obviously lasts a long time it looks that on my unit the adhesive has eventually cracked in places. (Vigorous switch activation and pressing / pulling on the switch handles also won’t be helpful in this respect…) One of the resistors just fell off at the slightest touch with fine tweezers. Anyhow, after removing the offending components, cleaning the pads of the adhesive, and soldering replacements in place, we have a perfect 99.9x ns with the 10 MHz on the commoned inputs. Happy days! So if any of your 5370’s have the kind of intermittent fault I described (and one or two other people seem to have reported) or instability that seems to originate from the A3 board – check the joints around the SMD’s. I wonder why / how it ended up having the adhesive instead of solder – were earlier / later instruments the same, or was this a build change introduced at a certain period? Hope the above is of help to somebody else, Thomas. Message: 1 Date: Sat, 15 Jul 2017 21:54:47 +0100 From: Thomas Allgeier To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] 5370B Question / help needed Message-ID: Content-Type: text/plain; charset="UTF-8" Hello Folks, I'm coming back to this after a few days of prodding etc. and there has been some progress. The fault has been tracked down to the A3 input board and it points at a crack in the board or a joint. Here is the sketch: After a good clean of the switches and re-seating all boards etc. the 5370 sprung back into life with almost-in-spec performance of 102.xx ns with it's own 10 MHz. Trouble is it didn't last - after a while and triggered by sliding some switches around it went back to the 14 ns. Fiddling with the BNC's may have the same effect, i.e. there is a mechanical element to it all. Turns out that running it with the front panel removed I can make it go from 14 to 102 ns by slightly bending the A3 board, certainly while it is cold. After a while this trick doesn't work anymore, my suspicion is whatever crack/gap is causing the trouble has expanded too far to close it tight. After cool-down we're back to square one. I notice there are a few SMD components on that board, right in the middle where it would bend most - basically on the reverse side of the switches. Capacitors and resistors I expect. I wonder if it is worth going over the solder joints of all these carefully. What has stopped me so far are 2 questions: Am I the only one with this observation or has anybody come across this before? Secondly the solder on these SMD's is coated with a black substance. Clearly this could be removed somehow but it is probably there for a reason. Has anybody re-touched joints like these before? On an instrument like this it is very much a case of "proceed with care" and I'd hate to do more damage by rushing in. On a related subject: last year there was a discussion over redesigning the input board(s) for the 5370 / 5345. Did this get off the ground? If my A3 packs up completely... Thanks in advance for any suggestions, Thomas. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
