Alan, I had a similar situation with a power supply from an HP scope. In my case, some of the electrolytics were overheating to the extent that electrolyte had leaked out onto the PCB and was sizzling. I removed all of the questionable caps, and since I do not own an ESR meter, I tested the leakage current of each cap at the rated voltage. There were 2-3 caps with significantly worse leakage than the others, and I replaced those. But first (and more importantly), I thoroughly cleaned the area of the PCB of all electrolyte. The electrolyte on the PCB was conducting current between two adjacent traces, and the excessive load was pulling down the supply. The traces were still OK, so no repair was necessary other than cleaning. After cleaning the board and replacing the bad caps, the unit worked perfectly. I don't know if a leakage test is a substitute for a proper ESR test, but it may be a quick check you can do without special equipment. -Randall > > ------------------------------------------------------------------------ > > Subject: > [volt-nuts] Keithley 2001 Multimeter Fault - Update > From: > "Alan Scrimgeour" <scrimgap@blueyonder.co.uk> > Date: > Mon, 15 Mar 2010 21:46:51 -0000 > To: > "Discussion of precise voltage measurement" <volt-nuts@febo.com> > > To: > "Discussion of precise voltage measurement" <volt-nuts@febo.com> > > > Here's a progress report: > Searching for a possible short circuited tantalum capacitor I tried to identify if any were connected to the 5V output of the overheating regulator. None on the visible side of the analogue pcb were. I dived in and removed the pcb and did a similar search of the tants on the rear. One, located right next to the regulator was connected. I replaced and tested it. It was a bit leaky, but ok, and the replacement made no difference. > I started probing around with a thermocouple looking for overheating chips connected to the 5V supply, but couldn't spot any. Then I accidently discovered that 5 electrolytics in the vicinity of the overheating 5V regulator were also overheating. Unfortunately the pcb does have buried layers so it's not easy to tell what connects to what, and I cant get to connections on the rear of the pcb when it's powered up, so the whole process is proving rather frustrating. I think I'll try removing the electrolytics and if they're still ok, putting them back on long wire legs to allow me to access the powered up connections. > Any bright ideas welcome! > > Alan > > > ------------------------------------------------------------------------ > > Subject: > Re: [volt-nuts] Keithley 2001 Multimeter Fault - Update > From: > Brooke Clarke <brooke@pacific.net> > Date: > Mon, 15 Mar 2010 16:53:47 -0700 > To: > Discussion of precise voltage measurement <volt-nuts@febo.com> > > To: > Discussion of precise voltage measurement <volt-nuts@febo.com> > > > Hi Alan: > > I'm importing and selling a combined ESR and capacitance meter. See: > http://www.prc68.com/P/Prod.html#ESR <- ordering > http://www.prc68.com/I/ESRmicro.shtml <- description > http://www.prc68.com/I/Capacitors.shtml <- measured results using a > number of instruments > > Have Fun, > > Brooke Clarke > http://www.PRC68.com > > > Alan Scrimgeour wrote: >> Here's a progress report: >> Searching for a possible short circuited tantalum capacitor I tried >> to identify if any were connected to the 5V output of the overheating >> regulator. None on the visible side of the analogue pcb were. I dived >> in and removed the pcb and did a similar search of the tants on the >> rear. One, located right next to the regulator was connected. I >> replaced and tested it. It was a bit leaky, but ok, and the >> replacement made no difference. >> I started probing around with a thermocouple looking for overheating >> chips connected to the 5V supply, but couldn't spot any. Then I >> accidently discovered that 5 electrolytics in the vicinity of the >> overheating 5V regulator were also overheating. Unfortunately the pcb >> does have buried layers so it's not easy to tell what connects to >> what, and I cant get to connections on the rear of the pcb when it's >> powered up, so the whole process is proving rather frustrating. I >> think I'll try removing the electrolytics and if they're still ok, >> putting them back on long wire legs to allow me to access the powered >> up connections. >> Any bright ideas welcome! >> >> Alan >> _______________________________________________ >> volt-nuts mailing list -- volt-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> and follow the instructions there. >> >> >> > > > > > ------------------------------------------------------------------------ > > Subject: > Re: [volt-nuts] Keithley 2001 Multimeter Fault - Update > From: > Robert Atkinson <robert8rpi@yahoo.co.uk> > Date: > Tue, 16 Mar 2010 07:44:25 +0000 (GMT) > To: > Discussion of precise voltage measurement <volt-nuts@febo.com> > > To: > Discussion of precise voltage measurement <volt-nuts@febo.com> > > > Hi Alan, > Have you put a 'scope on the 5V rail? overheating capacitors could be a sign of an unstable (oscillating) regulator. I'd just change the hot elecrolytics anyway, they have much reduced lives when they are hot. If you are testing them, you must include an ESR test of some sort (I've no connection to any vendors of ESR meters ;-) > > Robert G8RPI. > > --- On Mon, 15/3/10, Alan Scrimgeour <scrimgap@blueyonder.co.uk> wrote: > > > From: Alan Scrimgeour <scrimgap@blueyonder.co.uk> > Subject: [volt-nuts] Keithley 2001 Multimeter Fault - Update > To: "Discussion of precise voltage measurement" <volt-nuts@febo.com> > Date: Monday, 15 March, 2010, 21:46 > > > Here's a progress report: > Searching for a possible short circuited tantalum capacitor I tried to identify if any were connected to the 5V output of the overheating regulator. None on the visible side of the analogue pcb were. I dived in and removed the pcb and did a similar search of the tants on the rear. One, located right next to the regulator was connected. I replaced and tested it. It was a bit leaky, but ok, and the replacement made no difference. > I started probing around with a thermocouple looking for overheating chips connected to the 5V supply, but couldn't spot any. Then I accidently discovered that 5 electrolytics in the vicinity of the overheating 5V regulator were also overheating. Unfortunately the pcb does have buried layers so it's not easy to tell what connects to what, and I cant get to connections on the rear of the pcb when it's powered up, so the whole process is proving rather frustrating. I think I'll try removing the electrolytics and if they're still ok, putting them back on long wire legs to allow me to access the powered up connections. > Any bright ideas welcome! > > Alan > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > > > > > > > ------------------------------------------------------------------------ > > Subject: > Re: [volt-nuts] Keithley 2001 Multimeter Fault - Update > From: > "Alan Scrimgeour" <scrimgap@blueyonder.co.uk> > Date: > Tue, 16 Mar 2010 11:47:09 -0000 > To: > "Discussion of precise voltage measurement" <volt-nuts@febo.com> > > To: > "Discussion of precise voltage measurement" <volt-nuts@febo.com> > > > I think you're right, but the capacitors in question don't connect to > the 5V regulator (well, maybee one) so things are more complicated. By > proximity they appear mostly to be connected to bridge rectifiers. I > guess an oscillating regulator could put a high ripple current through > a capacitor on its input too. > . I've tested the overheating electrolytics and they all seem ok > (ignoring unknown ESR), but under a couple there's corrosion. There's > also possibly some heat damage to the pcb at one point that needs a > much closer look. I hope it's just more corrosion. > Unfortunately my scopes dead, which I'll have to sort that out, but > for now my meters ac range and frequency measurement mode should tell > me what I need to know. > > Alan > > > ----- Original Message ----- From: "Robert Atkinson" > <robert8rpi@yahoo.co.uk> > To: "Discussion of precise voltage measurement" <volt-nuts@febo.com> > Sent: Tuesday, March 16, 2010 7:44 AM > Subject: Re: [volt-nuts] Keithley 2001 Multimeter Fault - Update > > > Hi Alan, > Have you put a 'scope on the 5V rail? overheating capacitors could be > a sign of an unstable (oscillating) regulator. I'd just change the hot > elecrolytics anyway, they have much reduced lives when they are hot. > If you are testing them, you must include an ESR test of some sort > (I've no connection to any vendors of ESR meters ;-) > > Robert G8RPI. > > --- On Mon, 15/3/10, Alan Scrimgeour <scrimgap@blueyonder.co.uk> wrote: > > > From: Alan Scrimgeour <scrimgap@blueyonder.co.uk> > Subject: [volt-nuts] Keithley 2001 Multimeter Fault - Update > To: "Discussion of precise voltage measurement" <volt-nuts@febo.com> > Date: Monday, 15 March, 2010, 21:46 > > > Here's a progress report: > Searching for a possible short circuited tantalum capacitor I tried to > identify if any were connected to the 5V output of the overheating > regulator. None on the visible side of the analogue pcb were. I dived > in and removed the pcb and did a similar search of the tants on the > rear. One, located right next to the regulator was connected. I > replaced and tested it. It was a bit leaky, but ok, and the > replacement made no difference. > I started probing around with a thermocouple looking for overheating > chips connected to the 5V supply, but couldn't spot any. Then I > accidently discovered that 5 electrolytics in the vicinity of the > overheating 5V regulator were also overheating. Unfortunately the pcb > does have buried layers so it's not easy to tell what connects to > what, and I cant get to connections on the rear of the pcb when it's > powered up, so the whole process is proving rather frustrating. I > think I'll try removing the electrolytics and if they're still ok, > putting them back on long wire legs to allow me to access the powered > up connections. > Any bright ideas welcome! > > Alan > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > > > > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > > > > ------------------------------------------------------------------------ > > _______________________________________________ > volt-nuts mailing list > volt-nuts@febo.com > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts

I've had a closer look at the 'corrosion' damage from leaked capacitor electrolyte using a stereo microscope. Some very fine tracks have been completely eaten away in one area, but the path of the track is easy to follow in the green solder mask layer making it easy to e bypass with a wire. Looking in more detail at the 'Heat Damaged Area' I can see that the chemical attack from the capacitor leakage is far more advanced. In addition to copper track, it's eaten right through the solder mask and deeper down into the PCB resin leaving bare woven glass fibers visible. There are vias in this area and I'm concerned there may be internal layer connections that are damaged. In addition to conductive electrolyte trapped within the fibrous region I think some of the resin may have carbonised and provided another leakage path for current, although it might be melted black plastic from the capacitors insulating sleeve. A fix will require returning this area of pcb to a non conducting state. I might just need to flush it free of electrolyte and reseal with epoxy resin, but a thorough fix means carefully excavating the damaged area out. This is a lot more trouble than I was expecting, with no guarantee I'll eventually get the meter working, but at least it's something I can try which might help. I think I'm going to have to fully remove the pcb and work on it under the stereo microscope. This might also reveal any internal layer connection problems. The main offending capacitors are marked Nichicon VZ(M) 470uF,63V &1000uF,35V. Alan ----- Original Message ----- From: "Randall White" <randall.m.white@gmail.com> To: <volt-nuts@febo.com> Sent: Tuesday, March 16, 2010 1:55 PM Subject: Re: [volt-nuts] Keithley 2001 Multimeter Fault - Update > Alan, > > I had a similar situation with a power supply from an HP scope. In my > case, some of the electrolytics were overheating to the extent that > electrolyte had leaked out onto the PCB and was sizzling. I removed all of > the questionable caps, and since I do not own an ESR meter, I tested the > leakage current of each cap at the rated voltage. There were 2-3 caps with > significantly worse leakage than the others, and I replaced those. But > first (and more importantly), I thoroughly cleaned the area of the PCB of > all electrolyte. The electrolyte on the PCB was conducting current between > two adjacent traces, and the excessive load was pulling down the supply. > The traces were still OK, so no repair was necessary other than cleaning. > After cleaning the board and replacing the bad caps, the unit worked > perfectly. > I don't know if a leakage test is a substitute for a proper ESR test, but > it may be a quick check you can do without special equipment. > > -Randall >> >> ------------------------------------------------------------------------ >> >> Subject: >> [volt-nuts] Keithley 2001 Multimeter Fault - Update >> From: >> "Alan Scrimgeour" <scrimgap@blueyonder.co.uk> >> Date: >> Mon, 15 Mar 2010 21:46:51 -0000 >> To: >> "Discussion of precise voltage measurement" <volt-nuts@febo.com> >> >> To: >> "Discussion of precise voltage measurement" <volt-nuts@febo.com> >> >> >> Here's a progress report: >> Searching for a possible short circuited tantalum capacitor I tried to >> identify if any were connected to the 5V output of the overheating >> regulator. None on the visible side of the analogue pcb were. I dived in >> and removed the pcb and did a similar search of the tants on the rear. >> One, located right next to the regulator was connected. I replaced and >> tested it. It was a bit leaky, but ok, and the replacement made no >> difference. >> I started probing around with a thermocouple looking for overheating >> chips connected to the 5V supply, but couldn't spot any. Then I >> accidently discovered that 5 electrolytics in the vicinity of the >> overheating 5V regulator were also overheating. Unfortunately the pcb >> does have buried layers so it's not easy to tell what connects to what, >> and I cant get to connections on the rear of the pcb when it's powered >> up, so the whole process is proving rather frustrating. I think I'll try >> removing the electrolytics and if they're still ok, putting them back on >> long wire legs to allow me to access the powered up connections. >> Any bright ideas welcome! >> >> Alan >> >> ------------------------------------------------------------------------ >> >> Subject: >> Re: [volt-nuts] Keithley 2001 Multimeter Fault - Update >> From: >> Brooke Clarke <brooke@pacific.net> >> Date: >> Mon, 15 Mar 2010 16:53:47 -0700 >> To: >> Discussion of precise voltage measurement <volt-nuts@febo.com> >> >> To: >> Discussion of precise voltage measurement <volt-nuts@febo.com> >> >> >> Hi Alan: >> >> I'm importing and selling a combined ESR and capacitance meter. See: >> http://www.prc68.com/P/Prod.html#ESR <- ordering >> http://www.prc68.com/I/ESRmicro.shtml <- description >> http://www.prc68.com/I/Capacitors.shtml <- measured results using a >> number of instruments >> >> Have Fun, >> >> Brooke Clarke >> http://www.PRC68.com >> >> >> Alan Scrimgeour wrote: >>> Here's a progress report: >>> Searching for a possible short circuited tantalum capacitor I tried to >>> identify if any were connected to the 5V output of the overheating >>> regulator. None on the visible side of the analogue pcb were. I dived in >>> and removed the pcb and did a similar search of the tants on the rear. >>> One, located right next to the regulator was connected. I replaced and >>> tested it. It was a bit leaky, but ok, and the replacement made no >>> difference. >>> I started probing around with a thermocouple looking for overheating >>> chips connected to the 5V supply, but couldn't spot any. Then I >>> accidently discovered that 5 electrolytics in the vicinity of the >>> overheating 5V regulator were also overheating. Unfortunately the pcb >>> does have buried layers so it's not easy to tell what connects to what, >>> and I cant get to connections on the rear of the pcb when it's powered >>> up, so the whole process is proving rather frustrating. I think I'll try >>> removing the electrolytics and if they're still ok, putting them back on >>> long wire legs to allow me to access the powered up connections. >>> Any bright ideas welcome! >>> >>> Alan >>> _______________________________________________ >>> volt-nuts mailing list -- volt-nuts@febo.com >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >>> and follow the instructions there. >>> >>> >>> >> >> >> >> >> ------------------------------------------------------------------------ >> >> Subject: >> Re: [volt-nuts] Keithley 2001 Multimeter Fault - Update >> From: >> Robert Atkinson <robert8rpi@yahoo.co.uk> >> Date: >> Tue, 16 Mar 2010 07:44:25 +0000 (GMT) >> To: >> Discussion of precise voltage measurement <volt-nuts@febo.com> >> >> To: >> Discussion of precise voltage measurement <volt-nuts@febo.com> >> >> >> Hi Alan, >> Have you put a 'scope on the 5V rail? overheating capacitors could be a >> sign of an unstable (oscillating) regulator. I'd just change the hot >> elecrolytics anyway, they have much reduced lives when they are hot. If >> you are testing them, you must include an ESR test of some sort (I've no >> connection to any vendors of ESR meters ;-) >> Robert G8RPI. >> >> --- On Mon, 15/3/10, Alan Scrimgeour <scrimgap@blueyonder.co.uk> wrote: >> >> >> From: Alan Scrimgeour <scrimgap@blueyonder.co.uk> >> Subject: [volt-nuts] Keithley 2001 Multimeter Fault - Update >> To: "Discussion of precise voltage measurement" <volt-nuts@febo.com> >> Date: Monday, 15 March, 2010, 21:46 >> >> >> Here's a progress report: >> Searching for a possible short circuited tantalum capacitor I tried to >> identify if any were connected to the 5V output of the overheating >> regulator. None on the visible side of the analogue pcb were. I dived in >> and removed the pcb and did a similar search of the tants on the rear. >> One, located right next to the regulator was connected. I replaced and >> tested it. It was a bit leaky, but ok, and the replacement made no >> difference. >> I started probing around with a thermocouple looking for overheating >> chips connected to the 5V supply, but couldn't spot any. Then I >> accidently discovered that 5 electrolytics in the vicinity of the >> overheating 5V regulator were also overheating. Unfortunately the pcb >> does have buried layers so it's not easy to tell what connects to what, >> and I cant get to connections on the rear of the pcb when it's powered >> up, so the whole process is proving rather frustrating. I think I'll try >> removing the electrolytics and if they're still ok, putting them back on >> long wire legs to allow me to access the powered up connections. >> Any bright ideas welcome! >> >> Alan >> _______________________________________________ >> volt-nuts mailing list -- volt-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> and follow the instructions there. >> >> >> >> >> ------------------------------------------------------------------------ >> >> Subject: >> Re: [volt-nuts] Keithley 2001 Multimeter Fault - Update >> From: >> "Alan Scrimgeour" <scrimgap@blueyonder.co.uk> >> Date: >> Tue, 16 Mar 2010 11:47:09 -0000 >> To: >> "Discussion of precise voltage measurement" <volt-nuts@febo.com> >> >> To: >> "Discussion of precise voltage measurement" <volt-nuts@febo.com> >> >> >> I think you're right, but the capacitors in question don't connect to the >> 5V regulator (well, maybee one) so things are more complicated. By >> proximity they appear mostly to be connected to bridge rectifiers. I >> guess an oscillating regulator could put a high ripple current through a >> capacitor on its input too. >> . I've tested the overheating electrolytics and they all seem ok >> (ignoring unknown ESR), but under a couple there's corrosion. There's >> also possibly some heat damage to the pcb at one point that needs a much >> closer look. I hope it's just more corrosion. >> Unfortunately my scopes dead, which I'll have to sort that out, but for >> now my meters ac range and frequency measurement mode should tell me what >> I need to know. >> >> Alan >> >> >> ----- Original Message ----- From: "Robert Atkinson" >> <robert8rpi@yahoo.co.uk> >> To: "Discussion of precise voltage measurement" <volt-nuts@febo.com> >> Sent: Tuesday, March 16, 2010 7:44 AM >> Subject: Re: [volt-nuts] Keithley 2001 Multimeter Fault - Update >> >> >> Hi Alan, >> Have you put a 'scope on the 5V rail? overheating capacitors could be a >> sign of an unstable (oscillating) regulator. I'd just change the hot >> elecrolytics anyway, they have much reduced lives when they are hot. If >> you are testing them, you must include an ESR test of some sort (I've no >> connection to any vendors of ESR meters ;-) >> >> Robert G8RPI. >> >> --- On Mon, 15/3/10, Alan Scrimgeour <scrimgap@blueyonder.co.uk> wrote: >> >> >> From: Alan Scrimgeour <scrimgap@blueyonder.co.uk> >> Subject: [volt-nuts] Keithley 2001 Multimeter Fault - Update >> To: "Discussion of precise voltage measurement" <volt-nuts@febo.com> >> Date: Monday, 15 March, 2010, 21:46 >> >> >> Here's a progress report: >> Searching for a possible short circuited tantalum capacitor I tried to >> identify if any were connected to the 5V output of the overheating >> regulator. None on the visible side of the analogue pcb were. I dived in >> and removed the pcb and did a similar search of the tants on the rear. >> One, located right next to the regulator was connected. I replaced and >> tested it. It was a bit leaky, but ok, and the replacement made no >> difference. >> I started probing around with a thermocouple looking for overheating >> chips connected to the 5V supply, but couldn't spot any. Then I >> accidently discovered that 5 electrolytics in the vicinity of the >> overheating 5V regulator were also overheating. Unfortunately the pcb >> does have buried layers so it's not easy to tell what connects to what, >> and I cant get to connections on the rear of the pcb when it's powered >> up, so the whole process is proving rather frustrating. I think I'll try >> removing the electrolytics and if they're still ok, putting them back on >> long wire legs to allow me to access the powered up connections. >> Any bright ideas welcome! >> >> Alan >> _______________________________________________ >> volt-nuts mailing list -- volt-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> and follow the instructions there. >> >> >> >> >> _______________________________________________ >> volt-nuts mailing list -- volt-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> and follow the instructions there. >> >> >> >> ------------------------------------------------------------------------ >> >> _______________________________________________ >> volt-nuts mailing list >> volt-nuts@febo.com >> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there.

> I've had a closer look at the 'corrosion' damage from leaked capacitor > electrolyte using a stereo microscope. Some very fine tracks have been > completely eaten away in one area, but the path of the track is easy to > follow in the green solder mask layer making it easy to e bypass with a > wire. > > Looking in more detail at the 'Heat Damaged Area' I can see that the > chemical attack from the capacitor leakage is far more advanced. In > addition > to copper track, it's eaten right through the solder mask and deeper down > into the PCB resin leaving bare woven glass fibers visible. I find it hard to believe anything has eaten the epoxy. It's pretty inert to almost any chemicals. > There are vias in this area and I'm concerned there may be internal layer > connections that are damaged. > -John =============

Perhaps only the copper was 'etched', but I can imagine even epoxy being attacked by hot electrolysis taking place right next to it. Electrolysis could produce some very active compounds, depending on the electrolyte (and, I'm not sure, but in such close proximity to the electrodes there may also be some extremely reactive short lived species, or is that just Sci-Fi?). But by some mechanism the upper layer of glass fiber in the board was visible before I started digging it away. The excavation is progressing with care. In the centre the damage has gone right through the board to virtually the other side. Presumably air cooling stopped or slowed the progress of the damage actually through the very last layers of the board. It appears that once the hot electrolysis had begun to damage the pcb it carbonised and in that conductive state, drew current and generated yet more heat leading to a chain reaction in the form of a growing carbonised region. I've just had to cut a wide buried copper track in order to be able to remove the carbonised pcb beneath it, which is disconcerting, but it will just need soldering, or replacing with a piece of wire. I'm more worried about what to use as a 'filling' in this cavity. I said I'd use epoxy resin, but the usual stuff is damaged by soldering temperatures. I have some 'Auto Weld' which says it's resistant to a constant 300C and should do. Once I fill that hole back I'll never get it out again, so I'd better fix it properly! I'd like to add that I'm feeling pretty angry about those electrolytic capacitors. They are sheer vandalism! Time for some companies heads to bow down and appologise! Those unstable low dropout regulators are another annoying self destruct mechanism too!!! Alan ----- Original Message ----- From: "J. Forster" <jfor@quik.com> To: "Discussion of precise voltage measurement" <volt-nuts@febo.com> Sent: Wednesday, March 17, 2010 3:12 AM Subject: Re: [volt-nuts] Keithley 2001 Multimeter Fault - Update >> I've had a closer look at the 'corrosion' damage from leaked capacitor >> electrolyte using a stereo microscope. Some very fine tracks have been >> completely eaten away in one area, but the path of the track is easy to >> follow in the green solder mask layer making it easy to e bypass with a >> wire. >> >> Looking in more detail at the 'Heat Damaged Area' I can see that the >> chemical attack from the capacitor leakage is far more advanced. In >> addition >> to copper track, it's eaten right through the solder mask and deeper down >> into the PCB resin leaving bare woven glass fibers visible. > > I find it hard to believe anything has eaten the epoxy. It's pretty inert > to almost any chemicals. > >> There are vias in this area and I'm concerned there may be internal layer >> connections that are damaged. >> > -John > > ============= > > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there.