Re: [M100] Narrowing down issue, I think
Correct. Now examining PCB with magnifying glass and continuity tester to inspect circuit line that may look broken or brownish as earlier described as evidence of corrosion. Common sense, patience and willingness hoping for dumb luck. Never surrender! On Sunday, August 2, 2020, 05:58:35 PM EDT, Jeffrey Birt wrote: So the screen/kb from the unit you were working on worked fine on the other M100? (Just making sure.) Jeff Birt From: M100 On Behalf Of Chris Fezzler Sent: Sunday, August 2, 2020 2:51 PM To: m...@bitchin100.com Subject: Re: [M100] Narrowing down issue, I think Thanks. Dug out another Model T and swapped screens and keyboard. They worked flawlessly as suspected. So the LCD and keyboard side of the equation has been eliminated. On Sunday, August 2, 2020, 08:34:22 AM EDT, Jeffrey Birt wrote: If you look close you can just see a green trace under that block of solder so it looks like those two pins would be electrically joined anyhow. Sometimes this PCBs had messy solder joints from the factory. Probably the most common issue is a poor connection from the solder not flowing out properly originally and then developing cracks over time. Ideally the solder forms a tent like shape around the pin and flows down smoothly to the pad. A joint that did not have enough solder or that was not soldered properly will look more like a blob, there will not be a nice smooth transition from pin to pad. The where the solder meets the pad it tends to tuck back under itself rather than flowing out. If you look up at pin 40 in the picture you can see that is more of ball. This is probably a case of just too much solder there. Often times I will put some flux on joints like that and reflow them. It can be tough to find bad solder joints. Sometimes the cracks are obvious under magnification and sometimes they are not. Jeff Birt From: M100 On Behalf Of Chris Fezzler Sent: Saturday, August 1, 2020 11:36 PM To: M100 Mailing List Subject: [M100] Narrowing down issue, I think Please look at the PCB pic here. It is of the option rom socket from the component side. Those to points are not supposed to be soldered together, are they? My LCD issue may be related if they are not.
Re: [M100] Narrowing down issue, I think
So the screen/kb from the unit you were working on worked fine on the other M100? (Just making sure.) Jeff Birt From: M100 On Behalf Of Chris Fezzler Sent: Sunday, August 2, 2020 2:51 PM To: m...@bitchin100.com Subject: Re: [M100] Narrowing down issue, I think Thanks. Dug out another Model T and swapped screens and keyboard. They worked flawlessly as suspected. So the LCD and keyboard side of the equation has been eliminated. On Sunday, August 2, 2020, 08:34:22 AM EDT, Jeffrey Birt mailto:bir...@soigeneris.com> > wrote: If you look close you can just see a green trace under that block of solder so it looks like those two pins would be electrically joined anyhow. Sometimes this PCBs had messy solder joints from the factory. Probably the most common issue is a poor connection from the solder not flowing out properly originally and then developing cracks over time. Ideally the solder forms a tent like shape around the pin and flows down smoothly to the pad. A joint that did not have enough solder or that was not soldered properly will look more like a blob, there will not be a nice smooth transition from pin to pad. The where the solder meets the pad it tends to tuck back under itself rather than flowing out. If you look up at pin 40 in the picture you can see that is more of ball. This is probably a case of just too much solder there. Often times I will put some flux on joints like that and reflow them. It can be tough to find bad solder joints. Sometimes the cracks are obvious under magnification and sometimes they are not. Jeff Birt From: M100 mailto:m100-boun...@lists.bitchin100.com> > On Behalf Of Chris Fezzler Sent: Saturday, August 1, 2020 11:36 PM To: M100 Mailing List mailto:m...@bitchin100.com> > Subject: [M100] Narrowing down issue, I think Please look at the PCB pic here. It is of the option rom socket from the component side. Those to points are not supposed to be soldered together, are they? My LCD issue may be related if they are not.
Re: [M100] Narrowing down issue, I think
Thanks. Dug out another Model T and swapped screens and keyboard.They worked flawlessly as suspected.So the LCD and keyboard side of the equation has been eliminated. On Sunday, August 2, 2020, 08:34:22 AM EDT, Jeffrey Birt wrote: If you look close you can just see a green trace under that block of solder so it looks like those two pins would be electrically joined anyhow. Sometimes this PCBs had messy solder joints from the factory. Probably the most common issue is a poor connection from the solder not flowing out properly originally and then developing cracks over time. Ideally the solder forms a tent like shape around the pin and flows down smoothly to the pad. A joint that did not have enough solder or that was not soldered properly will look more like a blob, there will not be a nice smooth transition from pin to pad. The where the solder meets the pad it tends to tuck back under itself rather than flowing out. If you look up at pin 40 in the picture you can see that is more of ball. This is probably a case of just too much solder there. Often times I will put some flux on joints like that and reflow them. It can be tough to find bad solder joints. Sometimes the cracks are obvious under magnification and sometimes they are not. Jeff Birt From: M100 On Behalf Of Chris Fezzler Sent: Saturday, August 1, 2020 11:36 PM To: M100 Mailing List Subject: [M100] Narrowing down issue, I think Please look at the PCB pic here. It is of the option rom socket from the component side. Those to points are not supposed to be soldered together, are they? My LCD issue may be related if they are not.
Re: [M100] Narrowing down issue, I think
Unfortunately that is a pretty typical solder joint for an M100 it is OK. One thing you might want to look for is corrosion caused by flux residue that was left behind after the manufacturing process. It looks like a copper brown deposit but might hide a damaged track. I have worked on a few Mobos where the track has tested open circuit or very high resistance due to the residual flux corroding the track over time. Look particularly around the OPTROM socket or ROM socket where flux could collect after a bad¹ wash. Quite a lot of the tracks to the PIO are routed under the flash socket if they are bad then the PIO might not be working properly which will impact most of the board. It could also be a failed component which after 35years would not be unreasonable. Some output stuck high or low can cause issues elsewhere that can be misleading. From: M100 on behalf of Chris Fezzler Reply-To: "m...@bitchin100.com" Date: Saturday, August 1, 2020 at 9:35 PM To: M100 Mailing List Subject: [M100] Narrowing down issue, I think > Please look at the PCB pic here. It is of the option rom socket from the > component side. > > Those to points are not supposed to be soldered together, are they? > > My LCD issue may be related if they are not. > >
Re: [M100] Narrowing down issue, I think
If you look close you can just see a green trace under that block of solder so it looks like those two pins would be electrically joined anyhow. Sometimes this PCBs had messy solder joints from the factory. Probably the most common issue is a poor connection from the solder not flowing out properly originally and then developing cracks over time. Ideally the solder forms a tent like shape around the pin and flows down smoothly to the pad. A joint that did not have enough solder or that was not soldered properly will look more like a blob, there will not be a nice smooth transition from pin to pad. The where the solder meets the pad it tends to tuck back under itself rather than flowing out. If you look up at pin 40 in the picture you can see that is more of ball. This is probably a case of just too much solder there. Often times I will put some flux on joints like that and reflow them. It can be tough to find bad solder joints. Sometimes the cracks are obvious under magnification and sometimes they are not. Jeff Birt From: M100 On Behalf Of Chris Fezzler Sent: Saturday, August 1, 2020 11:36 PM To: M100 Mailing List Subject: [M100] Narrowing down issue, I think Please look at the PCB pic here. It is of the option rom socket from the component side. Those to points are not supposed to be soldered together, are they? My LCD issue may be related if they are not.
