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Solder sucker sucked up half of a solder pad

S

Saffire

Active Member
So, I have a vintage receiver that would occasionally go into protection mode, and I narrowed the issue down to the two voltage regulator transistors in the power supply. They both had cracked solder joints. Strangely, all of their solder pads seemed wiggly and loose, but I got them to stick down securely to the PCB.

Unfortunately, one of the solder pads got destroyed by my solder sucker... Half of it got sucked up, and I had to run a small piece of jumper wire to bridge it to the nearest joint:

20200916_203517.jpg

My question is, will this be a stable connection in the long term? I know that these voltage transistors get very, very hot, and the heating and cooling cycles can lead to solder joint breakage.
 
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Probably more reliable than the PCB pad since it can move with the lead as it expands / contracts. If you could have wrapped the wire a half turn or more around the regulator lead it would be even better, but what you have done will likely outlive you.

Terry
 
It's a good fix but as I see this, these transistors are already heat-sinked and yet, the PCB has been charred by heat.
The lead that replaces the wrecked pad appears to me - as I see the photo - to not reach to the leg of the transistor and solder makes up the connection. As solder has somewhat higher resistance than copper pads, I would prefer to have the wire touch the leg of the transistor - if it's not touching it already. Reason being, that the increased resistance of the solder will cause additional heat to be generated there.
 
SaSi said:
It's a good fix but as I see this, these transistors are already heat-sinked and yet, the PCB has been charred by heat.
The lead that replaces the wrecked pad appears to me - as I see the photo - to not reach to the leg of the transistor and solder makes up the connection. As solder has somewhat higher resistance than copper pads, I would prefer to have the wire touch the leg of the transistor - if it's not touching it already. Reason being, that the increased resistance of the solder will cause additional heat to be generated there.
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Ah, that makes sense, something I should keep in mind for the future. While it does look like that, I made sure to have the jumper lead touch the leg of the transistor while I was soldering. The way the solder covers the two leads makes it look like the jumper lead is shorter than it actually is. The burn marks on the PCB was a result of me being clumsy and slipping while I was trying to de-solder, as well as applying heat to try to get the loose solder pads to stick down to the PCB. Everything seems to work alright, though. :)
 
Bigbeard said:
Yup. Maybe a swab of IPA to make sure there's no conductive material left in the flux?
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Yep! I made sure to thoroughly brush the PCB with 70% IPA. Unfortunately, 70% is all I could find around here due to COVID. I did multiple cleanings until the PCB was flux-free.
 
Saffire said:
Yes, it was having intermittent protection issues due to the cracked joints of these voltage transistors. I've heard that it's a very, very common problem on vintage Pioneer receivers.
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It certainly is. And it was when those amps and receivers were new (2 to 5 years). I repaired them professionally then and it was nearly the only fault those things showed.
 
Always wrap the jumper wire around the component pin to form a new pad. To support the part and traces you can put some epoxy over the repair but then it makes it more difficult to replace parts later.
 
dr*audio said:
Always wrap the jumper wire around the component pin to form a new pad. To support the part and traces you can put some epoxy over the repair but then it makes it more difficult to replace parts later.
Click to expand...
The first part of your suggestion is very good. I have my doubts regarding the second one. This is because the leads of the devices on a PCB are important for the cooling of the device. As is the connection of the leads to the soldering pads and are the strip lines. Especially with stabilizing devices in Pioneer amplifiers. And the epoxy would lessen the heat dissipation here. The first measure however increases it.
 
Thorsten R. said:
The first part of your suggestion is very good. I have my doubts regarding the second one. This is because the leads of the devices on a PCB are important for the cooling of the device. As is the connection of the leads to the soldering pads and are the strip lines. Especially with stabilizing devices in Pioneer amplifiers. And the epoxy would lessen the heat dissipation here. The first measure however increases it.
Click to expand...
It is standard practice in industry to stabilize repaired traces.
 
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