I am new to the hobby. Can the experts here help me to identify the diode/component "69A" highlighted in the attached photo?
It is in a linear power supply, sitting next to 2 IN4004s. I was doing some reflow yesterday and this thing suddenly turned transparent, because of the heat I presummed, and it horrified me.
Thank you.
It is in a linear power supply, sitting next to 2 IN4004s. I was doing some reflow yesterday and this thing suddenly turned transparent, because of the heat I presummed, and it horrified me.
Thank you.
Attachments
I suspect there are more numbers hidden under it. As in something like 1N 52 69A. I suspect it is a zener diode. A 1N5269A would be an 87v 1/2 watt zener if my guess is right. It doesn't look clear to me, but it is a glass diode.
I would say Zener as well.
Does the supply still work correctly? If it does then measure the voltage across the part and see if that gives a clue. You might just have burned the paint off.
When soldering or reflowing something like these then using a small croc clip as a heat shunt clipped onto the component leg can give a lot of protection. Parts like that where there is a lot of copper around it need a lot of heat... a hot iron with a large tip and two or three seconds is all that is needed to reflow a joint like that.
Does the supply still work correctly? If it does then measure the voltage across the part and see if that gives a clue. You might just have burned the paint off.
When soldering or reflowing something like these then using a small croc clip as a heat shunt clipped onto the component leg can give a lot of protection. Parts like that where there is a lot of copper around it need a lot of heat... a hot iron with a large tip and two or three seconds is all that is needed to reflow a joint like that.
The amp seems to be working alright. I measured a voltage of 15.8V across the diode. Its slightly warm to the touch. So is it safe to leave it there?
It probably is OK, yes. Parts are pretty rugged and maximum junctions temperatures allowable are higher than you might think.
If circuit information was available we would be able to be more certain what it was but it really does look like a glass Zener.
If circuit information was available we would be able to be more certain what it was but it really does look like a glass Zener.
Thank you all. I will leave it as is. Just surprised that the paint could evaporate so easily. Right before my eyes.
It is probably a voltage regulator in the main supply.
Just check the DC to speakers.
If okay, enjoy the music.
Just check the DC to speakers.
If okay, enjoy the music.
Me too. It must have been soldered in? So is your solder technique so much more brutal than the factory's technique?
Reflowing existing solder is a bad idea, it does not give a good joint. If the original solder is lead free, the melting point is high and can cause damage
Its not that simple - you can reflow lead-free solder perfectly well if its eutectic (the 4% silver sort), but you always need plenty of flux for reflow to keep oxidation at bay (especially at the higher temperatures of lead-free solder).
The cheap lead-free solder is not eutectic and thus not really usable for hand soldering or rework, its designed for machine soldering AFIACT.
A eutectic alloy has a single melting point and doesn't go pasty.
Reworking on an unknown solder sort requires the old solder be removed as much as possible as a mix of two
different solders is very unlikely to be a workable eutectic.
Dictionary definition of eutectic :
relating to or denoting a mixture of substances (in fixed proportions) that melts and freezes at a single temperature that is lower than the melting points of the separate constituents or of any other mixture of them.
"the eutectic mixture melts at 183°C"
relating to or denoting a mixture of substances (in fixed proportions) that melts and freezes at a single temperature that is lower than the melting points of the separate constituents or of any other mixture of them.
"the eutectic mixture melts at 183°C"
Judging from the type of components I see and the presumed age of such, I seriously doubt that the original solder is lead-free.
Zener diodes can take a *lot* of heat before dying. The usual failure mode is for the diode to turn the PCB to charcoal or cause oxidation of the joint. I don’t see either happening here. Just one overheat event from a soldering iron won’t do anything to it. I burn my fingers with them when salvaging off PCBs all the time and they still work.
Zener diodes can take a *lot* of heat before dying. The usual failure mode is for the diode to turn the PCB to charcoal or cause oxidation of the joint. I don’t see either happening here. Just one overheat event from a soldering iron won’t do anything to it. I burn my fingers with them when salvaging off PCBs all the time and they still work.
Working fine. Since it almost completely burned off the paintwork on the diode, the temp must have been high. I've seen many zener in clear glass shell. Haven't seen a painted one until this. Just by looking at the size next to a 1N4004, can you tell the power rating? Voltage difference is 14.8 from start to 15.8V.
Since it is likely a 15 volt zener (if they are damaged somehow, they go open or short - not change voltage), what part number is both 15 volt and has the numbers “69” in it? That would end up telling you the wattage. 22 volt is too far off, so that’s probably not it. Wouldn’t be a 1 watt, because those are 1N4744 and have a sharper knee (less voltage variation), and they’re bigger around and “stubby”.
I've seen painted glass-body diodes like that before. Sure makes it easier to read the part number than printing on clear glass.