Aw poop! PL400 fried!

MarkWComer

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Replaced PS fuses today, went to do a DBT startup but pushed the switch the wrong way, so it went into a full current startup.

The odor of ozone and burned components came afterward...

So... Where do I go from here?



 
roccus

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wow sorry to see this... it just blew a fuse one day and this is the end result?
 
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I don't know if either Lee or Joe have test beds or fixtures for these boards but if they do I would pull that board and ask to send it to one of them.....
 
MarkWComer

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Pulled the MJ21195G that corresponds to the burned emitter resistor...

Base to emitter shows almost straight short- .5Ω
Same thing with base to collector (regardless of DVM polarity)
Emitter to collector also shows the same result.

Looks like a transistor failed...
 
roccus

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If transistor failed and blew the fuse before it burned every thing up wonder why it didn't just blow the fuse again?
 
MarkWComer

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roccus said:
If transistor failed and blew the fuse before it burned every thing up wonder why it didn't just blow the fuse again?
Click to expand...
So do I! Previous fuses were rated 35v, new fuses rated 250v. Hmmm...
 
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Vynuladikt said:
voltage rating should not be a factor, only current and speed rating e.g. fast or slow blo
Click to expand...
Yes- just learned that myself this week. They're 8a fast blo. Apparently they're not-fast-enuff blo!

Consulting the BOM, getting a parts order up, and training myself not to throw the switch in the wrong direction.
 
roccus

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8 amp fuse is what factory fuse should be.... wopls are no longer factory I wonder if we should be dropping the 8 amp fuse to a lower amperage fuse for wopl builds? Guess Joe would need to input on that
 
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Rails should be 5 amp, although a lot of 8 s are run. Mark , the short took out the fuse, when you put in a new one the additional time of current flow allowed the additional damage...
 
MarkWComer

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laatsch55 said:
Rails should be 5 amp, although a lot of 8 s are run. Mark , the short took out the fuse, when you put in a new one the additional time of current flow allowed the additional damage...
Click to expand...
Duly noted- add 5 amp fuses to the parts order. I went with what was indicated on the chassis cover.

Still can't believe I'm such a bonehead to flip the switch in the opposite direction. Shit...
 
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stuwee said:
I'm very sorry to hear this Mark.

I'm not understanding throwing the switch the wrong way part, can anyone explain that to us dummies? THXS!
Click to expand...
I think he built a dim bulb tester with a switch to bipass the bulb
 
MarkWComer

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stuwee said:
I'm very sorry to hear this Mark.

I'm not understanding throwing the switch the wrong way part, can anyone explain that to us dummies? THXS!
Click to expand...
I made my DBT device from a wall outlet, a wall receptacle box, and a SPDT toggle switch. I can use any standard table lamp as the light bulb portion of the device. The toggle switch will either put the lamp in series with the device to be tested or provide a straight connection to AC supply.

<iframe width="560" height="315" src="https://www.youtube.com/embed/83WSNeOsFJs" frameborder="0" allowfullscreen></iframe>
 
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Mark, I did something similar to mine but made it so I had to physically unplug the amp from one socket and plug it in to the other socket...
 
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laatsch55 said:
Rails should be 5 amp, although a lot of 8 s are run. Mark , the short took out the fuse, when you put in a new one the additional time of current flow allowed the additional damage...
Click to expand...
And this is just a guess Mark, but I have done the same thing when not checking to see if the fuse "went nuklar"....always a bad sign....
 
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