That could be good news. I assume the reg is still getting hot as well.
You now need to very carefully look at the output line from the regulator (because the manual we are working from isn't the same as yours) and be certain that it goes nowhere else that we don't know about. The manual we are using shows it goes only to pin 13 of that connector.
Also verify by continuity check that pin 13 is really and truly isolated electrically... it's a bit hard to tell in the picture. Be 100% sure.
Check the diode D3919 on the reg output and also the little 0.022uF cap.
If all that checks out then you could lift pin 3 of the reg (the output pin) and see if the reg still pulls the voltage down.
You now need to very carefully look at the output line from the regulator (because the manual we are working from isn't the same as yours) and be certain that it goes nowhere else that we don't know about. The manual we are using shows it goes only to pin 13 of that connector.
Also verify by continuity check that pin 13 is really and truly isolated electrically... it's a bit hard to tell in the picture. Be 100% sure.
Check the diode D3919 on the reg output and also the little 0.022uF cap.
If all that checks out then you could lift pin 3 of the reg (the output pin) and see if the reg still pulls the voltage down.
Yes still getting hot , my manual is on post 53 i looks only to be going to pin 13 .
checked pin continuity , also better photo ,,
D3919 is good C3916 measures 20.6 nf ?.
I had a bit of an issue lifting the output pin , it broke off ,
but now the psu voltage is staying up but the broken reg is getting hot quicker
checked pin continuity , also better photo ,,
D3919 is good C3916 measures 20.6 nf ?.
I had a bit of an issue lifting the output pin , it broke off ,
but now the psu voltage is staying up but the broken reg is getting hot quicker
So it is looking like the regulator is faulty. If its getting hot with the output pin snapped off I'd say it has to be duff.
I'm wondering if a 7805 would work as a test. There needs to be enough headroom (input voltage), say 7 volts or so. It might prove things.
Up to now then its looking promising.
I'm done for tonight... take it slowly if you try anything and check the pin outs if you do try a 7805.
I'm wondering if a 7805 would work as a test. There needs to be enough headroom (input voltage), say 7 volts or so. It might prove things.
Up to now then its looking promising.
I'm done for tonight... take it slowly if you try anything and check the pin outs if you do try a 7805.
The 7805 was just a quick idea to see if it worked OK and fixed the apparent short on the rail but you are probably going to need something more suitable. The one fitted is just a 5 volt reg but it has a low dropout voltage which means it regulates even if the input voltage is quite low.
There should be suitable equivalents available but I'd have to search the catalogues.
(and if you can get a 7805 locally then I'd still try one. If you have 7 volts or so on the input side then that should be enough. The 78L05 is a T092 package 100ma version)
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There should be suitable equivalents available but I'd have to search the catalogues.
(and if you can get a 7805 locally then I'd still try one. If you have 7 volts or so on the input side then that should be enough. The 78L05 is a T092 package 100ma version)
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All these parts often have loads of variations (just like good old 78 series ones). I'd say if it is the correct package then it will be fine. The DL1 bit seems to refer to the package outline which I think matches your board (but check).
Low Dropout NJM Regulator
Low Dropout NJM Regulator
It's getting there then hopefully 
I'll have a closer look tomorrow but if another reg is also pulling things down then the same applies, isolate the output of it to test it. Some of the regs might be switched (have an on/off function) so I'll take a look tomorrow.
If another reg is faulty then it sounds like something has zapped them rather than just a one off failure.
I'll have a closer look tomorrow but if another reg is also pulling things down then the same applies, isolate the output of it to test it. Some of the regs might be switched (have an on/off function) so I'll take a look tomorrow.
If another reg is faulty then it sounds like something has zapped them rather than just a one off failure.
That does seem fairly conclusive then. U3904 is a three terminal reg.
OK, so this now moves to a fault that doesn't quite fit the normal pattern. Why would two regs fail at the same time? We just don't know the answer to that. All you can do is replace that part as well and then take things from there.
The worry with any fault like this is whether or not there are going to be other issues further in such as being caused by a regulator 'spiking' on its output and damaging other parts.
Multiple failures in power supplies are often linked to transient events such as lightning damage and here the fault pattern is often illogical and random.
I can't remember if I asked this before but does this unit have a 'hidden past history'? such as eBay or do you know if it just failed in normal use.
OK, so this now moves to a fault that doesn't quite fit the normal pattern. Why would two regs fail at the same time? We just don't know the answer to that. All you can do is replace that part as well and then take things from there.
The worry with any fault like this is whether or not there are going to be other issues further in such as being caused by a regulator 'spiking' on its output and damaging other parts.
Multiple failures in power supplies are often linked to transient events such as lightning damage and here the fault pattern is often illogical and random.
I can't remember if I asked this before but does this unit have a 'hidden past history'? such as eBay
or do you know if it just failed in normal use.
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