Had power outage now Astron RS-50A not working right

[Eastside]

The power was flickering and then went out....today I turned on my radio and the ps does not have the poop to run it....any ideas what is wrong?

 

[VA3ES]

The power was flickering and then went out....today I turned on my radio and the ps does not have the poop to run it....any ideas what is wrong?

Almost sounds like blown pass transistors. Measure the output. If it's around 13.6 VDC or so, then it's your pass transistors which have blown. If they're what I think they are (2N3772), they're relatively cheap to replace.

 

[Eastside]

Almost sounds like blown pass transistors. Measure the output. If it's around 13.6 VDC or so, then it's your pass transistors which have blown. If they're what I think they are (2N3772), they're relatively cheap to replace.

Where can I order them?

 

[Eastside]

Its putting out 13.8

 

[wavrider]

Digikey has them.

 

[Eastside]

Digikey has them.

Thanks...appreciate it.

 

[RatsoW8]

Almost sounds like blown pass transistors. Measure the output. If it's around 13.6 VDC or so, then it's your pass transistors which have blown. If they're what I think they are (2N3772), they're relatively cheap to replace.

So, how do you know it's the PS and not the radio? Did you try another power source?

 

[Eastside]

So, how do you know it's the PS and not the radio? Did you try another power source?

Yeah....I got a backup PS.

 

[VA3ES]

Check the numbers on those transistors. They're probably either 2N3771, or 2N3772. but check to make sure what you've got.

They're probably easy to remove and mounted on sockets. If you know how to check transistors, check to see if they're shorted (or open, but more likely shorted).

If not... get a qualified technician to help you.

 

[Eastside]

Check the numbers on those transistors. They're probably either 2N3771, or 2N3772. but check to make sure what you've got.

They're probably easy to remove and mounted on sockets. If you know how to check transistors, check to see if they're shorted (or open, but more likely shorted).

If not... get a qualified technician to help you.

Yeah...they look like plug n play....and not expensive....hope that fixes it....would be a major bummer if it is ruined by that power outage.

 

[VA3ES]

Yeah...they look like plug n play....and not expensive....hope that fixes it....would be a major bummer if it is ruined by that power outage.

Astron's are notorious for certain failure modes. Generally, if your voltage is OK at the output, but you can't get current, it's the pass transistors. Occasionally, a component on the regulator board will fail and produce the same result. Check the pass transistors first. If they are good, I would Google "Astron power supply failure modes".

 

[Shockwave]

In 99% of cases when a pass transistor fails it will either short, or open. Having 13.6 volts of output with little to no current is an indication neither has happened to the pass transistors. The lack of current is coming from the IC regulator on the board with part number LM-723. Astron mounts this part in a socket since it's prone to failure. Nearly every Astron with these symptoms comes back to life after changing this $1 part.

 

[Eastside]

Astron's are notorious for certain failure modes. Generally, if your voltage is OK at the output, but you can't get current, it's the pass transistors. Occasionally, a component on the regulator board will fail and produce the same result. Check the pass transistors first. If they are good, I would Google "Astron power supply failure modes".

Thanks for the good info.....yep it will not take a load.

 

[Eastside]

In 99% of cases when a pass transistor fails it will either short, or open. Having 13.6 volts of output with little to no current is an indication neither has happened to the pass transistors. The lack of current is coming from the IC regulator on the board with part number LM-723. Astron mounts this part in a socket since it's prone to failure. Nearly every Astron with these symptoms comes back to life after changing this $1 part.

It has 13.8 but it will not take a load.

 

[VA3ES]

In 99% of cases when a pass transistor fails it will either short, or open. Having 13.6 volts of output with little to no current is an indication neither has happened to the pass transistors. The lack of current is coming from the IC regulator on the board with part number LM-723. Astron mounts this part in a socket since it's prone to failure. Nearly every Astron with these symptoms comes back to life after changing this $1 part.

Very good point, though I have seen shorted pass transistors that passed the 13.8. So, if the pass transistors show good, next step is replacement of the LM-723. I can't think of any other passive components that would fail under a power glitch.

A failed LM-723 is one of the common failure modes. and since changing out the '723 is easier than changing out the pass transistors, I would check the '723 first. Hopefully, it will be that simple. All those components are extremely easy to get. You could even try Radio Shack (brick 'n mortar, or on-line).