AGW Power Supply

[electricity_bill]

View attachment 302603Hello
I have an ancient 12V power supply made by AGW. It has has been very reliable for many years but now the red overload light is lit constantly and there is very little voltage output. I have had a look at the circuit board and there is nothing obvious to me. Any ideas?

 

[PhilP]

Probably an output transistor has failed short-circuit?

Is it a single, or the twin PE144?

I assume you have disconnected everything from the supply, and looked for odd, stray 'whiskers' causing a short somewhere?

PhilP

 

[electricity_bill]

Probably an output transistor has failed short-circuit?

Is it a single, or the twin PE144?

I assume you have disconnected everything from the supply, and looked for odd, stray 'whiskers' causing a short somewhere?

PhilP

It is a single and I have had a good look to no avail. Is the output transistor the one that was bolted to the frame? - bottom left in the picture
Bill

 

[PhilP]

It is a single and I have had a good look to no avail. Is the output transistor the one that was bolted to the frame? - bottom left in the picture
Bill

Yes, this is the one..

If you make sure you know how to connect it back up, you can remove it from the board, and do a crude test with a meter..

It should not be too onerous to get a replacement. - This is where we lament the passing of Maplins..

PhilP

 

[Greg Elmassian]

Youch! Almost all of the soldered connections could be touched up, and the flux cleaned off... has that board been worked on since it left the "factory"?

 

[electricity_bill]

It is a single and I have had a good look to no avail. Is the output transistor the one that was bolted to the frame? - bottom left in the picture
Bill

Yes, this is the one..

If you make sure you know how to connect it back up, you can remove it from the board, and do a crude test with a meter..

It should not be too onerous to get a replacement. - This is where we lament the passing of Maplins..

PhilP

Please tell me about the crude test.

 

[Greg Elmassian]

https://vetco.net/blog/test-a-transistor-with-a-multimeter/2017-05-04-12-25-37-07

Greg

 

[PhilP]

Nice one..
Greg beat me to it..

PhilP

 

[Greg Elmassian]

Quick Draw McGaw here.... just be careful I don't morph into El Kabong (wikipedia is your friend)....

Greg

 

[PhilP]

Quick Draw McGaw here.... just be careful I don't morph into El Kabong (wikipedia is your friend)....

Greg

Quick Draw McGraw (correct spelling) don't know about El Kabong..
I may not be old enough? - Or at least, no access to TV..

PhilP

 

[Greg Elmassian]

Hi alter ego, wore a mask, and knocked out the bad guys by hitting them over the head with an acoustic guitar

 

[Eaglecliff]

Yes, this is the one..

If you make sure you know how to connect it back up, you can remove it from the board, and do a crude test with a meter..

It should not be too onerous to get a replacement. - This is where we lament the passing of Maplins..

PhilP

Maplins? Sob, sob...