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ASP34-2 - Looking a bit burnt

Posted: Sat Nov 17, 2018 8:50 pm
by Icky
Popped open my STE to recap the PSU and got drawn to the large metal film resistor in the centre of the PSU. The resistor and pcb area looks a bit burnt.

Although the PSU is operating I may do the same as the SR98 and replace the metal film resistors.

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IMG_3293 (1).png (1.13 MiB) Viewed 1764 times

Re: ASP34-2 - Looking a bit burnt

Posted: Sat Nov 17, 2018 8:54 pm
by Maeke
clearly the resistor heated a little bit too much, you should check it.

Re: ASP34-2 - Looking a bit burnt

Posted: Sat Nov 17, 2018 9:01 pm
by PaulJ
Icky wrote:
Sat Nov 17, 2018 8:50 pm
Popped open my STE to recap the PSU and got drawn to the large metal film resistor in the centre of the PSU. The resistor and pcb area looks a bit burnt.

Although the PSU is operating I may do the same as the SR98 and replace the metal film resistors.


IMG_3293 (1).png
Icky not to worry.. think it has resister envy.. It wants new resisters just like the other supply. :) :) :)

Re: ASP34-2 - Looking a bit burnt

Posted: Sat Nov 17, 2018 9:08 pm
by Icky
Maeke wrote:
Sat Nov 17, 2018 8:54 pm
clearly the resistor heated a little bit too much, you should check it.
Absolutely - I intend to replace it.

Re: ASP34-2 - Looking a bit burnt

Posted: Sat Nov 17, 2018 9:09 pm
by Icky
PaulJ wrote:
Sat Nov 17, 2018 9:01 pm
Icky not to worry.. think it has resister envy.. It wants new resisters just like the other supply. :) :) :)
I know. I think it saw the other one and thought how do I get new resistors.

Re: ASP34-2 - Looking a bit burnt

Posted: Sat Nov 17, 2018 9:09 pm
by PhilC
Jeff's revenge.

Got to do an ASP34 myself soon, not quite so sunburnt though.

Re: ASP34-2 - Looking a bit burnt

Posted: Sun Nov 18, 2018 9:16 am
by rubber_jonnie
I smell magic smoke....

How does the underside look from a heat perspective? Hopfully the tracks are undamaged and you can just replace the parts.

Re: ASP34-2 - Looking a bit burnt

Posted: Sun Nov 18, 2018 11:08 am
by exxos
Looks like that psu must have been running a really really long time to get in that state. Its not that uncommon to see things like that. The resistors just get so got over time they start to burn, and burn the PCB as well. The resistor could actually be fine still, though always best to change parts which look burnt anyway.

Re: ASP34-2 - Looking a bit burnt

Posted: Sun Nov 18, 2018 3:08 pm
by Icky
rubber_jonnie wrote:
Sun Nov 18, 2018 9:16 am
I smell magic smoke....

How does the underside look from a heat perspective? Hopfully the tracks are undamaged and you can just replace the parts.
Not so bad underneath. A bit scorched but tracks are intact. Looking at the side of the transformer next to the resistor that is a bit scorched too.

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IMG_3295.png (778.58 KiB) Viewed 1710 times

Re: ASP34-2 - Looking a bit burnt

Posted: Sun Nov 18, 2018 5:06 pm
by rubber_jonnie
Looks like it's been left running for long periods, my only concern would be that the phenolic PCB could break down and fail and take the tracks with it, as under heat it can go that way. I have seen a lot worse though! (My Uncle was a TV repairman back in the days of valves and CRTs, and phenolic PCBs were quite common)