In article ,
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Watson A.Name \"Watt Sun - the Dark Remover\" wrote:



The resistor should never have been run at that close to its maximum
dissipation to begin with. That's a lack of what they call a
conservative design.

That's exactly right-and this story about "it worked right during
production testing" points up the fact that the price you pay for
misapplying a component is extended in-house testing designed at a
higher skill level than the usual application engineer possesses.

I worked for a small company that was owned by a conglomerate. The
conglomerate said that they'd never use any of our equipment that were
in a blue case. Which, since almost everything was in a blue case...

Anyway, we had problems with the 7805 regulators shutting down from
overtemp. They were mounted on the PCB with a small heatsink. So we
had to ECO them by adding a few inches of wire and bolting the 7805 to
the aluminum case, which soaked up plenty of heat. After that, no
more weird behavior.

--
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Anyway, we had problems with the 7805 regulators shutting down from
overtemp. They were mounted on the PCB with a small heatsink.

Hi all,
overheating should not be neglected. In my professional life I
encountered a device made by a famous company, which had a 7805 on a
heatsink, a processor and several customer chips inside a tightly
closed plastic box. All was O.K. at power-up. I was called for service
after two days. The device was hot and really did not work. I let it
cool down and all was O.K. again - for next two days. I was forced to
remove the top cover of the box forever. The device has been working
for several years now.
Proper cooling seems to be a must.

BR from Ivan OK1SIP

Anyway, we had problems with the 7805 regulators shutting down from
overtemp. They were mounted on the PCB with a small heatsink.

Hi all,
overheating should not be neglected. In my professional life I
encountered a device made by a famous company, which had a 7805 on a
heatsink, a processor and several customer chips inside a tightly
closed plastic box. All was O.K. at power-up. I was called for service
after two days. The device was hot and really did not work. I let it
cool down and all was O.K. again - for next two days. I was forced to
remove the top cover of the box forever. The device has been working
for several years now.
Proper cooling seems to be a must.

BR from Ivan OK1SIP

On 2003-11-26, Watson A.Name - Watt Sun, Dark Remover wrote:
I worked for a small company that was owned by a conglomerate. The
conglomerate said that they'd never use any of our equipment that were
in a blue case. Which, since almost everything was in a blue case...

Anyway, we had problems with the 7805 regulators shutting down from
overtemp. They were mounted on the PCB with a small heatsink. So we
had to ECO them by adding a few inches of wire and bolting the 7805 to
the aluminum case, which soaked up plenty of heat. After that, no
more weird behavior.

It wasn't WG Security Products, was it? Doesn't sound like it. A while
back I got a used video quad that they had made, and the 7805 was mounted
like that. Also, the 7805 was blown.

-- uns

On 2003-11-26, Watson A.Name - Watt Sun, Dark Remover wrote:
I worked for a small company that was owned by a conglomerate. The
conglomerate said that they'd never use any of our equipment that were
in a blue case. Which, since almost everything was in a blue case...

Anyway, we had problems with the 7805 regulators shutting down from
overtemp. They were mounted on the PCB with a small heatsink. So we
had to ECO them by adding a few inches of wire and bolting the 7805 to
the aluminum case, which soaked up plenty of heat. After that, no
more weird behavior.

It wasn't WG Security Products, was it? Doesn't sound like it. A while
back I got a used video quad that they had made, and the 7805 was mounted
like that. Also, the 7805 was blown.

-- uns