Diffferent techniques in troubleshooting

[Tim R]

On Saturday, January 2, 2016 at 2:04:06 AM UTC-5, jurb...@gmail.com wrote:

"Another unrelated problem. You being an engineer will enjoy this >one. The city has a water leak. They are not sure where the leak is. >They can not dig up a whole city block to find it so they use a >clever trick. They put two microphones about 50 feet apart where the >leak seems to be. Then then record the random sound of water hissing >out of the pipe. The two microphones are wired to left and right >channel of the recorder. By adjusting the time delay of the right or >left microphone they can find the sweet spot where the random noise >from one microphone matches the random noise of the other >microphone. Once the delay is know they know where the leak is >within 1 or 2 feet. That is a clever trick. "

HA, HAHAHAHAHAH

HydroTDR

Hah, I can top that one.

We had a power outage, traced to a break somewhere in an underground line. It was one of those ancient coaxial feeders, and it ran a good quarter mile through the woods, maybe more, it's been a while. How to find the break?

We hired this specialist with a thumper, which is a pulsed high voltage DC. It makes a noise like a gunshot when the arc jumps the gap. You walk the route of the line (which you never know exactly because your drawings are always a little sketchy) and listen.

Usually this works. Not this time - it arced for a while, then somehow the arc welded the break back together. No more pulses, no way to find the spot, we just turned the power back on and let it go.

 

[John Heath]

On Saturday, January 2, 2016 at 10:14:26 AM UTC-5, Tim R wrote:

On Saturday, January 2, 2016 at 2:04:06 AM UTC-5, jurb...@gmail.com wrote:
"Another unrelated problem. You being an engineer will enjoy this >one.. The city has a water leak. They are not sure where the leak is. >They can not dig up a whole city block to find it so they use a >clever trick. They put two microphones about 50 feet apart where the >leak seems to be. Then then record the random sound of water hissing >out of the pipe. The two microphones are wired to left and right >channel of the recorder. By adjusting the time delay of the right or >left microphone they can find the sweet spot where the random noise >from one microphone matches the random noise of the other >microphone. Once the delay is know they know where the leak is >within 1 or 2 feet. That is a clever trick. "

HA, HAHAHAHAHAH

HydroTDR

Hah, I can top that one.

We had a power outage, traced to a break somewhere in an underground line.. It was one of those ancient coaxial feeders, and it ran a good quarter mile through the woods, maybe more, it's been a while. How to find the break?

We hired this specialist with a thumper, which is a pulsed high voltage DC. It makes a noise like a gunshot when the arc jumps the gap. You walk the route of the line (which you never know exactly because your drawings are always a little sketchy) and listen.

Usually this works. Not this time - it arced for a while, then somehow the arc welded the break back together. No more pulses, no way to find the spot, we just turned the power back on and let it go.

Is the glass half empty or is the glass half full ? The way I see it you repaired the fault by sending a large EM pulse down the line knowing well that this would weld the two wires together therefore fixing the problem. That is the way I would write up the repair report.

 

[pfjw@aol.com]

For me, it is purely a hobby, with the occasional household appliance or vehicular item intruding on occasion. So 'production' is not an issue, and unless I see my worth, as it were, at very little, spending 12 hours and $20 in parts restoring a pre WW2 Hallicrafters ot 5 hours & $10 on a Dynaco ST120 is a fool's game were it not a hobby. But, as therapy, and as a source of quiet satisfaction, it is unsurpassed.

I tend to be fairly methodical, diagnostics, the repair based on same. Then about a 12-hour burn to make sure whatever it is is actually ready for polite society. No beancounters, no cost limits - a 'bulk' purchase might be 100 very common-value caps, or 20 common transistors, which might last a couple of years.

Peter Wieck
Melrose Park, PA

 

[Ron D.]

The st120 is an interesting beast. I did repair one in the 80's AFTER someone made swiss cheese out of it.

 

[pfjw@aol.com]

On Sunday, January 3, 2016 at 8:24:33 PM UTC-5, Ron D. wrote:
> The st120 is an interesting beast. I did repair one in the 80's AFTER someone made swiss cheese out of it.

Yeah - "interesting" is a mild descriptive of a beast that can range from a purring kitten to a rabid wolverine in its behavior. I have three examples in my immediate possession - not one from the same lot or with matching boards...


Peter Wieck
Melrose Park, PA

 

[Mark Zacharias]

<pfjw@aol.com> wrote in message
news:b32070d3-a677-4290-a36c-97c09439d778@googlegroups.com...

On Sunday, January 3, 2016 at 8:24:33 PM UTC-5, Ron D. wrote:
The st120 is an interesting beast. I did repair one in the 80's AFTER
someone made swiss cheese out of it.

Yeah - "interesting" is a mild descriptive of a beast that can range from
a purring kitten to a rabid wolverine in its behavior. I have three
examples in my immediate possession - not one from the same lot or with
matching boards...


Peter Wieck
Melrose Park, PA

ST-120's.

They're like Harley Davidson motorcycles.

If you love them, if you can fix them, if you don't mind the smell of
carburetor cleaner and the oil stains on your living room floor,

go for it!


Mark Z.