Mark goes at it again... just bought a PL700/II!

Are there any transistor covers out there for a 700 Series Two that anyone knows of?
Or... just keep my fingers away from the back when it’s turned on?
 
They create a heat envelope and, although I never took measurements, I'll bet it raises the temp 10-20 degrees. The heat sinks would be the only way to wick that heat out of there and it is really inefficient compared to using a small fan to shooooo it awayyyyyyy
 
Well
WOPL Sniffer said:
They create a heat envelope and, although I never took measurements, I'll bet it raises the temp 10-20 degrees. The heat sinks would be the only way to wick that heat out of there and it is really inefficient compared to using a small fan to shooooo it awayyyyyyy
Click to expand...
Well, then...
Nevermind!
 
I've taken temp readings with a thermocouple and infrared camera. When using the thermocouple I looked at case temperatures on all outputs to try to discern the effect of different silpads. The results were inconclusive. I recently took some infrared readings that showed even heat distribution across the heatinks and very little difference between case temperatures and the heatsinks. Based on this I don't think the covers make much difference. That said I don't install the covers.

I also did a test on a 400 with a member whose user name escapes me at the moment. He shot a video that someday will probably get uploaded. The intent was to show that amplifier failure is rarely dramatic. I pulled 2 of the 3 outputs on one channel and drove the amp at 70 watts for maximum temperature until it failed. We repeated this several times. To my surprise case temperature of the single output approached 200 degrees C. Yes 200 centrigrate. I expected failure in the 125-150 C range.

We also used a knife switch from collector to emitter on the positive rail to simulate ouput transistor failure and trigger the relay board. Attached was a cheap sacrificial speaker. I'm guessing we did this test 6 times or so. A couple times it took out a transistor in the negative rail. The speaker survived every time and the relay was not damaged either.
 
For me, it's just too easy to touch one the wrong way, and the next thing you know the cover itself is shorting right to the collector of either end of the row. I prefer removing them.. too easy to physically push into one when moving amps around.
 
Keep fingers away and buy the AC Infinity fan system......sounds like that is the conclusion!


That's what I have done..........
 
Mark,

What was the item number or description for the rack you ordered from Amazon? I can't find it.... I'd like one taller to fit more amps, but I like the look. Good find!!
 
Thanks Mark....I am researching and may buy the same rack. Any advice?? Did you order the shelves for the rack?
 
ksrigg said:
Thanks Mark....I am researching and may buy the same rack. Any advice?? Did you order the shelves for the rack?
Click to expand...
Didn’t order the shelves yet. Nor the power strip or the exhaust fan.
It’s always the options, right?
 
A little Q about the WO cylon meters:

In the case of overdriving the amp, do the last three segments flash?

Just reading the original user and service manuals, an overdrive situation caused temporary shutdown and the last three segments flashed.

Of course, all the WO upgrades pretty much invalidate most of the original info in those manuals.
 
Editing two videos for upload, should be finished by Friday...
 
Did you determine if the temporary shutdowns were heat related? In other words, caused by the thermal switches on the backplane? Mine did that once... Luckily, by reflex, I turned the amp down. Because when the thermal switches cooled a bit, the amp came back on with a vengeance!
 
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