ebay Phase Linear 700B rescue

NavLinear said:
Done. What kind of beer do you like? :occasion5:
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Cold! Actually I guess the last time I had a beer was around Christmas. My daughter's boyfriend gave me a couple boutique beers.
I used to drink quite a bit, but for health reasons I had to slow down. Actually stopped for about 4.5 years then went on a vacation with friends to Mexico and not drinking went out the window. I stopped for another couple of years, then only occasionally had a drink. In a couple of weeks I'm headed to Mexico with the same friends again, geez, that could be trouble.
 
Update, I finally received my 8 ohm test load in the mail and connected it to the right channel. I intended on doing a current sharing test. I drove the right channel to about 100 volts P/P (limit of my audio generator) and was going to measure the voltage drop on all of the output emitter resistors.

All was going well until two outputs shorted, one on each side of the right channel. I believe they over heated due to dried out heat sink compound, the stuff was like chalk.

I think its time to throw in the towel and start the White oak process.
 
100 volts P to P was a bit much for current sharing. 40 volts output at 200hz, then turn down the variac until there is a good clip, then measure...
 
They do that for the same reason that Pioneer has you set the current limiters at 8 ohms using a 4 ohm load, to keep the SOA away from an amp damaging event but still get an accurate pic of where the current limit needs to be set.
 
In other words, to generate the amount of current needed without the attending voltage....

In the PL current sharing test you output 40 volts at the amp outputs, then turn down the amp AC mains, creating a sag in the secondary volts while still keeping current high.....
 
Thanks Lee, I do not have a variac, the original service manual said that if you do not have a variac "if a variac is not available, drive the inputs such that the amplifier is well into clipping"

I guess on my amp with old dried up heat sink compound 100V p/p was too much.

What back plane board do I need from White Oak Rev A, or Rev B, or one of each?

email sent to White Oak requesting a quote for control board, driver, outputs, sil pads, and back plane boards.
 
The 700B backplanes are now Rev B ....they are symmetrical, one backplane kit...
 
Billboard said:
Thanks Lee, I do not have a variac, the original service manual said that if you do not have a variac "if a variac is not available, drive the inputs such that the amplifier is well into clipping"

I guess on my amp with old dried up heat sink compound 100V p/p was too much.

What back plane board do I need from White Oak Rev A, or Rev B, or one of each?

email sent to White Oak requesting a quote for control board, driver, outputs, sil pads, and back plane boards.
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Or you finally found your leakers.....same exact way I did on Tim's...
 
I cant imagine doing the factory short circuit test, drive the amp to 53 VRMS and short the output for 2 to 4 seconds then see if the amp resumes normal operation.

I guess that would smoke out some problem drivers and anything else that may be on the edge of failure.
 
You didn't read the test correct. Start at 0 volts output, at 20 hz, then slowly bring the variac output up to max. Notice that they didn't specify drive it at WHAT? input voltage and then only at 20 hz. So if you drive the inputs at just enough to register a short, you certainly aren't at 58 volts output with the output shorted. Again, an attempt to check an amplifier feature without damaging said amplifier in the process....
 
Actually between 2 service manuals, Ser I and a B, the B shows drive the inputs at .25 volts, but the rest the same..
 
There's a very good reason they don't drive the inputs at 20,000hz, and use 20 hz....
 
My manual is a bit more harsh

Section 5-7

Short Circuit Test: Drive the left channel with a 200 Hz signal to an output level of 53VRMS . Now short the output terminals with a jumper wire for 2 to 4 seconds. Remove the jumper wire and verify that the amplifier resumes normal operation. Repeat for the right channel.
 
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