PL 700 version

[timfountain]

Would somebody please open the manual I posted (#11) and tell me if it's legible?

Apologies, I missed the later schematic in the PDF. This one is legible. Thanks again.

 

[timfountain]

Ok, last question. I think I've narrowed the issue down to a bad SJ2741 on the left channel. Now the question is where can I find a repalcement? Seems like they are rarer than hens teeth. It theyre really unobtainium, what are my alternative options? I don't think the MJ15024 is an option on the early PL0171 boards.... Is the MJ410 a possibility? Anything else? I of course will get 2 of them so they are matched pre-drivers.

 

[laatsch55]

RCA 410'S

 

[VSAT88]

I did, but unfortunately the copy is no good. It's illegible. Not blaming you, but it's not useful. See this as an example of how it renders for me...

View attachment 81327

ETA - Just looked at page 10, maybe this will work... Thanks!

Don't talk shit about Bobs handwriting we may all agree.

 

[timfountain]

RCA 410'S

What do you think about MJE423's? 410's seem to be hard to find, but ISC still makes the 423. The datasheets look like they have the same HFE, Same Ft, same pinout, only the 423 has a higher Vceo, which is not bad thing.

 

[Gepetto]

What do you think about MJE423's? 410's seem to be hard to find, but ISC still makes the 423. The datasheets look like they have the same HFE, Same Ft, same pinout, only the 423 has a higher Vceo, which is not bad thing.

I think you mean MJ not MJE

 

[wattsabundant]

Ok, last question. I think I've narrowed the issue down to a bad SJ2741 on the left channel. Now the question is where can I find a repalcement? Seems like they are rarer than hens teeth. It theyre really unobtainium, what are my alternative options? I don't think the MJ15024 is an option on the early PL0171 boards.... Is the MJ410 a possibility? Anything else? I of course will get 2 of them so they are matched pre-drivers.

What's the criteria for a failure? Those drivers usually only fail when outputs go. See the manual for options on drivers. The MJ423 would be an option if you can test the channel with a scope to verify there is no high frequency oscillation.

 

[mlucitt]

RCA 410 Driver Transistors are the consensus here for ruggedness and stability in the Phase Linear Power Amplifier driver position. They are slow, so oscillation is not an issue. The role of the RCA 410 is to set up the bias and drive parameters for the Output Transistors that actually do the heavy lifting (high current) amplification.
I have many used (and tested good) RCA 410 transistors. PM me if you would like a matched pair. Phase Linear did no matching of the Driver or Output Transistors.