Transistor on 700B

[66stanger]

Hi,

What are sound differences between XPL609, MJ21196 or 15004 ?

Thank you,

Best regards,

 

[laatsch55]

The XPL-909's were originally developed for automotive ignition systems, the 15004 is an underated audio part, the MJ21196's are a DEDICATED audio design with exceptional SOA and ultra low noise and distortion figures.



BOTTOM LINE 21196's.....Period......

 

[66stanger]

ok, thank for your reply.
And about SJ2741, what is the best ?
I've the RCA...

Thank you !

 

[premiumplus]

RCA, all the way.

 

[laatsch55]

As above RCA-410's...

 

[66stanger]

MJ21196 vs MJ21194

Hi,

OK about the RCA410.
Do you know the equivalence ?

About MJ, the MJ21194 like better than the MJ21196.
On the datasheet, the maximum ratings are the same but the curves are better on '94 version...

Some threads about it ???

Thank you !

 

[wattsabundant]

On the quasi comp amps, the RCA 410 should not be replaced with the MJ21196. This sets up a condition that causes oscillations. Gepetto has written about this elsewhere. Fortunately the RCA 410's rarely fail and should be reused.

 

[gadget73]

I don't know how kosher it is, but I used XPL909's to replace a failed RCA410 on a PL700-II I rebuilt. I had the pile of them that I had removed when they got replaced with the MJ21196. After fixing some problems on the driver board that were not related, it was stable, did not oscillate, and passed all of the service manual tests with flying colors. Initially it had problems, but I chased them back to some failed resistors and I think one bad diode on the driver board. The resistors in the Zoebel network were also off value.

I killed the driver with a slipped test probe. One had been replaced with an actual RCA 410, and one was some random ECG part. All four are now XPL-909 transistors.


If you need one, I believe I have one or two good RCA 410 transistors left over from that project, and a number of XPL-909's as well.

 

[wattsabundant]

...I killed the driver with a slipped test probe. One had been replaced with an actual RCA 410, and one was some random ECG part. All four are now XPL-909 transistors...

The checkout procedure has you check load sharing by measuring voltage drop across emitter resistors. Extreme care must be taken as it is very easy to slip up. I use mini grabbers so I don't have to hold the probe in place while checking the reading.

 

[laatsch55]

The checkout procedure has you check load sharing by measuring voltage drop across emitter resistors. Extreme care must be taken as it is very easy to slip up. I use mini grabbers so I don't have to hold the probe in place while checking the reading.

That's the gospel right there...

 

[gadget73]

I was probing something on the driver board. I forget what I was looking for exactly, but I created a different problem in the process.

I used my grabbers to do the current sharing test. I don't use them terribly often, but they are exactly the right tool for that job. I used them to set the bias too.

 

[laatsch55]

I rarely take my mini's off anymore...

 

[gadget73]

Mine aren't especially small. Its the set you get in the Fluke test lead kit. They are too big to get into a lot of places. They only work on my digital meter anyway, which is not what I use most of the time. I do some RF work, and my cheap digital meter measures in ancient Egyptian around that stuff. I use the RCA VTVM or the Simpson 260 most of the time since they actually give me readings that modern man can interpret.

 

[laatsch55]

Cut my eye teeth on a 260 and still have 3 of Em . Pomona makes a nice set of minis for 18.00

 

[Gepetto]

Hi,


About MJ, the MJ21194 like better than the MJ21196.
On the datasheet, the maximum ratings are the same but the curves are better on '94 version...

Thank you !

SOA chart is better for the 21195/96 which is why we use them for these applications. That is the critical chart.