This site has some cool stuff - it might help as what a transistor does in the audio world as things gets complicated quickly. The load complicates it even more.
http://www.electronics-tutorials.ws/transistor/tran_1.html
New Record For A "HOT" PL 400 Power Transformer,,
- Thread starter laatsch55
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This site has some cool stuff - it might help as what a transistor does in the audio world as things gets complicated quickly. The load complicates it even more.
http://www.electronics-tutorials.ws/transistor/tran_1.html
SOA Charts
Hi Lee
Look at page 4, bottom for the important chart.
If you follow the 200V Vce line up from the bottom, you will see that the best transitor we are all using can only survive for 1 second at 800mA with 200V across it and for 10 msec (1/2 the time of a 50Hz signal) at 2.5A.
So to get any serious amps out of the amp at these sustaining voltages, you have to parallel up transistors. Remember also that in the PL700B, there is always, on average, at least 100V across each device.
Also note that the words to the right of the chart bring in the third element of second breakdown, temperature. This chart is the behavior of the junction at 200C peak temperature, which cannot be sustained either. High Tcase from running the amp very hard will rob from the available SOA current and voltages shown on this chart.
This chart give you the explanation of why amps die when they are pushed at very high volume levels (Vce approaching clipping on a repeated basis) for long periods of time (allowing the Tcase to heat up a lot). Poof!!View attachment MJ21195-D.pdf
Hi Lee
Look at page 4, bottom for the important chart.
If you follow the 200V Vce line up from the bottom, you will see that the best transitor we are all using can only survive for 1 second at 800mA with 200V across it and for 10 msec (1/2 the time of a 50Hz signal) at 2.5A.
So to get any serious amps out of the amp at these sustaining voltages, you have to parallel up transistors. Remember also that in the PL700B, there is always, on average, at least 100V across each device.
Also note that the words to the right of the chart bring in the third element of second breakdown, temperature. This chart is the behavior of the junction at 200C peak temperature, which cannot be sustained either. High Tcase from running the amp very hard will rob from the available SOA current and voltages shown on this chart.
This chart give you the explanation of why amps die when they are pushed at very high volume levels (Vce approaching clipping on a repeated basis) for long periods of time (allowing the Tcase to heat up a lot). Poof!!View attachment MJ21195-D.pdf
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4 amps at 100 volts for 50ms. Makin sense now Joe.
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Could also explain why the Spec 2 has lasted this long. I was more concerned with voice coil overheating, and would shut things down for 5-10 minutes after one or two songs after Mach 8. I figured the Spec 2 would take care of itself, and it did for 34 years. 150.00 on parts and she was off and running again.
It is more like 3.5A for 50 msec at 100V Vce
BTW the 555/600's are not as robust as the MJ21196 in the SOA department.
Nobody on earth makes semiconductors as robust as Moto/ON (except maybe IR in the MOSFET department).
Nobody on earth makes semiconductors as robust as Moto/ON (except maybe IR in the MOSFET department).
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Is an MJ410 a rebadged RCA or original Motorola part??
AFAIK Lee, those were original Moto parts. Perhaps modeled after the RCA410 but not a die licensing deal.
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OK, thanks again.