MPSA42 is a To92 package.
Many To92 packaged devices omit some of the coding due to lack of space.
Does your A42 LOOK LIKE the same device?
Many To92 packaged devices omit some of the coding due to lack of space.
Does your A42 LOOK LIKE the same device?
There are of course 2SA42, germanium, 2SC42 silicon and others to contend with. Japanese semiconductor factories only put the latter part of the name on as they are possessed with hfe figures for their own reasons. For instance *a32-120 or a or c etc.
Last edited:
A42/92 are very high voltage.
Many parameters are compromised to achieve HV ability.
That is typical of just about all HV transistors.
If you need better parameters, then choose 160Vce0, or 100Vce0, or 60Vce0, or 30Vce0 devices.
If you need 300Vce0 then you have few choices.
Many parameters are compromised to achieve HV ability.
That is typical of just about all HV transistors.
If you need better parameters, then choose 160Vce0, or 100Vce0, or 60Vce0, or 30Vce0 devices.
If you need 300Vce0 then you have few choices.
what are you trying to build by the way?
can you post pictures of the circuit?
so we are in a better place to help....
Per schematic shown: Q3 base at -55VDC and Q3 emitter at -61VDC.
How is this possible, forward biased junction blown open ?
How is this possible, forward biased junction blown open ?
let me try...
dc coupling emitter to grid of power tube allows for class AB2 mode of operation,
so that at positive grid voltage, current flows to the grid, grid impedance drop like a stone..
perhaps an MJE340 will be better in that spot or even a TIP50...
let's hear what the experts say....
perhaps a reversed biased diode, say an 1n4935 across emitter base juctions can mitigate damage...
dc coupling emitter to grid of power tube allows for class AB2 mode of operation,
so that at positive grid voltage, current flows to the grid, grid impedance drop like a stone..
perhaps an MJE340 will be better in that spot or even a TIP50...
let's hear what the experts say....
perhaps a reversed biased diode, say an 1n4935 across emitter base juctions can mitigate damage...
Hi
There is a mistake on the Mac diagram , voltages at Q3 should
emitter -61.6
base -62.1
Q5 emitter -62.8
There is a mistake on the Mac diagram , voltages at Q3 should
emitter -61.6
base -62.1
Q5 emitter -62.8
Vbe of most transistors is usually 600mVbe to 700mVbe.
Pins5 & 8 determine the voltages around the transistors.
What is the range of voltage difference that can appear between 5 & 8?
Pins5 & 8 determine the voltages around the transistors.
What is the range of voltage difference that can appear between 5 & 8?
output tube idle current is set by resistors R22/R23 on the top half and R24/R25 on the bottom half...
if the trannies Q3/Q5 and Q4/Q6 were not installed, the output tubes would have been at cut-off at -400volts g1..
but since trannies are there, about 1.8mA flows thru R22/R23 on the top half and R24/R25 on the bottom half biasing the output tubes to about 0.65v divided by the dc resistance of the traffo winding...and the grids at -62 volts...
slav, what model number is this amp?, looks like the first time i've seen one....
if the trannies Q3/Q5 and Q4/Q6 were not installed, the output tubes would have been at cut-off at -400volts g1..
but since trannies are there, about 1.8mA flows thru R22/R23 on the top half and R24/R25 on the bottom half biasing the output tubes to about 0.65v divided by the dc resistance of the traffo winding...and the grids at -62 volts...
slav, what model number is this amp?, looks like the first time i've seen one....
thanks slav, found service manual here.... McIntosh MA2275 | Owners Manual, Service Manual, Schematics, Free Download | HiFi Engine
- Status
- Not open for further replies.