Can anyone tell me if there are replacement transistors available for 240 amps?
I located replacement power transistors (MJ21193/94), but cannot seem to find replacements to Q507 (SJ2583) and Q508 (SJ2582) (TO39's) on schematic. Also the drivers Q510-Q511 are marked F S40445 and F S40446. Any help would be appreciated. Thanks!.
I located replacement power transistors (MJ21193/94), but cannot seem to find replacements to Q507 (SJ2583) and Q508 (SJ2582) (TO39's) on schematic. Also the drivers Q510-Q511 are marked F S40445 and F S40446. Any help would be appreciated. Thanks!.
Hi akaufman12,
I'm just repairing a Marantz 240 amplifier and found out that it is
the same circuit like the 250, but without front panel meters.
There is a big and very helpful thread here on diyAudio about repairs of the Marantz 250 Amplifiers with a big discussion about replacement for the unavailable transistor types, here is the link :
Marantz 250M Repair
I hope your Marantz is still waiting on a shelf for repairs and this will help, even if some time has passed
Best regards Mirko
I'm just repairing a Marantz 240 amplifier and found out that it is
the same circuit like the 250, but without front panel meters.
There is a big and very helpful thread here on diyAudio about repairs of the Marantz 250 Amplifiers with a big discussion about replacement for the unavailable transistor types, here is the link :
Marantz 250M Repair
I hope your Marantz is still waiting on a shelf for repairs and this will help, even if some time has passed
Best regards Mirko
Hello akaufman12- the Marantz 240 power amp boards have several components common to the Marantz 1200, with some key differences. There were also technical bulletins issued for these amps that were implemented according to the serial number of the amplifier.
2N5415 subs for the SJ2583, and 2N3440 subs for the SJ2582.
Q510 (SJ2515) and Q511 (SJ2516) are a little tricky. If you want to replace with a similar device to keep it looking like original, you can go on Little Diode's website and buy direct replacements. Little Diode had the Toshiba 2SD424/2SB554 to replace Q510 and Q510 last time I needed some in 2013.
Many people replace Q510 and Q511 with MJE15031 and MJE15030, both TO-220 mounted.
Best not to replace any transistors unless you know they are bad. The newer transistors had different frequency response than the early transistors, making it very easy to make these amps into a self destructing oscillator.
There are still a lot of these amps around for a reason.
2N5415 subs for the SJ2583, and 2N3440 subs for the SJ2582.
Q510 (SJ2515) and Q511 (SJ2516) are a little tricky. If you want to replace with a similar device to keep it looking like original, you can go on Little Diode's website and buy direct replacements. Little Diode had the Toshiba 2SD424/2SB554 to replace Q510 and Q510 last time I needed some in 2013.
Many people replace Q510 and Q511 with MJE15031 and MJE15030, both TO-220 mounted.
Best not to replace any transistors unless you know they are bad. The newer transistors had different frequency response than the early transistors, making it very easy to make these amps into a self destructing oscillator.
There are still a lot of these amps around for a reason.