2SA1137 transistor?

Hi
I've a problem on one channel of Drawmer 1962.....
I've compared the working channel with dead channel and I think the problem is with 2 transistor 2SA1137....
I've searched but it's obsolete
There is a real substitute?
If there is I must change the transistor also on working channel for stereo matching?
Thanks!!!

Hi


Try emailing Drawmer I'd bet they can supply spares at a reasonable price


tc

There are a load of equivalents for a 2SA1137
2SA954 Being just one

Thanks topcat!!!
Thanks s2udio!!!

s2udio said:

There are a load of equivalents for a 2SA1137
2SA954 Being just one

Click to expand...

that's quite obvious - just check the numbers: 1137 - 954 = 183  a beautiful number by itself and just one below the renown BC184....

but seriously - anybody with some better clues to transistors and equivalent replacement then just the usual  they use it / it has great HFE / my pal has a shitload of them ?

- Michael

PS: oops, seems I am not allowed to write shitload on this forum??? aarghh, you bloody Americans!!! smile...

but seriously - anybody with some better clues to transistors and equivalent replacement then just the usual  they use it / it has great HFE / my pal has a sh*tload of them ?

Click to expand...

To answer in general to do this properly you need to look at and hopefully understand the schematic.

In many cases the substitute transistor does not need to match the full specification of the original part to work in the application.

Many transistors are not sensitive about specs and just happen to be popular with that company designer. For my old kit business and later small company design I would use a small handful of devices, usually an NPN and PNP pair that would cover 99% of my needs. Then I would use the occasional oddball device like very low noise for mic preamp front ends.  These days more discrete transistor functions are showing up inside ICs so I expect the number of devices available to drop further.

I guess I could look up what a drawmer 1962 is, but I'll guess some kind of dynamics processor.

If the subject transistor is in a side chain circuit, yes you might want to consider making both channels the same. Small differences like even the forward Vbe could make a difference depending on the circuit.

JR


 

> some better clues to transistors

Figure out how it is used and what transistor parameters are most important. (Don't expect others to do the look-up and study for free.)

Find something to do the same job.

It does help to have read a lot of spec-sheets.

The stand-out specs on 2SA1137 are 80V and voltage noise 0.65 nV/rtHz (1KHz 3mA). (Or rbb=20 Ohms, which is about the same thing as the noise spec.)

I *assume* this is the mike preamp. It will "work" if you stick a jellybean 80V PNP in there (check pinout). A 50mA jellybean may give 5dB noise figure, a 500mA jellybean may give 3dB noise figure. In many situations (*especially* with condenser mikes), this is plenty good. There's probably a pair, replace both.

s2udio said:

but seriously - anybody with some better clues to transistors and equivalent replacement then just the usual  they use it / it has great HFE / my pal has a sh*tload of them ?

- Michael

Click to expand...

Transistor cross equivalent is not rocket science with todays available  data
PS My names not  Michael And thats not my quote
Kind regards