I'm working on an old monitor. The following obsolete transistors have failed and am trying to find replacements:
2SC1685 - 100mA, 50V, NPN, Si, SMALL SIGNAL TRANSISTOR, TO-92
2SD478 - TRANSISTOR,BJT,NPN,150V V(BR)CEO,2A I(C),TO-220

I've attached the datasheets for both devices but need some assistance to know which attributes I absolutely need to match 100%, and which ones may be ok to go higher/lower. Since there both used to amplify, I'm pretty sure HFE has to match as well as the Ic amp and voltage ratings

 

Hello,

Did you already have a look at the documents in this thread:
Cross reference information

Bertus

 

Thank you, looking through it now.

Hello,

Did you already have a look at the documents in this thread:
Cross reference information

Bertus

Thank you, this is very helpful

 

My take is that you don't have to match anything 100% exactly except:

1. semiconductor type, Ge vs Si
2. polarity, PNP vs NPN
3. package
4. lead identification

Check that the following match or exceeds original:

1. voltage
2. current
3. power dissipation
4. gain
5. frequency

 

According to my cross reference guide:

2SC1685 crosses to: 2SC1815, 2SC945, 2SC1740 among others (these are very common)
2SD478 crosses to: 2SC2073, 2SD401A, 2SD1138, 2SC901, 2SD1562A

Dan