What is this transistor doing here?

[Fet_street]

Can anybody tell me what this transistor is doing here? Yes I know it has an element of voltage divider but I wanna be sure I don't break the amplifier. The d600e transistor failed and I want to know if there's any way I could bypass this transistor to get it running today or any common transistor I may have laying around to replace it with

 

[Brett]

Can you share the entire schematic? It may be a little easier to decipher what's going on with more information.

 

[Feral Feline]

Computer’s in the repair shop, or I’d see what might be an equivalent trans in one of my comparison charts (all of which I found online * hint hint *)

 

[Mcknib]

It's an NPN power transistor so if you've any spares with the same voltage rating as the 2SD600E it should be fine I'd check anything you've got against its datasheet or just get one I think you can still get them easily enough

 

[JTEX]

It drops the 68V to 37.8V.

 

[bean]

Got yourself a custom regulator there. 68v in, voltage divider to provide ~40v to the transistor base, then ~38v out.

 

[Fet_street]

Got yourself a custom regulator there. 68v in, voltage divider to provide ~40v to the transistor base, then ~38v out.

Yeah I thought so but it also goes through all the channels so wasn't completely sure if it was for channel switching or what. Just a crappy salad from 1978

 

[andrewsrea]

It is acting as a voltage regulator, converting the Vcc of 68v to 38v (DC). The caps on the base and emitter are to bypass any ripple or jitter.

It is a 2SD600E (NPN) and substitutes would be: NTE373, ECG373 and SK9041 - or - contact Mouser or the like, for something with the same specs. This handles 8w at the collector (1A, max), Vcb = 100v, Vce =100v and Veb 5V (substantial power). I assume this is an older amp and am guessing the thermal grease dried out.

I'd personally replace the voltage divider resistors, just to eliminate the possibility that they might have drifted and caused the transistor to fail.

 

[Fet_street]

It is acting as a voltage regulator, converting the Vcc of 68v to 38v (DC). The caps on the base and emitter are to bypass any ripple or jitter.

It is a 2SD600E (NPN) and substitutes would be: NTE373, ECG373 and SK9041 - or - contact Mouser or the like, for something with the same specs. This handles 8w at the collector (1A, max), Vcb = 100v, Vce =100v and Veb 5V (substantial power). I assume this is an older amp and am guessing the thermal grease dried out.

I'd personally replace the voltage divider resistors, just to eliminate the possibility that they might have drifted and caused the transistor to fail.

Closest I have on hand is 2sc590

 

[andrewsrea]

Closest I have on hand is 2sc590

The 2SC590 falls way short of the 8w collector dissipation /1A max collector current. The question is, is that really required. If the regulated voltage is providing reference bias (Vref) than that transistor might do. However, if the regulated voltage is for some interstage amplification (like a driver before the output devices), then it won't work and may cause damage to down stream components (transistors typically fail to some combination of BCE short).

What is the device (amp, effect, etc., also letting me know how old the device is) that this transistor is in, what devices / function is down line of the regulated voltage (what function is this feeding - I will assess if it is truly a high current or if the wattage requirement is overkill) and how did it fail (open or short)? Can you send a link to the schematic?

If you have $12 and can wait a week, here is a link of NOS substitute you could use: https://www.ebay.com/p/12057033302?iid=255772971028

 

[andrewsrea]

@Fet_street from the schematic you sent, a substitute would need to have a collector-emitter max of at least 2.5w. Accordingly, a 2SC590 will not be sufficient for the job and I personally would not take the risk of killing those FETs down the line as they are unobtanium. I highly recommend buying the NOS from eBay.

 

[Fet_street]

Unfortunately I'm flat broke with no way to obtain any money so I'm going to have to risk it

 

[Stickman393]

That's super unwise, brotha.

If one has a car that runs on gasoline, and one has no money, one may be tempted to use a can filled with diesel that they have laying around to get the thing moving.

If one does so, the car may operate...briefly. It will then sputter to a stop and will not run when you put gasoline in it again, because diesel is incompatible with gasoline for a variety of reasons and will seriously fuck your car's shit up.

Want my advice? Wait. Don't do it. Don't even risk it. Take a breath, hold off until you get a little cash and can pick up something that you *know* will work.

Hell, if I had something suitable laying around I'd send you one myself.