Need help identifying ST48 Diode

[Moonheads]

I am in the process of repairing a plate amp from Dayton Audio. All of the active components
were fried. I have purchased replacements for them but am unsure about two diodes.
The only marking I can read on them is ST48, am I correct in assuming they are ST4148?
I have not been able to find a schematic anywhere.
Thanks much.

 

[AnalogPackrat]

Can you take pics of the diodes? Sometimes the type can be narrowed down by appearance. Also maybe trace the connected circuitry. Are they in the amp circuit or something else (PSU...)?

 

[user 130681]

Does it read like a diode? ... if it does, it is probably OK.

 

[Moonheads]

Thanks for the replies. Here is a photo, just below the ST is 84.
The diodes are shorted so I know they are both defective.
They are in the pre driver section of a transistor power amp.

 

[AnalogPackrat]

Can you trace any of the circuit where the diodes were connected?

 

[user 130681]

Schematic would help or even make and model to allow us to look for a schematic or at least some clues as to where they go in the circuit.
If they are input protection, then 1N4148/1N914 will be OK. Are they regulating zeners? We have no idea.

 

[CJ]

SPA250 sub wolfer amp?


That is a 1 watt zener, ST48xx.
You will need to get the last two digits in order to buy new ones. There might be more of them on the board. So you might be able to read their number. But finding out why the blew will be the hard part and I bet that is a complicated circuit , and i bet the company does not want you to have the schematic so you might be in for a tough time.

 

[CJ]

Looks like that crossed over to this schematic which has a lot of different zeners so assuming that the others on the board are a match is a no go. You know the zd number off the board silkscreen?

https://www.avsforum.com/threads/lo...yton-spa250-plate-amplifier-found-it.3182922/