Diode ID help

[Axtman]

I am working on a Peavey Artist VT Series hybrid amp (solid state preamp tube power amp). There are two diodes that I cannot identify. They are marked "SZ 30 05 OK". They appear to be a Motorla part., What are they and are there subsitutions?

[Tassieviking]

Do you know the part number on the PCB? If they are not on a PCB, what are they connected to ?
Do you have the schematic or any pictures of the diodes in place in the amp ?
Pictures of amps come only second to pictures of guitars, love them there pictures.
I have one schematic, but might not be of your amp.
Lots of very smart people here can tell you what you can use instead simply by looking at the schematic. ( I am not one of them)
The more information you can provide will result in more help and less wrong advice from well meaning people.

My Schematic: Peavey Artist sch.pdf


Found another schematic, its for the Mace, Deuce, VT, and has the power supply in it.
The power supply has 2 - 15V zener diodes in it, the SZ sometimes stand for zener diode in Japanese components I think.
Trace the circuit on your amp and see if it might be a zener diode

Peavey Artist VT Different With PS .pdf

[J M Fahey]

What are they connected to?

They go from where to where?

Is there any reason you suspect them?

What symptoms do you have?

[g1]

My guess is they might be the high voltage protection diodes for the OT. (SR 2873 on schematic).

[g1]

Further to what Tassieviking said, PV semi-conductor cross reference lists:
"SPZ-30050 1N4745 16V, 1W zener"

[TomCarlos]

The Peavey Cross Reference shows these diodes as a Tube Flyback. Look for "SR-2873", Peavey part # 70402873. 2K, PIV, 250ma.

Peavey_Cross_Reference.pdf

[Axtman]

Thank you Tassieviking for posting the schematic of the Mace/Deuce. I finally figured out those diodes are for the +/-15v low voltage power supply THAT IS NOT SHOWN ON THE SCHEMATIC!

I double dog dare anyone to find those diodes along with two dropping resistors (100 ohm @ 5W) and two capacitors (25uf @ 25v and 25uf @ 35V) on the Artixt schematic! Why would Peavey go to all the trouble of drawing as schematic just to leave those critical components off?!

[g1]

I double dog dare anyone to find those diodes along with two dropping resistors (100 ohm @ 5W) and two capacitors (25uf @ 25v and 25uf @ 35V) on the Artixt schematic! Why would Peavey go to all the trouble of drawing as schematic just to leave those critical components off?!

That is not an 'official' Peavey schematic, you can tell by the added header on the top of the pages. The power amp is from a different Artist series, non-VT, and the transformer does not have the extra winding needed to make a split supply for the VT preamp. Someone made a mistake and combined 2 drawings that should not be together.
The non-VT preamp would be running on a single supply and as far as I know, uses transistors instead of IC's.

Attached is the proper Peavey schematic for the Artist VT, which uses the Deuce VT power amp.
(which was already posted by Tassieviking above)