Vegas 400 volume issues

This forum is for talking about all kinds of Peavey guitar amplifiers.
Post Reply
PHSChrisby99
New Member
Posts: 1
Joined: Tue Mar 28, 2023 9:43 pm

Vegas 400 volume issues

Post by PHSChrisby99 » Tue Mar 28, 2023 9:46 pm

Have a Vegas 400 that gives little to no volume no matter the pre/post gain setting. What's very strange is that when it is powering down after I turn the power switch off, I hear a split second of "normal" volume level that quickly fades away. Anybody have a similar experience, or at least an idea where to start?

User avatar
Pappy B
Member
Posts: 762
Joined: Sun Jan 31, 2016 2:30 pm

Re: Vegas 400 volume issues

Post by Pappy B » Thu Mar 30, 2023 11:15 am

Before you do any trouble shooting do some maintenance. Use a contact cleaner on all the pots, jacks, switches and connectors. Best to to pull chassis to do this. Some jacks have little switch contact in them that corrode over time. Pots are easier to clean from inside to. Some times it;s necessary to lift the opamps out of their sockets and spray the legs and sockets. If you do this be careful not to bend the legs and make sure you reinstall them the same direction they came out. I always mark the board with a Sharpie or take a picture before I pull them. I always clean the reverb tank and speaker connections too.

Doing this maintenance first makes it a little easier to find problems by eliminating poor signal flow due to corroded or dirty connections.
The more I learn the more I realize how much I don't know.

User avatar
dak
Member
Posts: 428
Joined: Fri Dec 24, 2021 7:20 am
Location: Germany

Re: Vegas 400 volume issues

Post by dak » Thu Mar 30, 2023 11:27 am

PHSChrisby99 wrote:
Tue Mar 28, 2023 9:46 pm
Have a Vegas 400 that gives little to no volume no matter the pre/post gain setting. What's very strange is that when it is powering down after I turn the power switch off, I hear a split second of "normal" volume level that quickly fades away. Anybody have a similar experience, or at least an idea where to start?
Many Peavey amps have a JFET circuit for tamping down the switch-on pop (sometimes also the switch-off pop). If that circuit is faulty, it might stay in "power-on pop suppression" mode eternally but could possibly disengage when the power goes down. That's where I'd look first.

Simplest "remedy" is just removing the JFET altogether (and brace for the switch-on and switch-off pops that might be sizable) for a test.

Post Reply