08-03-2024, 02:33 PM
Hi Everyone!
Newbie here with a question about what tube I should use in a VT22 V4 amp I found on the side of road ready for trash guys.
I thought I was seeing things and didn't stop the first time I drove by it. On my way back an hour later it was still there so I stopped and loaded it up.
It sat in garage for about 6 months before I had a chance to put it on my test bench.
It's in good condition all things considered. Missing 1 tube ( could have been laying on ground and I didn't see it).
It currently has 6L6's in it but the schematic and tube chart indicate 7027A's. I understand these are okay to use. However my concern is the tube currently in V3 slot is a 7247 when schematic calls for 12DW7. I know both are dual pentodes but didn't find any info about substituting a 7247 for the 12DW7.
So that's my question for now.
I'm glad I found this forum as I've been hanging out asking all sorts of AMPEG questions on a generic tube and valve website. They've been helpful but I think they're a little tired of my dumb questions.
My background:
Starting playing music in 1964 and only in last 5 years basically retired from active gigs. Worked as an electrical apprentice for 3 years but left that - Florida construction is very hot most of the time. I was more interested in electronics.
Got a electronics technology degree and worked for a large multi-store musical store for over 6 years repairing equipment ranging from simple hi-fi stereo stuff, pro audio musical equipment, and big screen TV's. I was lead tech for my last 3 years but pay/benefits not so good so I found job in local hospital as a biomedical engineer. Basically a glorified tech but focused on medical equipment and systems.
Retired after 25 years.
I have several hobbies that keep me busy. One is building guitars, another woodworking, and doing electrical and electronic repair.
So I switch gears back and forth between hobbies. Right now working on getting this AMPEG up and running.
I'm not anywhere proficient on tube amps but know the basics. However for me to be successful in this repair I'm hoping for help from you folks who have mountains of knowledge from years of experience.
Hope you don't get tired of me asking questions about unfamiliar territory of tube amps.
I know I have lots of questions during this restoration especially if it starts self-destructing when I get into powering it up.
I've currently replaced all the electrolytic caps including the big filter caps. Been getting parts from Fliptops. Expensive but doesn't really matter. Replaced a few resistors here and there that were OOT or open. Removed death cap and added 3 prong AC power cord.
I've powered it on with both tubes out and recently with only the 2 12AX7's in preamp. Got some voltage readings that were crazy but was told that all tubes need to be in before you can start checking voltages.
So right now I'm ready to power on but am missing one 6L6 and not sure about the 7247. My Sencore tube tester says all the tubes are good so I'm fairly confident things are ok there.
I woukd appreciate any and all comments, advice, warnings, suggestions that you folks may have related to this amp servicing.
Thanks to ALL
Gary Gendron
More to come!
Newbie here with a question about what tube I should use in a VT22 V4 amp I found on the side of road ready for trash guys.
I thought I was seeing things and didn't stop the first time I drove by it. On my way back an hour later it was still there so I stopped and loaded it up.
It sat in garage for about 6 months before I had a chance to put it on my test bench.
It's in good condition all things considered. Missing 1 tube ( could have been laying on ground and I didn't see it).
It currently has 6L6's in it but the schematic and tube chart indicate 7027A's. I understand these are okay to use. However my concern is the tube currently in V3 slot is a 7247 when schematic calls for 12DW7. I know both are dual pentodes but didn't find any info about substituting a 7247 for the 12DW7.
So that's my question for now.
I'm glad I found this forum as I've been hanging out asking all sorts of AMPEG questions on a generic tube and valve website. They've been helpful but I think they're a little tired of my dumb questions.
My background:
Starting playing music in 1964 and only in last 5 years basically retired from active gigs. Worked as an electrical apprentice for 3 years but left that - Florida construction is very hot most of the time. I was more interested in electronics.
Got a electronics technology degree and worked for a large multi-store musical store for over 6 years repairing equipment ranging from simple hi-fi stereo stuff, pro audio musical equipment, and big screen TV's. I was lead tech for my last 3 years but pay/benefits not so good so I found job in local hospital as a biomedical engineer. Basically a glorified tech but focused on medical equipment and systems.
Retired after 25 years.
I have several hobbies that keep me busy. One is building guitars, another woodworking, and doing electrical and electronic repair.
So I switch gears back and forth between hobbies. Right now working on getting this AMPEG up and running.
I'm not anywhere proficient on tube amps but know the basics. However for me to be successful in this repair I'm hoping for help from you folks who have mountains of knowledge from years of experience.
Hope you don't get tired of me asking questions about unfamiliar territory of tube amps.
I know I have lots of questions during this restoration especially if it starts self-destructing when I get into powering it up.
I've currently replaced all the electrolytic caps including the big filter caps. Been getting parts from Fliptops. Expensive but doesn't really matter. Replaced a few resistors here and there that were OOT or open. Removed death cap and added 3 prong AC power cord.
I've powered it on with both tubes out and recently with only the 2 12AX7's in preamp. Got some voltage readings that were crazy but was told that all tubes need to be in before you can start checking voltages.
So right now I'm ready to power on but am missing one 6L6 and not sure about the 7247. My Sencore tube tester says all the tubes are good so I'm fairly confident things are ok there.
I woukd appreciate any and all comments, advice, warnings, suggestions that you folks may have related to this amp servicing.
Thanks to ALL
Gary Gendron
More to come!