Marshall Artist 3203 Repair
Posted: Sat Jul 15, 2017 3:04 pm
Hi all,
This is my first time posting on this forum. I figured this would be the right place to ask my question since it looks like there are some very knowledgeable folks around here especially in regards to circuits and Marshalls.
I'll start off with a little background info. I've been a 77' 2204 player for years now and have done a fair share of tinkering with tube amps, although no modifications lately just routine maintenance. I recently got the urge to have a stereo setup and found a great deal on a 1987 3203 head. I had one of these a few years back and liked it's clean channel along with it's price tag. I played it for a few days and started experimenting with swapping tubes from my collection in and out of the amp. My music gear is set up in my basement which I am currently remodeling and it's not very well lit down there. Without thinking twice I grabbed a pair of what I thought were two power tubes and popped them in the amp. I fired it up and the amp didn't made a faint sound and then went quiet. I shut it off and after about a second of investigating realized that I accidentally stuck an octal rectifier tube in one of the two power tube sockets, thinking that it was a 6L6 tube. I then threw the amp on the bench and opened it up. I found the R8 (270ohm) resistor charred, which caused damage to the R2 (56k) resistor. I replaced both hoping that I hadn't caused any damage to the output transformer and fired it back up, with two power tubes this time
Unfortunately, no sound.
Can anyone give me some guidance as to how to continue troubleshooting this problem? I'm no expert on circuit design, but I do understand the basic principles of tube amp operation and I do industrial controls engineering for a living so I know my way around a multimeter and how to be safe around high voltage. Any help would be appreciated.
Thanks!
This is my first time posting on this forum. I figured this would be the right place to ask my question since it looks like there are some very knowledgeable folks around here especially in regards to circuits and Marshalls.
I'll start off with a little background info. I've been a 77' 2204 player for years now and have done a fair share of tinkering with tube amps, although no modifications lately just routine maintenance. I recently got the urge to have a stereo setup and found a great deal on a 1987 3203 head. I had one of these a few years back and liked it's clean channel along with it's price tag. I played it for a few days and started experimenting with swapping tubes from my collection in and out of the amp. My music gear is set up in my basement which I am currently remodeling and it's not very well lit down there. Without thinking twice I grabbed a pair of what I thought were two power tubes and popped them in the amp. I fired it up and the amp didn't made a faint sound and then went quiet. I shut it off and after about a second of investigating realized that I accidentally stuck an octal rectifier tube in one of the two power tube sockets, thinking that it was a 6L6 tube. I then threw the amp on the bench and opened it up. I found the R8 (270ohm) resistor charred, which caused damage to the R2 (56k) resistor. I replaced both hoping that I hadn't caused any damage to the output transformer and fired it back up, with two power tubes this time
Unfortunately, no sound. Can anyone give me some guidance as to how to continue troubleshooting this problem? I'm no expert on circuit design, but I do understand the basic principles of tube amp operation and I do industrial controls engineering for a living so I know my way around a multimeter and how to be safe around high voltage. Any help would be appreciated.
Thanks!