Hello everyone! A very strange problem has appeared. Who has experience, please share.
I brought a dual rectifier from Japan. So what’s the trouble, the first section where Clean and Orange work flawlessly. Everything sounds as it should sound. The problem lies in the Red section. For some reason, there is not enough gain, as if some section of the preamp stage simply does not work. Compared with another mesa of the same revision, in fact, there is simply no part of the gain. I changed the tubes, it didn't work. Climbed into the scheme, no complaints at all. The only thing is that it is clear that for some reason the optocouplers (VTL5C9) were soldered. I gave it to the tech, he also said that there was no issue according to the scheme, he checked everything (or overlooked, I don’t know). If you have any thoughts or advice, please share here.
I brought a dual rectifier from Japan. So what’s the trouble, the first section where Clean and Orange work flawlessly. Everything sounds as it should sound. The problem lies in the Red section. For some reason, there is not enough gain, as if some section of the preamp stage simply does not work. Compared with another mesa of the same revision, in fact, there is simply no part of the gain. I changed the tubes, it didn't work. Climbed into the scheme, no complaints at all. The only thing is that it is clear that for some reason the optocouplers (VTL5C9) were soldered. I gave it to the tech, he also said that there was no issue according to the scheme, he checked everything (or overlooked, I don’t know). If you have any thoughts or advice, please share here.
