Crate VC 50 to Rocket Reverb?

[johnnyreece]

I recently scored a broken down VC 50 for cheap. Was thinking of ripping out the board and using what's left for a budget Rocket Reverb. She's heavy...it's the 3x10 combo. I've attached a schematic that does include a voltage chart. I think by swapping in a tube-ish rectifier (will either use a Weber copper cap or just run my own sag resistor since I don't have the 5V taps) I can get B+ in line. Any thoughts?

[johnnyreece]

I've been going over this schematic and am seeing something that looks funny...From the looks of it, the heater tap on the PT is putting out 8.8VAC. From there, they rectify it for DC and send it to the 12AX7 tubes. However, it looks like they're sending 8.8VAC to the power tubes. Can someone clear this up for me?

[rock_mumbles]

That's what it looks like ... Crate has done some funny things to perfectly good amp circuits ...

Maybe that's how it became a VC50 and not a VC30 ???

[akahoushi]

I think it's 8.8V peak-to-peak, which would be about 6.22V RMS.

[johnnyreece]

I think it's 8.8V peak-to-peak, which would be about 6.22V RMS.

Makes sense. I completely ignored the P-P in the measurement...

[skeezbo]

I hate to jump the thread, but I took a look at the schematic, and I have a question. What are all the optocouplers for? I don't think I have seen that kind of setup before.
Skeez

[johnnyreece]

From what I understand, they're for the channel switching. They also frequently go bad (as I believe they have in this case, too).

[johnnyreece]

Sorry to drag this back to the top, but I'm curious: Anyone know what C30 and C31 are for in the circuit? I'm reusing the switches that have the built in lamps, so I don't know if they're necessary for that or not. Thanks for the help! This thing's coming along, slowly but surely.

[cxx]

No, they are not part of the switch illumination. The switches just have bulbs in them.

[johnnyreece]

Thanks. I know I have to have some circuitry for the standby switch (or else I'd have full B+ hitting the bulb), but I wasn't sure on the mains switch. I appreciate you easing my mind!

[cxx]

Thanks. I know I have to have some circuitry for the standby switch (or else I'd have full B+ hitting the bulb), but I wasn't sure on the mains switch. I appreciate you easing my mind!

I assume you saw the resister to ground on the B+ side.

[johnnyreece]

Sure did. Thanks for mentioning it, though! I got the power section complete and powered it up. Both switches lit up and didn't explode, so it seems I at least got that part right! VVR seems to work well, too. Now I just gotta finish wiring the board in. Hoping to have it up and running this weekend.