Laney VC30 212

[jondoe]

Hi all,

I recently picked up a dead Laney VC30 that "just needed valves", I tried it out with some old tired valves and it fired up fine for an hour and seemed to be doing all that it should and sounded good. I invested in a full new set of valves and for a brief time it worked perfectly for 10 minutes, until it blew it's main (630ma) fuse. I've gone through the rectifier diodes and big power resistors, main caps, and they are all fine. The voltage regulators for the 15v are fine and I can't see any obvious signs of anything looking burnt/broken. I also can't find a schematic for this version PCB 9072_8 main board, the printed value on the silk screen doesn't match the colour code of some of the resistors or the 9072_7 schematic and below, the transformer wire colours are also different

Does anyone have that particular PCB version in their schematic stash?

Thanks.

[minim]

I can't help with a schem but I just happen to have my GC-30V apart at the moment (forerunner to the VC-30), so if you need to compare any voltages or whatever let me know. I have an intermittent distortion/fading out issue as the amp warms up.

[jondoe]

I can't help with a schem but I just happen to have my GC-30V apart at the moment (forerunner to the VC-30), so if you need to compare any voltages or whatever let me know. I have an intermittent distortion/fading out issue as the amp warms up.

Thanks minim, and the same to you if you need any I just rebuilt the amp, put the valves back in and a fresh fuse and it's chugging away on the bench not blowing it's fuse. The power consumption seems a little high, but my wall socket reader is a little inaccurate so I'm taking that with a pinch of salt. There is quite a bit of inrush when first turning on, a little higher than the fuse rating, but it quickly settles to below the fuse rating (although only by about 0.100 mA!). I'll leave it on and see if it misbehaves.

I found a schematic for a later version of the VC30 in a thread on here, looks that the one I have shares the same mains transformer color wiring, but has a different board layout, naming convention and plugs/sockets for connectors. This combo clearly had lots of revisions!

[jondoe]

Looks like the reverb tank is duff, that would explain why it was disconnected.... 3M Ohms on one side, 26 Ohms on the other

[J M Fahey]

Look at the open side with strong glasses and under good light, sometimes one of the tiny wires joining drive or pickup coil to RCA connector breaks, you may resolder it.

[jondoe]

Look at the open side with strong glasses and under good light, sometimes one of the tiny wires joining drive or pickup coil to RCA connector breaks, you may resolder it.

I broke out a magnifying glass and removed and reconnected the fine wires, it's still sitting somewhere between 3M and 5M, it varies a little based on handling, so I'm thinking the coil is a goner. Looks like I'm shelling out on a new one!

She blew a fuse for the first time in a while after I plugged it in to test, I hope it doesn't carry on blowing them when i get a new one. That said, one of my new 12AX7's seems a little funky, maybe it didn't like it.

To be continued.