There was no output when this monster came in. First thing I did, get the chassis out.


As you may be able to see, there was evidence of previous repairs around the rectifier diodes. I checked that area and everything was fine. I checked the fuses and sure enough one was blown. I first had to check what had caused that. Looking around I noticed one of the leads of the Choke was exposed(insulation off) which shorted to the chassis(460vdc!) therefor blowing the fuse.

Here you can see that:

And insulated with heatshrink(rated at 600v/125C):

With that done, it allowed me to fire it up again and give it a try.  This time we got output but very low. First test I did was to get the preamp out through the effects loop and into the direct in of another amp. The preamp was fine. I checked all of the tubes and all of them were fine. I used a list from GeoFX to test the output transformer and it turned out to be ‘blown’. An internal short is the most probable cause. For a replacement we went with the people of Triode Electronics. I’ve had very good experiences with them before and their stuff is great quality(and cheap)!

Stock OT to the left and the new one to the right:

The mounting holes were not the same so that had to be taken care of first. Once it was in, it was held very tight. It’s not going anywhere any time soon.

Here it is wired up:

The schematic of the Laney didn’t specify the common on the primary so I followed the ‘color code’. I turned it on, and while output was coming out, this really loud hum would come on after a few seconds of turning it on. I reversed the leads of the primary and that cured it.

Here’s that:

Shot of the new OT:

Shot of it back together during testing, which means it’s done!