Soulcrusher_X
New member
A buddy of mine has a Jet City JCA50H that suffered a failed PT. He managed to get a great deal on a Mercury Magnetics PT, so I took it to my workbench to plop it in. It wasn't a direct bolt-in deal, but we went over the issue with Mercury and they will be making accommodations for the future units. I will explain the whole thing in this write up.
Here is the patient:
So I replaced this:
With this:
Now, here's where I ran into problems. The mounting feet that are supplied with the MM unit are not even CLOSE to where they should be. Hopefully the pic is clear enough that you can see the right foot is lined up with the bolt hole, and the left one is 1/8"-1/4" off.
My buddy and I both contacted Mercury about this issue, and they said they would be able to send brackets with an inward offset to correct the issue. I however, came up with another idea......
The endbells are fairly similar in size. In fact, the bolt pattern of the EI core is the same dimension.
The guts of the MM unit are a lot beefier than the JCA unit, but all I needed to do was make some spacers with the old MM mounting brackets by cutting the 'L' feet off.
Then, install them on the PT core, like this:
Then bolt the JCA endbells on like this:
Then, bolt it to the chassis like this:
The chassis mounting bolts are a bit tight, and MAY need a hair of grinding if anyone does this swap before the newer brackets are released. OR, maybe you just want something that looks stock and stealth.
Next is wiring!
Here is the patient:
So I replaced this:
With this:
Now, here's where I ran into problems. The mounting feet that are supplied with the MM unit are not even CLOSE to where they should be. Hopefully the pic is clear enough that you can see the right foot is lined up with the bolt hole, and the left one is 1/8"-1/4" off.
My buddy and I both contacted Mercury about this issue, and they said they would be able to send brackets with an inward offset to correct the issue. I however, came up with another idea......
The endbells are fairly similar in size. In fact, the bolt pattern of the EI core is the same dimension.
The guts of the MM unit are a lot beefier than the JCA unit, but all I needed to do was make some spacers with the old MM mounting brackets by cutting the 'L' feet off.
Then, install them on the PT core, like this:
Then bolt the JCA endbells on like this:
Then, bolt it to the chassis like this:
The chassis mounting bolts are a bit tight, and MAY need a hair of grinding if anyone does this swap before the newer brackets are released. OR, maybe you just want something that looks stock and stealth.
Next is wiring!
OOps. So, 120v leads from the fuse block go on the terminals that face the bottom of the amp. 
)with my Nikon camera, both of 6L6s and with 6550s. Left all the knobs where they were for all clips to get a raw comparison. Clips were done on the OD channel, gain at 5, TMB and presence at 5.....mids might be a little higher...6...maybe, and volume at roughly 2~ish. Bias on the 6L6s is about 35mA, bias on the 6550s is about 45mA. Cab is a stock PV 5150 cab, guitar is a Les Paul Custom with Duncan Seth Lovers. Standard tuning. Nothing fancy. This is BEFORE the SLO mod.
