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test help...

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this must be a V1 Pt that I have in it now.. or something from a harley benton.. it has the black sealed up fuses

off the pt.

I did leave the orange wire fuse on.. although I have a panel fuse.. so I suppose this second one might have a bad fuse. .but..

I really doubt that.

I'll check it tomorrow. .everyone's asleep it seems.


I'm pretty convinced at this point that it's not the OT or PT.. in fact, I feel sure both of each are fine.

That means it has to be something on the board.. but I'm damned if I can find anything wrong.



the only things different on mine from turretboard fenderish layout is that my C5 and R14 go straight to the tube pin.

and my wire from R11 to C6 runs under the board.

I even pulled the board and checked those out. all fine.



there is ONE weird thing about this.. when I pull the wires, yellow and black, off the power switch. the little male pegs that take the female push on jacks come right out..

But it powers up and works so I'm pretty sure that it's getting juice and that's not a problem. They just come out and slide back in, there's contact for sure.


I'm going to go read the code on my Dexters PT and double check there's no difference in the wire colors.

looking at everything!


stumped again!

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There should be a color code chart on the top of the PT.


Anyway, you don't have to have a load on the PT's secondaries to measure 'em, but be careful and don't get zapped.


If you don't have any voltage at all between the two orange heater wires, try removing the fuse, and use the internal fuse contact on the PT wire end as your red meter probe contact point. You should read 3.5vAC on it with the black probe to ground, or over 7v with the black probe to the other orange heater wire.



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yep to the first


don't know what you mean by the second.


I'm measuring from one end of the purple heater wires.. tube to tube..to the other.

I never measured between them at the same tube..


let me see if I understand you..

measure between the two orange wires..

if there's no voltage..

pop out the fuse.. then connect red probe to that contact. and black probe to ground and look for 3.5Vac

then with the red probe still on the fuse contace.. black probe to other heater wire.. should see over 7V



I'll go do it right now.

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tubes pulled.. got tired of heating up that old motorola for nothing..

between orange wires I get 7.5VAC

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yeah it's wired exactly like the diagram.


pin 7 with R16 and orange wire runs to 4/5 on the pre.

pin2 with R17 and orange wire to pin 9 on the pre.

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there's just nothing left to look at.

Everything is where it should be.

the only thing left is the power tube..

so that means that, as I understand it, a bad tube might have done some damage.

Or the tube is just bad.


I have no idea if that really explains it not running. It's just all I have left.

I can't believe that the pot/R reversal on the NFB would somehow ruin te whole amp.

I can't believe that the ground off R6, somewhat loose, could have done this.


Because pt and ot were swapped after those things were made right.


it has the stock input jack, turretboards shows a switchcraft type. So I'll swap it.

But really.. we know it's not that I think.


so it's either spend money for a new jj. or put this second used tube in it.

given the first bad tube may be the problem, I guess I'll have to buy a new one.

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could it be the old tubes?

I dont' know .. they light up. they look normal. but there's no sound.

I hate to buy a new tube just to find out these tubes wrecked something else and then wind up wrecking the new tube.

there simply isn't anything wrong in there.

all parts are where they're supposed to be.. all wires and connections are correct..

the test bulb glows then dims.. every time.. nothing heats up.. no smoke..

I haven't left it on long enough to see if the transformers get hot..


only thing left to check is the enlcosed fuses on this new pt.. the other one had the white fuse holders, this one the black..

but. again, I doubt that's it because it acts exactly like the last.


so.. new tube or no new tube

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Hey, did you try the tap test? And are you sure that OT is even functional? I noticed there was only a 1v drop between B+1 and the 6V6's plate from the measurements you posted. Seems to me there should be a drop of about 5v across a Hammond 125xSE, and maybe 17v across the stock VJr OT's. That is, with the tube installed. if you don't know if the tube you're using is any good, get another.



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trying to get my head around 'em now.

yep. I didn't check the other thread well enough. all there.


I hate to replace the ot ... again.. and I need to test this one anyway, so I think I want to go with leaving it in and testing it.

but I have to find a small 6.3 filament transformer with 3A output first, I guess.

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