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TWANG

test help...

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If both your amps don't work on the current limiter, I would think its your limiter

instead of a 100w light bulb try a 30w light bulb in the current limiter.

 

Also remember the thin plug is the hot, wide is common and of course the ground at the bottom. so the current limiter socket should just be from the thin fin on the plug to the screw of the light sock, from the other side of the socket to the thin female of the of the plug.

Other than that the fat fin of the plug goes straight to the fat female of the plug and of course ground to ground.

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I'll go try that right now.

I swear.. I copied that diagram perfecty. but hell.. I've thought that before!

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cool.. had a 40 watt handy.. plugged her in after checking my wiring.. all was correct..

lit right up.. dimmed right down!

 

now.. I let it run and test voltages as per usual.. expecting goofy numbers..

or I unplug the bulb and put in the tubes.. or.. what!

 

yaaay!

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cool.. had a 40 watt handy.. plugged her in after checking my wiring.. all was correct..

lit right up.. dimmed right down!

 

now.. I let it run and test voltages as per usual.. expecting goofy numbers..

or I unplug the bulb and put in the tubes.. or.. what!

 

yaaay!

I'm not gonna comment because I like you Twang......8-[#-o

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if you take voltages just remember they are going to be high but I would think proportional (but you’ll only be measuring the B+ rail anyways… no tubes).

 

If you put the tubes in, leave it connected to the current limiter, its to give you a few milliseconds to turn it off quick if you need to.

 

If all seems fine take voltages (still on limiter)

After that take it off the limiter.

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Lay. thanks. *G*

 

ET.. cool going right out now. Man.. I knew the amp was right and I knew the tester was ok.. nobody ever mentioned a smaller bulb.

I '***' umed the 100 watt on the diagram was for safety.

thanks all.

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ok.. tubes in test results as follows..

wasn't sure what to test so I just did a few spots and thought I'd ask in here if anything was different..

 

r10 270/260

r12 250

 

ax7

1..240

3..3.0

6..246

8..4.6

 

6V6

3..242

5..248

6..15

7..8.4

8.. can't read my note.. *s* 129 or 12.9

 

how to test heaters on this one..

what values am I looking for on the 6V6

which pins do I test..

what about R3..

 

I am so tempted to plug in a guitar.

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Same way you check AC heaters on all the other tubes. One probe on one end of a filament, the other probe on the other end of a filament. In octals, the heater filament runs between pins 2 and 7. Don't forget to switch your meter to AC volts.

 

Are you sure you have a 100k in R3 and not a 100R or 1k? Pin 1 of the 12ax7 sure looks a little high. Or is that without tubes?

 

Gil...

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that was with tubes.

I'll see what I've got in there.. 100K R3 coming up, if not in there now.

probes at each end for ac setting. okey dokey.

brb

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Ok.. nothing on the heaters.. this is an old motorola tube.. so that could be the problem.

r3 100K.

 

r10 263/251

r12 251/248

 

r13 247

 

r3 238

 

ax

1 238

2 189

3 2.9V ?? *auto meter switched to V there*

6 244

8 4.5

 

6V6

3 240

8 12.8

 

I'll pull that tube and test again.. after someone replys here so I can see what's up with this for sure.

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Ok.. nothing on the heaters.. this is an old motorola tube.. so that could be the problem.

r3 100K.

 

r10 263/251

r12 251/248

 

r13 247

 

r3 238

 

ax

1 238

2 189

3 2.9V ?? *auto meter switched to V there*

6 244

8 4.5

 

6V6

3 240

8 12.8

 

I'll pull that tube and test again.. after someone replys here so I can see what's up with this for sure.

 

What PT are you using for this thing that only gives you a B+ of 263v?

 

There should be 7v+ across the heater supply wires if there are no tubes loading the PT winding.

 

And why is there such a small voltage drop across R3 and R4? I think maybe you should pull the preamp tube, and measure those plate resistors again, and this time, check the scale on the meter a little closer. And double check the value of the cathode resistors, while you're at it. Something is way wacky my friend. We got ferrets to bop! :-

 

Gil...

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odder still.

nothing on heater pins..

R3 was 260 on one end.. 257 on the other

pin 1 ax7 256

pin2 .1

pin 6 255

pin 8 just jumped around

 

that's all I did.

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stock pt. forgot to say.

don't remember .. could be a british audio pt I bought. have to go look and see if I can even tell which one that is.

 

test was with tubes.. then I pulled the preamp.

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Weellll, I guess you're just gonna have to go over it wire by wire. Just in case, I suppose I should mention that the tube socket pins run clockwise from the "key" when you're looking at 'em solder lugs up. Been there, done that. :-

 

Gil...

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well.. I did. and it's fine.

I was using the little numbers on the bottom of the sockets to test, same as I always do.

but. you say so. so I say so.

I'll look at it all again.

 

I checked off every wire and component twice on the layout already. but nothing wrong with three times.

 

if you think it's the pt.. no problem putting another in, I got 'em.

too bad there's no simple test for those things.

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Well.. very interesting.

Here's what I have.

 

R10

370/370

R12

365

R3

339/223

 

pin 1 (ax) 223V

2 .3mV

3 1.7V

4/5 zippadeedoodah

6

211V

8

1.8V

 

6V6

pin 3

369V

4

364V

7

zippyagain

8

364V

 

what's up with those heaters?

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Well.. very interesting.

Here's what I have.

 

R10

370/370

R12

365

R3

339/223

 

pin 1 (ax) 223V

2 .3mV

3 1.7V

4/5 zippadeedoodah

6

211V

8

1.8V

 

6V6

pin 3

369V

4

364V

7

zippyagain

8

364V

 

what's up with those heaters?

 

can it be the old 6V6 tube I have in it?

everything checks out.. I suppose I could go over it again.

the ground wire off r7 was funky.. It may not have been connected well.

what are the voltages I should be looking for with the 6V6.

I'll check the faq,etc.. but I don't recall seeing anything.

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Is there a fuse on the PT's heater tap? Might check that.

 

Also, the 12ax7's pins 4 and 5 are supposed to be jumpered, with one heater tap connecting to both, and the other tap to pin 9. Might be why you ain't got no heaters!

 

Heaters should be 6.3v.

 

Gil...

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uh.. hmmm.

there was a fuse. but it was good.

to pin 9?

there is no pin nine. there's only 8 pins.

on the turretboards fender layout 4/5 ax go to pin 7 6V6.

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I also got rid of the nfb pot for the time being.. and have been using a 47KR to the tap.

And since nobody was around for a while, I swapped out the PT for a new one.

same results.

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