dcribbs1412 wrote:
BTW no flash on start up with limiter 25 or 40 w bulb?
Darin
You should be able to test with just 2 power tubes.
I suggest you try the limiter with a working tube amp to get an idea of how it should glow normally. it's what I did the first time I used mine.
Make sure all the circuits (if any) that you had disconnected are back in line. Usually when you start with no tubes and there is no fault with all the circuits connected, you get a slight flash until your filter caps load up and then you see a faint but steady glow.
If you did not get an initial small flash then maybe your filters had not discharged at all from the last time you turned it on, but you should see the faint and steady glow. On a good amp (even without the tubes) there is some current being drawn causing a slight glow on the bulb. if there is no glow at all then either your limiter is not working or you are not getting any voltage into the amp.
As Stucto pointed out, you now need a load on your speaker jack when you begin installing your power tubes.
If all the circuits are connected (which you should have at this point), and you are getting a faintly steady glow, then proceed to install one tube at a time. Since you will be increasing the current draw with each tube you install, the glow will grow bit by bit with the installation of each tube. If you get a sudden relatively big jump in glow, that is where your problem most likely lies. It could be the tube or its associated circuitry as Zippi properly pointed out earlier. Replace the tube with a known good one and notice if there is any difference in the bulb's glow intensity. If it glows much less then it's most likely that the tube you took off is bad. On the other hand, if the glow is at the same intensity (or close to) as when you had the other tube installed, then the problem is on that tube's circuitry.
Make real sure that the light bulb limiter you built is correct.
the light bulb should only interrupt the hot side (black) of the circuit.
In other words, the light bulb is in series on just the black.
I was looking at your pictures again.
What value are your balance resistors on the two large filter caps?
I found a Pin 2 filament wire of a power tube laying against pin 3...
That said I loaded up with tubes and fired it up only to have
the bias way off... after switching off standby the tubes go blueish followed by a crackling/frying noise... fuse blows...using 3A SloBlo
not sure what is causing this new development.
Darin
As a reminder before installing the tubes throw a meter on the bias supply (or on 220k grid feeders) and crank up the supply all the way (so it reads the highest negative # cutoff) should be at least in the -50 or higher..Then fire it up and start plugging tubes in..After you get them all in let it sit a few.make sure you didn't damage the filament winding in the PT... If the bulb js still dim and the filament winding doesn't get hot on you bring the bias down and get them conducting...Do all this with a load of coarse..Also note you might have damaged some tubes with the shorted filament supply..
Good Luck and congrats on your 1st It's a BOY!!.
Tony
Last edited by talbany on Fri Jul 15, 2011 4:04 pm, edited 2 times in total.
" The psychics on my bench is the same as Dumble'"
As a reminder before installing the tubes throw a meter on the bias supply (or on 220k grid feeders) and crank up the supply all the way (so it reads the highest negative # cutoff) should be at least in the -50 or higher.
will do Tony
and I'm sure I killed that tube
Good Luck and congrats on your 1st Idea It's a BOY!!.Laughing
I was looking at your pictures again.
What value are your balance resistors on the two large filter caps?
Tom 270k 1 watt if your talking the ones below and above the 330uf power caps the rest are 470k 1 watt oxide
Bulb limiter seems to be working tried it with tubes(middle 2 power tubes) on by one
all seemed OK...tried with out the limiter and bias rockets way up..and sizzle sound...no blown fuses yet
not sure whats causing this...bad tubes,bias pot?
any comments would be greatly appreciated.
When you say sizzle, is it more of a loud squeal? and if so could be the OT primaries need to be swapped. If not please explain further. in other words is the sizzle loud? Is your MV all the way down and you still hear it?
The more info you can provide the more likely someone can help you here.
Sizzle is more in the power tubes not through the speaker...I don't think its the OT.Its not a loud sound...
master is down
tubes all check out good
bias pot doesn't seem to work with limiter
no adjustment...using a 60Watt bulb
Voltages are B+ 3..144V B+4..118V B+5..116V
not sure how to proceed..
Darin
Last edited by dcribbs1412 on Sun Jul 17, 2011 2:12 am, edited 1 time in total.
Tony
just so I'm sure what your asking
I have the meter on DC black lead in black bias jack
and red in red jack...I get 0 mv when I sweep the bias pot no tubes in
I hope this is right...
).
It's a BOY!!. 
