pentaboost ?'s

[PRR]

> I mis read the dmm

Slow down, you will save time. (Yours and everybody's!!)

> I am going to have to take a nap lol

Very smart plan.

aj> Spec above suggests the filament is 25ohm hot -  it will be lower than that when cold.
lsg> reading 9.87 or 10 k
lsg> 11 ohms not Kilo ohms

25 Ohms hot may be 10 Ohms cold. We can presume this filament is good.

Can you wire JUST the filament to a single AA cell battery? It should light-up like a dim flashlight bulb (the old kind that broke a lot, not these new LED flashlight bulbs). It may be super-dim, have a third hand to turn off room light.

[LightSoundGeometry]

> I mis read the dmm

Slow down, you will save time. (Yours and everybody's!!)

> I am going to have to take a nap lol

Very smart plan.

aj> Spec above suggests the filament is 25ohm hot -  it will be lower than that when cold.
lsg> reading 9.87 or 10 k
lsg> 11 ohms not Kilo ohms

25 Ohms hot may be 10 Ohms cold. We can presume this filament is good.

Can you wire JUST the filament to a single AA cell battery? It should light-up like a dim flashlight bulb (the old kind that broke a lot, not these new LED flashlight bulbs). It may be super-dim, have a third hand to turn off room light.

will set this up with pics in a few moments ..brewing coffee haha, despite sagacious advice heard
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okay, give me some time to get everything uploaded as I am doing this a little at a time:

AA reading for E, I and R

and yes I know the tube is socketed on a BB ..haha ..the leads are so short I wanted to to make sure I have conductivity to the device.




first tube did not glow, no heat dissipation and meter read 1.4 V3 to common.

let's try the RCA tube with better leads and cool box - I had a rat terrier who looked very similar to the rca puppy

ohmmeter reads from pin 3 to 5 :



I put a box over the board and looked with a magnifying glass, i cant see anything lighting up. hopefully its connected properly for the test.

[LightSoundGeometry]

Do check what Paul said, since the tube could be toast, but I'm still a little concerned with that oh-so-low plate voltage.  Try pulling the transistor (it's in a socket, right?) and putting a 100K resistor in its place (i.e. from 12V to pin 1).  This now turns it into the much simpler Pentaboost Mk I.  (No, really.)  What's the voltage at pin 1 now?  And more to the point (if we're lucky), how's it sound at the output jack?

nothing..I cant figure it out!







i see the cap off the output is parallel and switched, still nothing ..same results

[idiot savant]

nothing..I cant figure it out!



i see the cap off the output is parallel and switched, still nothing ..same results

Give this a shot. No part of that output cap should be grounded, and the load resistor should go to V+.

[amptramp]

The filaments for these 1.25 volt tubes do not show visible light - you may get a dull glow with no ambient light but not something you can see otherwise.

[LightSoundGeometry]

savant will give your idea a try.

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doesnt work at all ..no mater how many combinations I try

all 5 of my tubes cant be bad? a few have correct filament ohms

youu guys sure the circuit is drawn up right for a tube amp circuit lol ?