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my plexi cut out tonight at practice...nothing thru either channel...

I noticed last week that volume seemed up and down with some static...

preamp tube right?

Always suspect tubes on a working amp. So probably. Power still on?

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

yep..power still on...at least the jewel is lit.
just no sound at all
I used to have a spare 12AX7 kicking around, but I don't know where it is...I'll pick one up this week and report back...
gig on Friday...haha always the way

If you were to measure voltages you would know right away. But you can visually inspect them look for white spots inside the tube, or no heater glow or a cold (temperature) tube.
Replace one at a time. Check to see of it works,if not, replace original tube and move to the next one.
Good luck

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

bought a tube yesterday...this morning before I head to work I pulled the amp apart quick...no tube glow at all except for rectifier...

no voltage at all on the heaters...and...unless I'm doing it wrong, (I haven't pulled out my manual, but I think my knowledge isn't that far off)...B+ is 978V

I'm thinking power tranny? it's just over two yrs old...

thoughts?

sick PT would be rare indeed. You will need to pull all the tubes and test all the AC voltage secondaries under no load. and go from there.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Here is a great guide to help you track down the problem...

http://www.geofex.com/ampdbug/ampdebug.htm

Hope you get your baby fixed soon!

Thx dtp...ill check that later tonight...

Just had a few minutes...so i pulled it apart and started back in the manual at the testing page...

With no rectifier in place i have 320V going to pins 1&7

With the rectifier in...that doesnt change but rhe B+ is 969V, heaters are good...
Plate voltage on pre amps is 760V and power is 960

So...those numbers dont match...so...where to now?

Those numbers don't make sense. Do you know your multimeter is working as it should? Does it have a new 9V battery in it?

Is there a ground wire/connection missing somewhere?

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Are you sure those aren't mV (millivolts?)

That would make sense if there is no voltage at all.

There is no way 320V AC can get to those DC voltage levels (assuming those were DC readings).

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Well...i would assume if some numbers were right then the battery isnt the issue

I'll root around the ground wires...seems weird something would just come loose...but, weirder things have happened

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Idiot edit...
While the 320V is correct...i didnt switch from AC to DC for the other readings...

Ill recheck tomorrow...in the RIGHT setting...forgive my stupidity

Is it 320AC from each pin to ground, i.e. 640 across them?

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

i didn't measure across, i measured to Ground...when i first built it the reading was 316...so i didn't think it was too far off...

ok dokey...

so...with the multi-meter in THE RIGHT MODE (idiot)
my numbers are good for the rectifier and B+

when it comes to measuring the rest...not so good...i'm thinking i've lost a ground...
pins 1 and 6 on the pre-amps are showing 360V, and no reading at all on pin 3

i did notice that my B+ didn't drop with all the tubes in place...with only the rectifier i got about 420V, and it didn't drop with all the tubes in place

i would guess it would be the main line to the chassis ground, otherwise they all wouldn't be off the same...right?

in doing the testing...how hard is this on the tubes?

Tubes are fine

It's most likely the ground from the turret board (power side or preamp side to ground). The wire may be broken internally, at the turret or at the ground lug. Look carefully

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Measure the resistance from preamp end to ground. Should be less than .2 ohms

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

So...stephen...i got 0.6 a little higher but should be ok...

Using the continuity function it appears everything is grounded...unless this isnt an 'approved' method of checking connections...i clamped one probe to to ground lug, the used to other for ground turrets...

Next i guess i try that again with the components to see whats not passing

Thoughts?

should be Ok but the symptom is that ground from board. go back to the cathode resistors and meaure from the lead to ground. Measure along the ground bus bar and see if there is a break in it.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

i did do the ground bus...i'll move on to the resistors at lunch