Bassman Micro startup issues

[EricR]

I built up a bassman Micro LTP from robrobinette design. I turn it on and the light turns on, all tubes glow but no sound to the speaker. All heater pins are getting power. I'm getting power to plate pins 1 and 6 as well at cathode pins 3 and 8 on all tubes. One thing I don't get is hearing the pop when probing the grid on pins 2 and 7. I do get a pop from the speaker when probing the plate pins 1 and 6 on all tunes.

I've made sure speaker, speaker cable, guitar cable and guitar all work with another amp. Triple checked I have continuity on all jumper cables in the back and solder joints. Pulled out the board to make sure everything is correct. Any thoughts on what to check next? Thank you for your time.

[SILVERGUN]

post a schematic (as built), all voltages from all tube pins and hi-rez gut shots
The good news is, there aint a lot there to be wrong

[EricR]

I did delete the post phase inverter master volume, no fx loop and did a bright normal switch.

[EricR]

So Rectifer pin 3 is 314.
V4 pin 1 is 311, pin 2 is 0, 3 is 12, 6 is 311, 7 is 0 and 8 is 13.2.
V3 pin 1 is 286, 2 is 0, 3 is 14, 6 is 312, 7 is 0 and 8 is 14.
V2 1 is 150, 2 is 0, 3 is .8, 6 is 257, 7 is 150 and 8 is 157
V1 1 is 129, 2 is 0, 3 is 1, 6 is 129, 7 is 0 and 8 is 1.

All heater pins are 5.7

[SILVERGUN]

Is there a connection to ground from the point circled in red in my snip?

EDIT - just saw your voltages - of course there is, otherwise V3 wouldn't be conducting


BUT, you should be seeing some voltage on pins 2 and 7

[EricR]

Is there a connection to ground from the point circled in red in my snip?

EDIT - just saw your voltages - of course there is, otherwise V3 wouldn't be conducting


BUT, you should be seeing some voltage on pins 2 and 7

So 2 and 7 on v4 and v1 are .004 on v3 I have .20 abd v2 pin 2 I have to go to mV and get .2.

On robs site for troubleshooting I think it says I should have minimal voltage there. The one that get me is he says I should get a pop sound when probing 2 and 7 but that happens on 1 and 6 and not with 2 and 7

That spot has a jumper that hoes to the top of neg. Feedback then to number 3 on presence then to number 1 on mids with 4.7k resistor and then to ground

[SILVERGUN]

Re-measure pins 2 and 7 on V3 for DCV (V3 being the PI tube)

[SILVERGUN]

If still nothing check the resistor values in that part of the circuit...whatchu got?

[EricR]

Re-measure pins 2 and 7 on V3 for DCV (V3 being the PI tube)

I get .19 DC on 2 and 7 V3.

[SILVERGUN]

check the resistor values

[EricR]

check the resistor values

.991 and .989 on 2mill scale so close to 1mill. The tail that leads into that reads 6.8k

[SILVERGUN]

the brown one too

[EricR]

the brown one too

469k.

[SILVERGUN]

the brown one too

469k.

You don't want the K part

[EricR]

the brown one too

469k.

You don't want the K part

ohh I swear I checked them over 3 times. Good eye. Let me change it and see. Thanks!!Ill report back

[SILVERGUN]

 

[EricR]

Success!! Silvergun thank you so much. I think I would have just kept overlooking that. Well with all the reading I learned a lot more on tube amps. So we will take it as a positive. Such a lame mistake.

[SILVERGUN]

EricR, you are so welcome....it's why we hang out here. shooter was just about to step in but I didn't need him this time. I had all the fun without him.
It's actually a pretty common mistake. You did a good job of giving me what I needed.
 

[EricR]

EricR, you are so welcome....it's why we hang out here. shooter was just about to step in but I didn't need him this time. I had all the fun without him.
It's actually a pretty common mistake. You did a good job of giving me what I needed.
 

Well it is very much appreciated. 2nd amp done. I was a auto mechanic in my 20s and love to tinker. This is my 2nd amp build now. So much fun even with the hiccup. I'm eyeing sluckeys Vox 15 with vib and trem. But for now its time to play with this one. 

[shooter]

 
I was lerkin but the brain just wasn't doing tech today, did a morning shift at the BeerBaitNgas n got my soul singin....

[EricR]

Thanks again. Little photo of the setup.

[sluckey]

Is that a real spittoon on the hearth? I remember one in grampa's house. He was a dipper. I was told that in his younger days he could hit it from 8 feet away. I never saw it. Just a big mess all around it. In his later years he could barely hit the fireplace!

Thanks for the memory.

[shooter]

wow, must be something in the air, The fireplace looks a LOT like the one I had in Ft. Wayne, IN.  that goes back 40yrs now!


in case SG missed the reference

 

[EricR]

Is that a real spittoon on the hearth? I remember one in grampa's house. He was a dipper. I was told that in his younger days he could hit it from 8 feet away. I never saw it. Just a big mess all around it. In his later years he could barely hit the fireplace!

Thanks for the memory.

Ha it is. My grandparents had one back in the day. We rented this old 70s house up in Tahoe. Been having so much fun up here. Skiing, music and tinkering. I'm eying you Vox 15 next man! Looks like a fun build.