Issues with a submini tube amp

[The_Armadillo]

I read it directly from the source (where I've got all the plate resistors connected to on the board).

I tried waiting a bit for the the tubes to warm up to read the voltages again, but the voltage actually went UP! It was first around 170-180v (normal for startup before now), then it started to rise all the way up to 197v!

I've looked and looked for any sort of short, but have found none. How likely is it that the tube, or maybe one half, is bad? I got the tube from smallbear a while ago..

[The_Armadillo]

Wow. I feel stupid. I forgot to connect the heaters to their voltage. Stupid, stupid, stupid...

Got new voltages:

B2- 130.2v

1- 117
2- 116.8
3- 82.3
4- 0.00
5- 0.00
6- 82.3
7- 0.564
8- 128.4

The voltages seem much more reasonable on the second half of the tube, but I still haven't found any source for the almost identical plate (1) and grid (2) voltages...

[iccaros]

PM me and I can send you a tube or two so you can test if you have a bad tube..
any audio?

[The_Armadillo]

That would be really awesome.

I've got audio up to the grid of the second half (pin 7). Using an old Multi-Moog as a test oscillator works surprisingly well. Just bypass the loudness contour and wham-bam! Constant oscillator!

I'm guessing that this is because I got some sort of short thing going on (its quieter on the plate (1) than on the grid(2)), and then something screwy with the tube that shows up within reason on voltages but isn't passing signal.

Do you think you could take a look at my layout and see if it checks out?

[iccaros]

can you scan your layout? I'll take a look

[The_Armadillo]

I cant tonight, but I will be able to by tomorrow. I'll just post the actual layout from DIYLC. I only took a picture of it because I was (and still am) away from the computer that its stored on.

[The_Armadillo]

Layout for the preamp and phase splitter.


Layout for the power section.


I did it in two parts and printed onto the same page for the etching. I don't really know why, but I did!

[The_Armadillo]

Ok, so I got the tubes in the mail yesterday (thank you so much!) and plugged on into the circuit in place of the seemingly bad 6111. When I first opened the package, I noticed that the new ones had quite beefier guts inside. Hmm... popped out the old, in with the new (socketed, of course). I took a look at the stamp on the old tube and I found 6110 staring back at me.

Apparently, when I put the tube in, I neglected to look at the stamp. When it was on the board, all one could see was 611(other tube hiding the rest) or it was facing down.

Point is, the amp now works through the speaker and everything. I just need to update the 5840s with 5902s. Ive got sound, but only when its dimed.

Thank you for all the help!