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Merry Christmas !!!

It's alive, my first kit (plexi + 6v6) and no smoke or flames. ( credit goes to Steve for his excellent documentation )

The problem I'm having is that I don't seem to be getting any drive out of V2 possibly because V2's voltages are about 1/2 of what they should be.

Any suggestions on how to bring those voltages back in line ??


V1 - P1= 145, P3=.87, P6=145, P8=.95
V2 - P1= 93.6, P3=2.5(without boost)4.4 (with boost), P6=252, P8=102
V3 - P1= 183, P2=88, P3=89, P6=187, P7=60.5, P8=89

V4 - P3=11, P7=333, P9=320
V5 - P3=11, P7=330, P9=321

V6 - P1=307, P3=344, P7=307

6V6 tubes not measured

Check all component values on the board and re-trace all leads from the bottom of the board to the tube pins - carefully, with something other than your finger. With voltages that far off you have a lead in the wrong place or a wrong value component...

Post some pics and we'll look at it.

Merry Christmas and good luck!!

Also, check that the cathode end is grounded and the 100K resistor from pin 6 - 1 and back to 7 is installed correctly. Pin 6 voltage looks reasonable bit pin 1 is not. Measure resistance of that resistor too.

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

Thanks for your quick response.

I double checked all connections and values as per the layout and they seem OK.

I'll post some pictures soon.

Brian

some pictures....

Please let me know if I'v missed something

thanks...

http://s437.photobucket.com/albums/qq93 ... _1771s.jpg

http://s437.photobucket.com/albums/qq93 ... _1774s.jpg

http://s437.photobucket.com/albums/qq93 ... G_1775.jpg

http://s437.photobucket.com/albums/qq93 ... _1776s.jpg

It all looks hooked up correctly. Tubes in?

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

Hey Steve,

Tubes are in and all things seems to work - boost, switching between power tubes etc.

- in the drive channel, there is just very little drive even with the volume and gain "dimed".

- overall both channels seem a little quieter than I expected. ( compared to my Champ and another 18watter I have)

- also the tone controls seem to adjust the correct frequencies just the change is very subtle. I double checked the wiring and it seems OK, could that also be a result of a weak V2 ?

cheers,

Brian

Always a good test to swap tubes & check again.

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

I did swap preamp tubes ( JJ and Tung Sols) but didn't switch the power tubes. Is that worth trying ??

Probably not going to change V2 voltages. Is the other channel working?

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

Send a pic of the boost switch area. Can't see clearly. To what lead does the green jumper from pin 3 go??

thanks - I appreciate your assistance

Q: To what lead does the green jumper from pin 3 go??
A: Center postion of the boost toogle switch.

Q: Is the other channel working?
A: yes, although it seems a bit quiet as compared to my champ or my other 18 watter I have, but it's working and it's tone control seems to respong as you would expect.

Since the difference in tone is very subtle on the drive channel, do you think a wiring mistake their would affect the voltages on V2 ??

picture showing the boost switch...
http://s437.photobucket.com/albums/qq93 ... _1777s.jpg

Maybe I'm missing something but the boost requires a cap, not just a resistor. Counting from the corner - 5th turret (with blue lead) should have a cap in addition to the resistor.

But don't think that's your voltage problem. Guess I missed this yesterday.

The resource doc I'm looking at for a v6 (and it's the same on the sIII) shows two 0.0047 caps and then the lead to the normal volume channel?? Third empty turret from top corner?? The brown lead in your photo appears to be coming from the 4th turrent, and that should have voltage jumpered from the 16uf cap. Stephen's docs shows that node at 272 volts. It shouldn't have a lead...

Maybe somebody can check that but doesn't look correct to me and that would certainly lower the voltage for V2 pin 6 (and it's the same node for the top end of the two 100K resistors). Again, should be about 272 v.

On the Plexi model, this is a clean boost, you can add a cap for more dirt.

V2 P6=252v . It's pin 1 that's way off. So, measure the resistance of that 100K resisitor from pin 6 to 1, confirm the cathode resistors are 0 ohms to ground and they are the correct resistance.

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

The 100K resistor (pin 1 to 6) measures 99.6K.
The other cathode resistors (R9 and R34) are also in range and connect directly to ground.

As a test I put a second 100K resistor across pins 1 and 6 ( it then measured about 54K) but the voltage only went up a couple of volts.

That's as brave as I wanted to be. Please let me know if there are other similar things you want me to try.

Brian

more measured values...

P3 on V2 to ground
- 2.7K and 1.4K with boost enabled

P1 on V2 to B+ on the standby switch 111.3K

Try Reheating/reflow the solder joint on pin 1.

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

it's working better now.

I did 2 things, resoldered all pins on V2 and swapped tubes on V1 and V2.

Now the voltages on V2 are OK (see below), but V1 P1 = 58V, so I put another tube into V1 and it's voltages are back in line. What's weird about this is that I swapped the Tung_sols for JJ's a while back and it didn't make a difference. Perhaps I had several issues combined.

V2 - P1= 157, P3=1.1(without boost)1.4 (with boost), P6=250, P8=158

Also, you mentioned that you could add a cap onto the boost switch to add a lttle dirt, is that info in your book ???


thanks for your help.

That's better news. I suspected the tube esprcially when pin 6 was correct and the cathode resistors were grounded. Especially if that resistor was good and the solder joints were good.


You can put a cap across that second boost resistor . The sIII bosst cap is 25uf, but you can try anything from 1uf to 25uf in the same position.

It's not in the book.

Let us know how it all works now.

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