[Frihed89]

Quote:

Originally Posted by Bolder /img/forum/go_quote.gif Actually you should be fairly safe with the 6BL7/6BX7 as output tubes. They draw 1.5 amps each. It you use a 6SN7 as a driver, you would be pulling roughly 3.6 amps. The 6AS7 draws 2.5 amps each. Using those tubes would possibly be a problem. I would suggest that you consider completely disconnecting the switch and running the amp just off the regulated 260 V. Dr. Gilmore's simulations show much poorer performance at the higher voltage. The HV doesn't benefit anything and that switch could still fail. See what diodes are in your unit. The diodes in Tyson's are only rated to 1,000 volts and 3 amps. Turn on surge from trying to fill the big caps peak at well above that rating. The same diodes are used in the filament circuit. I think you would want to use something at least double those ratings.

Thanks again. Yes, I like the 6SN7GT as an output tube. That's what you mean by driver? Or did you mean input tube?

OK I will check, but help me find them, please....and thanks again. I peaked in today and wasn't sure what I was looking at.

I need to see if I can hear the difference between high and low power. I have never listened to the difference.

 

[n_maher]

Quote:

Originally Posted by Frihed89 /img/forum/go_quote.gif Thanks again. Yes, I like the 6SN7GT as an output tube. That's what you mean by driver? Or did you mean input tube?

Driver = input, at least typically.

 

[Frihed89]

Can someone point to the rectifier diodes, please, so I can check to see how they are rated?

Thanks.

 

[kevin gilmore]

filament diodes ----- the four big black diodes near the power
switch.

high voltage diodes---- the pair of diodes next to each other
about 1 inch from the back of the board, and about 1.5 inch from
the bottom edge of the board. under the red wires and lower right
from the orange drop.

 

[mrarroyo]

Kevin, any place where I could source four of those diodes (same shape) rated at 25 amps? BTW, at what voltage? Thanks again.

 

[Frihed89]

Quote:

Originally Posted by kevin gilmore /img/forum/go_quote.gif filament diodes ----- the four big black diodes near the power switch. high voltage diodes---- the pair of diodes next to each other about 1 inch from the back of the board, and about 1.5 inch from the bottom edge of the board. under the red wires and lower right from the orange drop.

Thanks very much.

 

[Frihed89]

Quote:

Originally Posted by mrarroyo /img/forum/go_quote.gif Kevin, any place where I could source four of those diodes (same shape) rated at 25 amps? BTW, at what voltage? Thanks again.

Thanks for asking the question, Miguel.

As a side note (you can PM me), do you know if this CANJAM thing is going to come off, or not? The RMAF folks are very excited and seem to have allocated a lot of space, but last time I looked (often) none of the mfrs. had signed up.

 

[Happy Camper]

Are the diode issues caused by the transformer issues or are they underspec'ed?

 

[kevin gilmore]

diodes that get that hot are being pushed way over their specifications.
That has nothing to do with the transformer.

 

[Happy Camper]

Thank you.

 

[Pricklely Peete]

Quote:

Originally Posted by mrarroyo /img/forum/go_quote.gif Kevin, any place where I could source four of those diodes (same shape) rated at 25 amps? BTW, at what voltage? Thanks again.

Have a look here. DIOTEC ELECTRONICS CORPORATION MANUFACTURES TVS DIODES FOR PoE SURGE PROTECTION,SOFT RECOVERY HIGH SPEED LEAD MOUNT/TAB MOUNT/BUTTON DIODES AND RECTIFIERS, PRESS FIT DIODES, DIODE CELLS, AND MORE

Maybe Dr Gilmore can suggest a good alternative from the many models these guys produce.

Peete.

 

[kevin gilmore]

i like the 35a lead mount diodes. Only thing is the diameter of the
wire may not fit in the circuit board.

And actually the 8 amp bridge can be coaxed into there with a bit
of bending.

 

[mrarroyo]

Quote:

Originally Posted by kevin gilmore /img/forum/go_quote.gif i like the 35a lead mount diodes. Only thing is the diameter of the wire may not fit in the circuit board. And actually the 8 amp bridge can be coaxed into there with a bit of bending.

Kevin, electronics is not my thing so sorry for the newby question. The 8 amp bridge has 3 legs, so how do I make it fit when the diodes in my MPX3 have two legs.

BTW, does the 6BL7 uses 2.5 amps or 1.5 amps? I have been told both numbers and I am confused. Thanks.

 

[tkam]

Both 6bl7 and 6bx7 have 1.5A heater requirements.

 

[kevin gilmore]

The 8 amp bridge has 4 wires. A plus wire, a minus wire, and 2 ac wires.

So the plus wire goes to either of the 2 anode connections pointing to the
inside of the chassis, the minus wire goes to either of the 2 cathode
connections at the outer edge of the chassis and the AC wires, one
goes to the front junction of the 2 diodes, and the other goes to the
back junction of the 2 diodes.

like this