Teeco 610D conversion

[angelodp]

Sounds good, I will do a graphic mock up first and report back. Thanks guys. Stay safe.

Ange

[Phil_S]

Rob Robinette has layouts for Model 26 and 5B3 on his web page. The 5B3 has voltages indicated and he says it is identical to the 5A3 except mounted in a different cab. You might benefit from a peek.

[angelodp]

Phil, excellent intel, thanks .... will do

[angelodp]

Hi, I have been eliminating various components that do not add to this amp and were used in the former circuit. I am eking out some useable amp tone and breakup at full volume. I know it will be better to have the schematic (working on it), but if you are able to have a gander and make any additional suggestions. The treble and bass pots are not as useable as one might like. Basically with the amp dimed on all pots I do get a useable tone. I am still moving towards a 5C3 rebuild, but am curious if anyone sees any quick changes that would improve tone and more early breakup.

[angelodp]

Sorry that last layout had an error - now fixed

[angelodp]

No takers, I know its a spaghetti plate. Working on the schematic, but its slow going. I am surprised at how good this is for now. Just want to have the tone stack more subtle.
I added a 33k to the input, just because. I left the input cap there for now. I also have a spst that shorts the input of the Treble and Bass input, kind of useful.

[angelodp]

I have some readings and a question.

The amp has 6V6 tubes, older and probably mis-matched. They share a common cathode resistor. Cathode is elevated at the heater?

Readings for the 6V6 tubes


Tube 1 140 ohms, 7.6 volt drop, 54mA, 320PV, 17.2W

Tube 2 160 ohms, 3.28 volt drop, 20mA, 324PV, 6.5W

I then flopped the tubes

Tube 1 142 ohms, 6.7 volt drop, 47mA, 316PV, 14.8W

Tube 2 160 ohms, 4.6 volt drop, 28mA, 319PV, 8.9W

I thought that the flopping of tubes would reveal that one tube was way off in value, but it seems that there is something else going on.
Can you guys chime in.

[martin manning]

You mean the heater string is elevated at the 6V6 cathodes, I think.

You say the 6V6's share a common cathode resistor but report two different resistor values? I'm not understanding that.

[angelodp]

The resistor values were for each side of the transformer.

Common cathode R is 260 ohms

[martin manning]

Ok, I see. So:

Tube 1 in socket 1 140 ohms, 7.6 volt drop, 54mA, 320PV, 17.2W

Tube 2 in socket 2 160 ohms, 3.28 volt drop, 20mA, 324PV, 6.5W

exchanging tubes:

Tube 2 in socket 1 142 ohms, 6.7 volt drop, 47mA, 316PV, 14.8W

Tube 1 in socket 2 160 ohms, 4.6 volt drop, 28mA, 319PV, 8.9W

My first suspicion is that socket 1 may have a leaking coupling cap connected to its grid lug. Pull the 6V6's out, power up, and check the voltages on pins 3, 4, and 5.

[angelodp]

Hi Martin - readings to ground all Volts


PIN3 PIN4 PIN5

socket 1 435 408 8

socket 2 434 407 .6

[martin manning]

The third number is pin 5? That should be zero, or very close to zero. Those are V? mV?

[angelodp]

Yes third number is pin 5 and yes in volts. So leaky caps, should replace right.

Ange

[martin manning]

Absolutely.

[angelodp]

Yes did the trick. I only have one .02 600v 715 on hand

Now

Tube1 Socket 1 142ohms, VD 5, 35mA, 343PV, 11.14W

Tube2 Socket 2 160ohms, VD 5.2, 32mA, 343PV, 10.9W

I am going to finish replacing the old wax couplers

Thanks Martin, much appreciated.