Early '60 Brown Super

[David Root]

Our local pro guitar repair guy, Fast Eddie Kasmir, showed me an amp while I was in his shop y'day to get my ES125TC worked on. Turns out it's a March 1960 Super. JC on the tube sheet. The underside of the chassis is completely unmolested, see pic. It need some tubes and checking out the filter caps, I had to replace two leakers, probably should change them all out.

I had not seen the so-called "pink Tolex" before but it looks a bit like a faded brown. You don't see that many unmolested 1960 chassis these days. The cabinet has late '59 P10Rs in it. The OT has been replaced with a correct '66 unit but the PT is an original Triad 8087.

Just thought folks might be interested in this. Just look at all them luvly Astrons!

Oh, there is a phone jack on the back apron of the chassis labeled Pulse Adj. and is not shown on the 6G4 schematic. It's connected to the speaker jack and I assume it's for checking the tremelo functions. Anyone know for sure?

[martin manning]

Nice, David! angelodp has a 6G4 like that (not a 6G4-A which has a different vibrato circuit). I don't understand why that jack you mention would be connected to the speaker out. The vibrato/tremolo isn't anywhere near that and there is nothing adjustable about it, is there?

[Reeltarded]

Would you guys like to look at a white Twin?

[David Root]

Martin, well I thought since the tremelo modifies the signal that shows up at the speaker jack, it would also be at this strange jack. It's wired to the speaker jack with 22ga wire so it's not been modified for use with an extension cabinet.

What else might it be??

Reeltarded, show us the white Twin!!

[martin manning]

Martin, well I thought since the tremelo modifies the signal that shows up at the speaker jack, it would also be at this strange jack. It's wired to the speaker jack with 22ga wire so it's not been modified for use with an extension cabinet.

What else might it be??

I recall reading somewhere that the earliest versions of that tremolo had an adjustment feature that was later eliminated (I just looked in "The Soul of Tone," and it doesn't seem to be there). It could be that the hole for that was indeed filled with another speaker jack.

[David Root]

I'll check the actual layout against the 6G4 schematic. Perhaps it originally had a full size trimpot in it.

[Firestorm]

I've never heard of anyone who has seen any Fender amp with a Pulse Adjust control installed (nor for that matter, anyone who is really sure what it was supposed to do). Models with that backplate apparently shipped with the Pulse Adj hole plugged. Whatever it was, it must have had some very serious drawback (or been completely worthless).

[billyz]

That is a real purdy one. Has the Volume control in the middle ? Usually those cabs have a sharper radius on the edges too. I think a blonde bandmaster I once owned had the pulse adjustment too. But it was not connected or used.

[David Root]

Yup, it's the reverse controls model. The cab has the sharp unrouted edge on the cabinet too.

The fixed bias is supposed to give -55V but I get -60V or so, too cold for the average power tube. Resistor drift.

SOoooo, I decided to use the Pulse adjust hole for a 10K bias pot, put a piece of blue tape over the word Pulse and write Bias on it, unsolder one end of the 10K bias resistor, and put a 220K 1/4W across pins 1 & 2 of the pot to save the tubes and that expensive '66 OT if the wiper ever goes out. Will have to mess with the tail resistor too I guess, and/or add a resistor ahead of the pot.

Dunno why it took me several days to figure that out!