Blonde Tremolux questions

Bandmaster, Bassman, Champ, Concert, Deluxe, Harvard, Princeton, Pro, Super, Tremolux, Twin, Vibrasonic, Vibrolux, Vibroverb and others

Blonde Tremolux questions

Postby Smolder on Tue Feb 21, 2017 2:54 am

Hi all... looking for some expert input. I just snagged this head... it was billed as a '61. Blond tolex with brown/rust grill cloth. It has a repro handle and no back.

Chassis serial number is 01523 - which would indicate 1962
Tube chart says 6G9-A (I know this can be suspect)
Output transformer... 125A7A 606145
Choke... 125C3A 606142
Power transformer 125P26A 606314

The choke and OT could be old stock in a '63 amp... or could be replacements. The PT is clearly '63.

The OT does not seem to be correct for this amp, but I'm not sure. It seems in that era there were lots of build variances... and data via search is ambiguous as to the load being 4 or 8.

It's in good but not great shape. It sounds really good and the term sounds good. All blue molded caps are still there.

Any thoughts? Any help or insights would be greatly appreciated.
Smolder
Peasant
 
Posts: 23
Joined: Sat Jul 30, 2011 3:54 pm

Re: Blonde Tremolux questions

Postby tubeswell on Tue Feb 21, 2017 5:01 am

pics?

The 125A7A OT is shown on the brown vibrolux schematic (6G11-A)
He who dies with the most tubes... wins.
tubeswell
Peasant
 
Posts: 41
Joined: Thu Dec 15, 2011 2:26 pm

Re: Blonde Tremolux questions

Postby Smolder on Tue Feb 21, 2017 5:16 am

tubeswell wrote:pics?

The 125A7A OT is shown on the brown vibrolux schematic (6G11-A)


Will get pics asap. I think I bought a bit of a mutt. According to all the transformer configuration (by number, not date) and chassis charts, none of these should be in the same amp. The 125P26A replaced the 125P6A in the blackface Tremolux.

I'll also pull the chassis and check the circuit against the A and B schematics available on Ampwares.
Smolder
Peasant
 
Posts: 23
Joined: Sat Jul 30, 2011 3:54 pm

Re: Blonde Tremolux questions

Postby Smolder on Wed Feb 22, 2017 6:15 pm

8) oPics...

Researching this for the last twenty four hours... I'm understanding that Fender, in '61-63 was not the high consistency well oiled factory that it became in the mid sixties... so variances were much more common.

The chassis being from '62, and the OT and Choke dating to '61 was a result of random use of parts vs first in first out.

While I've read the OT 125A6A is 4 ohm, and the 125A7A is 8 ohm, I'm finding conflicting transformer tables.

I'm speculating that the PT is a replacement... basically the same part but with a slight part number number change for the transition to AB763 circuit. I've not yet pulled the chassis to check if it truly is a 6G9-A or B, but will this evening. I'm using schematics from Ampwares as a reference.

Any insights or corrections to my deductions appreciated.

I plan to give it a full check for operating voltages, a filter cap refresh, have a replacement back panel made, and touch up the tolex. I typically don't see front corner cuts on stock Fender tolex so I suspect that it may have been recovered... and the grill cloth looks pretty new. I'll check staples, etc, when I pull the chassis. It's obvious the badge screws are not original.


Image

Image

Image

Image

Image
Smolder
Peasant
 
Posts: 23
Joined: Sat Jul 30, 2011 3:54 pm

Re: Blonde Tremolux questions

Postby Smolder on Wed Feb 22, 2017 9:07 pm

Digging in... the OT and the PT have either been pulled and put back, but more likely are not original to the amp. The splicing work and the soldering is obviously not from the factory.

The overall circuit composition is 6G9-A. However what would be a .00025 cap coming off of the PI circuit is a .001 as it is on the B schematic.
Smolder
Peasant
 
Posts: 23
Joined: Sat Jul 30, 2011 3:54 pm

Re: Blonde Tremolux questions

Postby Gasstationman on Wed Feb 22, 2017 10:00 pm

The OT is for the 6G9-A with a 1*10 8ohm tonering cab and is correct and the PT is from a Blackface. You have about 50V higher HT than original. Not much to worry about. I guess the amp sounds good as it is. Give the amp a good cleanup on the inside and it will sound fantastic.
Good luck!
Anders Gson
Gasstationman
Certified
 
Posts: 143
Joined: Tue Oct 14, 2008 8:53 pm
Location: Sweden

Re: Blonde Tremolux questions

Postby Smolder on Wed Feb 22, 2017 10:15 pm

Thanks gastationman. The bias circuit shows the B as 11 volts higher. I replaced the two odd caps in the bright channel tone stack with some old stock blue cylinders I had here (B values). I'm swapping out the electrolytics. I then plan to drop the bias probe on just to see where that falls and check other voltages.
Smolder
Peasant
 
Posts: 23
Joined: Sat Jul 30, 2011 3:54 pm

Re: Blonde Tremolux questions

Postby tubeswell on Wed Feb 22, 2017 11:21 pm

Looks nice inside
He who dies with the most tubes... wins.
tubeswell
Peasant
 
Posts: 41
Joined: Thu Dec 15, 2011 2:26 pm

Re: Blonde Tremolux questions

Postby Smolder on Thu Feb 23, 2017 12:31 pm

I'm tempted to find a current replacement for the PT that has the right voltage. Then offer the one installed for sale to someone restoring a BF amp with the period correct unit. I doubt it will devalue this blonde tremolux... and might be zero out of pocket cost to me. Thoughts?
Smolder
Peasant
 
Posts: 23
Joined: Sat Jul 30, 2011 3:54 pm

Re: Blonde Tremolux questions

Postby Gasstationman on Thu Feb 23, 2017 11:12 pm

Look for a PT for 18W Marshall. Very close in specs, Same coresize and fits like a glove. Magnetic Components and Hammond have them with 5/6.3V winding for rectifier tube. One bad thing, no bell on the inside.
Anders Gson
Gasstationman
Certified
 
Posts: 143
Joined: Tue Oct 14, 2008 8:53 pm
Location: Sweden

Re: Blonde Tremolux questions

Postby Smolder on Thu Feb 23, 2017 11:41 pm

Gasstationman wrote:Look for a PT for 18W Marshall. Very close in specs, Same coresize and fits like a glove. Magnetic Components and Hammond have them with 5/6.3V winding for rectifier tube. One bad thing, no bell on the inside.



Interesting. I have one sitting here on the shelf... hmmm.
Smolder
Peasant
 
Posts: 23
Joined: Sat Jul 30, 2011 3:54 pm

Re: Blonde Tremolux questions

Postby spoond on Tue Feb 28, 2017 8:05 pm

Serial number and EIA codes on the components date this amp to late 1961 or early 1962. Looks like original OT and choke, PT definitely not original. The output is for 8 ohm impedance, so this one was a 6G9-A model, and would have had the smaller Tone Ring cabinet with a single 10 inch speaker. It could use a little polishing up, and maybe a new repro cap barn.

I have had the good fortune to own a couple of these amps, with their awesome back porch tone at relatively low volume. This one is a player.

As for what to do, the PT voltage isn't really a problem. If you look hard you might find a correct PT for this amp on the fleeb, but I would concentrate on finding a not-too-beat blonde speaker cab with some original hardware and a tone ring (the repro tilt legs stick out like a sore thumb), and a vintage Jensen P10Q (find a nice organ pull, nobody will see it inside the cab). On the head, check all voltages etc. and use a chopstick to find any clinker resistors. Those blue molded caps almost never fail, but (even if they have been changed) replace ALL the electrolytic caps to correct new Sprague Atoms--bias cap and bypass caps on the board, and caps under the barn.
spoond
Knight
 
Posts: 1704
Joined: Wed Sep 20, 2006 4:00 pm
Location: seattle, wa


Return to Fender

Who is online

Users browsing this forum: No registered users and 3 guests