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Post subject: '61 Brownface Pro - cosmetically refurbish or not
Posted: Sat Sep 23, 2017 5:05 pm
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ImageI recently inherited this brownface Pro from an old band mate. It is in pretty rough shape. I am definitely going to add the correct handle just for safety sake. Beyond that, should I replace the grill cloth? I was going to go with period correct Oxblood. Some idiot painted the underscore on the logo White. It is also very scratched up. I ordered a replacement with the black underscore which I believe is period correct. Should I replace it, or try and clean the white paint out of the original? Despite the condition of the tolex, I'm going to try and clean it, although I was considering having it professionally recovered. So what are your opinions on whether I should do this work or not? By the way the amp sounds great even with a unknown speaker in it. A tech friend called it a POS. I just received a 1961 Jensen P15N which I will put in tomorrow.

(EDIT: I have added more pics. Does the inside look correct?)

More pictures at http://Finlayson.TV/Pro.html


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Post subject: Re: '61 Brownface Pro - cosmetically refurbish or not
Posted: Sun Sep 24, 2017 6:49 pm
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Finsnake, welcome to the Forum! :)

From the looks of the stampings on the choke & output transformers --- these parts have been replaced. AFAIK, the Pro brownface era lasted from 1960-63. The choke appears to have Schumacher (606) date of 1966, 16th week (616). And the output transformers looks like 1965 (39th week).

The grid stopper resistors are also post original, grey-green-red = 8500 ohm resistors. AFAIK, the 6G5 Pro circuit had no grid stopper resistors, from Fender. So, that kinda tells you something. Grid stoppers are used to help stop unstable oscillations amplifying in amps (esp high frequency instabilities). This large resistance, as normal Fender grid stoppers for 6L6GC amps is 1500 ohms. Plus, the replaced choke and output transformer may mean this amp may have went unstable and blew some parts, in its past.

The speaker is an aftermarket Rola (manufacturer #285), ceramic magnet speaker. Which may not necessarily make it a bad speaker. As Rola had a wide range of bad-to-good speakers in the 1960s. It appeared to be made in 1964, 4th week (404). I have no experience with the 15-inch Rola, of this era.

The circuit looks original, except for replaced bypass caps, added grid stoppers, and replaced filter caps in bias supply. Do you have photos of the main filter caps, under the doghouse?

http://ampwares.com/schematics/pro_6g5.pdf

FWIW... here's some photos of my 1962 Pro. It's a great amp. The transition era Pro is well worth full restoration, IMHO.

Image

Image

Image

Image

Image


Last edited by BMW2002Ti on Sun Sep 24, 2017 7:42 pm, edited 1 time in total.

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Post subject: Re: '61 Brownface Pro - cosmetically refurbish or not
Posted: Sun Sep 24, 2017 6:59 pm
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A few more photos. :mrgreen:

Image

Image

Image

Image

Image


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Post subject: Re: '61 Brownface Pro - cosmetically refurbish or not
Posted: Sun Sep 24, 2017 9:38 pm
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This is a response to both of the very helpful responses I have received so far. Thanks very much.

I am getting pretty familiar with the dating methods. And although my tube chart is totally screwed, I did find a chart of serial numbers. My serial number is in the low 04000 range, putting it squarely in the middle of 61.

The Rola company didn't start using the 285 manufacturer code until the early '70s, so I suspect the speaker is from '74. I haven't found anything that speaks highly of their guitar speakers, other than their relationship with Jensen, so out it goes (although it sounds pretty good!)

I am a novice at taking amps apart, but I have been a recording engineer since 77, so I know that there is stuff in there that can kill ya, and I thought I had to go through the other circuit board to get to the doghouse. (DUH!)

After seeing the pics, I realized that I just had to unscrew four screws and pop the lid. I added a pic.

Anyway, from your assessments so far, I think the insides are cool. I believe I have a transition period 1961 6G5-A, that at one point suffered a pretty catastrophic event requiring the replacement of all three transformers, and I would guess the first power tube socket. The repair tech seems to have tried to remain true to the period, or the event may have just happened that long ago. I am a little concerned that they are not the identical model numbers, but my knowledge comes to a screeching halt right about there.

Then at some other point, someone went in and carefully recapped what was necessary, added the three prong plug, etc. I am assuming the speaker was blown at some point and they grabbed an organ speaker they had lying around and threw it in.

I agree that my tolex doesn't look that bad, and I have made one pass with the toothbrush and dishwashing liquid. I may try some paint removing techniques I learned elsewhere on a few spots, after testing on the back.

I am relatively sure that the grill cloth was once oxblood, it is just VERY messed up and faded. It certainly was not the wheat, although I must admit your amp is gorgeous.

I never even noticed that the logo was once shiny! It's so scratched I thought it was brushed steel.

I have decided to build a new baffle, cover it in the oxblood, put in the Jensen P15N, and slap the new logo on the front. Then it will look nicer in the studio. I will then store the original baffle, grill cloth, and logo (with the Rola) for future reference/sale.

Since I started this post, I have noticed I am missing an entire piece of the back. That, I'm afraid will just have to be. I also noticed there are supposed to be chrome or nickel corners on the bottom. I can get those, but if you have recommendations I would love not to buy the wrong ones.

And, I will add a handle.

Thanks again. Anybody else, feel free to chime it.

PS Is the grid stopper on the schematic for the 6G5-A?

http://Finlayson.TV/images/Pro-6G5-A-Schematic.pdf


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Post subject: Re: '61 Brownface Pro - cosmetically refurbish or not
Posted: Mon Sep 25, 2017 2:32 am
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I believe that you are correct. Your amp is the 6G5-A circuit with six 12AX7 tubes. Mine is also. I love the three-12AX7 vibrato circuit (tube driven harmonic tremolo).

Those main power supply Sprague Atom caps look pretty new. Like 1990s or newer. The 1970-80 ones had yellow-orange plastic covers.

IMHO, that Rola speaker is 1960s vintage. I have seen this era (US models). They have that type of speaker basket. You can find them on the Net.

http://www.radiomuseum.org/r/rola_285_516.html

http://www.ebay.com/itm/1960-Rola-ALNIC ... Sw6Q1ZrHlo

There is NO grid stopper resistors on the 6G5-A circuit. Just the 220k-ohm grid-to-ground resistors and the 0.1mfd coupling caps are between the phase inverter tube and the 5881 tube's signal grid.


Grid stoppers on AA165 Pro Reverb (blackface):

Image

6G5-A:

Image


The grid stopper and screen resistors are usually soldered directly onto the socket tangs, to keep their lead distances as short as possible.

Image


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Post subject: Re: '61 Brownface Pro - cosmetically refurbish or not
Posted: Tue Oct 10, 2017 4:29 pm
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So, here we are, almost done...

What you can't see is the 1961 Jensen P15N speaker. Love it!

BTW, my chrome corners don't fit. The holes are almost 1/4" shy of the original holes. Anyone have a source for larger corners, two-leg with lip? These came from Studio Sound Electronics (http://www.amprepairparts.com) Everything else I got from them is perfect, but they say these are the largest they have.

And yes, every single piece removed is in a box in storage, including the original baffle, Rola speaker, grill cloth and logo intact.

Thanks for the help and inspiration!

Image


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Post subject: Re: '61 Brownface Pro - cosmetically refurbish or not
Posted: Tue Oct 10, 2017 10:13 pm
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Very nice! How do you like that tremolo-vibrato tone? Nothing like those transition-era Fender amps.

:)


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Post subject: Re: '61 Brownface Pro - cosmetically refurbish or not
Posted: Wed Oct 11, 2017 12:18 pm
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I ALWAYS loved the vibrato, from day one! I find myself playing everything with vibrato on now. The amp just sounds that much better through the P15N.


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Post subject: Re: '61 Brownface Pro - cosmetically refurbish or not
Posted: Fri Oct 13, 2017 7:04 pm
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Nicely done refurb!

T2

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Last edited by T2Stratman on Sun Oct 15, 2017 6:53 pm, edited 1 time in total.

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Post subject: Re: '61 Brownface Pro - cosmetically refurbish or not
Posted: Sat Oct 14, 2017 7:53 am
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looks great...congrats and enjoy!!

glad you kept the old parts in tact....


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Post subject: Re: '61 Brownface Pro - cosmetically refurbish or not
Posted: Sat Feb 17, 2018 10:49 pm
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Turns out my son's landlord, in addition to being a brilliant engineer, is also a certified Fender amp and guitar tech. Did some excellent work for me last weekend. We also put in new power tubes and a new preamp tube on the vibrato channel. More on the way.

Image


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Post subject: Re: '61 Brownface Pro - cosmetically refurbish or not
Posted: Mon Feb 19, 2018 1:39 am
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Good job. Number 3 resistors were 1500-ohm grid stoppers. Part of stability fix of blackface and silverface era amps. If your amp is stable, prolly won' t need them.

:)


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Post subject: Re: '61 Brownface Pro - cosmetically refurbish or not
Posted: Mon Feb 19, 2018 12:55 pm
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BMW2002Ti wrote:
Good job. Number 3 resistors were 1500-ohm grid stoppers. Part of stability fix of blackface and silverface era amps. If your amp is stable, prolly won' t need them.

:)


Yes, although that's not the way my guy described them, he said they were a Blackface era mod and he put the circuit back to original. As far as stability goes, I think we discussed long ago that this amp may have "blown up." Replaced transformers and scorched power tube are are a hint. Nevertheless, I trust this guy very much. Fingers crossed it doesn't blow again! Sounds great.


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Post subject: Re: '61 Brownface Pro - cosmetically refurbish or not
Posted: Tue Feb 20, 2018 2:48 am
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T2Stratman wrote:
Nicely done refurb!

T2


New grill cloth waves :(
I 'll redone the job


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Post subject: Re: '61 Brownface Pro - cosmetically refurbish or not
Posted: Tue Feb 20, 2018 9:50 am
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stratele52 wrote:
T2Stratman wrote:
Nicely done refurb!

T2


New grill cloth waves :(
I 'll redone the job


Yeah, I know, it was my first grill cloth. But given the option of sending my 57 year old amp to Canada, or pulling one staple and straightening it - yeah, thanks for the offer, but no.

:)


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