99J amp renovation

Bill Ashton

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Steve, when I replaced the ~8' zip-cord on my 66-J, I did the same thing, thinking that the original cord was way short. Now I wonder if it is too long! I think if gigging it would be great, but they might have had it right about keeping it shorter. YMMV, :)
 

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You may be right, Bill. I like putting longer cords on because my buddy's basement has a ton of two prong outlets, but only a few awkwardly placed grounded outlets.

Just out of curiosity, do both your amps have extension speaker jacks too?
 

Bill Ashton

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Yes they do. On the 66-J it originially came with a jack between the power and preamp tubes on the chassis, with the speaker cable attached to it internally and fed through it like a bushing...it was original, solder untouched (this was in 1968 when I got it.)

The 99-J has two similar jacks, but there was a molded plug attaching the speaker plugged into it, most probably not original, although the speaker was...(see it here viewtopic.php?f=7&t=23919&start=0)
 

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If it was a grey molded plug, it's the same one I have. Can't tell on the phone. ;-)
 

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Replacing the studs on the baffleboard. I carefully removed the grillecloth, which is oldstyle Fender oxblood. The gold swirllies are definitely some type of fabric paint, not stitching. The baffleboard shows no other staple marks, so I can say definitively, "That's the way they made them".
8)

img0770l.jpg
 

Bill Ashton

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...so, were the speaker screws/studs just broken off?

As to my impression of the speaker cable that was on mine, it did
not look as though the soldering on the speaker terminals was original,
which I why I though the moulded plug after-market...
 

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Yep, all four of the studs were broken off. I have no idea how, but maybe the speaker was rusted on? :shock:
Looks like I need to stop by the home repair place. I was there this morning and neglected to get a staplegun. :oops:

Next, lacquering the cabinet and then electronics work!
 

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Default said:
Yep, all four of the studs were broken off. I have no idea how, but maybe the speaker was rusted on? :shock:
Looks like I need to stop by the home repair place. I was there this morning and neglected to get a staplegun. :oops:

Next, lacquering the cabinet and then electronics work!

The original craigslist ad showed the amp with a speaker in it. I wonder what happened.

Dave :D
 

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Default said:
... I carefully removed the grillecloth, which is oldstyle Fender oxblood. The gold swirllies are definitely some type of fabric paint, not stitching. ...

Hey, Jackson Pollack needed a job, so...
 

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I must have missed out on the Dali model. ;-)

Dave, when I got the amp, there was one large woodscrew in the top. My guess is that he had it hanging like a picture.
 

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Have the box o' parts sitting in my truck with me, just waiting for the workday to end. Tonight, I'll staple the grillcloth to the baffleboard and reinstall that, then clip the deathcap out of the circuit and put in a new can cap.
 

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Default said:
I must have missed out on the Dali model. ;-)

Dave, when I got the amp, there was one large woodscrew in the top. My guess is that he had it hanging like a picture.

To tell the truth, I didn't look at it much, aside from pulling the tubes.

Dave :D
 

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he orange Spague cap pictured below was definitely a later add-on. It's supplementing the original .5 mfd Astron cap. I have no idea why they specified so little filtering on the first gain stage. :?

004vll.jpg
 

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When I pulled out the old can cap, I discovered two wires a 100mfd/50volt section of the cap. I wasn't surprised to see that one lead went to the 210 ohm cathode resistor, but the other was a discolored striped wire. Following a hunch, I put a voltmeter lead on the cap and one on a 6volt heater terminal on a 6L6 socket. Sure enough, there was a resistance of 10 ohms - Guild was using the free dc voltage on the cathode bias resistor to feed the tube heaters! I've seen that on an ancient Magnatone schematic, but no where else. Not surprising that Guild built dc voltage into most of it's mid sixties and later amps as a noise reduction technique.
 

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Cleaning off the chassis. The rust was bad, but in a lot of 'pinhole" spots. The chrome makes it difficult to take a proper picture.

img0774hx.jpg


img0772tx.jpg
 

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Back side of the baffleboard. There is only one set of staple holes, so it confirms that the grillecloth is original. All you need to replicate this cloth is standard oxblood grillcloth and gold sparkle fabric paint.

img0775m.jpg


Three prong plug. Note the wo wires going into the new can cap. The striped wire is the six volt center tap and the other wire is soldered to the cathode of the 6V6. This injects the 20-25 volts dc from the cathode resistor into the heaters, reducing noise. There is also quite a bit of shielded wire used, further reducing extraneous noise.

img0776n.jpg


All electrolytic caps replaced, getting ready to spray a fine coat of lacquer to keep the panel from rusting further.

img0777rn.jpg


Whoever owned this amp smoked a lot. I have had to clean the nicotine off the turret board with a q-tip.

img0778uh.jpg
 

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Whoah! That's amazing!...

Mott's Applesauce $1.49 :shock: :shock: :shock:

:mrgreen:

Good job!
 

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Arg. Next up on the agenda is superglueing the replacement speaker studs to the baffleboard. Installing the speaker isn't possible because they's just a-spinn' and a-spinn'. I have to buy some cupwashers and bolts to attach the top of the chassis to the cab. I'm also missing one dakaware knob. Fortunately, it's a stock Davies 1470, iirc, easily obtained and relicced to match the rest of them. To the Home Despot for the hardware!
On another forum, I was informed that copper was a base coat for chroming, so the chassis is not solid copper. :-( Also the paint on the grille was a shortlived fad in the fifties called "atomic loop". According to prr, you mixed the paint so it shot out of the gun in a string and the painter would spray loops on the cloth. From the look of the grillcloth, this was probably done on each individual piece of cloth.
 
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