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Post subject: Re: 1970 Bronco
Posted: Sat Jul 01, 2017 8:10 pm
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Location: Coastal Bend, Tx.
Ordered all the resistors today. Probably will get here the 10th or there about.
Did a little cleaning of the cabinet and chassis.
The chassis straps, handle ends and feet will need to be replaced. They are just to far gone.
The speaker frame cleaned up relatively good.
Took some 0000 lightly to the inside of the cab and the bottom to reveal a little grain.
The bottom piece of Tolex was removed, it tore like a piece of paper. The rest of the Tolex looks good.
The one spot on the bottom of the grill cloth, is likely some kind of adhesive and I don't know if I should or how to attempt that removal.
Removed the cap can, cleaned the pots, knobs(likely replacing them) and the sockets were serviced.
I couldn't get the face plate to cleanup as much as I wanted.
edit: dropped a few pics
Image
Image


Last edited by sfceric64 on Sat Jul 08, 2017 6:53 am, edited 3 times in total.

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Post subject: Re: 1970 Bronco
Posted: Sat Jul 01, 2017 9:36 pm
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I like Simichrome to finish up metal surface to natural shininess! :)

https://www.amazon.com/Simichrome-39005 ... B0002YUQ4E


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Post subject: Re: 1970 Bronco
Posted: Sun Jul 02, 2017 12:16 am
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BMW2002Ti wrote:
I like Simichrome to finish up metal surface to natural shininess!


Simichrome is great but do not use it on silverface front panels -- its solvent will soften and destroy the silkscreened lettering. The only safe cleanser for those is mild liquid dish detergent and warm water. The SF panels are overcoated with a clear lacquer or acrylic finish. For those that aren't too far gone, restoration may be possible by re-spraying them, either with gloss lacquer or gloss urethane.

Replacement straps, handle hardware, and feet (the nail-in type) can be found on Ebay. If you buy new straps, get new mounting screws as well.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: 1970 Bronco
Posted: Sun Jul 02, 2017 12:23 am
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Yeah, should have noted, no Simichrome on painted or decals on metals. :)


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Post subject: Re: 1970 Bronco
Posted: Sun Jul 02, 2017 10:53 am
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I started out w/ a soap mix and a soft cloth to removed the oxidation. Then tried a little naptha to get the small specs. That left fine little swirl scratches in the test area, so I dabbed a little brasso on the scratches.
The brasso lifted the scratches easily but didn't do anything for the specs.
Now I think I know what the specs actually are, thanks to Arjay.
Quote:
The SF panels are overcoated with a clear lacquer or acrylic finish
Maybe a previous owner used something that softened that coating and formed the little specs.
I can live w/ it but if I stumble upon an unblemished one I'll try to upgrade.


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Post subject: Re: 1970 Bronco
Posted: Sun Jul 02, 2017 11:22 am
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An unblemished Bronco front panel will be a tough part to score. You'd have better luck hunting down one for a silverface Vibro Champ, methinks.

Hope springs eternal though......

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: 1970 Bronco
Posted: Tue Jul 04, 2017 4:14 pm
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Got the cap can replaced and the other's swapped out, just waiting on resistors and replacement parts now.
Damned difficult to solder anything to the non steel chassis, it is a major heat sucker. Is there a trick I should know(extra rosin flux paste/really big tip)? I ended up getting some down w/ a 140w gun but decided to add a ground wire to the PT ground point and also epoxied the other can tabs down.


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Post subject: Re: 1970 Bronco
Posted: Tue Jul 04, 2017 7:58 pm
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I heat up the area on the chassis, before placing the cap can down. Then, solder while chassis is still warm. 100-watt Weller iron.

Solder the wires on after new can is soldered onto chassis.

Image


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Post subject: Re: 1970 Bronco
Posted: Wed Jul 05, 2017 1:50 pm
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Not as nice looking as the original, but I think it will work.
Waiting on parts; should be in on the 10th or the 11th.
Image


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Post subject: Re: 1970 Bronco
Posted: Sat Jul 08, 2017 7:24 am
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OK, got my basic thread pics back up.


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Post subject: Re: 1970 Bronco
Posted: Wed Jul 12, 2017 12:15 pm
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Just installed a new three prong, chassis bushing and replaced the resistors, waiting for epoxy to dry. Bought a SF Champ style amp cover from AES-Amplified Parts(fits the Bronco like a glove but a bit different material and no Fender labeling) replacement knobs and new chassis straps. Still need to purchase new handle hardware, feet and Tolex.
Is wildwood contact cement a proper glue for the Tolex replacement or is their a better product more suitable for the task?
A pic of the board, ready to test.
Image


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Post subject: Re: 1970 Bronco
Posted: Thu Jul 13, 2017 8:42 am
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sfceric64 wrote:
Is wildwood contact cement a proper glue for the Tolex replacement or is their a better product more suitable for the task?


I favor DAP contact cement for its superior durability, the brush-on formula in the red-labeled can.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: 1970 Bronco
Posted: Thu Jul 13, 2017 4:01 pm
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Thanks Arjay, pm you later on your Tolex offer.

Fired the little beast up this afternoon, no smoke or flames using the tubes that came with the amp.
Sounded very nice to my ears and everything worked as expected...Very quiet, light hum at about 9+ on the volume and starts to breakup between 6-7 depending on attack w/ guitar volume at ten. On 10 the guitar cleans up about 5 and really thumps on 10 :D

B+ was 370-363-340 on 121 vac from the wall.

One unexpected set of numbers on the V3, the (P3)plate was at 354 and the (P4)screen was 360 while the (P8)cathode was 20.2
I didn't pull out the bias probe, considering the difference between plate/screen.

Also on V2, my meter reading wouldn't settle on P1,P7 or P8.
Fortunately my meter has a low/avg/peak/hold function.
All three pins measured about the same, low 92-95 avg 161-164 peak 230-231
Pin 6 held at 362vdc.
The 470k resistor measured 503k, links pin 6-1-7.

Any thoughts, gonna get a fresh set of glass all around. Retested w/ all fresh tubes; same results. Running @ 14.34w or 102% at idle. Close enough for government work.

Still have to apply the aesthetic parts, then will post a new pic.


Last edited by sfceric64 on Fri Jul 14, 2017 7:49 pm, edited 1 time in total.

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Post subject: Re: 1970 Bronco
Posted: Thu Jul 13, 2017 4:02 pm
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double post be gone...


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Post subject: Re: 1970 Bronco
Posted: Thu Jul 13, 2017 5:04 pm
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I'll go down to S4 in the morning to inspect my stock of Tolex and size the piece using my '68 Bronco's cab as a template.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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