1972 Fender Bandmaster Reverb AA270 TFL 5005D

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xtian
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1972 Fender Bandmaster Reverb AA270 TFL 5005D

Post by xtian »

Hello, Craigslist! Scoooore!

Garage orphan. Dirty as f*ck, including critter poop inside the head shell. But! Inside: untouched, factory fresh. Also: works! No hum, good reverb, trem functioning. All pots noisy as hell, though, so must clean first. Includes matching 2x12 (huge style) cabinet--one cone totally ripped.

ALLLLL original RCA tube set!

Transformer, pot and cap codes all read '68 and '69, though inside of chassis is stamped "RICHARD HAND, JAN 4, 1972." So, do we call this a 1972?

BEFORE photos attached. Will show AFTER photos soon!
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Last edited by xtian on Wed Feb 24, 2016 9:04 pm, edited 1 time in total.
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Coyotesgator
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Re: 1972 Fender Bandmaster Reverb AA270 TFL 5005D

Post by Coyotesgator »

Nice find.

I'm guessing it doesn't smell minty fresh?
What Happened?

Who let the magic smoke out?
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sliberty
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Re: 1972 Fender Bandmaster Reverb AA270 TFL 5005D

Post by sliberty »

I had a Bandmaster Reverb as a kid, long before I knew the difference between a vacuum tube and toilet paper tube. I hated the amp. It always seemed anemic to me. Now, I wish I had it back so that I could CHANGE THE DAMN WORN OUT TUBES! I bet it would have sounded great if properly cared for. Yours looks like it could use some TLC for sure, but I bet you will get it in shape in no time.

Youth was fun, but man was I stupid about gear. I trust some of you can relate.
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xtian
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Re: 1972 Fender Bandmaster Reverb AA270 TFL 5005D

Post by xtian »

No, doesn't smell bad, fortunately!

Replaced the crumbling power cord and put in a new fuse holder. Sounding very good! All the pots cleaned right up. 450v on the plates and the screens. No bias adjustment, just balance. No hum, no hiss. May have to update the bias adjustment. 6.6vAC on heaters. Probably running hot.

Tremolo ticks, and is weak. Will try new tube.
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Colossal
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Re: 1972 Fender Bandmaster Reverb AA270 TFL 5005D

Post by Colossal »

Wow, that actually looks really nice! Very, very nice score.
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xtian
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Re: 1972 Fender Bandmaster Reverb AA270 TFL 5005D

Post by xtian »

Thanks, Dave! I got a lot of dirt under my nails today. It cleaned up very nicely.

LDR in opto bug is trashed. Other than that, it's rally nice.

I'll dig into the 2x12 cab tomorrow.
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Leo_Gnardo
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Re: 1972 Fender Bandmaster Reverb AA270 TFL 5005D

Post by Leo_Gnardo »

xtian wrote:Thanks, Dave! I got a lot of dirt under my nails today. It cleaned up very nicely.

LDR in opto bug is trashed. Other than that, it's rally nice.

I'll dig into the 2x12 cab tomorrow.
Nice photo 'xept for that MossValve peering into the frame. Good find too, congrats!

Try a diy LED opto bug, wave goodby to annoying trem click.

On amps with balance, I park a bias trim atop the existing balance control. "Just think, you could be having it all...!"
down technical blind alleys . . .
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M Fowler
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Re: 1972 Fender Bandmaster Reverb AA270 TFL 5005D

Post by M Fowler »

Nice find for sure.

Wish the Marshall I'm working on was that clean this one is full of white mold.
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xtian
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Re: 1972 Fender Bandmaster Reverb AA270 TFL 5005D

Post by xtian »

Yeah, the Mosvalve is photobombing!

Leo, Where can I find details of the LED opto? I'll do that!

Happy birthday, Mark!
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pdf64
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Re: 1972 Fender Bandmaster Reverb AA270 TFL 5005D

Post by pdf64 »

Nice find, well done!
I was surprised to see the 'total load 2 ohms' note on the back panel; are the speakers 4 ohms each?
That aspect at least seems to be different to the AA270 http://bmamps.com/Schematics/fender/ban ... _schem.pdf
DenDanger
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Re: 1972 Fender Bandmaster Reverb AA270 TFL 5005D

Post by DenDanger »

Wow, nice find. It's good to restore vintage stuff and restore a part of history.
Best of luck with it.

Denny
Gibsonman63
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Re: 1972 Fender Bandmaster Reverb AA270 TFL 5005D

Post by Gibsonman63 »

Nice find. That one is original original! I had one a 25 years ago or so. For the life of me I can't remember who I traded it off to.
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xtian
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Re: 1972 Fender Bandmaster Reverb AA270 TFL 5005D

Post by xtian »

Hey, Pete, I'll find out what speakers are in the cabinet later today (it's closed back, rear-mounted speakers, so have to remove the back panel). But you're right, 2-ohm recommended load is an odd duck. But I looked at all the schematic variations for the Bandmaster Reverb, and didn't notice any indication of OT secondary load. Where'd you see? (Yes, I see the label on the back of the amp chassis.)

Q: Do we want to manage the screen voltage better? Plates = 450, screens = 450. There is a beefy choke between B+ and screen node, and 470R screen resistors, but no significant voltage drop.

Q: Hoping to hear from Leo or someone on building an LED-based opto bug replacement.

Thanks!
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pdf64
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Re: 1972 Fender Bandmaster Reverb AA270 TFL 5005D

Post by pdf64 »

You will kick yourself when you check the schematic (link in my prev message) again - it shows 2 x 8 ohms speakers wired in parallel!

To keep screen grid dissipation reasonable, I always like to add a resistor in series with the choke, as required to get the total resistance up to at least ~500 ohms (per power tube pair).
So to keep the screen happy under heavy overdrive, use 470 ohms >15 watts.

Andy LeBlanc has some threads on the screen grid arrangement he's devised.

I think Leo has advised just to replace the neon with an LED; if you have a good search it should turn up. He may have recommended a suitable opto resistor, which I think is key to getting the right trem effect from a DIY bug.

EDIT http://ampgarage.com/forum/viewtopic.ph ... hlight=led
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xtian
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Re: 1972 Fender Bandmaster Reverb AA270 TFL 5005D

Post by xtian »

pdf64 wrote:You will kick yourself when you check the schematic (link in my prev message) again - it shows 2 x 8 ohms speakers wired in parallel!
Ha! I didn't look at the schemo you posted, because I thought I had a good one (http://vintagefenderamprepair.com/wp-co ... ematic.pdf)!

Thx for other advices-es.
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