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Originally Posted by Stringswinger
The bridge part is just how it's implemented, it's an arrangement (called a bridge circuit) of diodes that does the flipping.
In tube amps, there is often a vacuum tube taking that duty.
It generally goes
transformer - it lowers the voltage to something we can use internally by semiconductors. Transformers only work on AC
rectifier - makes the voltage all one polarity (say positive) but there are still humps
filter Cap(acitor)s - smooths out the humps into a steady DC (voltage that doesn't fluctuate)
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06-27-2018 10:54 PM
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Thanks everyone for their input on the repair option. Over three months later and 160 bucks.... I got my Poly back from repairs. Looks like it was the Power supply, something about a vertical rectifier or something. Thanks all.
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Originally Posted by Dave325
basically, it's a little part that sort of ensures the transformer is doing its job correctly...
so if there are fluctuations in the power coming in (the transformer basically will give a factor of the voltage like say 10% so if you feed it 100V then 10V will come out, but if you feed it 120V then 12V comes out), the voltage regulator says "I don't care if you are sending me 20V...I'm a 12V regulator so I'm only passing 12V of it because that's what the circuit is designed to handle"
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Glad you're back in business. Those 70s and 80s Polytone amps should be kept in rotation IMO. Folks need to hear that good jazz sound.
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I'm glad for you too. Congrats!
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Originally Posted by Dave325
good boy, $160 is good, and you still have good amp. So you now know, they are mainly repairable
apart from some 8" 4ohm Eminence 10 & 12 or 15" speakers are pretty easy to replace if need be. Reverb Tanks most Accutronics are available. Cosmetic things grilles foam badge harder to come by.
I have a few. They just have it Tone Wise.
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Originally Posted by Jonathan0996
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Yeah...behind them there is probably a lone IC and two jacks on a small circuit board.
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That's a good result, for not too much scratch. I'm liking my MB II the more I play it. I am curious about Evans, Bluguitar and the DV Mark micro CMT though ...
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I gig regularly with a very old MB II. It works great and sounds like a Polytone should.
An Evans would be a fine modern replacement.
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I remember looking for a Polytone around year 2000 or so and only being able to find one in an accordion shop.
I didn’t know they had accordion shops.
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Where did you think accordions come from? Guitar Center doesn't carry them.
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Polytones were THE accordion amps.
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Originally Posted by sgosnell
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Hard to imagine, but 60 years ago pianos, violins, and accordions were what parents had kids study...not guitars.
Otoh, parents did sign kids up for steel guitar...at least in Socal and Hawaii where I lived.
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Originally Posted by Stringswinger
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Originally Posted by Greentone
Aer, henriksen, etc are good machines.
They’re cold, digital reverbs doesn’t help to warming the sound.
Polytone is the warmest transistor for jazz.
I also like mambo amp, and yamaha g100.
Very good amplifiers, but polytone is the warmest.
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Originally Posted by Dave325
Back when I was working repairing industrial electronics I gave myself 20 minutes to diagnose the problem. More than 20 minutes I would consult with the factory or call in outside repair. Actual repair might take several hours or days depending on parts.
Three months I would find another repair shop.
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Originally Posted by Papawooly
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[QUOTE=Dave325;854163. Yesterday, I flipped on the switch and BAM.. It blew the fuse. I replaced the fuse and the same thing happened.
Regards,
Dave[/QUOTE]
7-8 years back I had that with two of my Polytones, i cant remember what exactly caused it but anyway its nothing much and cheap easy to fix by any repair guy,
i looked on a couple of old invoices but zulch he always scrawls some meaningless crap, but he does a good job so cant tell what it is.
Dont throw amp out if you like.
Developing an Individual Style
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