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Recent Posts

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1
Q & A / Re: Beta Lead sound cuts out.
« Last post by Number1Scatterbrain on April 03, 2021, 12:42:48 am »
Thanks, I?ll test it as you suggest.
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Q & A / Re: Beta Lead sound cuts out.
« Last post by loudthud on April 02, 2021, 09:58:19 am »
Try plugging a guitar into the "From Accessory" jacks on the back. This will tell you if the problem is in the preamp, or the power amp. Just expect a clean sound with no cut outs.

Does it happen on both channels ? Connect a spare guitar cable from the "To Accessory Master" to the "From Accessory" jack on the back panel. If it only happens on one channel, use the "To" and "From" jacks for that channel.
3
Q & A / Beta Lead sound cuts out.
« Last post by Number1Scatterbrain on April 02, 2021, 08:53:09 am »
I have a Sunn Beta Lead combo (s/n A 30844)
With a guitar plugged in, the sound cuts out when the guitar isn?t being played, and there is a slight
?pop? and split/second delay before the sound resumes, almost like a noise gate. Any answers out there?
4
Q & A / Re: Sunn Beta Lead repair questions
« Last post by Just_another_Beta_guy on April 01, 2021, 09:28:20 pm »
Any who, thank you loud for providing the info I need to get started on this repair.
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Q & A / Re: Sunn Beta Lead repair questions
« Last post by Just_another_Beta_guy on April 01, 2021, 07:52:35 pm »
I did forget to mention an important part of this deal...
The previous owner threw these chips in, forgive my ignorance lol.
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Q & A / Re: Sunn Beta Lead repair questions
« Last post by loudthud on April 01, 2021, 07:18:08 pm »
It can be pretty hard to tell the difference by just visual inspection. Usually the font of the printing on the chip is wrong, but you don't have a real part to compare to. Sometimes the date code may be wrong. The MC14506 hasn't been made in the last 30 or 40 years so that would be a clue. The biggest clue is that the parts just don't work electrically. Could be just the wrong part internally or nothing at all inside. The last time I went looking for these parts you could find people selling 50 or 100, but not one or two. Probably surplus inventory from some failed company.
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Q & A / Re: Beta Power+ Input Sensitivity
« Last post by loudthud on April 01, 2021, 07:00:53 pm »
Clipping is ok, it's just the way music is played. You should be using the "To Accessory Master" output on the amp that is driving the Power Plus Slave. Never use the Speaker Out to drive the Slave, damage may result.
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Q & A / Re: Sunn Beta Lead repair questions
« Last post by Just_another_Beta_guy on April 01, 2021, 06:57:46 pm »
In the Service Manual posted above it specifies MC 14506 BCP. MC1 is a prefix Motorola used, the BCP suffix is almost always a package and/or a temperature range specification. Some other prefixes are: CD = National or RCA, HD = Harris, MM = Teledyne, TP = Texas Instruments, F3 = Fairchild, and there are a few other players.

Beware that there may be fakes available on ebay.

Thanks for the specifications, I better do a little more studying on this system before I remove the board.. How would I be able tell a fake one from the real deal?
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Q & A / Re: Sunn Beta Lead repair questions
« Last post by loudthud on April 01, 2021, 06:44:45 pm »
In the Service Manual posted above it specifies MC 14506 BCP. MC1 is a prefix Motorola used, the BCP suffix is almost always a package and/or a temperature range specification. Some other prefixes are: CD = National or RCA, HD = Harris, MM = Teledyne, TP = Texas Instruments, F3 = Fairchild, and there are a few other players.

Beware that there may be fakes available on ebay.
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Q & A / Re: Sunn Beta Lead repair questions
« Last post by Just_another_Beta_guy on April 01, 2021, 01:58:10 pm »
I might have found a 14506 bcp chip, do you know the exact model number? There seems to be more than one variant of the 14506 chip.
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