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scarling
Copper Member
USA
7 Posts |
 Posted - 11/15/2005 : 00:11:22
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hi,
i recently picked up a mij black label bf-2
but the trimpots have been tweaked and with the res i get this siren like feedback so i was wondering if anyone possibly knew the factory settings?
thanks |
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bossarea
Forum Admin
United Kingdom
3652 Posts |
Posted - 11/15/2005 : 11:03:42
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It will probably hard to get it back to correct settings without using a signal generator and scope. I haven't got the schematic but it should describe the proper procedure.
It sounds like it is in a state where it can't get any worse so you might want to try to adjust the pots in small increments and see if it improves. |
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stahlhart
Platinum Member
1318 Posts |
Posted - 11/15/2005 : 19:15:03
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If it's anything at all like my Electric Mistress, and I were to assume that the "resonance" control governs feedback of the wet side, the way you'd adjust the trimmer would be to dime the resonance control and then back off the trimpot to just below the threshold where it starts to oscillate. But then you'd have to know which trimpot that is.
For some strange reason, I've got a BF-2 service manual at home -- strange, because I've never owned a BF-2. But I'll look it up when I get home this afternoonand will report back then...
C.K.
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stahlhart
Platinum Member
1318 Posts |
Posted - 11/15/2005 : 23:25:28
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Okay, here's the instructions:
CLOCK FREQUENCY
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Connect oscilloscope to TP-1.
Adjust VR7 for T = 25uS.
Rotate MANUAL FCW. T should be 2uS +/- 20%.
BBD BIAS
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Feed 200Hz, sine wave, 0dBm into INPUT jack.
Connect oscilloscope to Q3 emitter.
While turning MANUAL across its entire rotation range, set VR6 for clip-free waveform at the peaks.
RESONANCE
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Plug short circuit into INPUT jack.
Connect OUTPUT jack to an amplifier and speaker.
While touching screwdriver to TP-2, set VR5 to the point where oscillation begins.
Good luck! 
C.K.
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bf-2 trimpots
