There we have it, one 100b facelift. A quick run through left to right. 1 = Source selector. 2 = switch to left, vu low ( monitors vu from line level of the chosen source). Switch to right, vu high ( monitors vu of the speaker output volume). Top switch = panel meter lights. Lower switch = middle position, panel meters off, down position panel meters set to vu monitoring, switch up, panel meters set to bias monitoring. Switch 3 = switch to left, bias V1/V3, switch to right , bias V2/V4. Switch 4 = volume attenuator. Picture 1 = general layout ( notice the wires from the bias probe points, individually fused under the yellow heat shrink, screened and bonded as they travel across the centre of the board. The source wiring on the right enters, then exits the selector switch as individual screened left & right cables, to the attenuator ( Les noted Yaqin has left & right channels going through one screened cable, from the .25v/.6v switch to the volume pot, mine was the same and again open to cross talk). Picture 2 = Two extra boards, left = vu controller, right = vu to bias trim with shunt resistor, this enables bias voltage calibration to the panel meters ( I chose the lower % scale on the meters as voltage and 50% = 500mv). Picture 3 = Independent power supply to vu controller, vu meters, panel lights and inline fuse to protect this supply. Picture 4 = Panel meters showing V1/V3 bias monitoring ( just shy of 500mv each). Picture 5 = Assembled and ready to accept base plate. I must say getting rid of the ridiculous amount of screws Yaqin use to hold the front panel on, is a big bonus. Two captive 4mm rivet nuts, one each side, means 2 screws hold the front panel on, thats it! I will have to do a separate post to explain the improvements, just saying the added attenuator has taken the 100b to a whole new level. Happy days!! :-)
Posted on: Sat, 27 Dec 2014 20:18:19 +0000
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