OK, try here for quick reply on a modification option.
Seeking opinion on a built Amp board modified to remotely mount Output transistors and emitter resistors connected to driver board some 30mm away.
Currently, as built, all 11 transistors present along one edge of pcb, and these devices are mounted on 30mm x 30mm x 3mm Al. angle.
It is proposed that;
1) The 11 Transistor devices will be solder jointed to 1only new pcb board after mounting flat and tested for continuity to Grounded heatsink.
2) The vertical spacing of devices will be spread an additional 25mm apart.
3) The horizontal spacing between all devices will not change unless advised any merit in doing so. This keeps interconnect wire length uniform across board.
Like this:
3) Brass busbar strips installed to increase CSA of pcb cladding.
4) Emitter resistors mounted on this new pcb.
5) The 30mm flex wires have no crossover and are in direct alignment to driver board pads.
Merit is:
1) spreading a crammed arrangement with back to back mounting of 4 pairs of output + 3 single mounted over a larger heatsink area.
4off - KTB817 - [TO-3P]
4off - KTD1047
1off - 2SA1186
1off - 2SC2837
1off - 2SD669A - [TO-126]
I'm not happy with current arrangement of these devices on an Al. angle intended to bolted to large heatsink. Surface area to do such a coupled joint is smaller than total face area of all transistors - does not bode well.
To unbolt Trans and bend perpendicular to driver board [T shape] has been done by other users, but I don't suffer confined enclosure issues and have large heatsink area. Fiddly arrangement to mount all trans correctly and still cramped.
2) Trans. and Resistors mounted on pcb with 30mm of flex stranded wire back to driver board. Use of C and E common rails on this board reduces number of interconnects.
3) Flexibility between driver board and transistors, reducing mechanical loading on transistor legs.
4) Increases electrical clearance between heatsink and driver board live edges where transistors formerly lived.
5) Retaining close coupling of E resistors to Trans plus decreasing thermal sources and mass loading on driver board.
6) Easier to service if output trans 'pop'. More certain insulation between Trans and Heatsink isn't compromised by poor alignment and fastener torque.
So, that's the advantages....
Please advise any contradictions to doing this and how to limit any noise risk.
Seeking opinion on a built Amp board modified to remotely mount Output transistors and emitter resistors connected to driver board some 30mm away.
Currently, as built, all 11 transistors present along one edge of pcb, and these devices are mounted on 30mm x 30mm x 3mm Al. angle.
It is proposed that;
1) The 11 Transistor devices will be solder jointed to 1only new pcb board after mounting flat and tested for continuity to Grounded heatsink.
2) The vertical spacing of devices will be spread an additional 25mm apart.
3) The horizontal spacing between all devices will not change unless advised any merit in doing so. This keeps interconnect wire length uniform across board.
Like this:
[D] [D] [C] .... [A]
[ new pcb board & E resistors ]
[D] [D] .... [D] ....
[ new pcb board & E resistors ]
[D] [D] .... [D] ....
3) Brass busbar strips installed to increase CSA of pcb cladding.
4) Emitter resistors mounted on this new pcb.
5) The 30mm flex wires have no crossover and are in direct alignment to driver board pads.
Merit is:
1) spreading a crammed arrangement with back to back mounting of 4 pairs of output + 3 single mounted over a larger heatsink area.
4off - KTB817 - [TO-3P]
4off - KTD1047
1off - 2SA1186
1off - 2SC2837
1off - 2SD669A - [TO-126]
I'm not happy with current arrangement of these devices on an Al. angle intended to bolted to large heatsink. Surface area to do such a coupled joint is smaller than total face area of all transistors - does not bode well.
To unbolt Trans and bend perpendicular to driver board [T shape] has been done by other users, but I don't suffer confined enclosure issues and have large heatsink area. Fiddly arrangement to mount all trans correctly and still cramped.
2) Trans. and Resistors mounted on pcb with 30mm of flex stranded wire back to driver board. Use of C and E common rails on this board reduces number of interconnects.
3) Flexibility between driver board and transistors, reducing mechanical loading on transistor legs.
4) Increases electrical clearance between heatsink and driver board live edges where transistors formerly lived.
5) Retaining close coupling of E resistors to Trans plus decreasing thermal sources and mass loading on driver board.
6) Easier to service if output trans 'pop'. More certain insulation between Trans and Heatsink isn't compromised by poor alignment and fastener torque.
So, that's the advantages....
Please advise any contradictions to doing this and how to limit any noise risk.
Last edited:
LOL .... pic of me?
Not looking too good this morning.
The board... ebay listing # 111207981673 may help.
Board I have is untouched so far.
Still acquiring components to complete in one day.
Not looking too good this morning.
The board... ebay listing # 111207981673 may help.
Board I have is untouched so far.
Still acquiring components to complete in one day.
How about making a new PCB for the transistors, and use the existing mounting holes for a pin header?
New basic pcb board needed to neatly terminate transistor legs to wires for sure.
Header type pin idea not wanted due to rigidity and the double layer board of amp has limited VIA's [holes to pin mount] on 3 only of the total 11 transistors on that heatsink.
Decided not to move the emitter resistors.... tansistor legs extended only by 30mm maximum length wires.
Images show subject transistors, heatsink and incidentally 2 transformers also mounted on heatsink.
So, any real issues with extending these legs?
Any merit in using ferrite ring around emitter or all such legs?
I do not like the way these are mounted back to back or the limited area jointing between angle and heatsink.
Header type pin idea not wanted due to rigidity and the double layer board of amp has limited VIA's [holes to pin mount] on 3 only of the total 11 transistors on that heatsink.
Decided not to move the emitter resistors.... tansistor legs extended only by 30mm maximum length wires.
Images show subject transistors, heatsink and incidentally 2 transformers also mounted on heatsink.
So, any real issues with extending these legs?
Any merit in using ferrite ring around emitter or all such legs?
I do not like the way these are mounted back to back or the limited area jointing between angle and heatsink.
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