P68 Subwoofer Amplifier

[Engr. Dacuycoy]

san ba nakakalagay ang d2-d3? sa driver (as per esp) or sa output trannies heatsink?

All three driver transistors (Q4, 5 & 6)must be on a heatsink, and D2 and D3 should be in good thermal contact with the driver heatsink. Neglect to do this and the result will be thermal runaway, and the amp will fail. For some reason, the last statement seems to cause some people confusion - look at the photo below, and you will see the small heatsink, 3 driver transistors, and a white "blob" (just to the left of the electrolytic capacitor), which is the two diodes pressed against the heatsink with thermal grease.

[jlester87]

aw yan nga ang hassle part yung paggawa ng common heatsink sa drivers at paglapat ng thermal compensation diode, pano kaya ang design modification nito para independent heatsink nalang ang mga drivers? thanks

[Engr. Dacuycoy]

ito original pcb nya.. still finalizing were to put d2 and d3

[Engr. Dacuycoy]

extension output trannies muna 

top view and side view

[j a y k e z]

wow galing naman pagkalayout sis Engr +1

[Johannah Aleksandria]

ito original pcb nya.. still finalizing were to put d2 and d3

basta malapit lang sa heatsink, yung thermal paste na lang ang link ng thermal transfer.

[Johannah Aleksandria]

san ba nakakalagay ang d2-d3? sa driver (as per esp) or sa output trannies heatsink?

Sa driver lang tlaga. Di na kasi sakop ng Vbe bias ckt ang output trannies.

[tony]

ito original pcb nya.. still finalizing were to put d2 and d3

for D2.D3, you can use the base emitter junctions of an npn to-77 fully encapsulated trannies so that one of then can be mounted on a common heatsink with the drivers and the other one with the power trannie heatsink, this way all devices are covered...

[pEN DoTA]

ito original pcb nya.. still finalizing were to put d2 and d3

wow! ang ganda.
engr. saan mo nabili yung pcb board?
sana merong group buying.

[pEN DoTA]

+1 ka sa akin engr.

[Engr. Dacuycoy]

ayon o 



topview




sideview

[j a y k e z]

wow ganda +1 ulit Engr.

[p®otocol]

extension output trannies muna 

top view and side view

sprint gamit mo master?

[Ikasamoko]

Orcad yata to sis...

[jlester87]

thanks sa layout sir!, ilang watts kaya ang dissipated heat nito @ +-45VDC loaded rails?

[p®otocol]

Orcad yata to sis...

ah i see, thanks sis kamukha kasi nung sa sprint

[ultrasonic™]

pa marka

[kulapo]

sis J A, TO-3 ba  gamit mong transistor mula q7 to q12, wala bang ocillation? at ano nga bang number na gamit mong transistor?

[Johannah Aleksandria]

sis J A, TO-3 ba  gamit mong transistor mula q7 to q12, wala bang ocillation? at ano nga bang number na gamit mong transistor?

5200/1943 lang din sis. Di ko na test kung may oscillation pero nababad ko na ng husto to sa disco sis wala nmang problema.
BD139/BD140., MJE340/MJE350 lang sa Vas at driver. Dalawa kasi stereo amp ko nito.
MPSA42 sa input. Mainit ang amp na to kahit yung driver na 5200/1943 pero wla nmang nangyaring pumalya.
I suggest you use genuine parts. Sa akin yung resistor lang ang binibili ko sa lokal na tindahan, cap at tranny sa RS na.

[kulapo]

ok thanks.