Sakura Amp Modification

[labgruppen]

ito pa isa kong na notice sa mga class-H na design,kadalasan nakita ko ung  switch para sa high rails ay naka connect sa speaker out lang,ano kaya kung doon tayo mag connect sa outpur ng relay para sakaling may DC out at di mag ON ung relay di rin po mag ON ung switch sa high rails para iwas sa malaking trouble.

 gaya ng sa Lexus CA15 pag may DC out daming damay at burn pa ung board.

ano say nyo?

regards
Skyjham

DC-out ba talaga ang cause ng burning ng board ?   o epekto na lang ng burning ng board yung "DC-out"? 

anyway, i think mas magandang maglagay ng crowbar circuit.


connect the "A2" terminal of the triac to the output inductor. a fuse is recommended between the output node of the output stage and the output inductor. it is also recommended to take the feedback after the fuse.
ngayon kung sakaling magkaroon ng high level dc sa output, ma-tritrigger yung triac shorting out the output and blowing the fuse.  some might argue against shorting out the output, it should not be a problem. if the amp is operating normally, the amp will not output high levels of DC and the crowbar circuit will never be activated.  "DC out" is mostly caused by shorted output transistors. plus, for sure mas mahal ang speaker kaysa sa output trannies.

audiophiles might frown at the idea of a fuse at the output. no worries, the feedback is taken after the fuse so there should be no audible effect of the fuse.

N.B.
Note well, the circuit presented may not be suitable for amps with  turn-on / turn-off thump as it may be falsely triggered by the thump.
R255 may be reduced to 15k for lower powered amps.

[labgruppen]

... the mosfets acts similarly to a bootstrap, maintaining an almost constant Vce at the output transistors after the output voltage exceeds a certain threshold until a few volts within the upper rail.
ex. Crest Audio CA18


..

correction, Vce is not almost constant after the threshold due to the effect of R123/R122. i think the ratio of R210:R123 (for positive side) and R211:R122 determines how the voltage difference between the higher rail and the output is divided between the mosfets and the output trannies after the threshold is reached. sorry for the mix-up.

[Johannah Aleksandria]

Mapag-aralan nga to sir lab.

[tony]

with amp circuits circuits getting complex, it is out of reach of most diy'ers save for the real savvy ones.....

[Woots29]

[Johannah Aleksandria]

with amp circuits circuits getting complex, it is out of reach of most diy'ers save for the real savvy ones.....

Pag-aralan lang nman.
Wag kang mabahala.
Tingnan mo tuloy bumuntot sayo si woots.

[Woots29]

Pag-aralan lang nman.
Wag kang mabahala.
Tingnan mo tuloy bumuntot sayo si woots.

yes syempre bubuntot ako sa more experienced

[j a y k e z]

pabuntot din po para matuto

[eesbiboi]

class h k10 is too complicated for me, mahirap pa mghanap ng pisa...
kaya im asking if gagana sya na walang switches with voltage supply higher than LV but lower than HV...
jeje...

eesbibskie

[Johannah Aleksandria]

class h k10 is too complicated for me, mahirap pa mghanap ng pisa...
kaya im asking if gagana sya na walang switches with voltage supply higher than LV but lower than HV...
jeje...

eesbibskie

Ngawa ni sis skyjham ang class H.
Kung gustong matuto sa class H, it doesn't need to be high voltage. Can be 25v and 50v.
Sa 90vac mo na transformer sis, 127vdc ang mangyari, para sa akin wlang problema kung ideretso mo sa 127vdc ang ckt na walang switch, basta ba working tlaga ang input hanggang driver stage mo.
Pwede mo nman try yan sa 1 pair lang ng output muna pero hinaan mo lang.
Pinakamadali nga pala yung ckt ni Apex na H900, balak ko gawin na walang switch, para sa 76vac na trafo ko o kaya yung ckt ng Crown.

[Woots29]

I highly recommend 40 at 80v

[eesbiboi]

Ngawa ni sis skyjham ang class H.
Kung gustong matuto sa class H, it doesn't need to be high voltage. Can be 25v and 50v.
Sa 90vac mo na transformer sis, 127vdc ang mangyari, para sa akin wlang problema kung ideretso mo sa 127vdc ang ckt na walang switch, basta ba working tlaga ang input hanggang driver stage mo.
Pwede mo nman try yan sa 1 pair lang ng output muna pero hinaan mo lang.
Pinakamadali nga pala yung ckt ni Apex na H900, balak ko gawin na walang switch, para sa 76vac na trafo ko o kaya yung ckt ng Crown.

alam ko naman sis na kaya ng apex b500 yung 76ac(107vdc) kasi VAS palang, 120vdc maximum na...
ang di ko alam is kung paano econfigure yung mga output at drive tranny para kayanin ang matataas na rails na safe parin sila...


regards
ees

[ayet]

mga sir at mga master...
will this k10 work without the switch, gayah nung sa pic???...nka diy nadin ako nitong k10 kahit wagna gamitin step drive. matindi parin bumayo....si sis audiomachine and sis tony mahuhusay talaga sa mga amp....diba mga sisters am and tony?


regards
ees...

[eesbiboi]

^ganyan din ba ginawa mo sa k10 mo sis???...tsaka ilang volts PS gamit mo sis???...

[ayet]

^ganyan din ba ginawa mo sa k10 mo sis???...tsaka ilang volts PS gamit mo sis???...

   90v lang ginamit ko....oo dko na ginamit yung step drive.

[eesbiboi]

^ -+90vdc ba sis???...?
ok lng  ba kung wala nah yung HER204 diode sis???...

[ayet]

^ -+90vdc ba sis???...?
ok lng  ba kung wala nah yung HER204 diode sis???...

dapat meron yung HER

[ayet]

^ -+90vdc ba sis???...?
ok lng  ba kung wala nah yung HER204 diode sis???...

oo +-90v pero mas ok kung hiwalay yung supply ng VAS..gaya ng sabi ni audiomachine

[eesbiboi]

dapat meron yung HER

ano ba function nung HER diode sis???...

[ayet]

ano ba function nung HER diode sis???...

   hindi ko rin alam e...si master toni or master audiomachine....im sure alam nila. wait natin sila sis biboi