Denon Poa 1500 Help.. Advice......

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The Red and White Wires on Post#18 go to this:

HeadphoneJack.jpg



The board with the yellow relay is not in the schematics unless I'm blind but i have seen other Poa 1500 amp with it on. Obviously its for the headphones but why the extra board? Why not just connect it to the Speaker board with the two black relays? I never use the headphones anyways. Since I saw a puff of smoke. I would think something burned out but I see nothing unless that green from that resistor on the relay is it
 
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O.K

After further digging around, this is what I found, Sorry if I don't know the correct terminology.

Right Channel Semiconductors - POWER

2SA1386A-PNP-180V/15A/130W/40MHZ
2SC3519A-NPN-180V/15A/130W/50MHZ

Left Channel Semiconductors - Power

2SA1294-PNP-230V/15A/130W
2SC3519A-NPN-180V/15A/130W/50MHZ

The parts list calls for:
2SA1294LB(O)/(Y)
2SC32663LB(O)/(Y)

Could this be the reason why my left channel went out and probably the whole thing?
 
O.K

After further digging around, this is what I found, Sorry if I don't know the correct terminology.

Right Channel Semiconductors - POWER

2SA1386A-PNP-180V/15A/130W/40MHZ
2SC3519A-NPN-180V/15A/130W/50MHZ

Left Channel Semiconductors - Power

2SA1294-PNP-230V/15A/130W
2SC3519A-NPN-180V/15A/130W/50MHZ

The parts list calls for:
2SA1294LB(O)/(Y)
2SC32663LB(O)/(Y)

Could this be the reason why my left channel went out and probably the whole thing?

no i dont think so.

i should comunicate with you better. i have a low attintion span sorry.

at first i jumped to a conclusion. (only exersize i get).

now, after looking at what fried, compaired to what the scematic shows that cir doing, it might not be that bad...lets see first. your output stage might be fine...

the relays are switches that let the audio signal get to the speakers, if they do not pick....the signal dosenot get out. the cir that picks the relays is the one (sofar) that has the damage. it checks the output cir, the power cir and others to make sure it is ok before it will allow the audio go to the speakers....to keep from cooking them too.

im away from my office till monday. untill then im looking at this on a 4" screen and it is hard to fallow the lines on the scematic (attintion span) and trouble shoot like that.
if you are willing i would like to talk to you, one on one, monday or tuesday, after i have printed this out and taped it together to figure out where to start. and we can trouble shoot 1 board at a time...power...protect....output...etc.

but my brain cant do it like this. its the adhd sorry. also y i cant spell.

do you have a meter? fluke? Oscope freq generator ect? dose your meter have a ac freq setting? slodering iron?
if not you are going to need a meter and iron at least.

i think the headphone board must have been added later there is no way denon would have soldered the wires on later like that well get to that later.
 
no i dont think so.

i should comunicate with you better. i have a low attintion span sorry.

at first i jumped to a conclusion. (only exersize i get).

now, after looking at what fried, compaired to what the scematic shows that cir doing, it might not be that bad...lets see first. your output stage might be fine...

the relays are switches that let the audio signal get to the speakers, if they do not pick....the signal dosenot get out. the cir that picks the relays is the one (sofar) that has the damage. it checks the output cir, the power cir and others to make sure it is ok before it will allow the audio go to the speakers....to keep from cooking them too.

im away from my office till monday. untill then im looking at this on a 4" screen and it is hard to fallow the lines on the scematic (attintion span) and trouble shoot like that.
if you are willing i would like to talk to you, one on one, monday or tuesday, after i have printed this out and taped it together to figure out where to start. and we can trouble shoot 1 board at a time...power...protect....output...etc.

but my brain cant do it like this. its the adhd sorry. also y i cant spell.

do you have a meter? fluke? Oscope freq generator ect? dose your meter have a ac freq setting? slodering iron?
if not you are going to need a meter and iron at least.

i think the headphone board must have been added later there is no way denon would have soldered the wires on later like that well get to that later.


I'm Almost 100% this Board is what caused it:

PCBCRACK.jpg



I get almost no Continuity with the relay above the cracked PCB board. This is where the left speaker is connected to. now if I can find someone to make me a new PCB Board.. Happy hoildays to you and your family.
 
"Cool. I can keep up but I need a little instruction.

Its been a really bad week. I just received a bad pressing on vinyl of John Coltrane Giant steps. Man I thought it was supposed to be Christmas!!!"

keeping up not a problem....step @ a time

just saw the coltrane coment....id be upset too. was it all of them made by that company or you just got "lucky"?
i love his work. i would like to expand my knowlage of jass. i love nat king cole, nina samone, duke....i got a cd of the chicago sympany orcastra doing duke...i love it.

ive been thinking about phono myself, i found a web site that you can get justabout any vinyl you can think of new old....

send me your # or let me know when you are avalable tomarrow or tuesday and well talk.
after 2pm central. or i can give you my office #...whatever. email me if you wanna chat.
 
I got this Amp going but I need some advice on the Drivers? The original 2sa968Y and 2sc2238Y are damaged. Can someone name some new drivers that will work for this amp? I have some 2sa1930/2sc5171 and some 2sa1837 and 2sc4793. Not quite sure about the SOA on these. Any help would be greatly appreciated,

Cheers!!!
 
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how did you go

Hey migkiller, how did you go- I've got a few POA1500s sitting in the garage and can check the wiring to those parts you've pulled off by accident.
For the record, the service bulletin doesn't actually stop the bulbs blowing- the issue is the greater than expected (designed) voltage being applied to the lamps. The reasons the transistor driver was blowing was due to the filament blowing and shorting the internals of the lamp and taking out the driver tr. The solution is a higher voltage globe (if you can find one).
I toyed with changing to Blue LEDs or white LEDs.
If you have a EU model (we do here) they have a 220v primary (sticker saying 240) but all secondary voltages are at least 10-15% high. I have a multivoltage version which also runs way over the rated voltage readings on the unfiltered and driver rails.
The relay board is for the POA1500bk (bk = black) and came with the headphone socket and relay board, whereas the gold version did not have it. You have a POA1500 service manual. The reason they use a relay is a) protection for the headphones- imagine a dc fault into a pair of headphones as you cannot use the speaker relays as you could select A or B or neither or both- you need another relay board for the headphones.
Check the Nippon Chemicon 33,000uF caps underneath for swollen vents- they fail regularly as they are sitting very close to the rated 71v all the time.
 
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