Hi Budm
I did not ignore your advice......I somehow missed the largest diode on the board
Thank you and everyone who supported me in this task, I and probably others in the future will have learnt much from this....
Percyveer
Member
Last Activity: 03-05-2017, 04:30 AM
Joined: 01-29-2017
Location: Devon
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Re: JVC THS9 Home Cinema System SMPS No outputs or standby power
Hi Budm
I did not ignore your advice......I somehow missed the largest diode on the board
Thank you and everyone who supported me in this task, I and probably others in the future will have learnt much from this.... -
Re: JVC THS9 Home Cinema System SMPS No outputs or standby power
Hi Rievax,
Thank you for your detailed reply.
D953 was passing current both ways.
So the chain of events would have been, D953 breaking down (just because it gave up or mains spike?) and taking out IC901 due to stress from the forward overload current created?
I replaced with a 31DQ05....Leave a comment:
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Re: JVC THS9 Home Cinema System SMPS No outputs or standby power
BINGO away to go!
Reviewed D953 and found the solder pad damaged on PCB, reworked the arrangement.
So to wrap up, IC901 and D953 were defective.
Been studying the diagram, but I do not understand how the IC901 Vin voltage was being dragged down.
Can anyone explain this to me please.Leave a comment:
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Re: JVC THS9 Home Cinema System SMPS No outputs or standby power
I have actually found a defective component, D953.
I replaced it with an equivalent, but alas, no change in the operation, but could this point to something else defective, does it help to understand the issue?Leave a comment:
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Re: JVC THS9 Home Cinema System SMPS No outputs or standby power
But this never gets above 13.2v to start it, just measured it again using the touch/hold function on the Fluke as you suggested....Leave a comment:
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Re: JVC THS9 Home Cinema System SMPS No outputs or standby power
Hi Rievax
That is some good advice, my DMM does have peak hold.
I am not convinced the switching regulator is starting with that Vin at 13v, does anybody have any ideas why it is so low, when this is up to 16v it should start....Leave a comment:
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Re: JVC THS9 Home Cinema System SMPS No outputs or standby power
Hi Budm
Correct no output at all, but the voltages are weird if you look at the drawing I uploaded in my last post.
So why is it in startup/shutdown mode, and how do we fix it?...Leave a comment:
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Re: JVC THS9 Home Cinema System SMPS No outputs or standby power
Hi there Capleaker,
I have now replaced the STR G6651, no change in any voltages on primary side, except the Vin to the IC has gone down to 13v now, and have a few weird fluctuating voltages on the board outputs, which I have marked in megenta on the uploaded drawing.
Is it the Vin voltage too low at 13v, what could be causing this?...Leave a comment:
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Re: JVC THS9 Home Cinema System SMPS No outputs or standby power
That was puzzling me, thank you....Leave a comment:
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Re: JVC THS9 Home Cinema System SMPS No outputs or standby power
The STR-G6615 data sheet has no description of operation.
Are you talking about this IC or generally?
I have read some well written data sheets on similar IC's, and some of them start from the drain pin and then switch over to the Vin pin when running.
Looks to me like that is what happens with this one, because in the data sheet functional block diagram, it shows a zenner across source to drain, this is the start up is'nt it, if so it only passing from source to drain (o/c with...Leave a comment:
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Re: JVC THS9 Home Cinema System SMPS No outputs or standby power
Can you expand on that.
Is it nope I am missing something, or nope the existing 25v cap will not be OK, if so can you explain why?
Thanks Capleaker....Leave a comment:
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Re: JVC THS9 Home Cinema System SMPS No outputs or standby power
In the interest of educating myself, and maybe others here, with the IC now removed, and if I put a 16vdc power supply across pins 3 & 4, Grd & VCC, on a functional IC what should happen?
I guess pins 1 and 2 source/drain switch should start oscillating on/off, or is the feedback circuit needed on start up?
In other words how do you test it, and is it possible without an oscilloscope.
PercyLeave a comment:
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Re: JVC THS9 Home Cinema System SMPS No outputs or standby power
No, I also tried cycling the power on/off to unlatch as mentioned in data sheet, but it had no effect....Leave a comment:
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Re: JVC THS9 Home Cinema System SMPS No outputs or standby power
Thanks Rievax.
Yes the STR-G6651 has that feature.
Data sheet has been uploaded....Leave a comment:
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Re: JVC THS9 Home Cinema System SMPS No outputs or standby power
Maybe.
But surely it is only because the IC is out of circuit that the voltage gets to 37vdc, so with a new IC, the currently rated 25v one should be OK.
Or am I missing something?...Leave a comment:
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Re: JVC THS9 Home Cinema System SMPS No outputs or standby power
Good to know, on that basis I will place an order, and wait for them to arrive.Leave a comment:
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Re: JVC THS9 Home Cinema System SMPS No outputs or standby power
So have you bought IC clones, if so, is your experience a good one?...Leave a comment:
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Re: JVC THS9 Home Cinema System SMPS No outputs or standby power
It did not ramp up and down, just climbed to the max and stayed there.
I can only report what happened, it would not help my cause to say any different.
Just went out one day....Leave a comment:
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Re: JVC THS9 Home Cinema System SMPS No outputs or standby power
Vince: Thank you for the link.
Yes it is that package.
They do not state that it is made by Sanken, I am awaiting a reply from them, it should be at that price, but I think it will turn out be an expensive clone, which if it is the case, I may as well take a gamble on aliexpress at 65p each.
PercyLeave a comment:
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Re: JVC THS9 Home Cinema System SMPS No outputs or standby power
Unable to obtain these Allegro STR G6651 in UK.
Can get from china, probably clones, can anyone confirm these are reliable.Leave a comment:
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