Hi again.
Yeah mine has the remote turn on and off..
I've not actually had time to get back to it hese last fews days but am planning on connecting the filter caps via some long wires in order that the pwm controller chip can be accessed. At least that way, it should be possible to confirm (or not) that the chip is being powered......
Crystaleyes
Badcaps Veteran
Last Activity: Yesterday, 06:04 PM
Joined: 09-18-2021
Location: Rio
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Good idea, athough unfortunately that didn't help in this case. No voltages are present on any of the ouput pins.
A quick half-disassemble reveals that the Drain pin has voltage however nothing is triggering the Gate.
This is half what I expected due to the unit needing to be 'switched on' although perhaps it is permanently on once the mains switch is closed?
Someone with experience of these PSU's or some kind of schematic would be priceless here...
Posting some pics just coz it's possible and may help in some wayLast edited by Crystaleyes; 06-22-2024, 06:55 PM.Leave a comment:
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Regardless of dodgy agendas, the 1539 FET is now installed.
Considering that it is somewhat of a mission to reassemble all the PSU even before mounting it into the 37717B, does anyone have any suggestions as to how the PSU can be tested beforehand?
It's late here now but I'm thinking that there could/should be a standby circuit which will only activate the pwm chip with the correct signal.
Currently doing 12 hour days so only get to the bench late at night......Leave a comment:
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This is what happens when you have communist globalists running the show.
I feel for you in Canada. I forgot that you lot have Justin Castro fucking you over in his attemt to wipe you all outLeave a comment:
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Well, there has been some progress, and some hinderance.
Once again the Brazilian customs have shown themselves to be 0% for 'progress' and 1000% for keeping Brazil well and truly a third world non-entity.
The good news is the Fets arrived from abroad (as NO-ONE sells them actually 'in' Brazil).
The boring part is that the pwm controllers have been given a 100% import tax, which purely on principle shall not be getting paid.
Don't get me started on Brazilian backwardness and corruption as I'll probably get deported, however, a $1 (for 5) pwm...Last edited by Crystaleyes; 06-18-2024, 08:18 PM.Leave a comment:
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A quick update.
The parts are due to arrive in another two weeks.
In the meantime, I got the input section sorted and once again have voltage on the Fet drain, but no trigger from the PWM onto the Gate.
As mentioned the two large filter caps don't allow access to the pwm controller so I'm thinking of when I next have a moment, connecting them off of the pcb via some long wires. Seems like the best option as I write this, and I do wanna see where the circuit is failing.
CLast edited by Crystaleyes; 06-07-2024, 08:49 AM.Leave a comment:
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Hi robyb.
Glad you finally found the thread and I apologise for the lack of response.
I'm not sure if you even still have this problem, however if you read the comments above, the underlying message is to verify the solder joints in the switching section.
Regarding the different type of Fet.. That makes no difference in this caseLeave a comment:
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They say that every day is a school day, and indeed you have just taught me something which I didn't know.
Thank you...Leave a comment:
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Thank you R_J. This is info I could have done with last week.
So, after taking a closer look, I can now see how it is supposed to be wired. Something I couldn't readily find when first searching for info, so hopefully this thread can serve as a reference to future techs.
It is as you mention above only there is no option for 220vac with this particular unit.
Pin 1. Earth
Pin 2. Neutral
Pin 3. Live
Pin 4. Link (connected directly to Pin 2 and wired to 115v voltage selector)
Pin 5. Link (return from voltage selector)
Pin...Last edited by Crystaleyes; 06-03-2024, 06:21 AM.Leave a comment:
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There is a 10k actually a resistor from the source pin to ground although due to it being in parallel with a torroidal inductor it measures around 1 ohm across the resistor.
Back to the sot-23 question, I removed the suspect component and it is indeed a diode and is not shorted. Upon closer inspection there is a 15 ohm resistor, again connected in parallel, which confused my readings. As for testing the output pin of the pwm controller, that won be so straightforward due to it being hidden by one of the main filter caps.
On a different tip..
When...Leave a comment:
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[SIZE=16px]Thanks for the replies.
[USER="132583"]CapLeaker[/USER]
I shall be pulling this sot-23 off as I'm determined to do my best to fix this PSU.
Pin 3 of this particular component is connected directly to the pwm controller output pin, in fact there's not actually a lot between the controller and the FET Gate. There is only one other sot-23 (markings CP) and then a 1Ω ¼W resistor connecting the Gate.
As for the first component, after looking through various datasheets I am now certain it is a BAS16 diode manufactured by Philips in Hong...Leave a comment:
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So anyways, after a quick look, there is an sot-23 with the markings A6p which has shorted.
Looking online hasn't really helped as some say its a BAS16 type diode whilst I have seen say it as a PNP and another a zener....Last edited by Crystaleyes; 05-31-2024, 10:43 AM.Leave a comment:
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Omega MML200 Coutant Lambda PSU repair
Hi all.
Recently I picked up a vintage HP 37717B communications analyzer which uses one of these MML200 Coutant power supplies. Needless to say the PSU is not working, and surprisingly there is apparently nothing available on the web regarding repairing one of these. No stories, no schematics, zilch!
There[I] are [/I]however many companies offering repair 'services', however I don't have the luxury of sending it off, so am intending to do the repair myself.
I admit right now that I am no expert on smps repair, although I do have a grasp on the principle of the general...Last edited by Crystaleyes; 05-29-2024, 08:30 PM. -
Re: Onkyo TX-NR708 standby light
I say that because you momentarily have the juice to power the LED, but then you don't.
Voltage will always push a current via the 'path of least resistance' to ground, so perhaps something is a quicker/shorter path than your standby LED? Something quasi-shorting?
The voltage must be being diverted somewhere....Leave a comment:
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Re: Onkyo TX-NR708 standby light
Just a quick one, but considering that the unit is essentially dead, it wouldn't hurt to verify the power supply. You might wanna check everything including the large filter caps.
Something appears to be pulling the standby voltage down on start-up, so maybe see what else is in the stand-by circuit?
Even without the stby led, have you 'tried' to do the reset?
If you can share the service manual then I'm sure you'll get more help in finding the solution.Last edited by Crystaleyes; 10-18-2023, 10:38 AM.Leave a comment:
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Re: Repairing a snapped pcb
Some excellent tips and suggestions, most of which I can see being extremely useful, so nice one, for all the input.
Haven't had a free moment to try any of these out yet but gonna get on it in the coming days.
Wish me luck!Leave a comment:
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Re: Repairing a snapped pcb
Some excellent suggestions, so thank you sincerely.
One observation is that some of the broken traces are really fine, therefore it is easier to run longer lines and those would need some form of insulation.
As for using solid copper.. I like that, and have lot's of that here.
I-ll keep you all updated as I do this workLeave a comment:
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Re: Repairing a snapped pcb
This is also what had crossed my mind.
There are areas with just resistors or links (which could easily be replaced with longer legs), where another piece of board could be added and the holes re-drilled with a Dremel....Leave a comment:
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Re: Repairing a snapped pcb
Do you reckon I could get away with enameled speaker wire on the thinner traces?...Leave a comment:
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Re: Repairing a snapped pcb
Thanks for the suggestions...
To be honest, board strength has been my main concern, although after soldering the thicker traces, the board pictured is already fairly rigid again.
I should finally be back in England next month, earning real wages, so I was thinking of ringing up Allen & Heath and seeing if they had any old 'blank' boards laying around that they would sell?
I need both the boards with the LED power bars.
And seeing how I essentially got the mixer for free, it...Leave a comment:
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