Re: Dantax DVB-C 700 digibox chopper controller keeps failing
My guess is something else on the mainboard blew too, besides the PSU.
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Re: Dantax DVB-C 700 digibox chopper controller keeps failing
This what I built:
http://s807.photobucket.com/user/bud...tml?sort=3&o=0
http://s807.photobucket.com/user/bud...tml?sort=3&o=1
http://s807.photobucket.com/user/bud...tml?sort=3&o=3Leave a comment:
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Re: Dantax DVB-C 700 digibox chopper controller keeps failing
"Dim Bulb Tester". Google it. Likely the first result will be from an antique radio site, but this simple piece of equipment you can build in 10 minutes is of invaluable help when troubleshooting anything mains-powered. The only requirement is that you absoutely have to use a good old-fashioned filament bulb.
I've gotten so used to it that i never plug any unknown SMPS to the wall socket directly, i always use the bulb. Same when i'm modifying/building a power supply from scratch. I keep it plugged with the bulb in series until the final full load test.
By the sound of it you'll want to use a 40W lightbulb at most for this one. If the bulb lights up and then fades, everything's fine and you go to the next step: measuring voltages. If the bulb lights and stays on solid, you've got a short. Unplug and check.Last edited by Th3_uN1Qu3; 08-18-2013, 07:52 PM.Leave a comment:
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Re: Dantax DVB-C 700 digibox chopper controller keeps failing
Sorry it's been a while...been busy with tons of other things.
Snubber seems fine. All components measure correct values off-circuit. Secondary rectifiers are ok too. How would I go about measuring secondary loads?
Well, yeah, I surely would, if I had a way to make sure firing the circuit up wouldn't keep destroying my remaining yet functional TNYs.Leave a comment:
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Re: Dantax DVB-C 700 digibox chopper controller keeps failing
check +vcc of TNY266 and other pin voltagesLeave a comment:
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Dantax DVB-C 700 digibox chopper controller keeps failing
Hi there,
I got this Dantax cable TV digibox for free some time ago...I think it had suffered a mains voltage spike due to a lightning strike. Now trying to get it back working.
Initial inspection revealed that the chopper controller / mosfet chip TNY265PN had exploded. What was left of the mosfet drain pin was still attached to PCB but not to the chip anymore.
HV side of the circuit is constructed pretty much according to TNY datasheet recommended layout on page 12. All components in HV branches measured fine offline.
I had a TNY267PN I had salvaged from somewhere lying around. Replaced, turned the digibox on, something emitted an audible snap and the chip was dead. I figured either the chip was already somehow damaged or then there must be something else wrong with the circuit.
I got a good deal on a 5-pack of TNY266s on eBay. They arrived just today. Replaced, turned on....nothing goes off instantly, front panel leds are alive, chopper transformer secondary voltages seem ok. I went a few steps away to get the remote to see if it worked. Came back and the system was dead again.
Drain voltage is fine, steady ~ 325VDC (230V * sqrt(2)), so I suppose the culprit must lie somewhere in the feedback system. Other than FB exceeding the absolute maximum ratings (haven't had a chance to measure if it does), I don't see what could keep destroying the chip. I mean, TNYs have short circuit and over temperature protection so they should be immune to those, right? Right after the most recent failure the chip was quite warm, though. The print on the top had partially faded away, apparently due to heat.
Attached are the datasheet and pictures of the PCB. I've swapped and aligned the back side pic for easy comparison in image editors.Attached Files -
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I have several chopper units that need to be repaired but just repaired one of them to see if it could be done successfully which they can be repaired
The company that makes the IGBT module have discontinued this part as 5/30/2020 which our company has bought 12 IGBT modules which will allow me to repair 6 chopper units ( one note there is no direct replacement availability )
I am buying these modules directly from the manufacturer
But there is a 8 week lead time
Now you can find on EBay for half the price but I have a feeling that might be fake...06-07-2020, 11:08 AM -
We have a plasma cutting machine that cut metal on a table bed
We live in Florida and weather had been raining with 91 to 95 % humility
Here is where the problem starts we had this problem for about 2 years off and on when the weather would be raining and humidity at 90 to 95 % sometimes the plasma would fire and run but not always it would fire but not cut the problem would not stay there to figure out what the problem was
But when you would look at the trouble shooting screen on the machine controller it would not show any error message but the set point... -
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 are 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... -
Hi
I need the value of C102 .
Briefly : Blown Fuse . In-Series lamp lights fully = short on Hot Side - Bridge DC Holes are shorted !. Bridge OK out-of-circuit. Chopper Mosfet and Diode - OK. D102 ( T4 Diode ) measures In-Circuit 0.041V both ways but Normal outside. Other caps / diodes..ok. Short remains Haarg .
BUT ! , when C102 Cap ( between Main Cap legs , it doesn't show as I took it out for easier access ) was taken out - short is gone .
Thanks a bunch... -
Hi everyone!
I have a small 19" TV set that started flashing the front led while also dimly flashing the BL, like trying to start but it was power cycling
I opened it and found nothing clearly broken or visibly burnt, no visible bad caps.
I removed the PS to MAIN harness and PS to BL plug plug and nothing changed (these are the two only wires getting out of the PS). So my guess is that the problem MUST be in the PS board
I checked DC at the main capacitor and found a correct rectified main voltage
I went to the primary section...
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