(I'm secretly dreading the rational conclusion that I will have to replace the PWM IC if only to eliminate it as failing but I don't want to do that until I'm sure there's not still a circuit problem that will just blow it up again.)
Briesmith
Member
Last Activity: 12-23-2024, 08:21 AM
Joined: 04-08-2022
Location: RADLETT
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Thanks again everyone. RJ don't you know it's Christmas? Supposed to be a time of goodwill! (I'm secretly dreading the rational conclusion that I will have to replace the PWM IC if only to eliminate it as failing but I don't want to do that until I'm sure there's not still a circuit problem that will just blow it up again.)
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Grateful thanks to you both. The main buggeration is there's no time to test or measure anything before I have to switch the amp off to stop the resistor bursting into flames. At the moment I am removing items of interest and testing them on the bench to see if they are OK or not. But that's very destructive and a risky approach as it can introduce errors and faults that weren't there previously. Fault finding on equipment you can't turn on is very difficult!Leave a comment:
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Thank you Great Sage for taking the trouble to look at my problem. There are several structures, clusters of components, that I have no idea what their purpose is. And I've never encountered a design where the rectified output from from the Bridge rectifier is joined to the unrectified mains in as in this case. But thanks again for trying to get your head round things for me, much appreciated.Leave a comment:
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Need Help with a Yamaha DXR10 Smoking SMPS
I am trying to repair a Yamaha DXR10 powered amplifier but finding it difficult because I have a smoking resistor which starts to burn as soon as I switch power on. (So I have it turn it off straight away.) The fuses don't blow and I connect a dim bulb which goes dim so no straight short to find. I have attached a marked up circuit diagram and I am looking for help in identifying the best place to look for what's causing the excessive power draw. Needless to say the amp isn't working. The mosfet circled in red was the start of my problem when it exploded. I replaced it and the resistor network...
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Re: Can High Side damage on an SMPS get across the Transformer to the Low Side?
Thank you CapLeaker and everybody else who has helped with this. I'll remove the other MOSFET and report what I find.Leave a comment:
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Re: Can High Side damage on an SMPS get across the Transformer to the Low Side?
Update: I removed the 25F60CPM MOSFET and it tests as a resistor so it's definitely defective. Is the advice still to remove the other MOSFET or can I leave it where it is?Leave a comment:
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Re: Can High Side damage on an SMPS get across the Transformer to the Low Side?
Thanks everyone for replying. I'll let you know how I get on.Leave a comment:
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Can High Side damage on an SMPS get across the Transformer to the Low Side?
I have a blown smps and I am looking for some reassurance as to the amount of diagnosis I have to do. It blew the instant I plugged it in not under any load.
As you can see from the attached pix, the damage is located around the main or bulk capacitor (since removed for testing) and the resistor array/network that drives it (the bunch of SMD components to the left of the YAMAHA YC775 AMPS logo). The burn mark on the frame clearly shows the pins of the capacitor. And, for the avoidance of doubt, there is no way the board could have contacted the frame, it was correctly mounted on... -
Re: Help Finding a Replacement LED Strip
Meant to add that you are right about the 4 banks of 8 LEDs making up the 32 in total.Leave a comment:
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Re: Help Finding a Replacement LED Strip
I think the strips I am thinking of come with a driver board which needs a 12VDC supply and which takes the place of the integrated LED driver circuitry within the monitor?
I would need to find a place from which to tap a 12VDC supply and then use double sided tape to attach the replacement driver board to the monitor chassis.
I think
I don't know how I would integrate the panel controls that control the picture, brightness etc. Another problem!Leave a comment:
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Re: Help Finding a Replacement LED Strip
Really kind, much appreciate your help.
I've been on to their website but I don't think they've got any stock which doesn't matter because I can't find any way to pay them. Spent about an hour trying to setup an Alipay account (I'm in the UK) without success.
I think what I'll try and work out is how to use a strip of the right length and width (355mm & 5mm) even if it has more LEDs.
Wish me luck and thanks again for your help.Leave a comment:
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Help Finding a Replacement LED Strip
Hello Everyone
I've spent hours looking at Chinese (mainly) websites offering replacement LED strips for backlighting monitors, TVs etc but I can't find one to replace mine.
Mine goes into a BENQ GC2870, it contains 32 LEDs and is 355mm long. It is marked E117098 94V-0 on the front and NLM144LL077BDBKALB00751R901LGA on the back. I have attached some pix in case that helps.... -
BENQ GC2870 Floodlight effect from left hand edge of screen
I have attached an image of the screen showing the problem which is that I see a sort of floodlight effect shining on the screen from the upper top left edge. I think the image shows the defect better than I could describe it but I would be happy to add any further detail if that would help anyone trying to help me.
If you have seen this problem before or just know what it is from experience/knowledge etc I would be very grateful if you could pass on whatever it is I can do to fix it.
Many thanks
Brian... -
Re: New Members - please post your introductions here
Hi Everyone
I am recently retired looking for something reasonably/slightly challenging to do and I have lighted on electronics repairs and particularly repairs to musical instruments like digital pianos, amplifiers and the like.
I am thinking I am going to be very dependent on forums like this one and that's why I have registered. I look forward to being a member of this community.
Best wishes to everyone
Brian SmithLeave a comment:
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