Re: RCA 55" LED TV Screen Repair Help!!! (Model # RTU5540)
Hello, this is quite old, I wonder if someone has a dump of this model, mine it's continually flashing the test pattern screens, red, blue, etc. I assume it's a corrupt eeprom, I want to try to re-load the fw.
Thanks
dvd4me
Member
Last Activity: 08-25-2023, 10:44 AM
Joined: 05-28-2017
Location: Montreal
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Toshiba 40L310U Led issue
Hello,
I have this TV with the burned leds. I ordered the led strip from Ali and install-it. This is hard as there are a TON of screws to put back.
If you look at the leds they are just burned down, despite of the large aluminum heatsink.
The issue is that too much current is put into the leds, even if it's PWM-ed, it always peaks at 230mA.
So I check under that heatsink to see the Led driver, it's some obscure chip, OZ9998HDN that has no datasheet on the manufacturer website ( O2something).
They have a brochure that has a WRONG and very blurry picture... -
Re: Harman Kardon AVR 3700 blown standby power
Finally It's working.
I had waited for a long time for the Newark parts to come, it was on hold for no reason.
It works with the rebuild transformer, I just leave-it and not put the brand new replacement I bought, just curious. It does not warm up at all, nice job, ME!
To prevent a future failure of the transformer / driver chip and burn the main fuse, I added on the PCB an extra fuse 1A and a small cap 6uF at 400V I recovered from a little power adapter.. It was easy to drill 4 small holes and clean the green...Last edited by dvd4me; 04-12-2021, 04:36 PM.Leave a comment:
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Re: Harman Kardon AVR 3700 blown standby power
Yes, thank you for your suggestion, I tried first HK US and I was redirected to the Canadian side, for an "info@eriksonconsumer.com" support email and then to a company called Jam industries... quite complicated.
But I was surprised to receive an email from their rep and they actually got the transformer! I bought the last 2 they had, just in case... I might use-it or not, but I felt that for the price it was well worth-it. See the picture!
I also asked for a remote ( original), they have-it in stock...Leave a comment:
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Re: Harman Kardon AVR 3700 standby transformer
OK, so I did the transformer re-winding because I really wanted to see if it works, after I got the IKEA chip in place. I checked the transformer I just build with the universal meter, it measures quite good.
The burned TF91 had a short in the primary winding so it was measuring just 1.2 ohm, no mH reading.
Measuring the rebuild TF91 is a lot different. I believe this is easier than the "ringing" of the transformer others mentioned, much cheaper for sure.
Cheers...Leave a comment:
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Harman Kardon AVR 3700 blown standby power
Hello,
This is a new iteration of the same issue with the standby power being defective. Based on the past users experience and the AVR 370 schematic I was able to finally found all the bad parts and slowly going to put this back together. As a short pro-log, the initial state of the fuse (8A) led me to take a cautious approach to this.
Is never good to to replace the exact fuse and power back on, this is the worst approach.
Instead, put a small 1A fuse and use Variac to slowly increase the voltage. I did this and the 1A fuse blow quietly at very low voltage, with... -
Re: Harman Kardon AVR 3700 blown standby power supply
Fratele meu, Bro, I spent hours to redo the windings on this little piece of s*it!
I found another one to reuse the core I broke an arm when removing and they are not the same core, one has air gap the other one no...
Nici mesterul Manole nu se chinuia asa la zidit..
What a pain... Cheers...Leave a comment:
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TF91 in Harman Kardon AVR 3700 blown standby power supply
The pictures below are with the schematic of AVR3700 power board showing the blown parts and the transformer winding count. The windings are not exactly the same as in the AVR 370 schematics for the secondary part, the 5V standby is winded with a double 2 wire layer, both layers connect to pins 5 and 6, I edited the picture to show that. Also winding 9-10 in the schematic is actually.. 7-10 on the transformer! It ads up to the voltage of the 5V stand by.
So it must be some revisions on that transformer to reflect...Last edited by dvd4me; 03-26-2021, 04:57 PM.Leave a comment:
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Re: Harman Kardon AVR 3700 blown standby power supply
Hello,
Long story short..
I have the same issue with this AVR3700, the main fuse blown and the D901 D902 shorted,R928...R971, the 10 ohm resistors also burned. I ordered the diodes and resistors from Newark,
I also noticed the most common issue, the 2 C983 and C984 of 471/1kV caps that were browned... I put them on the order also.
These should come in next week.
The chip OB2358AP was cracked, I did ordered from china but it will take some time to get here.
On eevblog I saw some...Last edited by dvd4me; 03-26-2021, 03:28 PM.Leave a comment:
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HP EliteBook 8540, 8440 battery light flashing 8 times
What a coincidence,
I found another EliteBook 8540 this time, with the exact same issue, blue light blink 8 times. I was searching with Google and I found my post, I had completely forgotten about this solution I found back then in 2017.
So I see the power connector with the 5 pins on the pcb side, middle is the center pin of the connector. Added a 10k resistor straight on some empty spot near the connector itself and now the voltage is around 9V. The battery is charging and computer turns on!
There must be...Last edited by dvd4me; 12-24-2020, 09:58 PM.Leave a comment:
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Elitebook 8440p - not powering battery light flashing 8 times
Hello,
I just finished solving this mystery that was puzzling me for the last 2 weeks. I just found this dead EliteBook 8440p with the blue battery LED flashing 8 times.
Not much info in the web, found some schematics, but the total lack of info regarding the meaning of the 8 times blink code was frustrating. Many "experts" were recommending to call HP...
I like to take the hard road...
I have tried to find info on the SMSC KBC1098 controller that powers up the board....Leave a comment:
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