Yamaha RX-797 part 1
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- čas přidán 15. 09. 2023
- Playing whack-a-mole with faults. First up, it won't turn on!
CAUTION do not work on mains operated device unless you understand the risks and how to do so safely.
Tools I use -
Soldering
Quick 861DW hot air station
Duratech TS-1640 solder iron
Multimeter
RMM760D - can be found under many name badges
Microscope
Luzky Zoom 3.5 - 90x simul-focus single boom stand trinocular stereo microscope
Camera - Lucky Zoom HD 14MP
Oscilloscopes
Siglent SDS 1102CML 100MHz 2CH
Philips PM 3305 35MHz 2CH
Function generastor
FY6900 (many brand names)
Thermial imaging camera
FLIR ONE PRO on android
Bench supply
Powertech MP-3086 0-30V 3A
TL866II PLUS universal EEPROM programmer
The master is the on/ off button, the other one is for standby
Still early on in the video but my guess is C259 being off value, it is a capacitive dropper, low capacitance will result in lower voltage to the bridge. C254 is also a suspect.
I don't know if you have the same problem I've had, but the Yamaha I worked on was kind of doing the same as what this one is doing. The relay energizes and after a few seconds it de energize. I couldn't hear if your relay de energizes, but if it does I suspect capacitor (C254) is faulty which was in my case the problem. The ESR was too high and it caused for the optocoupler (IC251) not to pull the 5V (+5M) on the detect (DET) circuit to ground. As you can see if the circuit is healthy you should read 0.2V at the collector of the optocoupler (IC251) and not 5V.
That 3.4 and 3.7V on the 2nd bridge rec is confusing as. If you measured the ac side from a dc ground would you see 3.4 and 3.7 dc on a DMM? You must be one of the only people who has not already heard about the failing cap across the relay is it c259 on this one?
Hello! Please explain why you installed this mosfet (ipan60r600)? In according to its voltage characteristics, the drain-source voltage is only 20 volts maximum, but on the schematic diagram of power supply shows a value of minus 29 volts?!