I have a Sony EV-S3000 video Hi8 player on my bench, and could use some help sorting out a power supply issue.
According to the service manual, I should be seeing 3.3V +/- 0.3V at pin 2 of CN2. Instead, I'm measuring -21.1V. Here are my measurements at all five pins of CN2:
Pin 1: -24.4V
Pin 2: -21.1V
Pin 3: Ground
Pin 4: -30.4v (should be -30V +/-3V)
Pin 5: 0.00
I noticed that the difference between Pins 1 and 2 is 3.3V, though not sure what to make of that. Unfortunately, I can't find a schematic for this anywhere, and it wasn't included with my copy of the SM. It does, however, appear that the power supply for the EV-S3000 is very similar. Instead of 3.3V at Pin 2, the SM for the EV-S3000 specifies 5.7V.
According to the service manual, I should be seeing 3.3V +/- 0.3V at pin 2 of CN2. Instead, I'm measuring -21.1V. Here are my measurements at all five pins of CN2:
Pin 1: -24.4V
Pin 2: -21.1V
Pin 3: Ground
Pin 4: -30.4v (should be -30V +/-3V)
Pin 5: 0.00
I noticed that the difference between Pins 1 and 2 is 3.3V, though not sure what to make of that. Unfortunately, I can't find a schematic for this anywhere, and it wasn't included with my copy of the SM. It does, however, appear that the power supply for the EV-S3000 is very similar. Instead of 3.3V at Pin 2, the SM for the EV-S3000 specifies 5.7V.
Attachments
And you still have the fault on pin 2 ? If it is still -21.1V which according to your thumbnail should be 0.5 V as pin 1 should be but measuring -24.4 V then it must be coming from where you have marked it via R25 and R27 and if the combined series resistance is over 100Kohms to it then there is no load /current to reduce it, what is the series current?
Your input via the fuse says 9.7 on pin 5 and you get 4.97V then the only high voltage is what the chip itself is switching then it could be a faulty chip which I see has been discontinued in 2002 or the transformer and BJT are faulty , I would still check Q4 just to satisfy myself .
Your input via the fuse says 9.7 on pin 5 and you get 4.97V then the only high voltage is what the chip itself is switching then it could be a faulty chip which I see has been discontinued in 2002 or the transformer and BJT are faulty , I would still check Q4 just to satisfy myself .
Still have the fault at pin 2. That should be 3.3V. The schematic snippet I attached is for an EV-S3000, and I'm working on an EV-S2000. From looking at the board and components in the EV-S2000, it's very close to the schematic, with the main differences being some of the component values around the chip.
That being said, I measure 10.4V at pin 5 of the chip and 0.3V at pin 4. The emitter of Q4 measures 0V. I had also pulled Q4 to test it, and it was fine. I keep coming back to T2 as the issue.
That being said, I measure 10.4V at pin 5 of the chip and 0.3V at pin 4. The emitter of Q4 measures 0V. I had also pulled Q4 to test it, and it was fine. I keep coming back to T2 as the issue.
The voltage between pin 1&2 is for the heater=cathode of the display.
And the cathode has to be negative, and -22V is normal, with the anodes (segments) at ground level.
Mona
And the cathode has to be negative, and -22V is normal, with the anodes (segments) at ground level.
Mona
If the supply is running then it probably OK. Those voltages look like the values used to run some kind of display (-30 and a semi floating heater supply tied to another rail). 3.3v sounds like a valid filament voltage to me.
The -24v you have written on the diagram looks about correct to me. It is the AC winding being tied to the -30v rail via a 9v Zener but the high frequency AC waveform will make readings unreliable.
The -24v you have written on the diagram looks about correct to me. It is the AC winding being tied to the -30v rail via a 9v Zener but the high frequency AC waveform will make readings unreliable.