Hitachi 57F710E Loss of Power???

[ratdude747]

My old Hitachi 57F710E seems to have developed an issue with the power supply.

Symptoms: After several minutes of being plugged in (powered on or off), the main power supply dies. The green LED at the back of the power supply board just dims slowly... killing and immediatly reapplying 120VAC has no effect. The only way to reset it is to unplug it and wait several minutes.

It almost seems like there is a thermal cutoff device acting wonky... No bad caps that I can see (all are Rubycon, UCC, or Nichicon, none HM or HN).

Where to start with this? I don't have a service manual (or so I think, I'll have to check the server).

[budm]

Re: Hitachi 57F710E Loss of Power???

Pictures, pictures, pictures?

[R_J]

Re: Hitachi 57F710E Loss of Power???

Check the solder connections on DP32 bridge rectifier, they are known to go bad. It supplies the +7 volts and is also for the feedback
I believe there are two leds, Which one is lit up and goes out and is the other one not on at all? Should be DP40 & DP50
There are a few fuses (Green protectors), check them, they are labeled EP01, EP02
EP01 is in the +28 for the convergence ic's
It's been at least 10 years since I worked on one of these

[Andrew F. Ali]

Re: Hitachi 57F710E Loss of Power???

Pictures, pictures, pictures?

A bad cap on the PSU, perhaps?

[ratdude747]

Re: Hitachi 57F710E Loss of Power???

Pulled the PSU board. No cracked solder joints and no visibly bad caps. However, one cap did stick out to me a bit; it's a 250V 22uf Nichicon VR, only rated for 89C . If memory serves VR's are known to be trouble. It's also the primary cap for the standby power supply, and from my experience with PC power supplies, usually the standby fails first. hence why only unplugging it would correct the issue. All other caps are 105c rated rubycons, so my hunch is that this cap is fried. My good multimeter is at work right now, so I can't really test it at the moment.

Of course I don't have any of these magically sitting around, and I'm about to go on a two week work trip to Canada. Lovely.

[R_J]

Re: Hitachi 57F710E Loss of Power???

If this has the upright power supply board, (HA013xx) is there a 1.8 ohm 5w resistor with a black fuse attached to it, check the fuse, if it's open the relay across it is bad

The items I was refering to in #3 were on the power/deflection board.

[ratdude747]

Re: Hitachi 57F710E Loss of Power???

If this has the upright power supply board, (HA013xx) is there a 1.8 ohm 5w resistor with a black fuse attached to it, check the fuse, if it's open the relay across it is bad

The items I was refering to in #3 were on the power/deflection board.

^Yup, vertical power supply board, LEDs were on the HV board. Didn't figure that out until I looked closer. The fuse with black marker lines wasn't blown, I think? I'll re-check.

[R_J]

Re: Hitachi 57F710E Loss of Power???

The fuse (f104) I am talking about should be glued to the 5 watt resistor and looks similar to a to126 transistor

[ratdude747]

Re: Hitachi 57F710E Loss of Power???

Nope. The resistor itself is marked as F904, and had nothing glued on. See the attached picture.

[R_J]

Re: Hitachi 57F710E Loss of Power???

Is the resistor good? also I do remember replacing relays in these tv's
The board (HA01313) I still have around has the fuse mounted to the resistor.

[ratdude747]

Re: Hitachi 57F710E Loss of Power???

^I'd have to check. I'll fetch my meter from work tomorrow (maybe) and test it. I can't find my crappy meter, and I've always kept my good one at work (I'm not testing 480V on a crap meter, I'm not suicidal).

[R_J]

Re: Hitachi 57F710E Loss of Power???

Just check the resistance of the resistor, it could be open, and if it IS, there is a 99% chance the relay contacts are also bad (open)

[ratdude747]

Re: Hitachi 57F710E Loss of Power???

Nope. Found my crap meter (ok enough for this), 2.1 ohms (nominal 2.2). That was with it soldered and out of circuit.

Since I've resoldered many joints (anything that looked suspicious and/or land unplugged many things, I've thrown it back together minimally. Running a stream of music on the chromecast (through the TV, obviously), so far 15 or so minutes in it hasn't acted up. If it makes it for a few hours or so (while I run to dinner), I'll put it back together the rest of the way and figure it was something dumb like a bad board-to-board connection or the like. It did this to me with the HDMI input when I moved into my house last November... didn't like any of my HDMI devices (which are normally fed into it via a mutiplexer) for a week, then started working again. Odd.

[R_J]

Re: Hitachi 57F710E Loss of Power???

The current firmware for that set is 0113.0001

[ratdude747]

Re: Hitachi 57F710E Loss of Power???

Just died. Audio and everything. I heard relays click.

Will see if I can ID a hot area...

Is the DP32 on the HV board? I didn't find such on the PSU (just the big one for the main PSU, and the small for the standby).

[R_J]

Re: Hitachi 57F710E Loss of Power???

I will recheck the bulletin, it might have been for the other chassis
I was looking at the dp47 chassis, yours I believe is the dp55 chassis
The power supply that is mounted vertical supplies standby plus a lot of voltages to the signal board.
TP01 transformer on the deflection board supplies others for the delection and convergence

[ratdude747]

Re: Hitachi 57F710E Loss of Power???

Over the past week I did some testing on the caps on the power supply and signal boards. All passed my testing (capacitence only, I really need to get a proper ESR meter ). I resoldered some other potentially iffy joints... at least one popped which may or may not have meant anything. Put it back together tonight... testing it now. Maybe 10 minutes in at this point.

Note- this is my one week at home... tomorrow I'm back to Ontario for another two week work trip , hence why I'm testing tonight while I can.

[ratdude747]

Re: Hitachi 57F710E Loss of Power???

The current firmware for that set is 0113.0001

Missed this. I updated it when I first obtained it several years ago (curbside freebie). I always update firmware on things as soon as I receive them.

Note- still running a test stream on it... so far, so good... knock on wood.

[ratdude747]

Re: Hitachi 57F710E Loss of Power???

1 hour, no issues. maybe I did fix it???

[ratdude747]

Re: Hitachi 57F710E Loss of Power???

just shut her down... 3+ hours, no reset. Yay?