I did make some progress today. First I removed the voltage regulator just off of the switching transformer on the secondary side and tested it, there was a a steady 5 volts DC coming off of the output leg, so I reinstalled it. Then I removed capacitor (C940) and replaced it with another capacitor I had of the same capacitance but a slightly higher voltage spec. and applied power to the board, I then had a voltage reading of approx. 7.75 volts DC coming off of C940 and a steady 5 volts DC coming off of the voltage regulator, however I didn't hear any of the relays click in.
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Hitachi Power Supply Unit Interchangeability
I have a Hitachi 57F710E rear projection set with a bad power supply board. I've tried to fix it with help from this forum as well as another one, but without success. Today I found a Hitachi rear projection set for sale on Facebook that looked just like mine. After contacting the seller I found out it was a 51F510. According to the service manuals my set uses a HA01312, POWER UNIT DP4X-DM_24W and the 51F510 uses a HA01313, U901, POWER UNIT DP4X_24W.
Does anyone know if these 2 power supply boards are interchangeable?
Thanks.
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I ordered some components from Digikey and my order came today, the first thing I did was install the regulator IC (I901). Unfortunately that didn't fix the problem. So the next thing I did was replace the filter capacitor (C908), after that I noticed that the DC voltage coming out of the bridge rectifier was now reading a stable 167 volts. But nothing else changed, still no DC voltage on the secondary side. I then changed out C912, C911, C909, C905, and I904. There was still no change. R908, R909, R910, R906, D106, and D907 test ok.
What could be left, perhaps...
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I took a few new readings and thought I would post them. There is approximately 108 to 115 volts DC coming off of the new rectifier, it's fluctuating real bad. If I remove the glass fuse inline right after the DC positive leg of the rectifier, I get a reading of 113.3 to 113.4 volts DC with very little fluctuation. There is approximately 120 volts AC going into the rectifier. Still no DC voltages on the secondary side of the board.
I assume there is something wrong after the rectifier. There is a larger capacitor after the fuse and I believe some kind of switching chip or IC offline...Last edited by navagator; 12-16-2023, 01:18 AM.
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The rectifiers came and I installed one, replaced the glass fuse and plugged the board in. The fuse didn't blow and everything seems to be back the way it was. I checked C940 and got a reading of 12.7v AC. I checked the 2 Pico fuses you mentioned E940, E941 while in circuit for continuity and there was continuity. I couldn't find anymore fuses that resembled those, if you see anymore fuses please point them out to me and I'll check them.Last edited by navagator; 12-07-2023, 01:06 AM.
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Thank you for your help. I odered the rectifiers from Digkey. They were supposed to be here tomorrow but it appears the delivery date has been changed to Monday....
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Re: Hitachi 57F710E Power Issue
Can the legs be bent/adjusted enough to fit?
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Re: Hitachi 57F710E Power Issue
I'm looking for one that will fit correctly. I removed the rectifier from the board and measured the distances between the legs and found them to be approximately 7.5mm x 8.5mm.
The Diodes Inc. rectifiers you suggested have measurements of 7.6mm - 8.9mm x 5mm - 5.2mm. so I'm not sure they'll fit. What few S1WB rectifiers I found don't have any measurements for leg spacing.
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Re: Hitachi 57F710E Power Issue
Ok, I'll have to get one ordered. It's a S1WB S60B4N. I couldn't find this exact one online, is there another one that's interchangeable?
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Re: Hitachi 57F710E Power Issue
Or going by your diagram, when I touch my + meter lead to #4 and my - lead to # 3 my meter reads .482v and when I reverse the process my meter reads .OL, then I place the + meter lead on #2 and my - lead on #1 I get a reading of 0v and when I reverse that process I also get a reading of 0v.
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Re: Hitachi 57F710E Power Issue
I'm using the diode test on my meter. It actually reads .482v and .OL and the other 2 readings are both 0v.Last edited by navagator; 11-18-2023, 05:10 PM.
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Re: Hitachi 57F710E Power Issue
Ok, I did test the rectifier but I did so while it was still in line, I couldn't get downstairs at the time where my solsering iron is. I can remove it though later to test it if I need to.
I touched the + lead of my meter to the - leg of the rect. and the - lead of my meter to one of the AC legs of the rect. I got a reading of 482. Then I reversed this process and got a reading of 0.
Then I touched the + lead of my meter to the other AC leg of the rect. and the - lead of my meter to the + leg of the rect. And got a reading...
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Re: Hitachi 57F710E Power Issue
I was looking at the meter when it happened, so I not completely sure. But I was testing the + and - of D901, the bridge rectifier.
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Re: Hitachi 57F710E Power Issue
The fuses came today, I put one in and plugged it in, but unfortunately as soon as I plugged it in the fuse blew.
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Re: Hitachi 57F710E Power Issue
I found them on Amazon, I'll get them ordered. Thank you.
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Re: Hitachi 57F710E Power Issue
Okay, medium time lag. The blown fuse was a 8 amp 125v, but it didn't have a F, M, or T marking on it.
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Re: Hitachi 57F710E Power Issue
Could you tell me whether this is a fast or slow blow fuse? I can't see anything on the fuse to indicate this.
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Re: Hitachi 57F710E Power Issue
I'm sorry I was checking D940 instead of C940. I'll check C940 as soon as I can get a fuse.
Thank you for help.
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Re: Hitachi 57F710E Power Issue
There's around 12.8vac at C940, around 2.8vDC at D901, 121.5vac between k002 and k003. I went back to check D901 again because I didn't think I got a very good measurement before and unfortunately I hit a solder joint accidentally I shouldn't have and blew one of the glass fuses, F901, so I guess I'll have to order one of those before I can go any further. Also, I haven't checked any of the other fuses you mentioned yet.
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Re: Hitachi 57F710E Power Issue
No, I don'the hear any clicks.
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