Electronics > Repair
Hioki 3532-50 LCR Repair (One major problem solved, SM still wanted)
KungFuJosh:
I don't know if I'll bother replacing the original pot or not, but if anybody else needs one...
It's from ALPS, 10kΩ, and appears to be from their RK09L series (or at least very similar). However, it's a 35mm shaft, and 3B taper.
KungFuJosh:
I got a better resistor book in today, and tried the engineer's suggested values. They were worse than what I came up with. I tweaked the values a bit, and now I'm about where I was before as far as it looks.
This was today:
R1 392
R2 472 (not enough contrast range) -> 5.6k (better)
R3 823
R4 622 -> 5.6k (better but still a little flicker) -> 4.7k (better)
R5 392 -> 7.5k (too much Vertical line contrast) -> 5.6k (too much? has Vertical ghosting) - 4.7k still some minor ghosting but better
R6 822
I asked the seller to ask the engineer the specific function of each resistor so I can stop guessing on the others. Hopefully, he actually gets me that info.
KungFuJosh:
This was with the suggested values. It looks better in some ways besides the glaring issue. If I knew all the specific functions, it might actually come out well. 🤷
KungFuJosh:
I don't know if it's interesting, or annoying, but there's clearly a relationship between R1 and R2. Nothing looks better than R1 at 2.4k with R2 at 6.8k, but R1 at 1.2k with R2 at 7.5k is very close. In either case, the bottom right corner fades out.
With R1 at 2.4k and R2 at 5.1k, those vertical lines looked better, but the rest looked like crap.
R2 also shifts the contrast center, so there's more adjustable range with the contrast knob when R2 is higher. But the higher R2 goes, the more it screws up the verticals controlled by R1.
I think / hope that one of the other resistors has an effect on the relationship of R1 and R2.
R4 value has an effect on the flicker. I didn't notice any other changes when I adjusted R4.
R3 and R6 I have no clue about, but when I tried to change R6 it had almost no effect using a pot.
R5 previously did affect the vertical lines. I'm going to tweak that next and see how it goes. 🤷
Right now I have:
R1 1.2k
R2 7.5k
R3 82k
R4 4.7k
R5 3.9k
R6 8.2k
KungFuJosh:
R5 definitely improved the situation. I don't know if I want to tweak it anymore. I might try 5.1k if I get bored.
Current values:
R1 1.2k
R2 7.5k
R3 82k
R4 4.7k
R5 4.7k
R6 8.2k
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