| Electronics > Repair |
| Hioki 3532-50 LCR Repair (One major problem solved, SM still wanted) |
| << < (22/34) > >> |
| KungFuJosh:
Progress? Their engineer suggested the following changes: R1 392 R2 472 R3 823 R4 622 R5 392 R6 822 Unfortunately, the resistor kit I bought was limited, and I don't have the 39, 62, or 82 variants. So I tried with 33, 56, 75 instead. This is what it looked like: I also replaced the 10k pot on the PCB with a 25k trim pot. The original pot was mechanically unhappy. It's more stable now with the trim pot. I might try and find the replacement 10k pot, but, eh, I don't know if it's worth the effort. Since the change made some improvements, I tried changing R4 to 7.5k and that helped horizontally, but not vertically. So I tried changing R3 to 100K, and it was too much. Now I'm ordering a better resistor kit to put the suggested values in. I'm much more confident in the possibility of this working now though. |
| KungFuJosh:
I screwed around some more, and it got a little better: Suggestions -> substitutions: R1 392 -> 4.7k R2 472 R3 823 -> 100k R4 622 -> 7.5k R5 392 -> 4.7k R6 822 -> 10k I might try a 5.6k at R2. I ordered the resistor set, but that doesn't come until tomorrow. 😉 The 25k trim pot is useless with those values. It has be set to contrast fully on to see what's there. I know I have other trim pots...somewhere. I'm guessing/hoping that tomorrow with the correct values, everything will look betterer. |
| KungFuJosh:
This is getting interesting. I changed R2 from 4.7k to 5.6k, and it shifted the contrast center so that the trim pot became useful again. The image still wasn't great, so I increased it to 7.5k and we have better contrast, and more usable range on the trim pot. However, that shifted a vertical section out: Since I'm guessing, and don't have a schematic or datasheet to go from, I'm going to experiment with R4 next and see what happens if I increase that value. |
| KungFuJosh:
After some more experimenting, it looks pretty good! Here's my current R values: R1 5.6k R2 7.5k R3 100k R4 5.6k R5 7.5k R6 10k I'll ask the seller to ask the engineer if he thinks that can be improved upon. Thanks, Josh |
| Martin72:
Could you please take a good photo of the board side of the new display? |
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