pb908
Well-known
Hi, I just recently acquired a mint condition Yashica FC
looks very similar with my Yashica GL, specially the front lettering.
unlucky that when I put battery, metering always show HIGH lamp ON. so I decided to use my breaking talent to open all the assembly. Internally, just behind the front plate, there is a big PCB, and all components are lying there. As I begun to reverse engineering the schematic, I found out that the metering is controlled by one chip (I don't know if this is an OP-Amp, or Comparator, or transistor pair inside). but it is similar with the one I found on my Yashica GL.
It is 10pin DIP (Dual in package) chip, some of the pin are lifted out/up not use. the one it uses are:
- one pin for VCC (VBattery) and one pin for ground.
- one pin for the metering cell in series to either resistor or capacitor (selected when I push the shutter, that will be High/Low/Exposure resistor/capacitor)
- one pin connected to HIGH Lamp
- one pin connected to LOW Lamp and the exposure coil to hold the shutter leaf open.
the thing is I don't know what chip is this. so to replicate whatever it's function is hard. there are written but not that clear. What I can read is just NEC xxxxyyyy
looks like it's being made by NEC semiconductor in the past.
if any one open their Yashica and found/know what is the chip, I'd be happy knowing it's function and/or get the replacement.
Thanks a lot !
let me try to post some pictures later on
looks very similar with my Yashica GL, specially the front lettering.
unlucky that when I put battery, metering always show HIGH lamp ON. so I decided to use my breaking talent to open all the assembly. Internally, just behind the front plate, there is a big PCB, and all components are lying there. As I begun to reverse engineering the schematic, I found out that the metering is controlled by one chip (I don't know if this is an OP-Amp, or Comparator, or transistor pair inside). but it is similar with the one I found on my Yashica GL.
It is 10pin DIP (Dual in package) chip, some of the pin are lifted out/up not use. the one it uses are:
- one pin for VCC (VBattery) and one pin for ground.
- one pin for the metering cell in series to either resistor or capacitor (selected when I push the shutter, that will be High/Low/Exposure resistor/capacitor)
- one pin connected to HIGH Lamp
- one pin connected to LOW Lamp and the exposure coil to hold the shutter leaf open.
the thing is I don't know what chip is this. so to replicate whatever it's function is hard. there are written but not that clear. What I can read is just NEC xxxxyyyy
looks like it's being made by NEC semiconductor in the past.
if any one open their Yashica and found/know what is the chip, I'd be happy knowing it's function and/or get the replacement.
Thanks a lot !
let me try to post some pictures later on
