C1 and C3 values and purpose on MV1C

[madperry]

I had a rechargeable lithium 2032 battery that I soldered in and wouldn't retain a charge for backup memory. Read online that the c3 capacitor was the cause of some batteries discharging quickly. But I completely durped and removed C1(on the top of the board. Realized my mistake and then removed C3 on the bottom. Now my clock will not allow me to set. All zeroes. Does anyone know the exact purpose of each of those capacitors, and their original values? If I were to believe AI, they are .1uf caps.

 

[nauman]

C1/C2 are capacitors to stabilize the crystal and depending on which crystal you have it can be different values. 18pF or 22pF are valid starting points although removing the remaining C2 from the circuit and measure it would be the preferred way.

 

[madperry]

Thanks for that information. I will remove and test c2. Any idea what c3 should be? And if that would cause the clock to no longer set?

 

[nauman]

I am not 100% familiar with the MV1C board although the C3 would act as a "filter" for the battery power line which would indicate that most values would work without harm. Even without it, it would probably work fine.

If i recall correctly, when the BIOS tries to set/read the time, it is actually reading the time from the uPD4990AG chip. If the clock is missing, it wouldn't surprise me if it also starts tripping when you try to send actions to it, hence... setting the time is impossible

A side effect with not having the correct value would be a time source moving faster/slower or intermittent ability to change time. A 100% missing one would cause it to totally fail so any value (within reasonable range) would almost be better than none :p.

 

[madperry]

Thanks again. You have been very helpful.