Author Topic: UC10A counter repair  (Read 965 times)

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Offline texane

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UC10A counter repair
« on: September 27, 2015, 10:49:37 am »

I recently retrieved a malfunctioning uc10a frequency counter. I
opened it and tracked the issue to the icm7226a chipset. This chipset
implements the core frequency counting and display. I am using the
following datasheet:

The IC is powered correctly, but I noticed that there is no signal at
pin 38 (buf osc out). Thus, I suspect the main oscillator stage to be

When looking at the datasheet p.13, I see that the Pierce oscillator
caps (39pF) are connected to VDD, not GND. On the actual device, they
are connected to GND. Do you think there is a mistake in the datasheet ?

Thanks for your help !

Offline SeanB

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Re: UC10A counter repair
« Reply #1 on: September 27, 2015, 12:38:46 pm »
Makes no real difference, it just is the load capacitors are just required across the crystal, so where the midpoint is connected makes no difference from the loading point. As a quick test of the crystal unsolder it and solder it back in with the leads swapped. This often does work with old crystals to help them start up and work again. If it does work then you can either leave it in, and it will work for a few years again, or get a replacement one and solder it in.

Offline texane

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Re: UC10A counter repair
« Reply #2 on: September 27, 2015, 04:11:06 pm »

Thanks for the answer and tip. I tried to rewire the quartz but it did not help. Also, I tried with another new one, changed caps, built an external oscillator ... nothing worked. I guess the chipset is dead :/


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