ICF-C1 Clock runs fast

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Sony ICF-C1T

Sony ICFC1T alarm clock/radio is manufactured so that in the event of a power outage, you have the peace of mind that your device will continue working so you never miss an event.

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Rick Fecho @ricketts223

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发帖于: 2022年2月19日

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ICF-C1 Clock runs fast

Hi everyone - my ICF-C1 clock radio runs fast, gaining about 1 minute and 20 seconds every month. I cannot locate a schematic for this clock radio, so I am unsure if I can modify an RC/crystal circuit to adjust the timing or whether this uses the 60hz mains frequency as a reference. Has anyone had any luck in locating a schematic diagram or in replacing a resistor or capacitor to have more accurate time? Technician with 30 years experience here, just looking for a diagram or helpful advice.

Thanks,

Rick

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same problem. mine is about 1:30 per month. pretty close. there is nothing in sony support that acknowledges or addresses this.

由 tom.kearney 完成的 2022年2月19日

So no luck in finding a circuit diagram for this clock radio. The clock chip is a LC87BB08A-5CD7 but I cannot find any pinouts for this chip. Does anyone know a good location to view, or does anyone have a datasheet for this chip? None of the other Sony service manuals I looked through, that actually have a schematic and a parts list, use this chip.

Thanks!

由 Rick Fecho 完成的 2022年2月20日

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same problem. mine is about 1:30 per month. pretty close. there is nothing in sony support that acknowledges or addresses this. — tom.kearney
So no luck in finding a circuit diagram for this clock radio. The clock chip is a LC87BB08A-5CD7 but I cannot find any pinouts for this chip. Does anyone know a good location to view, or does anyone have a datasheet for this chip? None of the other Sony service manuals I looked through, that actually have a schematic and a parts list, use this chip.

Thanks! — Rick Fecho

jayeff @jayeff 声誉积分: 408千 9 335 1.4千 · Answer 1 · 2022-02-19T19:39:30-07:00

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jayeff @jayeff

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Hi @ricketts223 ,

Don’t know if this is helpful, but here’s a link to the service manual that whilst in itself is not helpful, there are links at the bottom of the page to the service manuals for other ICF C1xx models.

A quick glance through a few of them, shows no mention of a crystal oscillator module in the parts list, so it may be that the mains frequency is used for the time reference. Hopefully yours is the same

Note: You can view the manuals online but you need to select the next page at the bottom of the page to move through the manual. To download you have you sign up to the website.

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Thanks Jayeff - I'll check it out. I popped the lid and there are 2 crystals, one near the radio and one near the clock chip, but unsure exactly at the moment. Just an initial cursory look. I'll definitely check out the link - thanks!

由 Rick Fecho 完成的 2022年2月19日

Did you solve this? I have a SONY Dream machine ICF-C414 that also runs fast (but I have another, bit older ICFC180 and that one doesnt drift at all even after a year+.) Would like to know if replacement of crystal or as you said a resistor or something would fix it. I dont need atomic clock here, but reducing it to drifting a minute in more than a year would be a big improvement.

由 Andrei 完成的 2022年8月26日

Andrei, sorry, didn't see this until now. I never did solve the issue, sadly. I ended up giving the clock radio away and swore to never buy another Sony again

由 Rick Fecho 完成的 2023年1月18日

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Mahmoud Al-Qudsi @mqudsi 声誉积分: 13 1 · Answer 2 · 2023-01-18T15:02:39-07:00

You can't really fix this - I have the same clock and the problem is that Sony was too cheap to use a proper IC that tracks the time via the AC mains frequency (which power companies go to great pains to ensure averages exactly 50 or 60Hz over time). Here Sony is using a generic 8-bit microcontroller and running the clock off the base time-of-day counter w/out an RTC and w/ the lithium battery as a backup power source.

You can find the datasheet for this by searching the sister part number LC87FBG08A (with a different footprint), for example the datasheet is available via Mouser: https://www.mouser.com/ProductDetail/ons...

There is an onboard crystal oscillator (part S3X1, X2 on the PCB schematic) supplying the 32.768K oscillations. The best accuracy that can theoretically be achieved is ±20ppm at room temperature (~10.34 minutes gained or lost/year), but with the temperature swings on the board it's going to be worse than that.

An option which I haven't tried is to replace the XTAL with a DS3232 TCXO. Someone else figured out that you can add the TCXO instead, though your results may vary.

Sony's entire circuit is an exercise in cost savings and I cannot recommend using any Sony ICF-XXX clock to accurately keep time.

Thanks Mahmoud - sad to see a company such as Sony stoop to such sad design practices. I have an old low grade cassette/8 track stereo from 1980 with a built in digital clock that keeps perfect time - even to this day. — Rick Fecho

Sony ICF-C1T

ICF-C1 Clock runs fast

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