How to recover tuner memory

rgo · 18th June 2010, 10:03 PM

Have two Sony Hi-end tuners: St-s444 esII and ST-S550-ES that lose stored station memory when turned off. Does anyone know which specific capacitor's must be replaced in these models to restore stored memory?

bob91343 · 18th June 2010, 10:47 PM

I suspect there is a lithium battery that needs replacement.

rgo · 18th June 2010, 11:08 PM

There is a lithium battery in the s444 and I replaced it but that didn't cure the problem. I don't think the s550 has any battery at all.

Thanks for the reply..

Speedskater · 18th June 2010, 11:53 PM

The site below does memory retention mods on a newer Sony and has links to others that do similar mods:

88–108 MHz
Sony XDR-F1HD

rabbitz · 07:38 AM

There's a 0.1uF 5.5V super cap (also known as gold caps) used at C703 which can be found on the display / control PCB behind the front panel. I just replaced one with a 0.2uF 5.5V. Make sure of the correct polarity when installing.

They look like a squashed electrolytic..... like this:
SuperCap

davidsrsb · 19th June 2010, 09:36 AM

My STS-361 uses a supercap and still holds its memory for a month after >15years use.
Leakage has to be very low to last like that - your board must be clean with no conductive flux residue. If the charge goes very quickly, the ecap C701 in the above thumbnail is likely to have failed

Mooly · 19th June 2010, 10:37 AM

Those "supercaps" have a habit of failing for sure.

Also... and be very very careful here, but I have had odd logic issues on equipment like this and the problem seems to be CMOS logic frozen in an invalid state causing strange behaviour. You can disconnect backup caps etc but it doesn't clear the fault. What does is first remove (disconnect) the backup caps and make 100% sure there is no stray voltage left anywhere and then press a piece of tinfoil over the PCB and short all the pins on all the IC's together. Leave for a while, then remove and power up.
Have fixed many faults that way over the years... there's no actual hardware fault... just an internal lockup within an IC.

davidsrsb · 22nd June 2010, 02:29 PM

The Philips I2C memory uses a normal cmos technology, with no wearout mechanism, unlike EEPROMs

I think that the (cheap) conventional electrolytic is more likely to fail the the supercap.
The supercap only stores power, the high esr and series resistors make them useless for supply decoupling. Faulty decoupling could cause logic lockups

18th June 2010, 10:03 PM	#1
rgo diyAudio Member Join Date: Jun 2010	How to recover tuner memory Have two Sony Hi-end tuners: St-s444 esII and ST-S550-ES that lose stored station memory when turned off. Does anyone know which specific capacitor's must be replaced in these models to restore stored memory?

18th June 2010, 11:53 PM	#4
Speedskater diyAudio Member Join Date: Sep 2002 Location: Lakewood, Ohio	The site below does memory retention mods on a newer Sony and has links to others that do similar mods: 88–108 MHz Sony XDR-F1HD __________________ Kevin

19th June 2010, 10:37 AM	#7
Mooly diyAudio Member Join Date: Sep 2007	Those "supercaps" have a habit of failing for sure. Also... and be very very careful here, but I have had odd logic issues on equipment like this and the problem seems to be CMOS logic frozen in an invalid state causing strange behaviour. You can disconnect backup caps etc but it doesn't clear the fault. What does is first remove (disconnect) the backup caps and make 100% sure there is no stray voltage left anywhere and then press a piece of tinfoil over the PCB and short all the pins on all the IC's together. Leave for a while, then remove and power up. Have fixed many faults that way over the years... there's no actual hardware fault... just an internal lockup within an IC. __________________ ------------------------------------------------------- *A simulation free zone.* *Design it, build it, test it.*

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18th June 2010, 10:47 PM	#2
bob91343 diyAudio Member Join Date: Mar 2010	I suspect there is a lithium battery that needs replacement.

18th June 2010, 11:08 PM	#3
rgo diyAudio Member Join Date: Jun 2010	There is a lithium battery in the s444 and I replaced it but that didn't cure the problem. I don't think the s550 has any battery at all. Thanks for the reply..

19th June 2010, 09:36 AM	#6
davidsrsb diyAudio Member Join Date: Dec 2005 Location: Kuala Lumpur	My STS-361 uses a supercap and still holds its memory for a month after >15years use. Leakage has to be very low to last like that - your board must be clean with no conductive flux residue. If the charge goes very quickly, the ecap C701 in the above thumbnail is likely to have failed

22nd June 2010, 02:29 PM	#8
davidsrsb diyAudio Member Join Date: Dec 2005 Location: Kuala Lumpur	The Philips I2C memory uses a normal cmos technology, with no wearout mechanism, unlike EEPROMs I think that the (cheap) conventional electrolytic is more likely to fail the the supercap. The supercap only stores power, the high esr and series resistors make them useless for supply decoupling. Faulty decoupling could cause logic lockups

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