Home » Audio » Silicon Valley » memory presets won't hold frequency
memory presets won't hold frequency [message #7888] Sat, 22 April 2006 16:02 Go to next message
vinyltocdr@msn.com is currently offline  vinyltocdr@msn.com
Messages: 14
Registered: May 2009
Chancellor
Hello All,

i really enjoy the site. i have noticed that the digital tuning
line of the STA series of receivers such as the STA-2270, 2280,
2500, 2600 lose their memory preset stations if the receiver is not
turned on for a few days. the display goes to 87.9 when a
programmed preset is pressed.

I got my 2600 in 1989 and all thru the 1990's. it would hold the
memory presets for weeks if not months without being turned on.
Now, it will only hold them for a few days if the receiver is not
turned on DAILY. It is not really that important to me because i
rarely listen to the radio due to cd's and vinyl. if there is a
known easy fix, i would like to do it.

my questions to all: is anyone experiencing this problem in their
2500, 2600, 2270, 2280 receivers? is there a memory backup
capacitor that needs replacing? if so, where and which one? where
should i look? any help will be appreciated.

if there is one, perhaps the memory backup capacitor is not holding
a charge any more to provide a slight voltage on the chip to keep
the programmed memory presets in memory.

i do have the service manual for all of these receivers for
reference if any replies are posted. i have noticed this same
condition in the other receivers (listed above) when i have serviced
them over the past five years for others.

thanks for any help or suggestions.

steve



Re: memory presets won't hold frequency [message #7889 is a reply to message #7888] Mon, 24 April 2006 18:59 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18787
Registered: January 2001
Illuminati (33rd Degree)

If there is a large capacitor or battery connected to a pin on the tuner integrated circuit, that's what you'll want to replace. It may be placed after a diode in the line so that the cap or battery supplies power only to the preset memory when power is off. That's how you can probably identify it. Then again, it may be internal to the chip, and if that's the case, you'll have to replace the chip to fix the problem.


Re: memory presets won't hold frequency [message #7892 is a reply to message #7889] Mon, 24 April 2006 19:52 Go to previous messageGo to next message
vinyltocdr@msn.com is currently offline  vinyltocdr@msn.com
Messages: 14
Registered: May 2009
Chancellor
that is very helpful. as i look at the schematic, all the memory preset switches along with the "memory" button go into IC 401. on pin fourteen of IC 401 is a 2200 mfd 6.3v capacitor. the other side of the cap goes to ground. does this sound like the one??

Re: memory presets won't hold frequency [message #7893 is a reply to message #7892] Mon, 24 April 2006 23:51 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18787
Registered: January 2001
Illuminati (33rd Degree)

Sounds like that might be the one. Swap it and see if the problem goes away.


Re: memory presets won't hold frequency [message #7894 is a reply to message #7893] Tue, 25 April 2006 15:47 Go to previous message
vinyltocdr@msn.com is currently offline  vinyltocdr@msn.com
Messages: 14
Registered: May 2009
Chancellor
sounds good to me too. i now need to find the time to do it. thanks again.

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