Hello, I bought an SR10 receiver in a thrift store but it loses it settings after turning it off. Treble, Bass, Balance and tuner presets are all gone after turning power off. In the past I have replaced gold caps in receivers but I can't find anything like that in this receiver, just ordinary capacitors. I wonder if anyone can tell me where to look, I can't find a repair manual on the internet either. It looks like a great receiver with very capable power supply and worthwhile repairing.
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Cambridge Audio Topaz SR10 loss of memory
- Thread starter RobertPS
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supercaps are easy to spot. they are usually 5.5v. look for oddball colors too. oddball sizes too.
use google and look at images so you know what you are looking for.
sometimes they like to hide them on the display pcb behind the faceplate i've noticed.
sometimes they are physically close to the IC it is supply voltage too.
i can't tell you exactly where it is, i don't have the unit and a screwdriver in front of me...
I did and they sent me the service manual! Very nice people at Cambridge Audio. Now find the part that is responsible for storing backup power.
that's very cool of them!
i'd start by looking at the parts list and look for a 5.5v cap
cpt_paranoia
Addicted Member
Bottom left corner looks like there's a processor (some QFP package, on the reverse of the PCB). Below that is an 8-pin DIP. Could that be a serial EEPROM of some sort? Could it have gone faulty?
I was thinking of that too! Could they have used an eeprom (ic 6) to store the settings?
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cpt_paranoia
Addicted Member
24C02 EEPROM. Can't see what else they would use it for. So if there's no supercap and associated memory, then it's a good bet that they have used the EEPROM to store settings. What does the service manual say about IC6?
AT24C01A/02/04/08/16 (microchip.com)
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cpt_paranoia
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So there's no text description of the features, or of the test points to examine? Just the schematics? Not really what I'd call a service manual...
For debugging, I would start by examining the soldering on the EEPROM pins, at the EEPROM, and at the processor. Then, if you have a scope, monitor the SCL and SDA lines to see if it looks like the thing is being accessed, and responding to reads. Check the data sheet for the expected behaviour of the SDA line when reading and writing; especially the ACK bits, to make sure the EEPROM is responding.
Also check that the three address lines on the EEPROM are at the voltages expected; if they have allowed to float, it will change the device address, and it will not respond to read or write commands sent from the processor (which expects to see a particular hardware address, set by those pins). They should all be ground; check the lead on the package, not the soldered pin...
For debugging, I would start by examining the soldering on the EEPROM pins, at the EEPROM, and at the processor. Then, if you have a scope, monitor the SCL and SDA lines to see if it looks like the thing is being accessed, and responding to reads. Check the data sheet for the expected behaviour of the SDA line when reading and writing; especially the ACK bits, to make sure the EEPROM is responding.
Also check that the three address lines on the EEPROM are at the voltages expected; if they have allowed to float, it will change the device address, and it will not respond to read or write commands sent from the processor (which expects to see a particular hardware address, set by those pins). They should all be ground; check the lead on the package, not the soldered pin...