Hi,
I have a lovely Grundig T5000 tuner which seems to work lovely, apart from retaining the time when it's switched off.
I don't have the User Manual, but I can put the correct time in using the buttons on the front, but when it's switched off it doesn't retain the time.
I think the time is battery backed on a MCM5101P-65 chip, so am wondering if this could be the issue, and if I can get a replacement (can't see any on Ebay), or an alternative?
I get approx 3.6volts on pin 22 when there's no power to the unit, just the batteries. Which seems about right.
Please see the attached pictures or further information.
Thanks, Rob
I have a lovely Grundig T5000 tuner which seems to work lovely, apart from retaining the time when it's switched off.
I don't have the User Manual, but I can put the correct time in using the buttons on the front, but when it's switched off it doesn't retain the time.
I think the time is battery backed on a MCM5101P-65 chip, so am wondering if this could be the issue, and if I can get a replacement (can't see any on Ebay), or an alternative?
I get approx 3.6volts on pin 22 when there's no power to the unit, just the batteries. Which seems about right.
Please see the attached pictures or further information.
Thanks, Rob
Attachments
There is an off-drawing wire "batt". Let's see the WHOLE plan.
Grundig T 5000 AM/FM Stereo Tuner Manual | HiFi Engine
Page 8, that wire runs to "2X alkali mignon zelle". My German is poor but I smell an Alkaline battery, and a G-search finds the same phrase as "1.5V AA". TV Remote batteries! That should not be too hard to find in there. And if you never replaced them, they sure are past their freshness date by now. They may even be the Stützbatterie on the chassis layout. Next to the power transformer.
Grundig T 5000 AM/FM Stereo Tuner Manual | HiFi Engine
Page 8, that wire runs to "2X alkali mignon zelle". My German is poor but I smell an Alkaline battery, and a G-search finds the same phrase as "1.5V AA". TV Remote batteries! That should not be too hard to find in there. And if you never replaced them, they sure are past their freshness date by now. They may even be the Stützbatterie on the chassis layout. Next to the power transformer.
Attachments
I've replaced the batteries, and have traced the voltage through to pin 22 on MCM5101P-65 chip, so I don't think the back up battery voltage is the issue - I think. This voltage is there when no power is applied to the unit from the mains.
Is it likely that it's the chip (MCM5101P-65) that is causing the time not to be held, and if so is there any stock of these or an alternative that can be bought?
Rob
Is it likely that it's the chip (MCM5101P-65) that is causing the time not to be held, and if so is there any stock of these or an alternative that can be bought?
Rob
When I type MCM5101P-65 in duckduckgo, it claims it's a random access memory rather than a real-time clock. In fact your schematic fragment says the same. Maybe it's used for remembering station presets, but not for keeping time.
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On my Kenwood set, the presets were kept in memory by a large capacitor, if you kept it off mains for a few days it would lose the memory. Reconnecting and keeping on for a few hours got it back.
There may be a similar setup in your set. And the capacitor may have gone weak. Look for a large cap, 3300 on wards, in low volts, less than 15.
First leave it on after thorough cleaning, for more than 24 hours, see if it helps.
And stupid stuff like conductive glue, corroded sockets and so on need to be checked.
There may be a similar setup in your set. And the capacitor may have gone weak. Look for a large cap, 3300 on wards, in low volts, less than 15.
First leave it on after thorough cleaning, for more than 24 hours, see if it helps.
And stupid stuff like conductive glue, corroded sockets and so on need to be checked.
The OP is concerned that the TIME CLOCK is not keeping TIME after being turned off.
The comments all concerning station MEMORY keeping are not relevent.
The OP should troubleshoot the circuitry concerning the time keeping area.
The comments all concerning station MEMORY keeping are not relevent.
The OP should troubleshoot the circuitry concerning the time keeping area.
He was looking at a chip which is a RAM, not the clock chip.
My microwave will not keep time if mains is off...first check that it really does have a clock backup, in the sense that it does have a time retention function, and for how many hours.
Then find the chip, see how it is supplied when power is off, and check that the power is in fact available at the right voltage, if something is for example corroded the supply will not be sufficient.
Also bear in mind that while battery is the preferred source, some designs used a capacitor.
My old Ericson cell phone had a tagged cell on it for backup, apart from the battery, just as in computer motherboards, only this was soldered rather than in a holder as in motherboards.
My microwave will not keep time if mains is off...first check that it really does have a clock backup, in the sense that it does have a time retention function, and for how many hours.
Then find the chip, see how it is supplied when power is off, and check that the power is in fact available at the right voltage, if something is for example corroded the supply will not be sufficient.
Also bear in mind that while battery is the preferred source, some designs used a capacitor.
My old Ericson cell phone had a tagged cell on it for backup, apart from the battery, just as in computer motherboards, only this was soldered rather than in a holder as in motherboards.
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According to the service schematic of this unit, the main power transformer is always powered.
With that stated, there is always DC available, as well as AC for a clock frequency time generator.
The service manual has all the details.
I'm not 100% sure the time should be retained when the power is switched off via the switch on the front panel (still plugged into the mains supply though), but it would make sense for it to be. I don't have the user manual, which would probably detail this function, and don't seem to be able to find one to download.
I thought that as there was batteries they'd be used to retain the clock, as well as the presets etc, which is why I started looking in that direction on the schematics etc.
I do have a copy of the service manual, which is mostly schematics etc. I'll try and see if I can work out where the chip is that holds the clock circuitry, but if anyone knows it would be helpful. I can then see if there's any voltage on it when powered down, or would it be able to retain the setting without voltage being applied? Someone mentioned a large capacitor.
I'll open the lid up again this morning and take a look at it and the schematics, to see if I can work it out.
Rob
I thought that as there was batteries they'd be used to retain the clock, as well as the presets etc, which is why I started looking in that direction on the schematics etc.
I do have a copy of the service manual, which is mostly schematics etc. I'll try and see if I can work out where the chip is that holds the clock circuitry, but if anyone knows it would be helpful. I can then see if there's any voltage on it when powered down, or would it be able to retain the setting without voltage being applied? Someone mentioned a large capacitor.
I'll open the lid up again this morning and take a look at it and the schematics, to see if I can work it out.
Rob
You mean the unit is on standby if left connected to mains, that is how power is available to the clock?
So really no battery backup, and so if there is a power outage there is going to be a memory loss, and the battery is for the RAM holding tuning presets..
Okay...
So really no battery backup, and so if there is a power outage there is going to be a memory loss, and the battery is for the RAM holding tuning presets..
Okay...
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Please see attached pictures below.
I think I might have worked out (without a user manual) how it should work.
Looks like the battery backup (two AA batteries) "might be" just for storing the presets in MCM5101P-65, which someone has said is just a memory chip. So these would be maintained under power cut conditions.
On the left of the front panel there's a switch marked "Netz Power", and to the right of it one marked "Aus Off". I've just been using the Netz Power button, but I think this should be left on all the time, and the Aus Off button just used for turning it off (putting in standby mode)? Without a user manual I can't prove this, but it seems to make sense. If this is correct you would lose the time setting if you get a power cut, or you turn off the Netz Power button.
So maybe this tuner is working as it should be after all.
Thanks, Rob
I think I might have worked out (without a user manual) how it should work.
Looks like the battery backup (two AA batteries) "might be" just for storing the presets in MCM5101P-65, which someone has said is just a memory chip. So these would be maintained under power cut conditions.
On the left of the front panel there's a switch marked "Netz Power", and to the right of it one marked "Aus Off". I've just been using the Netz Power button, but I think this should be left on all the time, and the Aus Off button just used for turning it off (putting in standby mode)? Without a user manual I can't prove this, but it seems to make sense. If this is correct you would lose the time setting if you get a power cut, or you turn off the Netz Power button.
So maybe this tuner is working as it should be after all.
Thanks, Rob
Attachments
usually "netz " power means mains power..........
with a dmm in ohm mode - connected to the mains plug- you can measure
the res of the transformer primary , switch on and off "netz power"........
aus/off should be " standby "
with a dmm in ohm mode - connected to the mains plug- you can measure
the res of the transformer primary , switch on and off "netz power"........
aus/off should be " standby "
On my Diana camera, Ein - In
Aus - Out
My German is non existent, maybe one of the German speaking members can clarify
Aus - Out
My German is non existent, maybe one of the German speaking members can clarify
Asides from all the discussion about On and Off stuff.......
Killing the AC by the main power switch is going to kill the 50/60 Hz signal to the clock circuitry, so naturally the clock won't be able to keep proper time, and likely reset.
Killing the AC by the main power switch is going to kill the 50/60 Hz signal to the clock circuitry, so naturally the clock won't be able to keep proper time, and likely reset.
"Netz" can be many things. But we are not catching fish. It is surely "power network". In fact bottom of page 8 is our Rosetta Stone: Netz, MAINS, SETEUR (Fr: sector of a net), RETE (It: net).
Also: "POWER CONSUMATION{sic} Standby 15W, Operating 30W" says a LOT of it stays on when "off".
I do not see this "time keeping area." Is it hidden inside the CPU?
Note that it is not counting 50/60Hz. The only AC off the transformer goes to the display. The CPU of course has a crystal as accurate as a Seiko watch. But the CPU take more power even idle-clocking than a watch, so it has to have Netz power all the time.
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Expensive in terms of power consumed, and also dangerous for the unit in case of a power surge.
If time display is not important, leave it off at the mains, from the wall switch.
Think about how much effort it will take to fix it, most parts are not available.
Except in the USA, I have not come across mains frequency being used as the time base for electronic clocks, the actual frequency here is 50 +/- 0.5 Hz, at which point the power distribution sub station is tripped by a frequency relay.
So your mains frequency operated clock will not be accurate.
Quartz crystal based clocks are a lot more accurate, and a single AA carbon zinc cell lasts for 30 months. AC supply is more expensive than a 10 cent cell for that period.
If time display is not important, leave it off at the mains, from the wall switch.
Think about how much effort it will take to fix it, most parts are not available.
Except in the USA, I have not come across mains frequency being used as the time base for electronic clocks, the actual frequency here is 50 +/- 0.5 Hz, at which point the power distribution sub station is tripped by a frequency relay.
So your mains frequency operated clock will not be accurate.
Quartz crystal based clocks are a lot more accurate, and a single AA carbon zinc cell lasts for 30 months. AC supply is more expensive than a 10 cent cell for that period.
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