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QUAD FM4 battery check

Jim Audiomisc

Jim Audiomisc

pfm Member
My FM4 has now (twice) 'forgotten' its presets overnight. This makes me wonder if the battery is blutered and needs replacing asap.

However having looked at the checklist for diagnosis that QUAD issued I also wonder if it might be that I've left the tuner connected to mains but not used/on for a lot of the time.

i.e. Does the 'top up' current for the battery only operate when the FM4 is switched on and powered? Or does the charging run if it is given a mains connection but the on/off switch is 'off'? The diagrams omit this... or at least so far as I can see.
 
Hi,
You can replace the battery with a PIC chip that Quad sells. It also doubles presets.
Give Rob Flain a ring perhaps.
 
Jim Audiomisc said:
i.e. Does the 'top up' current for the battery only operate when the FM4 is switched on and powered? Or does the charging run if it is given a mains connection but the on/off switch is 'off'? The diagrams omit this... or at least so far as I can see.
Click to expand...
Charges only when switched-on/unit running.
Mine is healthy - it held presets for some months in storage before I bought, and powered-up.
 
martin clark said:
Charges only when switched-on/unit running.
Mine is healthy - it held presets for some months in storage before I bought, and powered-up.
Click to expand...

Thanks. I'll experiment pro tem with having it left on for a while each day. I'll also have a look inside before I do to check the battery isn't leaking, etc. Results will determine how swiftly I email Rob. :)
 
Have you identified the battery and checked for physical leakage? IIRC is an issue with FM4s as it is with so many computers of its era. I’d be looking very carefully for corrosion and getting it out of there ASAP.

PS I’ve just googled it and it is indeed the Varta type that shits itself across so many computer boards resulting in corroded traces, the need for serious board rework etc. Just get it out of there!
 
To check is so easy on an fm4 obvs ... two screws on teh back, slid the case sleeve off. Instant complete access to both sides of the PCB. A joy.

... Late model FM4s actually have the rechargeable battery sat inside a kind of plastic cup to prevent leakage causing damage!
 
I've now had a chance to slip off the sleeve and have a gander. The serial no sticker has vanished from the back of the case but it looks like a late issue of the board. The battery is, indeed, in a rectangular plastic 'cup'. the board has "Q 017357" on it. Overall, it looks perfect at first look... but closer inspection does show some tiny whisps of 'white feathering' around the metal poking out of the battery itself at one end. The control is a Texas TMS1000MLC and this is in a multipin socket.

I'll see if I can just get a replacement battery as I don't really use the presets at all, so the existing number is fine. Helps to keep it in 'original condition'.

Q. Not studied the circuit enough to tell. So will ask:

Does the tuner still work OK *without* any battery? i.e. the only change is that the presets don't work? My impression is that's happening anyway at present, but want to know if this risks something else if I go on using it with the battery removed? Anyone know? Otherwise I'll email Rob about a new battery and replace the existing one to make 'as new'.

Ta. :)
 
Get rid of the battery altogether Jim and install the PIC chip instead, really.

You won’t ever have to worry about leaving the tuner on from time to time, or replacing the expensive battery.

In your case the battery has started leaking. Clean very thoroughly because the chemicals will continue their corrosion work.
The tuner should work with no battery, on manual (red LED) anyway.
 
Thanks. I'll remove the battery and use it without pro tem.

Just to make sure I have this right. Does the PIC chip:

A) Fit into the same socket?

B) mean it won't need a new battery?

The only sign of corrosion is on the metal on the battery IN the plastic 'cup'. So it looks like no damage outwith that. However I'll check when I've lifted the battery + cup out.
 
It's dead easy to replace the battery. They're as cheap as chips on eBay. I've just done mine with a bit of helpful advice from fellow pfmrs. If I can do it anyone can :)
 
FWIW I've now removed the battery OK. One curio was as follows:

The battery is in a cup as per above. Wired in via a pair of wires coming up to the 'rim' of the cup from the board. These soldered to two other wires from the battery up to the rim.

One of these solder joints fell apart as I started to move the wires getting ready to break the connection. So the connection was mostly 'proximity' anyway. That may have been why it got unreliable.

Nevertheless, now removed. Email sent. :) I've put the FM4 back into use as is whilst awaiting a new controller chip.

Thanks to all for the help. :)
 
Hello, good morning everyone,
Recently I've noticed a problem on my FM4 due to the battery leakinto the PCB. I've cleaned it and tested the continuity of the PCB components near the battery. But, the LEDs don't turn on, neither the display changes from 84.9 MHz.
https://imgur.com/a/hagmE4r
https://imgur.com/a/njPzmV2
I think that the IC1 isn't Ok. Is there any possibility to change it?
Thank you very much for your help in advance.
Best regards,
 
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