Hey guys,

I recently won a SRF-201 on eBay complete with charger and original headphones. I'd say it's in good condition cosmetically and great condition functionally, with the exception of the internal batteries. The sound is very impressive for such a compact device.

I decided to crack it open tonight to see about replacing those batteries. The device is made up of a plastic frame with front and rear metal plates. The plates are held to the frame with screws going through one plate into these threaded caps with smooth chrome heads going through the other plate. I had no problem removing the screws until I got to the last one. When I tried to remove the screw the cap on the other side began to spin.

JohnEdward mentions this in another post about the SRF-201 and as he states, the chrome plating chips very easily on the caps and you can't get a hold of them to stop them from spinning. In my case, the one that was jammed was near the battery and my guess is that the leakage seized the threads.

I finally gave up on saving the looks of the cap and used an x-acto knife to cut a slot into the top of the cap. They are brass underneath the chrome and cutting the slot wasn't very difficult. Just be careful not to slide off the cap and scratch the plate. Once the slot was sufficiently sized to fit my 1.8mm slotted jewelers screwdriver I was able to hold one screwdriver in each hand and work the screw loose.

Next was the tuning control which has a cover glued on the knob hiding the screw which holds it to the variable capacitor. The glue on my unit was like concrete and I had to work my way around the underside of the knob cover with the x-acto to free it up. Of course the collar on the knife nicked the paint on the plate. Crap, I wished I'd thought to have covered the plate with paper tape before I started this.

Once the knob was off, there are a couple more screws under it and you have to loosen a snap near the volume control, then you can work the plate off. Another gotcha here is that the paint on the plate is very brittle. It flaked off a bit in the lower right corner but I finally have the plate removed.

Inside, there are two batteries model "GF40" which I had no luck finding via Google. The size is similar to a CR2025 but I have no idea if these are 1.5V or 3.0V. I'm also not sure if I should try to find lithium, alkaline or silver oxide. Any help or suggestions would be much appreciated.

One of the batteries in my unit has leaked pretty significantly so I decided to go on a tear mine all the way down to clean it out. I was surprised to find that the board is actually permanently adhered to the back plate. There's one more screw, a couple of snaps around the sides and then you must desolder the headphone and battery connections. Finally, there's a bit of adhesive holding the back plate to the frame, but it wasn't difficult to get it loose.

Now I've cleaned up all the acid and have the unit ready to go back together once I have batteries. I'll snap some photos during re-assembly and post them.


Thanks,
Cameron

Can you post some photos of those batteries?  I don't recognize GF40 but nearly every coin-shaped battery I've encountered is 3V. But this was equipped with a charger pack so you're dealing with rechargeable batteries.  The voltage varies on those....

If they are rechargeable lithium batteries they could be replaced with 3v Panasonic VL2020 that are 20mm diameter by 2mm thick and hold 20mAh. The operating voltage maybe on the unit or charger may give some kind of clue as to the technology of the batteries, assuming these are rechargeable coins.

Here's some photos of the internals of the SRF-201. Notice the close-up of the troublesome threaded cap I had to cut a slot into in order to open the unit.

I did also think to measure the voltage of the batteries and they are both producing about 1.3V. I've done a bit more research on suitable replacements and most of the information I've read indicates that the standard lithium batteries should not be charged. I'm now considering scraping the idea of using coin type cells and using a more modern NiMh or Li-Ion cell. Surely there would be suitable sized pack made for Bluetooth headsets.

I'll keep you posted as to my progress on the restore.

Cameron

Hi Cameron,



Thanks for sharing the pictures with us. I've got a NIB Sony SRF-201 and it would really be a pity to have to strip it down to replace the batteries. It appears to be an impossible task without incurring a bit of damage. At least I now know what's involved.



This radio does sound great, amazing sound for it's size. I would imagine that the batteries are Ni-Cd coin batterries at 1,2v per cell. If you use a Li-Ion rechargeable battery, which is 3v per cell, then either use one or if you use two then just solder them in parallel as opposed to series which the original batteries would have been connected.



Cheers,



Greg