Roberts R24

[Refugee]

This one does not look like there is much to do on it.
I have not powered it up yet but the visual inspection has revealed that all the brights are present although one is damaged.
The volume control feels like the nut is loose and there is a small rust mark on the mains transformer bracket from a well rotted battery that was still in the set when found.
There is even a mains lead with a period plug on it. I bet there is a 13 amp fuse in it
The clear part of the tuning dial is also loose.

It is in good condition except for the dented volume knob bright.
It still has the back grille and a good aerial.

I will have power on it after I have sorted the car out.

[AlanBeckett]

Although I'm not a Roberts fan That one looks promising.
I filled a similar Battery with AAs and Wax for my Test Gear.

Alan

[Refugee]

The snaps are still good on the rusty battery so either I will fit a modern AA holder to the top from the scrap battery or re-stuff with cells from an old 286 laptop battery I have. For this I would be tempted to add an internal charger that has an extra pair of pins on the pack to plug it onto. I could hide a switch inside close to the battery cover lift hole to prevent over charging if it is running on mains.
NIMH cells do not work very well if they are left on charge for too long so the switch would be needed.

[Old Sparky]

Am I misssing something here? The corroded battery is a PP9 and these are still widely available, admittedly at around £5 each. AFAIK rechargeable versions are/were on the market, too. I'm not familiar with the R24, although I've repaired quite a lot of Roberts radios, both the older 'genuine' ones, and the ones withmore modern Sangean or other Chinese Electronucs inside. The 24 looks like one of the earlier examples of the latter type (if that makes any sense!)

[Refugee]

It is a 1980s original Roberts from just before they sold out there name. The PCB looks like it may be bought in as it has a solid dielectric tuning capacitor.
It is not a digital set and has FM.
I always save the snaps from old PP9s and have fitted adapter plates made with these to use the AA packs with PP9 style snaps as I found a modest batch of NOS ones many years ago. They are nearly all used up now.

[AlanBeckett]

NIMH cells do not work very well if they are left on charge for too long so the switch would be needed.

You can Float Charge sealed Button Cells at .01C - see ebay Item 131027010778. However, they don't come cheap

Alan

[Refugee]

I was thinking of adding a third snap so that it can be changed over for charging from the internal transformer.

[Mark Hennessy]

Nice sets, but the top panels are a real pain. Hacker had the same problem with their Sovereign III range - for whatever reason, the silk-screen doesn't stick very well to the anodised aluminium. These Roberts sets were quite a bit later than the affected Hackers, so it makes you wonder why Roberts didn't learn from Hacker's mistake. Perhaps the problem wasn't really apparent at that time.

I've got an R800 with the same problem. My R24 - also in red - is OK. It's a matter of luck with these sets.

I'm always inclined to avoid modifications to these sets, so I would prefer any battery charging arrangement to be external to the radio. As the PP9s are so cheap and long-lived, I've never got around to it, but I vaguely plan to put some cells into a dead battery, along with a charger IC (e.g. Maxim), and a standard 2.5mm DC socket. It should work well. But we get more than a year from our PP9s in our Hacker sets, and ones that get used most heavily are powered from the mains anyway.

Good luck with the restoration. Those side panels will come really nicely with a bit of Danish oil. I usually unhook the grey piping from the sides (no need to remove it completely). The grille is very fragile, but yours looks to be very nice. Just in case you're not aware, foam cleanser can remove the black stripes (which surprised me, as it's normally pretty mild!). Red Rexine can be awkward, depending on what caused the marks, but I reckon it'll clean up nicely.

Pictures when finished, please

Mark

[Refugee]

I have had some workshop time this evening.
It was pretty easy to open it up.
The handle is best removed. This is done by placing the set across your knees and patting the carry handle down so that it clicks off the studs. Once the screws are out the front panel needs to be eased off the backing plate with some care as it has tabs that are bent into slots. The knobs are different. The volume is a round shaft and the tuning has a flat.

The little patch of rust on the transformer bracket is small enough that it is likely to end up looking worse if an attempt is made to remove it. I will leave it alone.
The loose volume control nut was indeed just the fixing nut so it was a quick fix.
The dial is clear PVC and the original glue was too brittle and had let go. I have used some slow setting conformal stuff that shot under the inside by capillary action and must now be left to set over night.
The PCB has got a clean bill of health on all three bands and requires no work. It is just two chips and three transistors. It looks like the oscillator coil for the FM is on a former slipped over the transistor. That is a cunning way of getting a bit of coupling between the two components for sure.

If I do go for an on board charger there is a plug in trick without modification.
There is a link plug between the transformer plate and the main board. A pair of connectors to fit this will be needed and then all other charging gear can hide in the NIMH battery itself including a charge state test device and all that sort of stuff.
There is a diode that prevents the battery trying to take charge from the transformer. This is odd as there is switching ganged with the mains lead connector. This means that with a battery fitted the set is uninterruptible in the event of a power failure. Perhaps a diode was cheaper than four soldered connections in the day.
There is an odd resistor on the rectifier that appears to be across the battery on the unswitched side that would make the battery go flat. It appears to have been cut out as a factory modification and rightly so too.

[Mark Hennessy]

Service data here: http://elektrotanya.com/roberts_r24_am_f...nload.html

I see what you mean about that resistor - see the note at the end of the PDF. Bit of an "oops"