Roberts radio

[Graham hunt]

Hello,new to the forum and new to electronics but hopefully can learn , I've a Roberts radio that runs fine on its rechargeable battery's for about 20 mins then looses it signal . To get it working again I have to remove battery's for a while then replace , the longer the battery's are out the longer I can get a radio station, the battery's are rechargeable and when the radio is plugged into the ac adaptor the charger interferes with the reception as well.the third problem which I think are all related is when I switch the radio off the LCD display still appears to be slightly lit which could explain why the battery's don't last very long and need recharging every other day , hope some one can help , cheers graham

 

[davenn]

it also sounds like the rechargeable batteries need replacing

 

[Martaine2005]

when the radio is plugged into the ac adaptor the charger interferes with the reception as well.

Apart from the batteries as Davenn suggested.
Are you testing this with wires all tangled up?
Try a re-test with nice neat wiring going to the radio without other chargers or adapters connected.

Martin

 

[Graham hunt]

Thanks for reply , these are the second set of batteries I've used , the radio uses alkaline or rechargeable with the radio recharging them in the radio . The alkaline went flat over night as do the rechargeable aswell just as though the radio is switched on still , when I press the off switch the lcd display still seems to be slightly lit, I've also tried the ac adaptor on different mains outlets and with the cable at different positions ,not sure if this will help diagnose or not but the radio has a switch under the battery's to flick from alkaline to rechargeable battery's , could this be faulty or am I barking up wrong tree

 

[Martaine2005]

Hi Graham,
if the LCD is still lit after power off, that would explain draining the batteries.
It seems like you may have to do some invasive surgery.
The switch under the batteries sounds like an accident waiting to happen too.
Does the LCD stay 'slightly' lit when on power adaptor with no batteries inserted?
It would definitely be worth while checking the connections on the switch under the batteries. And the switch too.
It is clearly connected to the power input side for charging.

Martin

 

[Graham hunt]

Have done a check and removed the batteries while plugged into the mains .the signal is very crackly and I can only just here the station channel. If I removed the batteries the signal stays the same and then when I switch it off the lcd display is still lit for about 5 seconds then goes blank which would explain the draining of the battery's , also the AC adaptor is only supposed to charge the batteries when the radio is switch off , so when it's on a station it should only run on batteries , could it be trying to charge while it's on and that would explain the interference. It's all very baffling

 

[Martaine2005]

What model radio is it?
I would be very surprised if you HAVE to run it on batteries! The adaptor should be to run it when you DON'T want it on batteries.
It also sounds like the adaptor needs filtering.
Let me have a read of the specific model first.

Martin

 

[Graham hunt]

It's a Roberts doulogik,,,,,I've just tried it again and when I switched it on the display just flashed on and of , then I removed batteries for 5 mins and tried again it worked fine ,thanks for helping

 

[Martaine2005]

Hi Graham,
Here is a snippet from the user manual.

"We would recommend for economy that the
duologic is used via the AC adaptor whenever possible with battery operation for occasional or
stand-by use only. If extended listening using batteries is anticipated,
then the use of rechargeable batteries is recommended."

Can you check the AC adaptor? It appears that it is not charging or powering the radio.
EDIT: Can you also check the radio with standard D batteries.
Martin

 

[Graham hunt]

Hello, I've used standard batteries with the same effect as the rechargeable ones , the radio worked for a short time then lost its signal just as though there was no signal and same effect happened with the rechargeable ones . It runs normal for about 20 or 30 mins , the signal then disappears and I have to remove batteries to get it to work again , the standard D batteries were flat over night even though I'd only used them for 20 mins of listening. The rechargeable ones do the same over night but will recharge over a few hours and the radio works for a short time again. With no batteries in the radio will work but with a lot of interference so like so say it may need a filter . The AC adaptor I purchased of eBay was supposed to be a Roberts replacement power supply. If I could get the radio to work just on batteries would be fine and just charge it over night as there supposed to run for quite along time on just batteries, but 30 mins is top then I loose all signal .

 

[GPG]

With no batteries in the radio will work

For how long?

 

[Graham hunt]

If I remove batteries and just use the AC adaptor it does work but with a lot of interference ,ive got it running now to see how long it will stay on for , I'm guessing it will stay on constant but all I can get sound wise is crackling and the lcd display is not properly lit it's blocky which it also does when it's just using batteries. The fault with the lcd display is intermittent sometimes it lights up as it should . Is it possible something like a transistor or diode is at fault , thanks graham

 

[Graham hunt]

The AC adaptor is a replacement from eBay which I can understand could give electrical interference, I could live with that and just use it on batteries then leave on charge over night , but the short time it runs on batteries then cuts out or gets interference is strange

 

[Graham hunt]

I really know nothing about electronics but could it all be related to the built in battery charger ,when I switch the radio of with batteries in and the AC adaptor plugged in, the LCD display is slightly lit and blocky looking , if I then remove a battery The display goes blank as it should and when replaced the display is still blank so does this mean it's not switching of properly or switching over to mains somehow .

 

[nepow]

I really know nothing about electronics but could it all be related to the built in battery charger ,when I switch the radio of with batteries in and the AC adaptor plugged in, the LCD display is slightly lit and blocky looking , if I then remove a battery The display goes blank as it should and when replaced the display is still blank so does this mean it's not switching of properly or switching over to mains somehow .

I'm somewhat confused reading your problem. using on AC will switch out the battery circuit but how can you use standard cells when these are not rechargeable? or are they saying you can use re chargeable batteries that normally would be charged by an alternative means!! I wouldn't think the mains adapter serves as a charger for the radio's internal batteries should they be none recharge standard cells.

 

[Graham hunt]

Hello thanks for the reply, I think it uses the AC supply when plugged in even if rechargeable battery's or alkaline are inserted ,I've tried different things with it to try and solve problem , and noticed if the mains is not connected the radio will play but when you switch it off although it appears to go off the LCD display is still slightly lit and drains the battery's. I then have to remove a battery and re insert it so the LCD display completely gos out. When using the AC all I get is interference . Thanks Graham

 

[Graham hunt]

Ps , on the above reply , the radio has a built in battery charger and has a switch to swap from alkaline to rechargeable

 

[nepow]

Ps , on the above reply , the radio has a built in battery charger and has a switch to swap from alkaline to rechargeable

Hi Graham, OK that was my concern as standard batteries shouldn't be recharged of course. I think without a service manual or at least a schematic your going to struggle sorting the fault. Like most other domestic electrical products it would cost more to fix than the value of the radio should you opt for a repair. Many years back I sold Roberts Radio's when they were hand made in the UK later products manufactured overseas. Shame we can't offer you more help. Kind Regards

 

[Martaine2005]

Hi Graham, OK that was my concern as standard batteries shouldn't be recharged of course. I think without a service manual or at least a schematic your going to struggle sorting the fault. Like most other domestic electrical products it would cost more to fix than the value of the radio should you opt for a repair. Many years back I sold Roberts Radio's when they were hand made in the UK later products manufactured overseas. Shame we can't offer you more help. Kind Regards

That radio has a switch to choose rechargeables or alkaline batteries.
I have already said to check that switch. There obviously is a lot of leakage from the main circuit or charging circuit.

Martin

 

[Graham hunt]

Fine with checking the switch but any pointers on what to look for on power supply ,thanks