Roberts R900. Noisy volume control. - UK Vintage Radio Repair and Restoration Discussion Forum

Steve Helm · 10th Dec 2011, 5:12 pm

I recently bought a Roberts R900 and cosmetically it is in fantastic condition. It also sounds fantastic. But, when I increase or decrease the volume it crackles really badly until I arrive at the desired sound level. Once at the level it's fine.

Is there any easy fix? If so could someone please advise me on what to do? Apologies but I'm not too technically gifted.

Thanks in advance.

Steve

ms660 · 10th Dec 2011, 6:13 pm

It sounds as if it needs cleaning, if that fails check for DC on the pot...shouldn't be any, if that fails change pot if available or if you can get one.

Lawrence.

wireful3 · 10th Dec 2011, 7:52 pm

Hello Steve,
When I get these symptoms my first step is to clean the volume potentiometer track. This is usually not very difficult and with the R900 I think it can be done without any major dismantling. The chassis can be released by removing three screws, two on the side just above the handle fixings and one at the base securing the FM aerial. This then enables the chassis to be pushed upwards a few centimeters to enable access to the volume control. From memory the leads are long enough so don't need to be disconnected.

I use switch cleaner that comes in a pressurised can with a long flexible nozzle. The tricky part is getting the stuff inside the potentiometer without major surgery. I have usually found a gap where the rear cover is fixed to the main part. This allows switch cleaner to be squirted inside. Moving the control backwards and forwards a few times is usually enough to clean it after that. If you have the battery still connected it gives an idea whether it has been successful.

The main concern is to be careful not to damage anything when extracting the chassis. As it has been in place quite a few years it can be a bit wedged in the case. In which case it will need pushing up from below with a wooden rod. The end under the battery gives a clear patch to push against.

I have gone into a relatively detailed description because you said you did not have much technical experience but I am sure with this fault you stand a chance of making an impression that will give you confidence.

The R900 was one of the first Roberts sets I got when I started collecting and I was always impressed with it.

Good luck

Steve Helm · 10th Dec 2011, 9:11 pm

Thanks, I'll let you know I get on.

geofy · 11th Dec 2011, 11:11 am

There is an easier way which usually works, just carefully prise off the volume control knob and dribble the switch cleaner down the shaft, rotate the control over its full sweep a few times. Use switch cleaner such as Servisol Super 10.

wireful3 · 11th Dec 2011, 11:39 am

Thanks for mentioning it Geof. It is even easier than my way and should certainly be tried first.

geofy · 11th Dec 2011, 11:51 am

Quote:

Originally Posted by Steve Helm

Is there any easy fix? If so could someone please advise me on what to do? Apologies but I'm not too technically gifted.

Quote:

Originally Posted by wireful3

Thanks for mentioning it Geof. It is even easier than my way and should certainly be tried first.

Hi John, As Steve says he is not too techy, a strip down of the radio might be tricky, though a good way to learn. As the control knobs would have to be removed anyway this method might as well be tried first, one thing to be careful of is not to wash out any of the lube that is in the control already.

Steve Helm · 19th Dec 2011, 7:20 pm

Thanks fellas. a removal of the volume knob and a dribble of the fluid did the trick. Sounds like new.

Steve Helm · 20th Dec 2011, 2:58 pm

So, after the success of curing the crackling Roberts volume control I set about my Hacker Hunter. I bought it in fantastic cosmetic condition but was told there was a black spot in reception in the mid ranges.

A few squirts of the switch cleaner and I cant believe my ears, a fully functioning Hunter. (For an hour or so after the cleaning the frequencies slightly moved though, now they are spot on)

I bought the switch cleaner from Maplins for a reasonable £3.99. Bargain, considering I now have a fully functioning piece of British history.

Thanks again.

Station X · 20th Dec 2011, 9:38 pm

If you want to discuss the Hacker Hunter further please start a new thread.

60 oldjohn · 20th Dec 2011, 10:03 pm

Hi Steve,

While you have a set handy with the switch cleaner it is often worth giving the wavechanger a drop and working the switch may just improve reliability in the future, but keep it away from coils. Remember that some switch cleaner fluids have been reported to harm plastics.

John.

10th Dec 2011, 5:12 pm	#1
Steve Helm Retired Dormant Member Join Date: Dec 2011 Location: Preston Posts: 6	Roberts R900. Noisy volume control. I recently bought a Roberts R900 and cosmetically it is in fantastic condition. It also sounds fantastic. But, when I increase or decrease the volume it crackles really badly until I arrive at the desired sound level. Once at the level it's fine. Is there any easy fix? If so could someone please advise me on what to do? Apologies but I'm not too technically gifted. Thanks in advance. Steve Last edited by Station X; 10th Dec 2011 at 5:56 pm. Reason: Title made more meaningful.

10th Dec 2011, 6:13 pm	#2
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Roberts R900. Noisy volume control. It sounds as if it needs cleaning, if that fails check for DC on the pot...shouldn't be any, if that fails change pot if available or if you can get one. Lawrence.

10th Dec 2011, 7:52 pm	#3
wireful3 Retired Dormant Member Join Date: Sep 2003 Location: Bristol, UK. Posts: 808	Re: Roberts R900. Noisy volume control. Hello Steve, When I get these symptoms my first step is to clean the volume potentiometer track. This is usually not very difficult and with the R900 I think it can be done without any major dismantling. The chassis can be released by removing three screws, two on the side just above the handle fixings and one at the base securing the FM aerial. This then enables the chassis to be pushed upwards a few centimeters to enable access to the volume control. From memory the leads are long enough so don't need to be disconnected. I use switch cleaner that comes in a pressurised can with a long flexible nozzle. The tricky part is getting the stuff inside the potentiometer without major surgery. I have usually found a gap where the rear cover is fixed to the main part. This allows switch cleaner to be squirted inside. Moving the control backwards and forwards a few times is usually enough to clean it after that. If you have the battery still connected it gives an idea whether it has been successful. The main concern is to be careful not to damage anything when extracting the chassis. As it has been in place quite a few years it can be a bit wedged in the case. In which case it will need pushing up from below with a wooden rod. The end under the battery gives a clear patch to push against. I have gone into a relatively detailed description because you said you did not have much technical experience but I am sure with this fault you stand a chance of making an impression that will give you confidence. The R900 was one of the first Roberts sets I got when I started collecting and I was always impressed with it. Good luck Last edited by wireful3; 10th Dec 2011 at 7:54 pm. Reason: typos

10th Dec 2011, 9:11 pm	#4
Steve Helm Retired Dormant Member Join Date: Dec 2011 Location: Preston Posts: 6	Re: Roberts R900. Noisy volume control. Thanks, I'll let you know I get on.

11th Dec 2011, 11:11 am	#5
geofy Retired Dormant Member Join Date: Jun 2006 Posts: 1,798	Re: Roberts R900. Noisy volume control. There is an easier way which usually works, just carefully prise off the volume control knob and dribble the switch cleaner down the shaft, rotate the control over its full sweep a few times. Use switch cleaner such as Servisol Super 10.

11th Dec 2011, 11:39 am	#6
wireful3 Retired Dormant Member Join Date: Sep 2003 Location: Bristol, UK. Posts: 808	Re: Roberts R900. Noisy volume control. Thanks for mentioning it Geof. It is even easier than my way and should certainly be tried first.

19th Dec 2011, 7:20 pm	#8
Steve Helm Retired Dormant Member Join Date: Dec 2011 Location: Preston Posts: 6	Re: Roberts R900. Noisy volume control. Thanks fellas. a removal of the volume knob and a dribble of the fluid did the trick. Sounds like new.

20th Dec 2011, 2:58 pm	#9
Steve Helm Retired Dormant Member Join Date: Dec 2011 Location: Preston Posts: 6	Re: Roberts R900. Noisy volume control. So, after the success of curing the crackling Roberts volume control I set about my Hacker Hunter. I bought it in fantastic cosmetic condition but was told there was a black spot in reception in the mid ranges. A few squirts of the switch cleaner and I cant believe my ears, a fully functioning Hunter. (For an hour or so after the cleaning the frequencies slightly moved though, now they are spot on) I bought the switch cleaner from Maplins for a reasonable £3.99. Bargain, considering I now have a fully functioning piece of British history. Thanks again.

20th Dec 2011, 9:38 pm	#10
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,286	Re: Roberts R900. Noisy volume control. If you want to discuss the Hacker Hunter further please start a new thread. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

20th Dec 2011, 10:03 pm	#11
60 oldjohn Dekatron Join Date: Dec 2004 Location: East Yorkshire, UK. Posts: 3,985	Re: Roberts R900. Noisy volume control. Hi Steve, While you have a set handy with the switch cleaner it is often worth giving the wavechanger a drop and working the switch may just improve reliability in the future, but keep it away from coils. Remember that some switch cleaner fluids have been reported to harm plastics. John.