Roberts R737 MW and LW fading up when cold - UK Vintage Radio Repair and Restoration Discussion Forum

TrevorM6TSE · 3rd Aug 2022, 8:07 pm

Hi All,

I'm chasing a rather odd fault on a Roberts R737 at the moment. It's been woken up after a long time unused and at first it was fine.

What I'm finding now is that when you first turn it on, MW and LW are completely silent. If you leave it about 20-30 secs you can start to just hear audio, but very quiet. Over the next minute the audio fades in and comes to full power. I haven't noticed it on FM.

Now I'm suspecting a capacitor, but there's an awful lot of them in there! Rather than do an en mass replacement I wondered if anyone had experienced this before, or there's a common theme. Googling brings nothing back.

The R737 is (I assume) microprocessor controlled, and all wave change and power buttons are soft press. Only the volume pot is a standard pot.

Any help greatly received!

Trevor

agardiner · 4th Aug 2022, 9:56 am

I agree that it sounds very capacitor. Maybe careful use of a hairdryer and freezer spray?

TrevorM6TSE · 6th Aug 2022, 6:53 am

Yes that sounds like it may be my plan.

I was just hoping for a simple route!

3rd Aug 2022, 8:07 pm	#1
TrevorM6TSE Heptode Join Date: May 2003 Location: Old Tupton, Derbyshire, UK. Posts: 539	Roberts R737 MW and LW fading up when cold Hi All, I'm chasing a rather odd fault on a Roberts R737 at the moment. It's been woken up after a long time unused and at first it was fine. What I'm finding now is that when you first turn it on, MW and LW are completely silent. If you leave it about 20-30 secs you can start to just hear audio, but very quiet. Over the next minute the audio fades in and comes to full power. I haven't noticed it on FM. Now I'm suspecting a capacitor, but there's an awful lot of them in there! Rather than do an en mass replacement I wondered if anyone had experienced this before, or there's a common theme. Googling brings nothing back. The R737 is (I assume) microprocessor controlled, and all wave change and power buttons are soft press. Only the volume pot is a standard pot. Any help greatly received! Trevor __________________ I'd just like to say "Good luck, we're all counting on you"

4th Aug 2022, 9:56 am	#2
agardiner Octode Join Date: Sep 2020 Location: Thetford, Norfolk, UK. Posts: 1,739	Re: Roberts R737 MW and LW fading up when cold I agree that it sounds very capacitor. Maybe careful use of a hairdryer and freezer spray?

6th Aug 2022, 6:53 am	#3
TrevorM6TSE Heptode Join Date: May 2003 Location: Old Tupton, Derbyshire, UK. Posts: 539	Re: Roberts R737 MW and LW fading up when cold Yes that sounds like it may be my plan. I was just hoping for a simple route! __________________ I'd just like to say "Good luck, we're all counting on you"