ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
Hi all!
Well thanks to the advice here I now have output from my Beolit 600! However the problem now is that there is no reception on FM below 95MHz. Above that the stations come in loud and clear albeit slightly out from the tuning scale. Reception on MW & LW is fine across the scale.
Any ideas anyone?
Thanks!
Whats the lowest fm frequency station you can receive with your Beolit?.Here in the Midlands it's radio 2 .I just wondered if you could identify the lowest frequency station,as a clue to what might be happening?
Is the calibration correct on am?ie,do the stations tune at the correct markings on the scale?
Regards,
Nick
Hi Nick
Thanks for the reply!
The lowest station I can currently receive on the Beolit 600 on FM is a local station ‘Signal 1’ broadcasting on 96.4 - this is however displaying as around 95.7 on the scale and comes in very weakly. Above that the stations come in loud and clear. I can receive lots of other stations loud & clear below 95 down to Radio 2 at 88.3 on all of my other radios. A strong signal is normally received from BBC Radio Stoke locally at 94.6 which is silent on the Beolit. The inter-station noise also drops off below 95. Interestingly when I powered the radio up this morning I briefly received a weak signal around 93 - however it faded away after a short time.
Medium Wave appears to be displaying correctly on the tuning scale with Radio 5 coming in clearly at 909 & 693 - similarly Long Wave with Radio 4 coming in at 198.
I should point out this is a later Beolit 600 type 1501-06
Thjis might seem a silly question,but are the batteries ok?
It seems as though the fm local oscillator is stopping below 96mhz,and thi s may be due to low supply voltage.If the batteries are good,or better still if you have a mains adaptor,you can check the supplies at the tuner module.The red wire should carry 7volts,and the dark blue wire 5.9v.
There are two 470uf 6v electrolytic caps on the main board,and I would change these as a matter of course,although one of them is involved in the output amplifier,the other one is the supply decoupling for the tuner.They can both leak and are "usual suspects" regardless of problem.
The tuner is mechanical in this model rather than voltage tuned as found in later equipment,although there is dc afc,but his wouldn't cause the drop off you're noticing.
The actual fm local oscillator transistor may be faulty within the tuner module too,but check the voltages and replace the caps first.
OK I tried it with a mains adaptor - no change. So I checked the voltages. There isn't a dark blue wire going into the tuner module - but there is a violet wire - no voltage on that. However there is 6.9v on the red wire & 5.9v on the orange wire.
I replaced the 500uF/6v supply decoupling cap (numbered 16 on the schematic) with the nearest I had lying around (470uF/16v) and that made no difference either
UPDATE!!
OK so I thought I would take a look inside the tuning module... I removed both covers and checked the solder joints which all looked nice & bright. Then I tapped around - and when I tapped the tuning cap some crackles came forth!! I tapped a bit more & tuned down below 95MHz - et voila - stations!!
I just re-flowed all of the joints on the board and the connections to the tuning cap and it all now seems to be working fine! All the stations are coming in loud & clear below 95MHz including a local station at 87.7MHz.
So I've no idea what it was - aside from a dodgy connection somewhere in there...?!
Well sorted sir!
Although the scientific approach is ideal,often we have to resort to using guile and a good "nose"for some faults?
I guess with hindsight the problem was caused by a poor ground or intermittent connection to a trimming cap?
Sorry about the "red herring" over the cable colour codes.I "should have gone to Specsaver's"?
Pleased to hear of another nice old radio back in service.
Enjoy!