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 Tuning problem HMV floor standing radio model 661
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 Return to top of page · Post #: 1 · Written at 8:07:30 PM on 19 July 2018.
Bruce's Gravatar
 Location: Sydney, NSW
 Member since 25 July 2012
 Member #: 1193
 Postcount: 6

Hi all,wondering if anyone can help with my tuning problem,issue is that half of the AM band has dissappeared..unfortunately along with it my favourate station 2CH..1170.. I can hear where stations are,the hum changes when I'm on the station but there is no audio..
radio picks up other stations past 1269 strongly but nothing before it..radio has been worked on and all caps etc replaced in past,i always did have trouble picking up 2CH but I got a fantastic tunable loop aerial that pulled it in but even that doesnt do it anymore..
could it be something simple like a tube problem.?? anyone got any suggestions ? greatfull for any help..cheers,Bruce


 
 Return to top of page · Post #: 2 · Written at 8:47:18 PM on 19 July 2018.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6013

First thought is to check the tuning capacitor for plates that are touching and for shorts to earth. Second thought is the converter valve (6J8G?) is not running properly, either because it's on the way out or voltages are wrong (crook resistors), or both. Failing that, maybe something gone awry in the IF chain.


 
 Return to top of page · Post #: 3 · Written at 11:31:42 PM on 19 July 2018.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 4347

I think a chassis check is in order also. Totally agree that it is likely to be a bent plate. During servicing, if the plates are left open the outer ones can get bent. One often wonders who serviced it and how. I have had a run of sets of late where there were problems left, or not addressed.

It is common for Pentagrids like 6J8, 6A8, etc. to die at high frequency not low and from lack of voltage: Often that being caused by the failure to check resistors when changing caps. "Deaf" (insensitive) sets is normally the result of poor alignment.

I just went through a similar tuning gang episode with a Monarch "Minstrel", Sloppy factory work, I ended up removing it & attacking it with Aluminium Wheel cleaner & a few other things to get the dirt & bits of solder out of it? It was no longer arcing on the shaft at 250VDC once I sorted that.

If I can get 2CH from 500km away, you should not have a problem.


 
 Return to top of page · Post #: 4 · Written at 2:20:12 PM on 20 July 2018.
Gfr53's Gravatar
 Location: Harston, VIC
 Member since 28 February 2009
 Member #: 442
 Postcount: 145

Another possibility maybe bad tracking, requiring realigmnent.

Cheers, Graham...


 
 Return to top of page · Post #: 5 · Written at 4:57:28 PM on 20 July 2018.
Bruce's Gravatar
 Location: Sydney, NSW
 Member since 25 July 2012
 Member #: 1193
 Postcount: 6

Thanks all,i will check the plates in tuning capacitor and also what valves are in set,never looked at them before except to check that they all light up..hopefully I'm on the path to redemption..cheers,Bruce


 
 Return to top of page · Post #: 6 · Written at 10:34:05 PM on 20 July 2018.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 4347

90+% of the time its external to the valve, not a defective valve. A 6A8 will run in a 6J8 hole and vise versa. In sets like Astor JJ & a few others that can cause band spread issues. But that is not important, if you are just valve jockeying to see if you have a dud valve.


 
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