Cossor 501AC Radio Repair

Well done Marc, I was only just discussing in the staff room with the team, that we need to encourage the Radio lads up to the bench.

Well a "TV lad" doing a radio might just encourage them to get out of their comfy armchairs, grab a set off the to-do-pile for a nice winter project to share with the Radios-TV folk.

I had one of these Cossors many moons ago. I always wanted one after I saw "The Snowman" and David Bowie had one in the loft room during the intro he did.

Excellent timing Marc, now we're entering the festive season and the perfect time for cosy bench-side chats over a project. I'm sure we'll all look forward to your next installment.

Hi Chris,

Happy coincidence indeed, It's a while since I had a play around with a radio and I do have a few more to look at so who knows over the next few months......

I have now separated the chassis from the cabinet and taken a few more photo's before I clean it.

Nice and dusty, just how we like them. Will be interesting to see what you find when you do its first baseline evaluation.

As an aside and not wanting or encouraging off-topic chat in this thread. I really like the new forums presentation for viewing photos, side-swipe allowing back and forth. None of this returning to post and then having to click on the next or previous photo.

Forgot to say, if you need the service data I can scan for the library.

Should be quite a good set. They are not the best of performers if I recall but are easy to fettle and sound quite good.

Posted by: Chris

Forgot to say, if you need the service data I can scan for the library.

I already have the Trader sheet 1133 but it still might be a good idea to pop it in the library for others to see.

The set has now had a good vacuuming and the cabinet has had a wash so hopefully no more sneezing at the bench now ! 

Pulling the valves out certainly shows the pins need cleaning and I also presume the sockets will need a good sorting too.

Is there a frame aerial fixed onto the card back of the set?

Plenty of room inside that chassis, the radios I fixed a couple of years ago were partly chosen to allow easy access, hands not as flexible has the used to be.

I am sure you will get it working, watching with interest.

Posted by: Nuvistor

Is there a frame aerial fixed onto the card back of the set?

 

Hi Frank,

Yes there is a frame aerial on the back card, I'll try and pop a photo on later.

Now done.....

Marc.

It's good to see a wireless now and then.... and this one looks very good, no nasty rusty chassis lol.

Posted by: PYE625

It's good to see a wireless now and then.... and this one looks very good, no nasty rusty chassis lol.

Hi Andrew,

I reckon that nice thick coat of dust did this chassis a favour protecting it. 😉

I've had the main smoother cap (16uf/32uf) attached to my Cap re-former for around an hour on each side and the whole can looks good now with 1mA leakage showing.

Hi Marc,  your set is the later version  equipped with B8A base valves. Despite the strange type numbers the valves were made by Mullard.  There's an earlier version of the 501AC in the shop, almost identical circuit but fitted with earlier loctal valves.  7S7 frequency changer. 7B7 IF amplifier. 7C6 detector, AVC and audio amplifier. 7C5 output. 7Y4 HT rectifier.    I recently serviced  a similar Cossor radio, the model 520.  Some of the servicing notes apply to the 501 Link to the UKVRRR:   https://www.vintage-radio.net/forum/showthread.php?t=141208

The 520 didn't require much work to get it going but did need realignment. Here in Geordieland BBC Radio 4 can be received on 503meters.  The station was coming about in 460meters  on the tuning scale although stations at the high frequency end of the band were coming in on the correct positions on the tuning scale.  The Cossor 520 has a fixed value MW padder capacitor, slight alteration of the value corrected the alignment at the LF end of the MW waveband.  Offending capacitor is marked C13 in the 520 circuit.

Till Eulenspiegel.

I think the one I recently moved to the loft uses the loctal range. (I may have to get it down just to have a look.....see what you have started Marc? lol )

The ones Marc has I believe are ECH42, EF41, EBC41, EL41 and EZ40  but with Cossor markings obviously. 

Posted by: PYE625

The ones Marc has I believe are ECH42, EF41, EBC41, EL41 and EZ40  but with Cossor markings obviously. 

Yep, spot on Andrew...Cossor 62-TH, 62-VP, 62-DDT, 67-PT and 66-KU.

Posted by: Till Eulenspiegel

Hi Marc,  I recently serviced  a similar Cossor radio, the model 520.  Some of the servicing notes apply to the 501 Link to the UKVRRR:   https://www.vintage-radio.net/forum/showthread.php?t=141208

Till Eulenspiegel.

Thanks for the info Till, it may well prove useful. 😉

Marc. 

Just remind me, someone, was this set one the many, also called, "Melody Maker" models produced by Cossor?

Yes the one I had used Loctal valves. I wasn't impressed by its performance. I passed it on to a fellow collector

Posted by: Katie_Bush

Just remind me, someone, was this set one the many, also called, "Melody Maker" models produced by Cossor?

Certainly was Marion, I should have put that on the thread title.

Posted by: sideband

Yes the one I had used Loctal valves. I wasn't impressed by its performance. I passed it on to a fellow collector

I wonder if this later set with it's B8A valves will perform any better ?