Hacker Sovereign - no FM.

[Yorkie]

My son has a chum who has a Hacker Sovereign (doesn't know which version). It walked fine on all bands, but has stopped working on FM.

I don't really want to get involved in sorting it, but I wondered if there are any pointers as to typical faults, specifically on the Sovereign range that are likely to be possible causes of the loss of FM. EG, switchery, which a squirt of Servisol might set to rights, or loose FM antenna connection - or rather more involved - dodgy FM tuner transistors/diodes or whatever. I know in a way that it's a bit of a daft question, but without having the set in front of me, I can't be any more specific.

I note that the FM tuner of the RP18 has six transistors (AF121, AF125, 4 x AF114, and three diodes - BA112, 2 x OA79), so if just one goes down, that could silence the FM section. I also note that the FM section is a self-contained tuner unit ('Gorler' - not Mullard) and that the Service Data states: "It is recommended that servicing of the FM unit is confined to voltage tests and alignment, and should be returned to the Works should other servicing be required". Not a hopeful sign!

Any thoughts anyone please?

[Mark Hennessy]

The 4 generations of the Sovereign are all quite different from each other, so we really do need to know which version he has.

The Gorler tuner tuner in the RP18 is very reliable - you almost certainly wouldn't need to venture in there. But as you've said, there are 4 AF114 beasties on the FM IF PCB. These are easy to remove and zap, and I've yet to have a occurrence of problems.

If it is an RP18, the electrolytic capacitors are usually of the unreliable types. If not blue Mullards, expect to replace a few.

The later sets use BF194/5 types, and are more reliable - although they can fail with low gain. Most FM faults are caused by them. Rather than get into the details here, I'll refer you to an article I wrote which discusses transistor problems: http://www.markhennessy.co.uk/articles/v...istors.htm

Signal diodes are pretty reliable in my experience - a failure of one in a ratio detector should cause distorted audio rather than no audio.

The RP25 (and RP75) had inter-station muting - make sure that's not engaged and/or misadjusted...

I've had the usual faults with passive components along the way. The switchbanks tend to be reliable enough - the FM switching is very straightforward - in most cases it just switches the power to - and audio from - each tuner (the first three generations of Sovereign use separate tuners for AM and FM - the later Sovereign IV did not).

The service manuals for these sets can be found at the Yahoo Hacker Radio group. Registration is free. I've done a fair few of the scans, as have the other mods. (please refer people to the group rather than posting the manuals elsewhere). The Sovereign IV manual isn't brilliant in image quality terms, but we're always looking for a better quality version if anyone has one.

You've said previously that Hacker (and Roberts) sets aren't your cup of tea, but of all the transistor sets out there, Hackers are the easiest to work on by a long way - and the service manuals are a revaluation compared to the others. Give it a go - you might be pleasantly surprised

Weak/no FM counts as just about the worst fault for a transistor set for me. I usually start by injecting 10.7MHz. With a known-good set for comparison, it's easy to determine if the lack of sensitivity is being caused by the front end or the IF, or both. If the front end is poorly, you have the pain of separating the PCB from the tuning capacitor - but again, as awkward as that might be, it's so much better than on other sets.

[Yorkie]

Many thanks for your prompt, helpful and comprehensive reply Mark.

I do have the Vintage Radio Data DVD which appears to have the full range of Hacker manuals.

With regard to your excellent and well researched article about transistors Mark, have you offered that to Carl Glover (Editor) for possible inclusion in the BVWS Bulletin?  I'm sure it would be very well received.  I always smile when people say things like: "I don't touch modern stuff with  'three-legged fuses' - only vintage stuff with valves".  Many transistor sets are fifty years old or more, and overlapped the valve era for several years, so I'd assert that they fit comfortably within the definition of 'vintage radio'.

I'm visiting my son at the weekend, so I'll take a quick look at the radio to see which model it is and if it's anything obvious, but I don't really want to bring it home and be obligated to repair it as I've so many other things on the go.

I'll let you know if I make any headway.!

[Mark Hennessy]

Ah yes - if you have the DVD then you're OK for the first three generations.

I'm in the same predicament - yes, I know that I'd be able to fix it, but when? My to-do list is already several years long...

Thanks for the kind words about the article. I don't subscribe to the BVWS, so have no idea if it would be suitable for inclusion - feel free to mention the idea to Carl if that's easy for you to do, but given that it's already in the public domain, will he be interested?

Anyway, let me know what the set turns out to be - as I'm sure you know, I'll give whatever advice I can to get it back on the road

Mark

[ppppenguin]

Not being a BVWS member isn't a barrier to submitting a Bulletin article. Though if you're not a member then why not? Mark, knowing your lucid writing style I reckon Carl would very much welcome your article. Don't think I've seen anything like it in the Bulletin which makes it even more valuable. Just send it to him at the email address on the BVWS website. You can even say that I put you up to it.

[Yorkie]

Carl is always on the lookout for new articles and does an outstanding job of editing the Bulletin - each one seems better than the last.

I think Carl would be most interested in the article. You can contact him by e-mail at: bulletin_editor@bvws.org.uk

Why not e-mail a copy of the article to him?

Go on Gary - you tell him!!  

(Mark that is).

[Mark Hennessy]

OK - now I'm blushing

I'll give it some thought. Having just re-read the first half of it, I've spotted loads of minor things I'd change about it (always the way), but I dare-say it could be edited down and tidied up for inclusion. If I get around to emailing Carl, I'll refer him to this thread.

Thanks for the encouragement and kind words

Mark

[Radio Fixer]

Just read Marks article and thought it excellent. It shows that many people don't always come across things posted on web sites (some BVWS member don't even bother with computers much or at all) and the BVWS Bulletin is still useful in spreading knowledge.

For me its decades since I touched a germanium transistor and I never repair radios that use them. They never come my way and I wouldn't buy any as I really like the 30's valve sets the most. So a good refresher and possibly useful if a friend or neighbour says "would you have a look at this for me". I used to design with silicon devices and have in recent years designed and built the odd circuit but again the article is a useful refresher. I say that as I have beautiful Goodmans Tuner Amp that came with the full Service Manual (those were the days) that has been dead on FM for years. Yes! I'm going to repair it some day when all the valve sets are restored and actually feel primed to do it after reading Mark's input.

So, I heartily endorse sending it to Carl for inclusion in a Bulletin. Useful and interesting copy is always in demand and the Bulletin is part of the BVWS effort to keep the Society alive and flourishing.

Some suggestions for a revamp, before sending, would be to add some pictures of the radios discussed and possibly break the text down into even smaller headed bites. The Bulletin format used, to me, is ponderous for large chunks of text.

Gary