BANG & OLUFSEN BEOLIT DE LUXE 611 FME (tr36)

[Carlh93]

I bought this ultimately marvellous set in 10/1965 on a work colleague's advice.

There were few B&Q selling dealers, then. My nearest (to Farnborough, where I then worked) was a small shop in west London, putting my motorcycle's carrier to good use!

I say "ultimately marvellous" because, from new, the sound lacked bass, and was generally not outstanding compared with my friend's earlier model which had so impressed me.

I complained about the sound quality to the dealer. The set was returned, they said, to B&O and the outcome was the usual one in those days: NFF (no fault found).

I got used to the sound, which was still far better than that of most British small radios. By 2002, however, the original slight hissiness on FM had become intolerable. I sent the set, with its original wiring diagram. to that brilliant man Lester Moon. Lester found that the output transistors were the source of the problem, but also the source of the less-than-outstanding sound from new. They bore the wrong number (according to the diagram) - only two zeroes instead of three, or something like that.

The impedance mismatch was eliminated and the sound transformed when he returned the set. The sound has deteriorated only slightly over the ensuing 21 years.

However, very recently the sound has started fluctuating in volume. I googled this phenomenon, which suggested a faulty AVC - a relatively simple job, but not one that I would attempt myself.

I talked to Lester about this. He was very sceptical that the AVC was to blame, pointing to the age of the first stage transistors and all the capacitors. But he no longer does repair work himself.

I talked to to a couple of people whom he suggested, but who said they were too busy to take on this job. One them suggested I post the problem on this forum.

So I am now doing this, as probably a last resort.

I'm very reluctant to scrap the set. Apart from its technical excellence, it has, genuinely, great "sentimental value": it was my treasured companion in my early career, accompanying me in various rented accommodations until I got married in 1969, and on motorcycle (later car) holidays to France, and within the UK. My wife is as fond of it as I am, because, still rarely in a portable set, it does a splendid job on classical music programs. Not stereo sound? Of course not. The BBC was still trialling pilot-tone stereo broadcasting in late 1965. And, without separate speakers, more modern small sets do not project much in the say of a stereo sound image, and few have simple and effective bass and treble controls.

So, within reason. the cost of getting an effective repair done is not an obstacle. It would sadden me greatly if all I can do now is to advertise my dear old friend on Ebay as a source of spares - and now much of it would be economically re-usable by now, anyway? So I would probably just scrap it if no-one is willing even to have a go at dealing with the fluctuating volume.

Any suggestions about how I might proceed would be very much appreciated.

[paulsherwin]

Is this it?

https://www.beoworld.org/prod_details.asp?pid=843
https://www.radiomuseum.org/r/bang_beolit_611_k.html

It's certainly going to be repairable, so don't scrap it! Mid 60s radios used transistors that are prone to specific stock faults with age, and other components may also be failing. There may also be simple faults like dirty switch contacts. A professional functional restoration won't be cheap given the complexity of these sets, but it shouldn't be hugely expensive either. There are a number of forum members who offer restoration services.

You can ask commercial restorers to contact you here: https://www.vintage-radio.net/forum/...play.php?f=145

[Boulevardier]

Can't find any technical info on this set, but if it's anything like my Beolit 609 (1963, and a recognisably similar case and layout) it will be crammed full of AF11x transistors, which have been an ongoing source of problems.

Printed circuit board in mine is also very difficult to work on - components tightly packed and copper tracks detaching and disintegrating at the sight of a sokdering iron. Of course, this may have improved by 1965.

Excellent sets when working though and well worth persevering with, if you have inexhaustible patience.

Mike

[Carlh93]

You (Boulevardier) may well be right. The 609 was my erstwhile colleague's Beolit, the sound from which so impressed me nearly 58 years ago..

I am familiar with the appearance of the innards of my 611, which look very much as you describe the 609. The 611, though still very plump by modern standards, seemed slimline in comparison in 1965, so is therefore likely to be even more tightly packed internally.

I wonder if that may explain the reticence which I have encountered when enquiring about repairing my set. Am I contacting people who already know - either directly or from hearsay within the fraternity - how problematic repair attempts can be with these sets, particularly when they are seriously aged, and hence avoid them like the plague?

Of the two men that I spoke to yesterday, the first was helpful and pleasant, and advanced how busy he already was as the reason for not taking on the job. He recommended me to another man, who would have the great advantage (from the point of view of getting the set to a repairer) of living only about 20 miles from me. I was given both this man's phone numbers, and left messages on both yesterday (aha, the first one identifying the set in question!). He hasn't replied. That doesn't mean that he won't (he may be away on an Easter holiday), but, after what you say, I can't help wondering.

If these sets are a risky pig to deal with, and. at best, are likely to be a "rolling restoration", which would not surprise me, I should take note of the lack of interest so far experienced.

There would be no point in sending it to someone well-intentioned, but unaware of its reputation, and who then gets into an awful pickle when trying to work on it! Mine might well have to be written off as unrepairable, leaving the intended repairer bruised and out of pocket, and me as one of those creatures described as "a sadder, but wiser man"!
Thank you very much for your ideas, paulsherwin. I'll give them a try, but I have to be realistic given Boulevardier's focussed criticisms of the 609.

[paulsherwin]

They aren't really risky to work on, but not something for a beginner. Working on old transistor sets like these is a specialist skill and modern general repair technicians are unlikely to be familiar with them. As an example, you refer to 'a faulty AVC' which is 'a relatively simple job'. AVC problems are extremely unlikely to cause variations in output volume, particularly on FM, and AVC operation involves lots of separate components anyway.

The fact that you aren't getting lots of responses from chancers offering to 'have a look at it for £50' is a good sign. You already have one offer of help from an established forum member, and may well get others over the next few days.

A genuine expert will normally be prepared to work on a 'no fix - no fee' basis, but you would obviously need to agree terms before any work started.

There is a very good chance that this fault is simply caused by oxidised switch contacts on the (complex) wavechange switchgear, rotary controls or sockets.

[Boulevardier]

Originally Posted by Carlh93

You (Boulevardier) may well be right. The 609 was my erstwhile colleague's Beolit, the sound from which so impressed me nearly 58 years ago..

I am familiar with the appearance of the innards of my 611, which look very much as you describe the 609. The 611, though still very plump by modern standards, seemed slimline in comparison in 1965, so is therefore likely to be even more tightly packed internally.

I wonder if that may explain the reticence which I have encountered when enquiring about repairing my set. Am I contacting people who already know - either directly or from hearsay within the fraternity - how problematic repair attempts can be with these sets, particularly when they are seriously aged, and hence avoid them like the plague?

Of the two men that I spoke to yesterday, the first was helpful and pleasant, and advanced how busy he already was as the reason for not taking on the job. He recommended me to another man, who would have the great advantage (from the point of view of getting the set to a repairer) of living only about 20 miles from me. I was given both this man's phone numbers, and left messages on both yesterday (aha, the first one identifying the set in question!). He hasn't replied. That doesn't mean that he won't (he may be away on an Easter holiday), but, after what you say, I can't help wondering.

If these sets are a risky pig to deal with, and. at best, are likely to be a "rolling restoration", which would not surprise me, I should take note of the lack of interest so far experienced.

There would be no point in sending it to someone well-intentioned, but unaware of its reputation, and who then gets into an awful pickle when trying to work on it! Mine might well have to be written off as unrepairable, leaving the intended repairer bruised and out of pocket, and me as one of those creatures described as "a sadder, but wiser man"!
Thank you very much for your ideas, paulsherwin. I'll give them a try, but I have to be realistic given Boulevardier's focussed criticisms of the 609.

Your comments remind me just how good these earlier 1960s Beolits are! I must fish mine out from the cupboard and see how well it's working now - it certainly gave me the run-around about ten years ago when I dealt with all those faulty transistors, but a lovely radio, with excellent battery life.
Good luck with yours - it's well worth reviving.

Mike

[Boulevardier]

Another interesting point is that they seem to be relatively rare. I seem to remember that only about a thousand of the UK (European?) version of the 609 FM were ever manufactured, and when my father bought ours in 1963 they were pretty well unknown in the UK. So there won't be many around as a source of original spare parts.

And don't make the mistake of trying to wash the back of the tuning scale clean - the station markings are a water-transfer (on the 609 anyway), and will go straight down your plug-hole!

Mike

[Carlh93]

Thanks very much, both of you, for your hopeful comments etc.

I will follow up the contacts from repairers, but there are some details that they won't like:-

1. Clutch allowing waveband frequency pushbutton controls to alternate between AM and FM failed last year. No detriment to us as AM performance without a very good external aerial was very poor.

2. More recently, FM indicator stopped moving, and set could not be tuned in. I found that the pulley for FM tuning capacitor had disintegrated (even ABS has a lifetime!).

My temporary solution was to remove the handle and relevant side strut (case join cover/securer), making set much less "portable"! I improvised a control direct on the capacitor spindle. Too high geared, so tricky to adjust. But AFC very good, so holds frequency once found.

And now the up and down volume!

Lester Moon shared (very firmly) your doubts about this being caused by faulty AVC. I will check as many as I can of the other points that you mention, but please bear in mind that waveband changes are no longer possible, so the waveband changer button is out of bounds, due to the failed clutch. Yes, the volume control is a possible source of the problem.

No sockets are in use. The bass and treble controls work nicely and the changes in the loudness (?) of the upper/lower frequency bands concerned is smooth.

While the absence of AM is not (for us) a detriment at all, I doubt that the FM tuning array can be replace and work again because there surely won't be any spare cord pulleys now in sound enough condition to justify re-winding etc etc.

And the need to leave the carrying handle off to access my Heath Robinson (I'm unfair to that remarkable man!) FM tuning "control" is regrettable, to put it very politely!

[Carlh93]

Mike ("Boulevardier"),

Many thanks for extra advice. I'm sure you're right about parts (eg FM TUNING PULLEY!).

Cheers,

Carl

[Carlh93]

A strange but welcome development

I did some of the checks suggested, and tried the set again. No change - much the same, but even worse volume fluctuation, plus dreadful distortion.

That's the end of the set, we thought - just when it looked like making 60 (in 10/2024).

Then Mr Bright Spark (me!) thought of what should have been the first thing to suspect, and was now about to be the last - the BATTERIES.

I hadn't already acted in this respect because the need for new batteries has always been "signalled" by a gradual drop in volume, plus sometimes reluctance of the AFC to hold a frequency. The Beolit "Radicator" (optimal tune/battery voltage indicator) would confirm this.

The Radicator seems no longer to work in battery mode, only in its default mode of showing best signal strength for a given frequency (AFC off). This may be because the clutch to switch from FM tuning to AM failed last year. You need to press say the LW and MW buttons down together to make the indicator change mode.

Enough of excuses for the inexcusable!

The batteries in the set were of a brand (Panasonic) which I had recently found better, as AA and AAA, than the GP Ultra to which I have been faithful for a good few years. I seem to have heard that the technology of the Panasonics is in some way different from that of traditional zinc/carbon dry cells.

I removed and tested the six in use. All showed between 1.2 and 1.3 Volts, which I would normally associate with reduced performance, but NOT with vigorously trampolining volume. with distortion at peaks.

I opened three new packs of the same batteries. All tested at comfortably over 1.5 Volts.

I installed them. Then, with the FM aerial** fully extended and vertical (Holme Moss is stated to emit a "mixed polarisation" VHF signal), and with baited breath, pressed down the On button. The set was already tuned to 93.7 Hz for BBC Radio 4. with AFC On.

What a (very pleasant, and completely unexpected) surprise. The set was back in brilliant form. Wow!

I do feel a dunce for not having suspected the batteries, which now seem pretty definitely to have been the cause of the problem. But the strange behaviour that I had reported to anyone who would listen to me seemed non-indicative of something so simple.

WHERE FROM HERE?

Do say if I am wrong, but repair of the FM/AM clutch, which would need a new FM tuning capacitor pulley, and a very tricky re-string, to resume normal tuning, appears out of the question. I know of no source of new parts. I do have a second-hand FM tuning pulley. It is ABS, and so suffers from the old-age problem of this generally excellent plastic. It is cracked, so on the way to the disintegration which occurred last year to the pulley which was in the set.

I don't mind the fiddly (far too high-geared) tuning action allowed by direct turning of the FM capacitor spindle, and we are quite content to use the set for FM only.

What is a nuisance, though, is the short battery life: 6 X D battery (9 Volts) at a throw. This means always having a set of in stock, but not for too long!

We don't resent the cost or inconvenience, but my improvised FM tuning "system" means the absence of one of the case side struts, which means that the HANDLE can't be fitted.

So the set is now a forcibly dedicated "table model"!

It would be sensible and convenient to supply its current from the AC 230 V mains via an adjustable, or fixed 9 Volt, output, plug-type transformer/power supply unit. This was investigated years ago, when we had started assigning an intermittent "table-model" role for the set. Neither of the two that I bought was screened/filtered to block the strong RF emissions which all basic transformers, whether wire-wound or switched-mode type, emit. And the Beolit is clearly completely unscreened against such radiation. It was apparently not foreseen in the early 1960s as a likely future domestic pest.

Is anyone who hasn't by now completely lost patience with me able to suggest a suitable PSU - preferably a plug-in unit?

Best wishes to anyone still dedicated enough to be following this thread!

Carlh


** The instructions say to raise both aerials and lay them flat, for best reception. However, the second aerial appears to be for short-wave frequencies only! There's the usual, and, in this set, pretty useless, internal ferrite rod for LW and MW AM). Years ago, I got very good AM performance, but only with a long wire aerial strung between the two ends of our then house roof.

[paulsherwin]

I'm glad things are looking up. Tired batteries can indeed produce strange symptoms.

You now need to decide if you want to live with the radio as it is, warts and all, or pay someone to restore it properly. There's no point in dealing with specific faults like the clutch while leaving lots of other faults unaddressed, though you could discuss priorities with any potential repairer.

It's relatively easy to modify a radio of this type to use an external 'wall wart' type mains power supply.

[Radio Wrangler]

Not all wall wart power supplies play happily with radios. Some have 'switch-mode' circuitry inside them to make them light in weight and efficient. The snag is that many of them radiate a lot of radio interference, and send it up their output cable straight to the set.

Older ones may have linear circuitry and an iron transformer. You certainly will notice the weight of one of these, but they are a better bet for using near a radio. You also want the supply to be 'regulated' because this prevents mains voltage variations and worst of all, surges from reaching your set. Your set was designed for battery use, and so the designers would not have taken any measures against the spikes and surges that happen on the mains. This leaves the set vulnerable to damage if used with too simplistic a mains adaptor.

So you ideally want a 9v, linear, regulated power supply. Try a post in the wanted section of the forum.

David

[marceljack]

Originally Posted by Radio Wrangler

So you ideally want a 9v, linear, regulated power supply. Try a post in the wanted section of the forum.
David

In fact if the set is only to be used on FM (much likely these days), a small regulated SMPS adjustable between 3 and 12V will probably give satisfactory results.
These SMPS are intended to be used with portable radios and are relatively quiet, and almost totally at FM frequencies.

Something like that:
https://www.ebay.com/itm/393211793229

[agardiner]

Are the Panasonic batteries you are using their red Zinc ones? If so, switch to Alkaline and the battery life with be dramatically increased. Don't beat yourself up about the odd behaviour with the previous set of batteries. As paulsherwin says, tired batteries can produce odd symptoms. Unless you test them under load, you don't know exactly what was going on with them; it may be that one or more of the cells voltages were collapsing under load.

Re the FM pulley that has disintegrated. Am I correct in understanding that you have another pulley that is in tact, but cracked? It would be possible to have this reverse engineered and 3D printed if you wanted to go down that route.

[Boulevardier]

Going back to your battery-life problem - I can only speak from my experience with the 609, but I can say that ours was used for many years as the main (only) family radio, and it was thus used for perhaps 2 - 3 hours every day. I was only a young teenager then, so it was a long time ago, but as far as I remember a set of D batteries used to last a long time - I reckon about six months (in fact it was always a bit of a memorable event when the batteries were replaced!). .. Certainly battery life was never seen as a problem, and I used to be surprised how long they lasted.

But perhaps the 611 was very different...? Have you tried measuring the current being drawn by the set from the batteries?

Mike

[Boulevardier]

Originally Posted by agardiner

Re the FM pulley that has disintegrated. Am I correct in understanding that you have another pulley that is in tact, but cracked? It would be possible to have this reverse engineered and 3D printed if you wanted to go down that route.

Other possibilities - have you considered the super-glue + baking powder thing to reconsolidate the pulley? It can be fantastic for sorting broken/cracked mechanical parts. I used some recently to fix a captive nut that had broken free of its captivity - excellent solution and completely painless if there is enough of the pulley left to pull back together.


Mike

[cathoderay57]

Could the replacement batteries be concealing a fault such as leaky output transistors, that are less tolerant of reduced battery power than fully functional devices? Jerry

[Carlh93]

Thanks for so many responses. I'll deal with these by topic, so when i say "you" I mean the author/s of the relevant posting/s.

BATTERIES

The ones which had been in for a couple of months when the ups and downs, and eventually violent "trampolining", of volume occurred (and the new set currently in the radio) were/are Panasonic D type (6 of them), RED, so nickel-carbon, which type is stated by Panasonic to be for low energy devices.

I bought these because the life of the GP Ultra alkaline ones which I had favoured previously had been poor.

How does the Beolit FM611 rank as an energy consumer?

The FM611 manual states:-

1 .BATTERY DRAIN: @ low volume, approx 16 mA. @ 50 mW output power (high volume), 57 mA.

2. POWER OUTPUT: 1.4 Watts.

COULD BATTERY MISBEHAVIOUR/SHORT LIFE BE CAUSED BY THE OUTPUT TRANSISTORS LEAKING CURRENT?

These are modern transistors, fitted in 2002 by Lester Moon to replace the original ones (germanium?), which had become very noisy. The new ones are by now no doubt old enough themselves to be "showing their age", so your suspicion may be well founded.

Lester found that the originals did not have the number shown in the B&O wiring diagram. There was an impedance mismatch, which explained why the sound, right from new, had lacked bass. The new output transistors cured this problem, and transformed the sound.

FM CAPACITOR PULLEY FOR TUNING CORD

I doubt that gluing the crack in the ABS spare pulley which I have would be reliable enough to justify the cost of getting the complex and tricky cord rewound on correctly. The pulley will be cracked due to the plastic work-ageing, due to the stress from the cord when under pull. Plus the general ageing of even a good plastic like ABS.

I will examine the pulley to see if it looks sound enough to be a pattern for 3-D printing replication - thanks very much for that suggestion. I'll visit your suggested website if it does.

Being able to tune the FM band in the original way would be very helpful. My "Heath Robinson" alternative is fiddly to use, because it is too high geared (it turns the FM tuning capacitor spindle directly). Getting rid of this "semi-bodge" would also allow the side "strut" (for want of a better term!) to be replaced, which would allow the carrying handle to be refitted.

BROKEN FM/AM BANDS TUNING CLUTCH

I wasn't contemplating trying to get this fixed. Probably impossible without re-engineering it as there will be no spare parts - at least, in re-usable condition.

As we have no interest in AM broadcasts we are more than happy to consider the set "FM only".

PSU

The two which I bought some years ago are "wall warts" - lightweight, so they use switched-mode transformer technology. They both caused the set to emit so much racket that one could not hear the broadcasts! Bear in mind that the set was then always in the same place, which is close to an FM socket connected to our large and excellent outside aerial, and the set was connected to this socket by 75 Ohm coax cable. This normally gave brilliant reception!

I will try for a 9 Volt linear, regulated PS. Thanks very much for the focussed spec description.

[paulsherwin]

You actually don't need a regulated supply, though it's desirable. A 6V unregulated supply should be OK in normal domestic use - the voltage will sag if you turn the volume up, but this shouldn't be noticeable in normal use. Somebody may have something suitable in the junk box.

Not all SMPSUs are noisy, they just need to be decent designs. Again, somebody may have something suitable lying around.

If you suspect that the radio is using excess current then you need to confirm it by measuring it. You can buy a cheap meter on eBay for under £5 that will do the job if you don't already have one. Excess current is a fault condition which needs to be identified and fixed before the radio dies altogether.

[Philips210]

It's all too easy to be caught by failing batteries. It's happened to me quite a few times.
My Roberts R707 radio behaves in a similar fashion when the two 6 Volt lantern batteries are running down. The volume will go up and down fairly regularly. Failing electrolytic caps across the supply can cause instability such as motor boating.
Today, something similar happened with my Escort capacitance meter when measuring a large value electrolytic cap. The display would regularly pulsate but when measuring lower value caps it was fine. The PP3 zinc battery was responsible and probably due to high internal resistance.

Regards,
Symon