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Old 21st Sep 2017, 12:52 pm   #1
DCBassman
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Default Grundig Concert Boy 1100

Hi folks, new here.

Have searched quite widely for info on these, and have found some nuggets, but not enough to solve the problems I'm having.

1100 #1 Woody: My dad bought this in Malawi eaons ago, and gave it to me when he stopped working overseas. It's given a LOT of good service, but looks much the worse for wear at the moment. Works well on FM, but pretty poorly on AM bands. Did find and re-attach a wire from the ferrite which had come adrift, helped a bit.

1100 #2 Black Case: was acquired yesterday from ebay, very cheap, in order to cannibalise for antenna and slider knobs.
Antenna was most needed, and duly transplanted about an hour ago.

However, gave #2 a clean up, and it is working, albeit incredibly faintly. Pleased that the tuning gang wasn't seized; I understand this is quite a common problem.

So, to sum up: does anyone know what the AM fault on Woody might be, or why the other one is so faint?

Your knowledge much appreciated!
Den
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Old 21st Sep 2017, 2:30 pm   #2
Leon Crampin
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Default Re: Grundig Concert Boy 1100

Welcome to the Forum Den.

As it happens, I've been restoring one of these sets and have got to know them quite well. If your sets(s) are working at all on AM, the oscillator is running. These sets have separate oscillator and mixer transistors on AM; T04 and T03 respectively.

I'm assuming you have the Grundig service data and I will use their circuit references.

I would recommend a few quick checks before delving too deeply. Firstly check the power supply voltages including the 9V stabilised line to the RF stages. From experience, the bias diode for the front end of the set is also worth a check. It's D03 and should be checked by measuring the voltage across R518 which should be 1.35V at 9V supply (not mains), MW setting and gang fully meshed with no signal. The problem is, you can't get to R518 because it's in the IF can.

Translating the German, it's evident that Grundig realise this and give the corresponding voltage at IF module on pin 5 relative to -ve, which is 1.4V under the same conditions (important). You can access this point without any extra dismantling by locating contact g6 on the LW switch bank. It's accessible from the top. The adjutment is made by setting preset R515 which is in the IF can. Use a well insulated long thin screwdriver to reach this pot via the hole in the heatsink. It doesn't line up perfectly...

If the bias is correct, check T03 itself for low gain, then check the AM RF alignment as on the sheet. You will see that there are small marks on the tuning scale at the setting reference frequencies. I use a modulated AM generator and monitor the audio level (with an analogue meter) to set the trimmers and aerial coils whilst keeping the input signal at a low level to avoid AGC action. If your sets have had a rough life, the coils may well have shifted on the ferrite rod.

One tip: When it all works, change C806 (power supply reservoir) to 2.2 mF at 25V. The 16V rated component fitted originally has about 17V across it on UK mains and ends up dead short - a Grundig cock up. These sets work very well when properly set up - but there are no short cuts and bodging the alignment doesn't work. Check the output stage quiescent current setting - there's a soldered up break in the print adjacent to T013 collector to facilitate this. Use a 9V supply when setting.

I have a small favour to ask: If, when your job is finished, you happen to end up with a spare battery cover (or mains lead box cover) could you send me a PM? I need one.

Leon.

Last edited by Leon Crampin; 21st Sep 2017 at 2:37 pm.
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Old 21st Sep 2017, 3:21 pm   #3
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Default Re: Grundig Concert Boy 1100

Hi Leon, many thanks for the reply. I've not yet got the full data, but to be honest, I have no way of diving in to a great extent, or the equipment to do it. I'm limited for space, and a to a Fluke 29MkII multimeter! I suspect you are right about the AM on Woody, rod coils look a bit shaky. For the other one, I've also noticed that if I touch certain parts of the case, mains hum, which is always present, gets much louder. This suggest to me that there might be a cable break of some sort, but it's only a guess. Audio is the same through headphones.
I'll be happy to give you a battery cover - I never use these on battery power, so I'll keep one and you can have the other!
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Old 21st Sep 2017, 5:38 pm   #4
Leon Crampin
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Default Re: Grundig Concert Boy 1100

Greetings Den, I appreciate that a fair bit of equipment is needed to get these sets to full spec - however compromises can be made.

I aligned my Concert Boy yesterday - so it's all fresh in my mind. The IF stages don't need to be touched as long as they are undisturbed. Their position discourages twiddling anyway. The position of the aerial coils on the rod is critical. If the dial calibration (ie. stations in the right places) is OK, don't touch the oscillator adjusters.

You can set the aerial coils/trimmers on signal if you're careful. For MW the calibration points are 560 kHz and 1450 kHz - you will find small marks on the tuning scale at these points. For LW the points are 160 kHz and 240 kHz. I'll assume you're just going to peak the aerial coils/trimmers. The aerial coils on these sets have a high Q and the settings are critical.

Find a signal as close as possible to 560 kHz. Rotate the set to make the signal barely receivable (to minimise AGC action). Chip away the wax on the MW aerial coil (right hand as you look at it with the back off). Work the coil from side to side with your fingers until the wax seal breaks and it's just free to move. Now set the coil position for the best signal - it's critical. Retune to 1450 kHz (calibration mark) and select the nearest station and weaken it by turning the set. Now peak the MW aerial trimmer - it's the middle one of the three grouped together on the board to which the ferrite rod is attached.

For LW, select 160 kHz and attempt to find a near station (nothing audible here in Surrey). Adjust the left hand aerial coil for a peak. Select 240 kHz and with the nearest station peak the aerial trimmer which is right hand trimmer of the group of 3 on the aerial board. If you can't get LW signals near the set point, I would set the aerial coil for the best signal at 198 kHz and leave the trimmer alone.

Finally, make a few chips of candle wax, apply them to the ends of the aerial coils and melt the wax carefully with an (old) soldering iron to fix the coils to the rod. Avoid melting the formers. The trimming capacitors do not need to be sealed.

I found that by far the biggest error on my set was due to the aerial coil setting - although they were undisturbed. I ended up moving each one about 2 mm to the left - which made a huge difference to the set's sensitivity.

Don't attempt SW alignment without a generator.

Best of luck - ask if you need more guidance. These sets align and track beautifully.

Thanks for your very kind offer of a battery cover - it will complete my almost perfect set. We may not be able to communicate by private message until you have made a few posts - unless the mods can fix this.

Leon.

The mains hum is probably a severely distressed smoothing capacitor. It's the biggest one on the board - but watch out when you change it - there are 3 negative connection points which have to be linked together. A modern replacement (25V) is smaller and fits in easily.
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Old 22nd Sep 2017, 10:41 am   #5
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Default Re: Grundig Concert Boy 1100

I've chosen the better of the two, packed and ready to go!
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Old 23rd Sep 2017, 9:43 pm   #6
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Default Re: Grundig Concert Boy 1100

Hi Den. I have one of these sets as well but haven't got around to even powering it up yet as it's a long way down in the restoration pile. I do have a signal generator that will cover the whole radio which you are welcome to come and have a play with as I am not that far away.

Have fun

Graham
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Old 23rd Sep 2017, 10:36 pm   #7
Leon Crampin
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Default Re: Grundig Concert Boy 1100

A signal generator is definitely a great asset when aligning this receiver. The front end tuned circuits tune very sharply (meaning that the position of the aerial coils on the rod are critical) and all the trimmers need to be set carefully. The AM sensitivity and calibration accuracy are good when the set is properly aligned - possibly LW performance is slightly compromised by the use of a common oscillator coil with MW, which compromises tracking.

In case there are problems translating the German (I have not found a proper service sheet in English), the signal for RF alignment on LW and MW is introduced via a small coupling coil adjacent to the ferrite rod. I add a 75 Ohm resistor to preserve generator matching. For the SW bands, the signal is coupled to the telescopic aerial connection via a 15 pF capacitor.

The spot frequencies and trimmer locations are given on the sheet and alignment follows normal practice, but I would recommend using a modulated signal and monitoring the AF output with a meter when setting. I power the set from the mains during alignment, as this is how it will be used for most jobs.

Having completed this job recently, let me know if you need any help.

Leon.
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Old 23rd Sep 2017, 11:15 pm   #8
Leon Crampin
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Default Re: Grundig Concert Boy 1100

I have just printed off the "Trader sheet" for this receiver - available above or from Paul's ROM.

Regrettably, there is a serious error in the alignment procedure which does not occur on the official Grundig sheet. When aligning the AM RF stages, it is essential that MW is adjusted first, then LW. This is due to the shared oscillator coil, whose resonating inductance must be set to allow for proper tracking on MW. For LW, the coil is shunted with a trimmer capacitor, which is set subsequently.

Further, the Trader Sheet does not include output stage quiescent current adjustment and it also does not include the bias setting for the RF stages, set with R515.

Moral: always use the maker's data wherever possible - even if it's in German.

Leon.
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Old 24th Sep 2017, 12:44 pm   #9
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Default Re: Grundig Concert Boy 1100

Hi Graham, thanks for the offer, will keep it in mind for when I get around to the setup. It's a daily user set, always on FM, so although I'm keen to get it up to spec, it's not yet a priority. Leon, I want ot have a go at changing the resevoir capacitor on the black-case version, to see if that brings it any more to life. I'm presuming that there's some way to extract the entire assembly without un-stringing the tuning? Really don't want to do that if at all possible, but will if needed...Battery cover ready to post, by the way.
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Old 24th Sep 2017, 3:04 pm   #10
Leon Crampin
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Default Re: Grundig Concert Boy 1100

OK, to dismantle the set, disconnect from the mains and lay the set on a soft cloth, on its front. Remove the 2 screws from the bottom and lift the back cover at the bottom by a few cm., then disengage the top which hooks in. The connection to the telescopic aerial will be disconnected automatically, but the 2 halves of the set remain connected by the red/blue twisted pair for the power supply. Either unsolder these from the power supply board, or unhook the wire from the plastic clip, when it is just possible to lay the two halves side by side.

To release the main pc board, first set the tuning gang to maximum capacitance. Note the position of the tuning pointer which should be near or at zero on the logging scale. Then remove the 2 screws securing this board, one next to the tuning gang on the metal bracket, and the other on the pc board, central right.

The tuning drive can be left fully threaded in the cabinet. To do this, take a broad screwdriver and very gently ease the tuning drum off the gang's geared spindle whilst gently easing the board to the right. It will eventually come free to the extent of its connecting leads, and the tuning drum will be retained in its plastic clips in the cabinet - a neat design.

It is now possible to turn the board over to replace the capacitor. There are 3 negative connections and a central positive. A new component (2.2 mF at 25V) will fit neatly between the central point and one outer, but the 3 negative connections on the print must be joined together with wire.

If you wish to set the output stage quiescent current, now is a good time, but you need either a set of batteries to give an accurate 9V or a lab supply. Break the solder link in the track adjacent to the collector connection of T013 (RH end of heatsink when in its usual position) and insert a 0 - 10 mA meter. With the volume control at minimum, set the collector current to 7.5 mA with R650, moving the wiper around the set point a little to clean the track.

Reassembly is the reverse, but set the pointer to its previous position, fully mesh the gang and gently ease the board into position as the drum is engaged with the spindle. There will be a piece of rotting foam at the upper right corner of the board - replace this to minimise rattles.

Leon.

Den, if you are able to send me a private message, I can give you my contact details. I have also left these in a private message to you. Thanks once again for your generous offer of a battery cover for this set.
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Old 26th Sep 2017, 1:53 pm   #11
Leon Crampin
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Default Re: Grundig Concert Boy 1100

Den, many thanks for sending me a battery cover for this set (at no cost). It's much appreciated and my Concert Boy is now fully restored - a powerful and weighty set with 6 "D" cells fitted. It's good to now have the option of running it on batteries.

Let us know how the restoration of your set goes.

With thanks, Leon.
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Old 27th Sep 2017, 2:02 pm   #12
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Default Re: Grundig Concert Boy 1100

Glad to be of help!
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Old 3rd Oct 2017, 12:21 pm   #13
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Default Re: Grundig Concert Boy 1100

My next problem is finding a replacement antenna, better yet, two! These seem to become detached from the solid end piece. One is ok-ish, the other a wreck. Lots of ebay searches only reveal much lighter weight telescopics. Does anyone have any pointers, or am I looking at getting hold of several sets and see what I can salvage?
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Old 3rd Oct 2017, 1:39 pm   #14
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Default Re: Grundig Concert Boy 1100

Have a look at the twin telescopic aerials sold in Poundland. I think you may have to live with a more lightweight aerial - the ones used in 70s Grundig sets were very substantial indeed.
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Old 3rd Oct 2017, 4:35 pm   #15
Leon Crampin
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Default Re: Grundig Concert Boy 1100

Den, I might be able to help you out. I have a spare correct aerial for the Concert Boy 1100 which is in good condition apart from missing the top section (solid rod) and attached "button" for the very top. The rest of it is all OK, the sections move correctly and the swivel/rotating base works properly.

It's yours if you would like it (free, of course) - all it needs is a "button" (araldited dome nut?) fixing to what is now the top section. If you choose a suitable top button, it will look original.

Send me a PM if you would like me to post it to you.

Leon.
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Old 3rd Oct 2017, 4:45 pm   #16
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Default Re: Grundig Concert Boy 1100

I don't need to remind Grundig collectors that the solid swivel base of the telescopic antenna when extended, connects to a metal socket soldered onto the pc and this holds the antenna, by means of a sprung ball bearing contained within the antenna base, vertically & horizontally.

The difficulty, if there is one, is the joint between the thin telescopic part and the solid base which has a circular groove formed in the circumference which the antenna is crimped into during manufacture.

The metal part, soldered to the pc, through which the antenna is pulled, is to German engineering standards and is almost an interference free fit to the antenna so should the crimped part becomes loose it fouls the part.

My recommendation would be to super glue the two parts together whilst looking out for either a non working Concert Boy or Yacht Boy 1100 on ebay.

If you can't wait, from just searching on the web, I believe the satellite 200 one can be used and is yours for 40 euros from Rainers Candy Store USA.



Chris nee Simpsons
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Old 3rd Oct 2017, 5:05 pm   #17
Leon Crampin
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Default Re: Grundig Concert Boy 1100

I agree, the joint between the thin telescopic lowermost section and the swivel base often becomes loose - the metal is too thin to crimp firmly. Running a bead of Loctite 601 (high strength grade) provides a permanent fix with no dismantling.

The aerial fixing on the 1100 is a bit different - a bracket fixes the aerial assembly to the back moulding of the case; the electrical connect is made automatically to the print when the back is removed. There's a sprung slot in the aerial bracket to make this connection.

Leon.
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Old 3rd Oct 2017, 5:35 pm   #18
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Default Re: Grundig Concert Boy 1100

I'd be most grateful for that, Leon, and I'll get some Loctite to do the other set too! Will PM address.
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Old 5th Oct 2017, 3:51 pm   #19
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Default Re: Grundig Concert Boy 1100

And before I do something very dim, 2.2mF = 2200-uF, correct?
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Old 5th Oct 2017, 4:14 pm   #20
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Default Re: Grundig Concert Boy 1100

Quote:
Originally Posted by DCBassman View Post
And before I do something very dim, 2.2mF = 2200-uF, correct?
Yes, 2.2 mF (millifarad) = 2,200 uF (microfarad)

Not to be confused with the old mfd which is uF (microfarad)

Lawrence.
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