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Old 9th Dec 2015, 3:20 pm   #1
stevehertz
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Default Grundig Satellit 650 problems

I'm presently restoring/repairing a Grundig Satellit 650. The set is stripped down, well, front and back case removed, and I'm waiting for a replacement speaker surround (all in hand), but meanwhile I'm addressing some other issues. The set will tune in to stations and all functions seem to work, although obviously the sound is thin and lacking bass due to the missing bass unit surround. I guess the sensitivity could be better though? Audio is absolutely fine through headphones. FWIW, the headphones output is derived from the main output trannies, so no issues there as such.

1) The signal strength meter doesn't appear to do much at all? Saying that, just to throw a spanner in the works, I seem to recall it was working a week or so ago..

2) I got some new 6-7V, 30mA bulbs to replace faulty ones each side of the LCD display, and also behind the signal strength meter. I fitted them and as you can see in the photo, they barely glow orange. On measurement, the voltage applied is just 3.6V - way short of the specified 6 to 7V. Clearly there seems to be a low supply voltage issue? BTW, the much brighter bulb (that wasn't faulty) at the top left that illuminates the main tuning dial is specified as being 7V, 80mA and that has 4.6V measured on it - again, it's low, but a bit better, hence it's brighter. Any ideas? As I say, it looks like a low DC supply somewhere, but I was just wondering if anyone has experience of this particular set? As you can imagine, it is not the easiest to get to right inside, ie where all the PCBs etc are, so being pre-armed with ideas would be a bonus and maybe save me hours in stripping down sections that I don't have to.

I'm thinking there's maybe a 'master' DC rectification issue, giving a low HT and other DC voltages too? I haven't begun to get my head around the pages and pages of circuit diagrams yet..
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Old 9th Dec 2015, 6:45 pm   #2
MotorBikeLes
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Default Re: Grundig Satellit 650 problems

I have a Satellit 600 which is more or less identical to the Sat 650. I have some of the OEM bulbs, LA1,LA2,LA3 and LA4. The last one is shewn as 7v 80mA, with the first three as 7v 30mA.
However, in a tech note (KDI 3/89) LA1 and LA2 (the display pair) are changed to 5v 60mA. I assume LA3 and LA4 remained as original. It then continues "Remove R920 (120R). Change R921 (120R) to MSW39R, 0.3 W." (MSW = non flammable if I remember correctly)
The KDI also mentions possible "Does not switch on if amb. temp is very low, change R816 (1K5) on display panel to MSW 2K2, 0.3W"
The sig strength meter may be "normal" on FM, but for any AM station you MUST use the manual preselector tuning. By pressing the button, it "tunes itself", but mine is way off, so if I change between two AM stations well separated on the scale, I press the button for coarse adjust, then release and manually adjust.
Not the easiest to work on. As you must have found, remove all front knobs and lie on front handles. Next remove bat lid and batteries (inc backup), remove screws from back bottom and take off back. Pull out chassis. When reassembling, you first ensure that all push buttons on front line up, AND the push button on rear (antenna switch). Mine got panel damage due to my failure to position it carefully.
I had a problem of very low volume (muted) which occurred when it was cold, and the battery (accu) was fully charged. It lead me a merry dance, including trying to modify muting circuit, replacing control transistor and chip. I eventually cured it by cleaning the on/off switch and changing base bias resistor (R612) from 47K to 27K. Not sure which was actual cure. There was also a meter deflection with set OFF, and I think that is why I cleaned the main (on/off/armed) switch.
It has been wakening me every morning for the last 30 years, but I found in the early days when I lived out in the country, a power cut in the night meant no alarm (always when an important event) so I only ever plug in mains for charging once per week after rising from bed.
If you tire of this, give me first refusal! Fantastic sets.
Les.
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Old 18th Jan 2016, 12:42 pm   #3
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Default Re: Grundig Satellit 650 problems

As I mentioned in another thread, the replacement 6-7V, 30mA bulbs that I bought were incorrectly marked as being that. On the bench, at 7V the current draw was 60mA and the filament was still not bright. I did not turn up the PS voltage to check (I didn't want to blow one as I was sending them back), but I'd guess that they were more like 12V, 120mA to attain a normal brightness. Anyway, they have been returned to the supplier and they reckon it will be 10 to 14 weeks for replacements from our far eastern friends.

So I decided to put the chassis back into its case and use it. The lack of illumination is not really too much of an operational problem, albeit one that I want to fix in the fullness of time.

Now.. I mention above that the signal strength meter is not doing much. Well, it still isn't. But I'm thinking there's perhaps another reason for this. On FM, the set seems to work fine with good audio quality and ability to pick up stations as I would expect. On AM - where I am led to believe that this set should perform amongst the very best - the performance is less than stellar when it comes to pulling in stations. On LW and MW I would say it's only average, and on SW it seems below par compared to my Zenith TransOceanic Royal D3000.

So, I'm thinking that the signal strength meter may only be telling the truth; that there's not a lot of signal within the set? But if that's the case, then why is the SS meter equally dormant on FM where the performance seems ok. Note that in the recent past ie since I have owned it, the meter has kinda 'worked' sporadically, but now it doesn't seem to do much at all?
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Old 19th Jan 2016, 2:50 pm   #4
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Default Re: Grundig Satellit 650 problems

Actually, messing around with the set today, I reckon that the signal strength meter is simply not working properly, regardless of whether I have a low gain/low sensitivity issue on AM. Why? because I connected an external roof mounted FM aerial to the set, and on a weak station I switched between internal or external aerial using the switch on the set for that purpose. As you'd expect, the sound quality and background noise improved drastically when switched to the external aerial, but the SS meter still didn't budge, it doesn't appear to be functioning correctly, yet in the past it has 'moved' and shown a signal strength.
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Last edited by stevehertz; 19th Jan 2016 at 2:56 pm.
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Old 20th Jan 2016, 2:39 am   #5
unitaudio
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Default Re: Grundig Satellit 650 problems

Do you get continuity on the meter coil itself? If it has worked sporadically, that's where I'd look first. That sort of thing's caught me out more than once.

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Paul
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Old 20th Jan 2016, 9:35 am   #6
stevehertz
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Default Re: Grundig Satellit 650 problems

Good point Paul. I'll check that in due course.

The other thing is, does the SS meter need 're-calibrating'. In this tutorial, it details how to do this. Interestingly, he refers to it as the 'AM signal meter', although in the operating instructions I can see nothing to say that it is not operational on FM too. Then again it's also used to show battery condition. Anyway, here's the procedure, I'm wondering if it needs performing? : http://myweb.tiscali.co.uk/grundigradioboy/650adj.htm
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