grundig: Grundig 4010 (W); "station displacement".

ID: 80245
This article refers to the model: 4010 (W) (Grundig (Radio-Vertrieb, RVF, Radiowerke))

grundig: Grundig 4010 (W); "station displacement". 
07.Dec.05 13:01
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Bruno Gandolfo-Canepa (RCH)
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Bruno Gandolfo-Canepa

Respected Members,

In the Grundig 4010(W) restoring process I have notified two errors in the schema. 

1.The EF41, pin 6 grid 1 cannot have 120 volt.  I think that voltage corresponds to Grid 2, pin5.  2.The power supply diodes are in inverse sense with the positiv voltage to the chassis. 

Now the radio is working well and has impressed me its high  sensitivity especially in its threee KW bands.
Nevertheless when the circuits heat, the radio stations displace to the left always to a greater frequency and requires re tune the radio. 
My question is if this corresponds to a pending problem in the radio or the design suffers from that defect. 
Respectfully,
Bruno Gandolfo.

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 2
Station Displacement 
08.Dec.05 00:44

Henning Oelkers (D)
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Henning Oelkers

Dear, Sir,

i took a look at the Diagram, and i think, You are right about the rectifier, and the g1 / g2 mismatch.

About the station Displacement: Even, if i don't have this specific Radio, I would expect that a Station, once correctly tuned, should be at the same place, and retuning the Station schould not be needed during warm up of the Radio.

Can You give some more Informations on this:
- does it happen only on short wave, or also on medium wave?
- what is the frequency you dial in, and how much is the displacement in kHz?
- how long does it take, after turning on the Radio, until the Radio is stable, and the Displacement stops?
- do You have a second ECH81 to change for Testing, or another Radio, to test the ECH81?

I will watch for Your reply,

best Regards,

Henning Oelkers, Berlin, Germany

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 3
"Stations displacement" 
08.Dec.05 03:54

Bruno Gandolfo-Canepa (RCH)
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Bruno Gandolfo-Canepa

Good morning Herr Oelkers,

Again you attend my consultation in the forum and I am very thanked therefore. 
Unfortunately the forum in English has less activity than in German.  In Spanish, my native language, almost there is not activity. 

I have checked all the tubes in my Mercury 2000 tube tester and the ECH81 original had 1500/500 and 6000/3000 Gm in the Heptode and Triode respectively.  It was replaced by a Tungsram NOS. 

The station displacement is notorious especially in KW 1,2 and 3.  In MW is not perceived but the radio signal is wider and only I can tune one station in 720 KHz. 
The displacement is of approximately 100 KHz and always toward a greater frequency.  The duration is from 15 to 20 minutes.  Then the stability increase and the displacement is of some 50 Khz.  To the 30 minutes there is not more displacement. 

Thank you so much Henning, I thank a lot its time and interest in this curious problem. 

Merry Christmas,
Bruno.

 

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 4
 
08.Dec.05 09:57

Henning Oelkers (D)
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Henning Oelkers

Dear Mr Gandolfo,

i took  a look in  detail into the Diagram. Most Radios of that time had a Tuning Capacitor of apx. 500 pF. This Grundig Radio has a much lower Capacity of 195 pF, and this in series with a 150 pF. That means, that Capacity displacements of the ECH81 would have a much bigger Effect, than on other Radios, but with a very stable Oscillator Tube, it would work well. 

The Brand Name Tungsram is known to me, as only of mid Quality. In a Radio, only providing Medium Wave and Long Wave, together with a Tuning Capacitor of 500 pF, a Tube Capacity Displacement during warm up of about 5 pF only would make 1%.

In that Grundig Radio, the same Tube will make a Displacement of 4 %. If a shortwave Range for Example is from 6 Mhz to 12 Mhz  a Displacement of 5 pF may make a frequency displacement in the area of 120 kHz easily.

So i still see the Tube as the Number one Candidat for the Problem. From  the Factory this Radio would have either a Valvo, a Siemens, or a Telefunken tube. 

Most Tube Testers only test for Emiision, and Grid shortcuts. They do not Test for Capacity ( and we are dealing in the pF Range ).

So, if You have another ECH81 in any other Radio, please check theses Tubes in the Grundig, and notice the Frequency Displacement during Warm up. Please let The Radio Cool down for at least 1 - 2 Hours, then turn on, and dial a Station. Please make notes of the Displacement. If You have more than one ECH81 available, try Brands like Valvo or Telefunken first. Please notify from where You removed a Tube, because after Tube is replaced by not the same tube, the Radio may need alignment.

But i have a Number 2 Candidat: Is the Tube socket of a Pertinax Type ( the cheap Hard Paper Material, also used for Printed circuits ? ) If Yes, did anybody Spray any Contact Spray onto that Socket? If Yes too, then this might be the Problem as well, because the Material will stay kind of wet and the Isolation would not be the best. This may led to Displacement also.

This is now a lot of Questions to deal with, but i hope, we can get the Radio stable.

I will watch for Your Reply.

Best Regards,

Henning Oelkers, Berlin, Germany

 

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 5
 
09.Dec.05 06:19

Omer Suleimanagich (USA)
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Omer Suleimanagich

What about just changing the socket,replace all the caps and/or resistors to the socket, check out the voltages after, and try a few different ECH81's?

Omer

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 6
 
09.Dec.05 10:24

Henning Oelkers (D)
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Henning Oelkers

Dear Sirs,

i would not recommend changing Capacitors without knowing, that this is needed. Here is Why:

Every Part has a specific Reaction on Temperature Changes. To stabilise Oscillators, normally the Capacitors are selected, as to compensate the Changes of Coil Inductivity during warm up. Therefore, to make it perfect, the design of the Circuit often consist of Ceramic and Styrofoil Capacitors, because one has a negative going Change with Temperature, the other one positive going. Parts are selected at the Factory for Optimum Compensation.

If You decide to change Capacitors, i would recommend changing only one at a time, replacing it by exactly the same type and Capacity, and then make exactly notes of the Frequency Displacement during warm up.

As i mentioned before, in my Oppinion the Tube is still the Number one Candidat.

Best Regards,

Henning Oelkers, Berlin, Germany



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 7
Stations displacement...Thermal drift? 
09.Dec.05 13:27

Bruno Gandolfo-Canepa (RCH)
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Bruno Gandolfo-Canepa

Good evening Herr Oelkers and Mr. Suleimanagich.

I have taken some time in responding to be able to perform several tests.  After changing the Tungsram ECH81 by a Telefunken new and sealed in box, the station displacement does NOT IMPROVE.  The radio requires re tune in the station some three times during the first half an hour of use.  Then it reaches the stability desired. 

The tube socket really is of the pertinax tipe.  But it is absolutely clean and I have not used contact cleaner.  Can be observed in the up loaded photos to the G 4010 W model the chassis has a meticulous cleaning.  I have checked all the voltages and they are in normal rank.  I changed only the 25n EL12 grid1 capacitor because they had + 13 volts in EL12/325 grid1. 

I does not convince to accept the idea that a high price superhet. model wit RF amp stage can be behaved so unstable. 

Thanks by the continuous support. 
Best regards,
Bruno.





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 8
 
09.Dec.05 20:58

Omer Suleimanagich (USA)
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Omer Suleimanagich

Did you check all the capacitors and resistors in the area? What about All the Capacitors and resistors around the EABC80, or the IF tube? How are the EABC80 and IF tubes?

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 9
Local Oscillator Drift or not 
09.Dec.05 22:59

Henning Oelkers (D)
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Henning Oelkers

Dear Mr. Gandolfo,

I have seen the Pictures of Your Radio. It looks fantastic!

I have also seen Your last Answer. So i think we can state, that the Tube itself is OK. Now we need to know for shure, if the Local Oscillator is drifting.

I do not agree with the Idea,that something with the IF Stages is wrong, because You said, the Sensitivity is very good. But we will find out.

To test the Local Oscillator for drifting, You need a second Radio, preferable with Digital Frequency Display. Tune Your Grundig for Example to 7 Mhz in Short wave. Place the second Radio nearby, and tune for ( 7Mhz + 468 kHz ) 7.468 MHz. You schould hear the noise dissapearing on the second Radio, if You recieve the Local Oscillator. You propably need some patience to find the Local Oscillator Signal. This way You can check the Local Oscillator Frequency, and You can test for Drifting in every Band ( K1, K2, K3, M1, m2, L ).
The Frequencies Found for each Band when cold, and after warm up, would be a good help, to locate the defective Part.

I will continue to watch Your Reply,

Best Regards,

Henning Oelkers, Berlin, Germany

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 10
 
10.Dec.05 02:20

Omer Suleimanagich (USA)
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Omer Suleimanagich

Possibly, you might want to resolder anything that is soldered to ground around the ECH81 too. 

Of course, following the suggestions in the previous messgage is the right way to go too.

I find in a lot of the Grundig radios I have tinkered with of this vintage, that sometimes, solder joints from components to the radio's body need to be refreshed.  I came across a situation like this, but on FM, and it was remedied when I went all over resoldering these joints.

A lot of these radios are stored in cold areas, that experiance slight condensation, and that probably affects the solder joints in some way.

I'm still am of the school that paper capacitors of 0,001 uF and above should be replaced along with all electorlytics, and all resistors should be checked to see if any are open or out of tolerance. Power resistors in these radios sould also be junked, and replaced with nice sandstone resistors of higher wattage ratings (especially the black power resistors).

I like my radios to scream than crash and burn because of a faulty component.

Omer

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 11
Practical oscillator test 
10.Dec.05 04:00

Bruno Gandolfo-Canepa (RCH)
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Bruno Gandolfo-Canepa

Good Morning Herr Oelkers and Mr. Suleimanagich,

I performed your  practical oscillator test and I can obtain two conclusions:

1. the G4010 is perfectly aligned since in cold state the oscillator emits the tuned frequency more the FI.  That is to say tuning in 11.5 MHz the satellite radio tunes very clearly in 11.968 MHz.  Likewise in K1,K3,MW1,MW2.  I did not be able I check LW. 

2. when the radio warm, the oscillator diminishes the frequency since is necessary to tune in a higher frequency (50,100.150 KHz) to maintain the same signal in the satellite receiver.  That is to say to tune in the 11.968 in the second receiver I need to tune in 11.550 or 11.600 in the G 4010.  

I know the concept of check/replace components and re-weld the earth connections, but intent to identify where is the problem and then the components that directly I should replace. 

Thank you so much for maintain this stimulating dialogue. 
Bruno.




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 12
 
10.Dec.05 13:38

Henning Oelkers (D)
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Henning Oelkers

Dear Mr. Gandolfo,

i came in Contact about this Issue with one of our Grundig Experts, ( Mr. H.M.Knoll ). He would recommend to put a 4,7 or 10 nF Keramic in Parralel to C7 ( Kathode of ECH81 to Ground ), and then to check again for Oscillator Stability during warm up.

Please try, and state Your Results.

Best Regards,

Henning Oelkers 

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 13
 
14.Dec.05 06:42

Omer Suleimanagich (USA)
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Omer Suleimanagich

 14
C7 replaced 
30.Jan.06 04:30

Bruno Gandolfo-Canepa (RCH)
Articles: 132
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Bruno Gandolfo-Canepa

Dear Mr. Oelkers,

I apologize not to answer before the forum but I was in holidays and I took up again my activities some days ago. 
C7, The ECH81 catode paper capacitor was bad and was replaced by one of 10 nf, 630 volts.  The receiver recovered its stability and although I have tested it a brief period I believe that all is in order. 

Now I need to expand the upper UKW limit to 100.5 MHz to receive my favorite classical station.  I will be very thanked if you guide myself which is the trimmer that should adjust in the 4010W to expand the high end. 

I want to thank you and to Herr Knoll the aid and continuous support in recovering the stability to my grundig 4010W. 

thanks again and best regards,
Bruno.

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 15
Congratulations 
30.Jan.06 21:11

Henning Oelkers (D)
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Henning Oelkers

Dear Mr. Gandolfo,

I am happy to see, that in a Team around half of the World we found the Problem. My special Thanks to Mr. H. M.  Knoll!

About the FM Alignment. I translated the Alignment Table into English:

Alignment of/ Generator Setting / Radio Setting / Element to align

1. Oscillator/ 92,5MHz /92,5MHz /Ferrite Core ( h ) to Maximum

2. coupler Circiut/ 87,5MHz /87,5MHz /Ferrite Core ( i ) to Maximum

3. coupler circiut/ 97,5MHz /97,5MHz /Trimmer ( k ) to Maximum

4. Pre Circuit /92,5MHz /92,5MHz /Ferrite Core ( l ) to Maximum

Pleas find the Diagram of the "Spulenplatte" for the Locations of the Trimmers and Cores


Please follow these four steps, but have the Generator Frequency 1 Mhz above the 
value in the List. 

There is only the Oscillator Coil (Core) for Alignment, there is no "C" to align the FM Oscillator. 
But it is only a little "Distance " from 100 to 100,5 Mhz, so it schould Work.

Please be very carefull not to damage the Cores, because they are very fragile, and normally fixed with Wax, so it might help to warm them carefully and slowly until the Wax melts.

Good Luck!

Best Regards, 

Henning Oelkers

I can't remember, but if You don't have an HF Generator please let me know, and we will find a different Method for alignment.
 
 

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 16
FM alignment 
30.Jan.06 21:59

Bruno Gandolfo-Canepa (RCH)
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Bruno Gandolfo-Canepa

Dear Herr Oelkers,

Thanks by your attentive and quick answer. 
Not. I am sorry, I do not have a HF generator.  I bought recently a Heathkit IG-102 signal generator but is in trip to my hobby workshop. 

I have identifying the "Spulenplatte" and I need to know which trimmer I should move to expand lightly the high end. 

I understand the risk to damage a cores.  Which is the best method to melt the wax? 

Thanks again and best regards,
Bruno.
Warm North of Chile. 

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 17
Alignment without HF Generator 
30.Jan.06 22:45

Henning Oelkers (D)
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Henning Oelkers

Dear Mr. Gandolfo,

to align the FM Unit with the present Radio Stations You would need a Station at 91 - 93 Mhz, and one in the 98 zo 100 MHz Range.

If, for Example, You have a Station at 99MHz , please make a little Mark on the Dial glass at 99 MHz ( where the Station now is ) and a second Mark exactly ond MHz below ( 98MHz ) ( where Station schould be after the " Shift " .
As there is no "C" trimmer in this Radio for the Oscillator, You only have the chance to align with The Oscillator Core ( Letter h on the "Spulenplatte" ).

Please Tunt to the station at 99MHz, make a little turn at the Core ( until the Station just disappears  ) and with the Dial Knob try to find the Station again. ( if You get closer to 98 Mhz You are turning in the correct direction, if You get closer to 100 Mhz, the direction is wrong. ) You are finished when You reach 98 Mhz ( this is, where Your second Mark is ).
Now You schould be able to tune to Your favorite  100,5 Mhz Station by turning to 99,5 on the Dial Glass.

Please check, if the Sensivity of Your Radio is still good. If not, You need to Align points 2. to 4. from the Table above. You find the Positions given by the Letters h, i, k and l on the "Spulenplatte" Diagramm. Instead using the Generator, You can use a radio Station in the given frequency area.

To melt the Wax, You can use a Hairdryer to get warm air to the Coils and cores. Please be patient, it will take a while. If the Coils are inside the FM Housing, You may need to open it.
Do not overheat, because the coils body is plastic!  

Best Regards,

Henning Oelkers

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 18
 
07.Sep.06 20:26

Bruno Gandolfo-Canepa (RCH)
Articles: 132
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Bruno Gandolfo-Canepa

Hello Henning,

Finally the G 4010W UKW high end was expanded to the 101 MHz. The sensitivity remain good and the radio are working perfectly in UKW.
Unfortunately in KW 1-2-3 the tuning always drift to the left after 10 a 15 min when the radio warm up.
I changed all the paper caps around the oscillator circuit and the problem persist.
The sensibility and selectivity in all bands are very high.
I thanks any suggestions.
 
Best regards,
Bruno.

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 19
Rectifier ? 
10.Sep.06 01:17

Burkhard Hasselmeier (D)
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Hello !
Maybe, this sounds quite strange :
Some years ago, a 1953 Saba was driving me nuts- it was instable in a similar way you described.
All these paper caps had been replaced; the alignment was perfect, tube replacement didn't help, etc.
Then, with the radio playing, I accidently hit the knob of my variac, thus making the voltage rising up from 230VAC to 240VAC - and again, the station disappeared ! It reappeared after setting it back to 230V ! Quite interesting.....  varying the B+ (+/-8V) caused the oscillator to shift the frequency a bit.  What made the B+ vary during warm-up ? The selenium rectifier ! Since replacing it, the radio plays as it should....
Simply connect a Meter to observe the B+ during warm-up. Maybe, your Grundig has the same problem ?
If that does not help, I'd strongly recommend to replace all these old paper caps now... obviously, you didn't yet ! They definitely ARE MAD !
If the problem still persists, let us know...... but I do own several Grundig 4010(F, W*2 and GW*3) and also the 5010(*2) ... and none of these behaves that way !

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