grundig: 5040W (5040 W);
ID: 120289
This article refers to the model: 5040W (Grundig (Radio-Vertrieb, RVF, Radiowerke))
grundig: 5040W (5040 W);
04.Sep.06 21:57
0
Hello,
one beautiful Grundig5040w is in my family for over a 50 years.
There is one technical problem with shematics for this radio,
and that is capacitor betveen EABC80 triode and output EL12-
in my shematic this capacitor is marked 10nF,but in shematics I found in
radiomusem capacitor is 25nF,so what is correct?Problem is in my capacitor in
the radio-is shorted,and it is no possible to see value on the capacitor.
Does anybody have suggestion for me?Thanks,Peter.
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G 5040W coupling cap.
05.Sep.06 03:48
Hello Mr. Adnadevic,
I have this Great radio and the original Grundig Reparaturhelfer 5040W.
The EABC80-EL12 coupling capacitor correspond to the C22 10nF 500V = DIN E 41166.
I hope this information can help you.
Respectfully,
Bruno Gandolfo.
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Both values will work !
05.Sep.06 04:20
It won't matter whether you install 10 or 25nF at this particular point of the circuit. You may also choose 15 or 47nF or anything else around 10...47nF. But it is absolutely essential to replace any and all paper capacitor within your radio while more or less, all these will show poor isolation, thus weakening the electrical safety, the sound, power output, sensitivity, selectivity and so on of your radio. Usually, you cannot check that with an Ohmmeter; you'll need an isolation meter applying at least 50volts or even more. (Most isolation meters apply 100 or 500V) But, there's no need to have an instrument of that kind because any of these paper caps definitely is mad.....
By the way, styrene caps as well as ceramic ones do not show that. But you may check their capacity.
If you do have an insulation meter : Discard any cap below 200MegΩ
(The foregoing does not apply for electrolytics!)
By the way, styrene caps as well as ceramic ones do not show that. But you may check their capacity.
If you do have an insulation meter : Discard any cap below 200MegΩ
(The foregoing does not apply for electrolytics!)
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All paper cap replacement.
05.Sep.06 14:20
Hello Herr Hasselmeier,
Some months ago with my esteemed friend Robert Sarbell in US we assembled the Isotest 6 and the experience has shown that in the vintage radios almost the 100% of the paper capacitors have a resistance less to 200 M ohms.
If we measure its conductivity all they have more than 15 to 20 n Siemens, nevertheless many times the capacitance is conserved in normal tolerance values. Then it seems prudent to replace the paper caps.
The Isotest 6 is not suggested to evaluate Elko. Do you know how to evaluate an Elko without using ESR since all the tester with ESR capability have a very high cost.
Best regards,
Bruno.
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05.Sep.06 18:14
Hello Bruno,
whilst I wouldn't presume to criticise any of the foregoing
advice, because it's obviously excellent,- I do sometimes think we tend
to get a bit too technical and precise about our radios in some respects!
For instance, although I do have quite sophisticated measuring devices,
when it comes to checking cap.'s in an old radio, (anything over 5nF.or
so,) I only ever use two relatively simple tools,- an ANALOGUE meter,
(20,000 ohms p/v. an AVO 8 is excellent) and the most simple - ME!
I really mean a bit of experience and common sense, in other words if
I have a radio from the 1960's or earlier, I'll replace all paper cap.'s
and unless the Elko's/electrolytics are exceptional, those too,- really
old ones, and high voltage ones, ALWAYS!
To check, obviously disconnect one end of cap. with meter set to
highest ohms range, connect to cap. (pos. lead to negative on cap.
usually) Note how long it takes pointer to ZERO, if it doesn't, scrap
the cap. It's a good idea to practise on a range of good new cap.'s
Obviously, the bigger Elkos take longer to charge, but in all cases
leave connected.for a minute or two, disconnect and leave 5 min.'s
or so, watch the pointer carefully when reconnecting, ideally it
shouldn't move - the more it moves the more likely the cap. needs
replacing!
The skill(?) is in relating charge time to cap. size, amount of pointer
deflection, & charge retention, but it's soon aquired with experience.
For close-tolerance mica or ceramic cap.'s only the bridge will do!
Hope this doesn't insult or upset too many experienced technicians!
Regards, John.
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Another simple check
09.Sep.06 18:19
Hello John !
Sure, if someone just wants a radio to play again, those 'rules of thumb' you gave will, in most cases, enable anybody who owns a multimeter to repair/restore a radio that way successfully.
But, since most of us do have more sophisticated instruments, why don't use them ? I did not purchase/calibrate etc. these just to check out the density of dust accumulated on their surfaces ;-)
The ohmmeter- method will NOT always work !
Why ? Sometimes, electro-chemical processes develop an own potential, a 'charge' inside the cap which can prevent the current from the ohmmeter to go through the cap ! That's why any and all isolation meter (in GB, well known as 'Megger' ;-) ) do use these high voltages !
However, here's another great method for those few who do not own anything else but a multimeter :
This requires no skills in relating anything to anything - and will also work right from the beginning if one uses a different instrument.
Sure, if someone just wants a radio to play again, those 'rules of thumb' you gave will, in most cases, enable anybody who owns a multimeter to repair/restore a radio that way successfully.
But, since most of us do have more sophisticated instruments, why don't use them ? I did not purchase/calibrate etc. these just to check out the density of dust accumulated on their surfaces ;-)
The ohmmeter- method will NOT always work !
Why ? Sometimes, electro-chemical processes develop an own potential, a 'charge' inside the cap which can prevent the current from the ohmmeter to go through the cap ! That's why any and all isolation meter (in GB, well known as 'Megger' ;-) ) do use these high voltages !
However, here's another great method for those few who do not own anything else but a multimeter :
- Unsolder one lead of each (paper) cap found inside the set (disconnect the lead electrically closer to ground!)
- Remove any and all tubes
- Apply B+ voltage - or simply switch on the set if mains trannie, rectifier, B+ 'lytics, etc. are good or already have been replaced
- Now, connect the negative/ground lead of your instrument to the chassis
- Set it to a range where it has an internal resistance of at least 1 MegΩ (that's, for example, the 50V range on a 20kΩ per volt instrument - if it is able to handle the full B+ even in that range. Otherwise, set it to a higher range and calculate the internal resistance it will show in that range)
- Now, connect the positive lead to each unsoldered capacitor lead, one after another; wait, until it has charged and read the voltage displayed by the instrument. Since now, the leaky cap and your instrument will work as a voltage divider, you'll be able to calculate the (approx.) internal resistance of the cap's isolation. Using that method, you should have a second instrument reading the voltage present at the point of the cap closer to the B+ since it will not always be the full B+.
This requires no skills in relating anything to anything - and will also work right from the beginning if one uses a different instrument.
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On the electrolytics...
09.Sep.06 23:53
Hello Mr. Gandolfo-Canepa !
There are at least three checks necessary to decide whether a 'lytic is still good or should be replaced :
#1 : You need a resistor around 100kΩ, the 'lytic under test, a dc supply capable of supplying the 'lytic's rated voltage - and at least a few hours; sometimes days. If the 'lytic under test is larger than 50µF, you may insert 82kΩ or less. Adjust your supply to the 'lytic's maximum continuous rating, place the resistor in series and connect the whole thing to your dc pwr sply. Now, simply wait until the voltage across the 'lytic almost equals the voltage supplied. Checking a 350V type, for example, a remaining 10 or 20V difference is ok. If you do not have such a sply, just take a radio transformer, a silicon diode like the 1N4007, connect it in series with the plate supply windings, connect the resistor and the 'lytic under test. Now, the 'lytic should build up a charge almost equivalent to 1.41 times the effective AC voltage supplied into the circuit. The difference 'allowed' here may be a bit larger. Since the voltage supplied by your trannie usually will not exactly match your needs, place a variac between the power line and your trannie.
Optional : If the 'lytic holds the voltage, heat it up (Hot Air gun, candle, ...) until it reaches 50°C. The isolation must not break down now; but the voltage may drop a bit now (around another 20V)
Charging it for the first time, it may take up to several days until the voltage across your 'lytic stops rising ! But, that way, I already 're-vitalized' vintage Siemens 'lytics from 1937 and Draeger from '51 which never ever have been in use before ! They're better than good now.... excellent !!
#2 : Carefully discharge the 'lytic now across a resistor (e.g., 1kΩ) until it reaches ZERO volts, let the res connected for a few minutes. This is to protect your capacitance meter. Now, check for capacity. The more sophisticated capacitance meters do charge the cap until it reaches a certain voltage and afterwards discharge it to determine the amount of energy stored inside the 'lytic by multiplying U*I*t during the discharge cycle only. This process will be performed a few times per second by most instruments. The cheap instruments do simply apply a square wave voltage and let you know the current through the cap. This, of course, does not give reliable readings. That's why those instruments usually read too high while checking leaky paper caps !
#2½ : Don't have such a capacitance meter ? This checks for capacity AND ESR but gives a rough estimate only : Take a set of known good caps and 'lytics and let someone else who has such an instrument determine their exact values. Now, compare these caps to your 'lytic under test : Charge the known good one having the same capacity like that one under test until both of them reach the same voltage, 350VDC, for example. Now, take a storage scope plus a 1:10 probe (to protect the scope); connect the scope in parallel to a resistor around 10Ω, put the whole thing in series to the 'lytic under test. Discharge the 'lytic (over these additional 10Ω) across 500 or 1000Ω and store that process. Repeat that using the known good 'lytic. Both figures on the screen should look quite similar. You may have to repeat the process. If your device under test shows an overall smaller figure, it has low capacity. If it shows less height on the screen but the whole process takes remarkably longer, the device under test shows too high ESR. If both curves do look quite similar, the 'lytic under test is good.
#3 : Take a sine wave AC supply such as your transformer's B+ windings again, put the diode in series again, charge the capacitor. Now, load the circuit using a resistor or a bulb drawing 80mA approximately (for a 47 or 100µF 'lytic) . Take your Multimeter, choose the 30 or 100VAC range, connect a 0.1µF cap in series to the MM, and measure the AC component across the load that way. It should not read more than a few volts now. Compare to a known good 'lytic of same capacity. If the remaining AC component is too high, the 'lytic under test shows an ESR which is too high.
You cannot 'repair' low capacity or high ESR. But you may easily destroy forever a 'lytic capacitor which hasn't 'seen' electricity for extended periods of time by forcing voltage across it ! According to my experiences, after 're-forming', most vintage caps do show too low capacity only. 35µF instead of 50 is a typical value. But otherwise, they're still ok. These can be kept in use - just add another 32µF or sth around that under the chassis. More often, the Pre-WW2 'lytics cannot be kept in use. But sometimes, even these are good ! Personally, I do prefer sets which are as original as possible inside. Paper caps always need to be replaced, no way out. But 'lytics often don't ! At least, I did not, never ever face any ''electrolytic trouble'' ! I do own hundreds of vintage 450/550V 'lytics - inside my Tektronix scopes. I did have to replace exactly ONE during the past years ! Ok, the quality used by Tektronix may be far beyond the quality used in consumer equipment like radios. But, if made by Siemens (or Draeger, Frako, Valvo/Philips) the old caps very often can be kept in use without facing any trouble. And, if a 'lytic should fail later, it (most likely) will disconnect internally or lose capacity ( the radio develops a strong hum) OR will build up ESR (also a hum will develop) OR it will develop a short - the fuse will immediately blow. So, letting the vintage 'lytics inside usually will not damage your set even if they should fail some day. To be sure, I usually add a B+ fuse right behind the rectifier - if the cap or sth else draws too much current, this fuse will protect the rectifier (tube) and the trannie, too. Remember, even the best output tube may suddenly become soft ('gassy'), drawing high currents then which will easily destroy the output trannie, the choke and, finally, the mains trannie. And, another point to mention : Also today's high-voltage 'lytics fail sometimes ! You're not automatically safe after replacing the old ones with new ones.
What I always do replace are the fuses - measure the current that really flows using a true RMS meter and install a fuse matching the flowing current or even a bit below that; a Slow Blow fuse will not blow even if slightly overloaded. I always do so since the old fuses are very likely not to switch off at the current limit they should switch off any more AND usually, they were dimensioned around one and a half times or twice the current normally flowing. While today, new mains trannies for our vintage sets are not available anymore easily ;-), we should accept to (maybe) sometimes replace a fuse - instead of sometimes replacing a trannie........
There are at least three checks necessary to decide whether a 'lytic is still good or should be replaced :
- Isolation
- Capacity
- Equivalent Series Resistance (ESR)
#1 : You need a resistor around 100kΩ, the 'lytic under test, a dc supply capable of supplying the 'lytic's rated voltage - and at least a few hours; sometimes days. If the 'lytic under test is larger than 50µF, you may insert 82kΩ or less. Adjust your supply to the 'lytic's maximum continuous rating, place the resistor in series and connect the whole thing to your dc pwr sply. Now, simply wait until the voltage across the 'lytic almost equals the voltage supplied. Checking a 350V type, for example, a remaining 10 or 20V difference is ok. If you do not have such a sply, just take a radio transformer, a silicon diode like the 1N4007, connect it in series with the plate supply windings, connect the resistor and the 'lytic under test. Now, the 'lytic should build up a charge almost equivalent to 1.41 times the effective AC voltage supplied into the circuit. The difference 'allowed' here may be a bit larger. Since the voltage supplied by your trannie usually will not exactly match your needs, place a variac between the power line and your trannie.
Optional : If the 'lytic holds the voltage, heat it up (Hot Air gun, candle, ...) until it reaches 50°C. The isolation must not break down now; but the voltage may drop a bit now (around another 20V)
Charging it for the first time, it may take up to several days until the voltage across your 'lytic stops rising ! But, that way, I already 're-vitalized' vintage Siemens 'lytics from 1937 and Draeger from '51 which never ever have been in use before ! They're better than good now.... excellent !!
#2 : Carefully discharge the 'lytic now across a resistor (e.g., 1kΩ) until it reaches ZERO volts, let the res connected for a few minutes. This is to protect your capacitance meter. Now, check for capacity. The more sophisticated capacitance meters do charge the cap until it reaches a certain voltage and afterwards discharge it to determine the amount of energy stored inside the 'lytic by multiplying U*I*t during the discharge cycle only. This process will be performed a few times per second by most instruments. The cheap instruments do simply apply a square wave voltage and let you know the current through the cap. This, of course, does not give reliable readings. That's why those instruments usually read too high while checking leaky paper caps !
#2½ : Don't have such a capacitance meter ? This checks for capacity AND ESR but gives a rough estimate only : Take a set of known good caps and 'lytics and let someone else who has such an instrument determine their exact values. Now, compare these caps to your 'lytic under test : Charge the known good one having the same capacity like that one under test until both of them reach the same voltage, 350VDC, for example. Now, take a storage scope plus a 1:10 probe (to protect the scope); connect the scope in parallel to a resistor around 10Ω, put the whole thing in series to the 'lytic under test. Discharge the 'lytic (over these additional 10Ω) across 500 or 1000Ω and store that process. Repeat that using the known good 'lytic. Both figures on the screen should look quite similar. You may have to repeat the process. If your device under test shows an overall smaller figure, it has low capacity. If it shows less height on the screen but the whole process takes remarkably longer, the device under test shows too high ESR. If both curves do look quite similar, the 'lytic under test is good.
#3 : Take a sine wave AC supply such as your transformer's B+ windings again, put the diode in series again, charge the capacitor. Now, load the circuit using a resistor or a bulb drawing 80mA approximately (for a 47 or 100µF 'lytic) . Take your Multimeter, choose the 30 or 100VAC range, connect a 0.1µF cap in series to the MM, and measure the AC component across the load that way. It should not read more than a few volts now. Compare to a known good 'lytic of same capacity. If the remaining AC component is too high, the 'lytic under test shows an ESR which is too high.
You cannot 'repair' low capacity or high ESR. But you may easily destroy forever a 'lytic capacitor which hasn't 'seen' electricity for extended periods of time by forcing voltage across it ! According to my experiences, after 're-forming', most vintage caps do show too low capacity only. 35µF instead of 50 is a typical value. But otherwise, they're still ok. These can be kept in use - just add another 32µF or sth around that under the chassis. More often, the Pre-WW2 'lytics cannot be kept in use. But sometimes, even these are good ! Personally, I do prefer sets which are as original as possible inside. Paper caps always need to be replaced, no way out. But 'lytics often don't ! At least, I did not, never ever face any ''electrolytic trouble'' ! I do own hundreds of vintage 450/550V 'lytics - inside my Tektronix scopes. I did have to replace exactly ONE during the past years ! Ok, the quality used by Tektronix may be far beyond the quality used in consumer equipment like radios. But, if made by Siemens (or Draeger, Frako, Valvo/Philips) the old caps very often can be kept in use without facing any trouble. And, if a 'lytic should fail later, it (most likely) will disconnect internally or lose capacity ( the radio develops a strong hum) OR will build up ESR (also a hum will develop) OR it will develop a short - the fuse will immediately blow. So, letting the vintage 'lytics inside usually will not damage your set even if they should fail some day. To be sure, I usually add a B+ fuse right behind the rectifier - if the cap or sth else draws too much current, this fuse will protect the rectifier (tube) and the trannie, too. Remember, even the best output tube may suddenly become soft ('gassy'), drawing high currents then which will easily destroy the output trannie, the choke and, finally, the mains trannie. And, another point to mention : Also today's high-voltage 'lytics fail sometimes ! You're not automatically safe after replacing the old ones with new ones.
What I always do replace are the fuses - measure the current that really flows using a true RMS meter and install a fuse matching the flowing current or even a bit below that; a Slow Blow fuse will not blow even if slightly overloaded. I always do so since the old fuses are very likely not to switch off at the current limit they should switch off any more AND usually, they were dimensioned around one and a half times or twice the current normally flowing. While today, new mains trannies for our vintage sets are not available anymore easily ;-), we should accept to (maybe) sometimes replace a fuse - instead of sometimes replacing a trannie........
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13.Sep.06 00:04
Hello Mr. Gandolfo,
I'm sorry for a late answer but I wasn't at home until today.
Thank You for the information,it is great help for me.Now I know what
to do with bad capacitor.
Sincerely,Perica.
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13.Sep.06 00:15
Hello Mr.Hasselmeier,
thank You for all informations.
Belive me Your advice came to late,and my unknowlege cost me a destroyed beautiful EL12-Valvo.Some two month ago capacitor between anode and ground shorted and destroyed Selen rectifier and G2 in EL12 was burned.Now I know that all paper caps must be replaced.
Thank You.Sincerely Perica.
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13.Sep.06 00:19
One more question-if styroflex caps are bad what can replace them succesfuly.
Thanks,Perica.
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13.Sep.06 03:52
Hello Perica!
Don't worry - usually, these 'styroflex' (polystyrene) caps are good and can be kept in use. Sure, check these as described above. If you really should locate a faulty one, those capacitors labeled 'MKS' do also contain PS between their conductive foils and therefore electrically, these should behave the same. These 'MKS' can easily be found in old TV sets made in the '70s...'90s. In addition, any electronic component retailer will provide these, like RS-components, mouser.com, Bürklin, Schuricht, DigiKey and so on. If you prefer those having axial leads, check out www.tubesandmore.com ; that's Antique Electronics Supply - a nice shop (and nice staff there!) in Tempe, Arizona, USA.
Don't worry - usually, these 'styroflex' (polystyrene) caps are good and can be kept in use. Sure, check these as described above. If you really should locate a faulty one, those capacitors labeled 'MKS' do also contain PS between their conductive foils and therefore electrically, these should behave the same. These 'MKS' can easily be found in old TV sets made in the '70s...'90s. In addition, any electronic component retailer will provide these, like RS-components, mouser.com, Bürklin, Schuricht, DigiKey and so on. If you prefer those having axial leads, check out www.tubesandmore.com ; that's Antique Electronics Supply - a nice shop (and nice staff there!) in Tempe, Arizona, USA.
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