Grundig 1088 Help

12/5/2010 1:16:24 PMBubba

Anyone have this radio? I am having a couple issues and need to compare voltages etc. One thing is I seem to have an issue where I cannot turn it down volume to a quiet enough level on FM or AM. Even at 0 it is too loud. Not blaring but too loud. It seems to vary volumes when I turn it on at first also. (Bias resistor cap of EL84?) I checked the bias on the single ended EL84 and it was drifting but not sure if this is cause by it or the tube before it.. I am assuming the problem is in the output or tube before the output. I need tome voltage measurments to see what I am supposed to have. I have the schem but not test voltages.. When I wiggle or move the 2nd last tube (one before the output) I get really loud scratching through the speaker almost unbearble boom... I am unaware if this is normal or not. I need to compare to someone elses. THanx

Bubba

12/5/2010 2:25:29 PMWarren

Test the resistance of the volume control. Think this set should be 1.3Meg ohm across the terminals. Also check if there is a resistor from the low side of the control to ground. Remove the EABC 80 tube, and clean the pins. Static is due to dirty socket contacts.

12/5/2010 6:17:46 PMBubb

Will do Warren. If you ever have the bottom off your unit and it is convienient, could you measure all relivent pins to ground on the last 2 tubes? in Output?

THX

Brian

:Test the resistance of the volume control. Think this set should be 1.3Meg ohm across the terminals. Also check if there is a resistor from the low side of the control to ground. Remove the EABC 80 tube, and clean the pins. Static is due to dirty socket contacts.
:

12/5/2010 7:57:10 PMBubba

Warren thanx it was definatly the EABC80. I sandpapered it and cleaned the connections with Spray. Then I did the switches. Then it lit on fire briefly. I blew it out. For a 2nd there I did not know what was going on because it was unplugged. Been a tech for years.. I never knew switch cleaner could ignite so easily. Must have been the heat of a tube or somthing. Works perfectly. THX

:
:
:
:
:
:
:
:Will do Warren. If you ever have the bottom off your unit and it is convienient, could you measure all relivent pins to ground on the last 2 tubes? in Output?
:
:THX
:
:Brian
:
:
:
:
:
:
:
::Test the resistance of the volume control. Think this set should be 1.3Meg ohm across the terminals. Also check if there is a resistor from the low side of the control to ground. Remove the EABC 80 tube, and clean the pins. Static is due to dirty socket contacts.
::
:
:

12/6/2010 11:23:44 PMBubba

It is a 330 Ohm from Low side of pot leg to groud. Can I decrease this to make it more quiet when I turn the volume down? What is the lowest I could go? Or will it cause problems?

THX

12/7/2010 2:47:17 AMWarren

This sounds like the volume control has a near open condition at the low side of the control. With the volume turned all the way down, jumper the center lug to the low end side. If the set goes quiet, it's the volume control that needs attention. The carbon disk could have a poor connection where it is attached to the low side lug.

12/7/2010 11:03:07 PMBubbA

Well when I look at the schematic I am pretty sure it reads 330 ohm resistor between the outer lug and ground. So it looks like it is designed to aways have this little resistance. I just wondered if I could decrease this value. But I will try what you say.

:This sounds like the volume control has a near open condition at the low side of the control. With the volume turned all the way down, jumper the center lug to the low end side. If the set goes quiet, it's the volume control that needs attention. The carbon disk could have a poor connection where it is attached to the low side lug.
:

12/9/2010 7:26:11 AMRolf Zetterberg

Yes,there's a 330ohm resistor between the (normally) earth lug on the pot and down to earth.It's part of the feedback system that forms the different frequency curves obtained by pressing the three tone buttons(and also not pressing a single one).It would be to go too far to recalculate and replace all caps and resistors,so my advice is to see to that the volume pot works as intended.
Have you tried spraying?
My 1088 leaves just a faint sound when turned down that cannot be annoying to anyone.

In my experience the most common faults on these radios are
"that capacitor"-replace-that's the FIRST thing to do!!
Bad contacts in valve holders-spray
bad contacts in buttons-spray
It's not meaningful to measure any voltages until you've replaced that capacitor and preferably even more paper caps.

12/9/2010 9:56:24 PMBubba

THX Rolf. I replaced all the paper caps a while back. What is "That Capacitor" you speak of? Do you mean the filer caps? If so I did them too.. Yes I sprayed the switches and it made a big difference. I am going to test that POT to see if it works as intended. It is quiet when I turn it down but I wish it was even more quiet. I listen to it when I am sleeping at night.

Thanx for your input.

:Yes,there's a 330ohm resistor between the (normally) earth lug on the pot and down to earth.It's part of the feedback system that forms the different frequency curves obtained by pressing the three tone buttons(and also not pressing a single one).It would be to go too far to recalculate and replace all caps and resistors,so my advice is to see to that the volume pot works as intended.
:Have you tried spraying?
:My 1088 leaves just a faint sound when turned down that cannot be annoying to anyone.
:
:In my experience the most common faults on these radios are
:"that capacitor"-replace-that's the FIRST thing to do!!
:Bad contacts in valve holders-spray
:bad contacts in buttons-spray
:It's not meaningful to measure any voltages until you've replaced that capacitor and preferably even more paper caps.
:
:
:

12/9/2010 9:56:36 PMBubba

Thanx for your input.

12/9/2010 10:44:55 PMEdd

Sir Bubba . . . . .

It is quiet when I turn it down but I wish it was even more quiet.

I listen to it when I am sleeping at night.

I won't even attempt to touch that one . . .

From my technical perspective . . . . the definitive "that capacitor" . . . .in that Gruuuun-dig set of yours would be the C63 .01 ufd coupling capacitor from the plate of your problemative EABC80 tubes plate . . . coupling into the AF output tubes 1st grid.

The way I clean miniature bare wired tubes is to take an Exacto knife with an #11 blade in it and start the blade at the glass base end of a pin and pull it towards the end for a long linear scrape.

Then you go back and start right beside the first scraping and repeat until you have worked ALL of the way around the pin.

Then take on the rest of the pins.

One usually finds the long time onset of the oxidation is being formed primarily on that 1st 1/8 in of the pins out from the glass envelope.

That area is more troublesome than the actual tube socket connections, as the sockets pins have not been flexed to degrade, and the then plugging in of a tube gives some cleaning action in the primary socket contacts pressure areas.

Then I spray clean and put on a light coat of DOw Corning Z5 silicone grease / Plumbers silicone grease with a sable artists brush.

It will hold and retain a protective film from tube heat re-induced oxidation, to the metal pins.

The time spent in scraping the pins is a good thing to do while watching TV . . . multi-tasking . . . . for an otherwise somewhat idle time with your hands.

73's de Edd

:THX Rolf. I replaced all the paper caps a while back. What is "That Capacitor" you speak of? Do you mean the filer caps? If so I did them too.. Yes I sprayed the switches and it made a big difference. I am going to test that POT to see if it works as intended. It is quiet when I turn it down but I wish it was even more quiet. I listen to it when I am sleeping at night.
:
:Thanx for your input.
:
:

:
::Yes,there's a 330ohm resistor between the (normally) earth lug on the pot and down to earth.It's part of the feedback system that forms the different frequency curves obtained by pressing the three tone buttons(and also not pressing a single one).It would be to go too far to recalculate and replace all caps and resistors,so my advice is to see to that the volume pot works as intended.
::Have you tried spraying?
::My 1088 leaves just a faint sound when turned down that cannot be annoying to anyone.
::
::In my experience the most common faults on these radios are
::"that capacitor"-replace-that's the FIRST thing to do!!
::Bad contacts in valve holders-spray
::bad contacts in buttons-spray
::It's not meaningful to measure any voltages until you've replaced that capacitor and preferably even more paper caps.
::
::
::
:
:

12/13/2010 4:33:15 PMdude

i think i just shitted my pants. i ate to much taco bell yesterday and been farting all day. last one felt moist

:Well when I look at the schematic I am pretty sure it reads 330 ohm resistor between the outer lug and ground. So it looks like it is designed to aways have this little resistance. I just wondered if I could decrease this value. But I will try what you say.
:
:
:
::This sounds like the volume control has a near open condition at the low side of the control. With the volume turned all the way down, jumper the center lug to the low end side. If the set goes quiet, it's the volume control that needs attention. The carbon disk could have a poor connection where it is attached to the low side lug.
::
:
:

12/11/2010 1:29:42 PMBubba

Anyone got a schem for this 1088? I have one similar but not the exact.

:Anyone have this radio? I am having a couple issues and need to compare voltages etc. One thing is I seem to have an issue where I cannot turn it down volume to a quiet enough level on FM or AM. Even at 0 it is too loud. Not blaring but too loud. It seems to vary volumes when I turn it on at first also. (Bias resistor cap of EL84?) I checked the bias on the single ended EL84 and it was drifting but not sure if this is cause by it or the tube before it.. I am assuming the problem is in the output or tube before the output. I need tome voltage measurments to see what I am supposed to have. I have the schem but not test voltages.. When I wiggle or move the 2nd last tube (one before the output) I get really loud scratching through the speaker almost unbearble boom... I am unaware if this is normal or not. I need to compare to someone elses. THanx
:
:Bubba
:

12/12/2010 10:31:33 AMPaul Knaack

Hey Bubba, Sams 408-8 sent, it shows voltages on pins, Good luck,
Paul

12/12/2010 11:37:25 PMBubba

Thanx Paul. My voltages are mostly very close, The only thing I found odd was my EL84 has 260 on the Plate (Pin 7) and 248 on Pin 9. 12 volt difference only.. The diagram has alot larger voltage drop it has 260 on Plate (pin 7) and 210 on Pin 9. 50 volts difference. Not sure why mine could only have a 12 volt drop and the schem has a 40 volt drop there. My radio is the German midel not the North American.. I did rebuild the elecrostatic speaker as the foam was toast. Speaking of that does anyone have the honey comb type foam that goes inside the foil of the electrostatic speaker or can give me tips on rebuilding it?

THX

:Hey Bubba, Sams 408-8 sent, it shows voltages on pins, Good luck,
: Paul
:

12/13/2010 12:09:47 AMBubba

Also could someone tell me what this Half moon symbol is. It seems to indicate 2 voltages. With that symbol beside one. It is closer to the grid voltage I have.

THX here s a link to a photo of the symbol.

http://img404.imageshack.us/img404/3553/moonsymbol.jpg

:Thanx Paul. My voltages are mostly very close, The only thing I found odd was my EL84 has 260 on the Plate (Pin 7) and 248 on Pin 9. 12 volt difference only.. The diagram has alot larger voltage drop it has 260 on Plate (pin 7) and 210 on Pin 9. 50 volts difference. Not sure why mine could only have a 12 volt drop and the schem has a 40 volt drop there. My radio is the German midel not the North American.. I did rebuild the elecrostatic speaker as the foam was toast. Speaking of that does anyone have the honey comb type foam that goes inside the foil of the electrostatic speaker or can give me tips on rebuilding it?
:
:THX
:
:
:
:
:
:
:
:
:
::Hey Bubba, Sams 408-8 sent, it shows voltages on pins, Good luck,
:: Paul
::
:
:

12/13/2010 6:33:09 AMrghines1

Designates on the capacitor can which cap value belongs to which solder terminal. Other symbols used are triangle and square. Richard

:Also could someone tell me what this Half moon symbol is. It seems to indicate 2 voltages. With that symbol beside one. It is closer to the grid voltage I have.
:
:THX here s a link to a photo of the symbol.
:
:http://img404.imageshack.us/img404/3553/moonsymbol.jpg

12/13/2010 10:32:59 AMBubba

That does not explain 2 different voltages beside it? I am trying to figure out why the 2 different voltages at the same point. Everywhere on the schematic there are 2 volages listed there is that symbol. I do not see any caps there.

:Designates on the capacitor can which cap value belongs to which solder terminal. Other symbols used are triangle and square. Richard
:
::Also could someone tell me what this Half moon symbol is. It seems to indicate 2 voltages. With that symbol beside one. It is closer to the grid voltage I have.
::
::THX here s a link to a photo of the symbol.
::
::http://img404.imageshack.us/img404/3553/moonsymbol.jpg
:
:

12/13/2010 12:37:39 PMEdd

Sir Bubba. . . . .

Strange that your snippet just so coincidentally seems to have included an electrolytic being included on its portion also.

In this case the answer is not the traditional Half moon . . . Square . . . triangle . . . Bar/Blank that one sees designating the different sections of electrolytics.

BUT . . . since this is a Samuels schematic , you need to look down at the bottom and read the fine print of the contract . . . err . . . schematic, and it should explain that the difference of the two voltages being given at that point is relevant to the function switch of the unit being set at a different position.

Therefore the loading on that line is different and the voltage is being different.

Usually . . . this is most commonly for the set being in AM mode versus FM mode.( Tuning eye tube being active during AM reception . . . disengaged during FM operation . . . unless it is put in circuit to designate FM Zero center tuning ? )

Expect the mentioned info at the bottom to fill you in on that specific situation.

73's de Edd

:That does not explain 2 different voltages beside it? I am trying to figure out why the 2 different voltages at the same point. Everywhere on the schematic there are 2 volages listed there is that symbol. I do not see any caps there.
:
:
:
:
:
::Designates on the capacitor can which cap value belongs to which solder terminal. Other symbols used are triangle and square. Richard
::
:::Also could someone tell me what this Half moon symbol is. It seems to indicate 2 voltages. With that symbol beside one. It is closer to the grid voltage I have.
:::
:::THX here s a link to a photo of the symbol.
:::
:::http://img404.imageshack.us/img404/3553/moonsymbol.jpg
::
::
:
:

12/13/2010 1:31:42 PM . . .confirmed

To wit . . . . . on a convenient Grundig 2060 schema on a flash drive at hand,and in reviewing, with it ALSO being a "Thamuels" schematic, with a full likelihood of this specific designation being repetetive between schematics.

In looking at the voltage/ resistance charts for unit referencing . . . . just below them are the different symbols being utilized . . . and explained . . .with your dark semicircle being " measurement taken in AM mode"

73's de Edd

:
:

:
:
:
:
:
:
:
:
:
:
:
:
:Sir Bubba. . . . .
:
:
:
:Strange that your snippet just so coincidentally seems to have included an electrolytic being included on its portion also.
:
:
:In this case the answer is not the traditional Half moon . . . Square . . . triangle . . . Bar/Blank that one sees designating the different sections of electrolytics.
:
:
:BUT . . . since this is a Samuels schematic , you need to look down at the bottom and read the fine print of the contract . . . err . . . schematic, and it should explain that the difference of the two voltages being given at that point is relevant to the function switch of the unit being set at a different position.
:
:
:Therefore the loading on that line is different and the voltage is being different.
:
:
:Usually . . . this is most commonly for the set being in AM mode versus FM mode.( Tuning eye tube being active during AM reception . . . disengaged during FM operation . . . unless it is put in circuit to designate FM Zero center tuning ? )
:
:
:Expect the mentioned info at the bottom to fill you in on that specific situation.
:
:
:
:
:
:
:
:73's de Edd
:
:
:

:

:
:
:
:
:
:
:
:
:
::That does not explain 2 different voltages beside it? I am trying to figure out why the 2 different voltages at the same point. Everywhere on the schematic there are 2 volages listed there is that symbol. I do not see any caps there.
::
::
::
::
::
:::Designates on the capacitor can which cap value belongs to which solder terminal. Other symbols used are triangle and square. Richard
:::
::::Also could someone tell me what this Half moon symbol is. It seems to indicate 2 voltages. With that symbol beside one. It is closer to the grid voltage I have.
::::
::::THX here s a link to a photo of the symbol.
::::
::::http://img404.imageshack.us/img404/3553/moonsymbol.jpg
:::
:::
::
::
:
:

12/14/2010 12:42:49 AMBubba

Cool thanx. That is what I was looking for.

:
:

:
:
:
:
:
:
:
:
:
:
:
:
:To wit . . . . . on a convenient Grundig 2060 schema on a flash drive at hand,and in reviewing, with it ALSO being a "Thamuels" schematic, with a full likelihood of this specific designation being repetetive between schematics.
:
:
:In looking at the voltage/ resistance charts for unit referencing . . . . just below them are the different symbols being utilized . . . and explained . . .with your dark semicircle being " measurement taken in AM mode"
:
:
:
:
:
:73's de Edd
:
:
:

:

:
:
:
:
:
:
::
::

::
::
::
::
::
::
::
::
::
::
::
::
::Sir Bubba. . . . .
::
::
::
::Strange that your snippet just so coincidentally seems to have included an electrolytic being included on its portion also.
::
::
::In this case the answer is not the traditional Half moon . . . Square . . . triangle . . . Bar/Blank that one sees designating the different sections of electrolytics.
::
::
::BUT . . . since this is a Samuels schematic , you need to look down at the bottom and read the fine print of the contract . . . err . . . schematic, and it should explain that the difference of the two voltages being given at that point is relevant to the function switch of the unit being set at a different position.
::
::
::Therefore the loading on that line is different and the voltage is being different.
::
::
::Usually . . . this is most commonly for the set being in AM mode versus FM mode.( Tuning eye tube being active during AM reception . . . disengaged during FM operation . . . unless it is put in circuit to designate FM Zero center tuning ? )
::
::
::Expect the mentioned info at the bottom to fill you in on that specific situation.
::
::
::
::
::
::
::
::73's de Edd
::
::
::

::

::
::
::
::
::
::
::
::
::
:::That does not explain 2 different voltages beside it? I am trying to figure out why the 2 different voltages at the same point. Everywhere on the schematic there are 2 volages listed there is that symbol. I do not see any caps there.
:::
:::
:::
:::
:::
::::Designates on the capacitor can which cap value belongs to which solder terminal. Other symbols used are triangle and square. Richard
::::
:::::Also could someone tell me what this Half moon symbol is. It seems to indicate 2 voltages. With that symbol beside one. It is closer to the grid voltage I have.
:::::
:::::THX here s a link to a photo of the symbol.
:::::
:::::http://img404.imageshack.us/img404/3553/moonsymbol.jpg
::::
::::
:::
:::
::
::
:
:

4/21/2011 9:56:47 PMed

:Anyone got a schem for this 1088? I have one similar but not the exact.
:
:
:
:
::Anyone have this radio? I am having a couple issues and need to compare voltages etc. One thing is I seem to have an issue where I cannot turn it down volume to a quiet enough level on FM or AM. Even at 0 it is too loud. Not blaring but too loud. It seems to vary volumes when I turn it on at first also. (Bias resistor cap of EL84?) I checked the bias on the single ended EL84 and it was drifting but not sure if this is cause by it or the tube before it.. I am assuming the problem is in the output or tube before the output. I need tome voltage measurments to see what I am supposed to have. I have the schem but not test voltages.. When I wiggle or move the 2nd last tube (one before the output) I get really loud scratching through the speaker almost unbearble boom... I am unaware if this is normal or not. I need to compare to someone elses. THanx
::
::Bubba
::
:
:

4/21/2011 11:27:22 PMEdd

Sir Bubba. . . . .

" Anyone got a schem for this 1088? I have one similar but not the exact."

Been awhile since activity on this thread . . . so you are wanting the original GRUUUUNDIG . . . in addition to the prior supplied Samuels ?

What operational / functional deficiencies do you STILL have with the set presently ?

An immaculate peripheral scrape cleaning of the tube pins of grey oxide of the 1st audio tube, along with a spritz of contact cleaner to the pins and the tube socket contacts should have cleared up the touchiness to movement of that tube.(Also additionally plugging the tube into its socket about 'lebenteen times, should further clean the tube socket contacts.

Cleaning of the volume control would be the potential cure for the inability of transistion down into low or an almost no volume setting.

That, additionally considerting that there is no additional problem with that 330 ohm resistor from the bottom terminal of the volume control to ground . . . or connectivity of their solder junctions.

That 330 ohm lift up from ground will inhibit the set from ever being turned down to zero volume level.

Grounding the bottom of the volume control to ground would accomplish a no audio output, but you would then be sacrificing a bit of frequency response enhancement from the negative feed back loop from the output transformer secondary winding that is passing thru a R/C network, and then into that 330 ohm resistor.

Its your call.

73's de Edd

::Anyone got a schem for this 1088? I have one similar but not the exact.
::
::

::
:::Anyone have this radio? I am having a couple issues and need to compare voltages etc. One thing is I seem to have an issue where I cannot turn it down volume to a quiet enough level on FM or AM. Even at 0 it is too loud. Not blaring but too loud. It seems to vary volumes when I turn it on at first also. (Bias resistor cap of EL84?) I checked the bias on the single ended EL84 and it was drifting but not sure if this is cause by it or the tube before it.. I am assuming the problem is in the output or tube before the output. I need tome voltage measurments to see what I am supposed to have. I have the schem but not test voltages.. When I wiggle or move the 2nd last tube (one before the output) I get really loud scratching through the speaker almost unbearble boom... I am unaware if this is normal or not. I need to compare to someone elses. THanx
:::
:::Bubba
:::
::
::
:
: