Grundig model 2077, no FM

8/2/2012 4:50:42 PMMitch

Hello everyone,

The radio does play BC and SW with very good selectivity and sensitivity and volume control after i cleaned the push buttoms.

I tested the tubes and they test good, the weakest is the EF89 but there are no shorts or leakage in any of them.

On the FM band there is no static or noise, just the tone from the radio. I do have limited access to the chassis from the bottom of the radio, the complete chassis is still mounted in the cabinet. I will also have to modify the AC cord if it is necessary to remove the chassis.

Any ideas or thoughts on what to check for first is appreciated.

Thank you,

Mitch

8/2/2012 5:05:38 PMLou

Does this set have a ratio detector tube(6T8)? You should check it and the bias conditions around it. Also check for any bad electrolytics around the chassis.

Lou

:Hello everyone,
:
:The radio does play BC and SW with very good selectivity and sensitivity and volume control after i cleaned the push buttoms.
:
:I tested the tubes and they test good, the weakest is the EF89 but there are no shorts or leakage in any of them.
:
:On the FM band there is no static or noise, just the tone from the radio. I do have limited access to the chassis from the bottom of the radio, the complete chassis is still mounted in the cabinet. I will also have to modify the AC cord if it is necessary to remove the chassis.
:
:Any ideas or thoughts on what to check for first is appreciated.
:
:Thank you,
:
:Mitch
:

8/2/2012 5:13:57 PMMitch

:Does this set have a ratio detector tube(6T8)? You should check it and the bias conditions around it. Also check for any bad electrolytics around the chassis.
:
:Lou
:
::Hello everyone,
::
::The radio does play BC and SW with very good selectivity and sensitivity and volume control after i cleaned the push buttoms.
::
::I tested the tubes and they test good, the weakest is the EF89 but there are no shorts or leakage in any of them.
::
::On the FM band there is no static or noise, just the tone from the radio. I do have limited access to the chassis from the bottom of the radio, the complete chassis is still mounted in the cabinet. I will also have to modify the AC cord if it is necessary to remove the chassis.
::
::Any ideas or thoughts on what to check for first is appreciated.
::
::Thank you,
::
::Mitch
::
:
:
The radio does have a EABC80 (6T8) and it does test good.

Mitch

8/2/2012 5:51:17 PMLewis L.

::Does this set have a ratio detector tube(6T8)? You should check it and the bias conditions around it. Also check for any bad electrolytics around the chassis.
::
::Lou
::
:::Hello everyone,
:::
:::The radio does play BC and SW with very good selectivity and sensitivity and volume control after i cleaned the push buttoms.
:::
:::I tested the tubes and they test good, the weakest is the EF89 but there are no shorts or leakage in any of them.
:::
:::On the FM band there is no static or noise, just the tone from the radio. I do have limited access to the chassis from the bottom of the radio, the complete chassis is still mounted in the cabinet. I will also have to modify the AC cord if it is necessary to remove the chassis.
:::
:::Any ideas or thoughts on what to check for first is appreciated.
:::
:::Thank you,
:::
:::Mitch
:::
::
::
:The radio does have a EABC80 (6T8) and it does test good.
:
:Mitch

The first thing I always do with a dead radio is check the local oscillator with another radio. This can be done with a hand held transistor, and requires no connections to the radio under test. Can you hit the FM-AM switch with contact cleaner? A good shot of de-ox and a little clicking of the switch might have you in business. Other than that, I'll have to look at a schematic for more ideas.
Lewis
:

8/2/2012 6:03:21 PMMitch

:::Does this set have a ratio detector tube(6T8)? You should check it and the bias conditions around it. Also check for any bad electrolytics around the chassis.
:::
:::Lou
:::
::::Hello everyone,
::::
::::The radio does play BC and SW with very good selectivity and sensitivity and volume control after i cleaned the push buttoms.
::::
::::I tested the tubes and they test good, the weakest is the EF89 but there are no shorts or leakage in any of them.
::::
::::On the FM band there is no static or noise, just the tone from the radio. I do have limited access to the chassis from the bottom of the radio, the complete chassis is still mounted in the cabinet. I will also have to modify the AC cord if it is necessary to remove the chassis.
::::
::::Any ideas or thoughts on what to check for first is appreciated.
::::
::::Thank you,
::::
::::Mitch
::::
:::
:::
::The radio does have a EABC80 (6T8) and it does test good.
::
::Mitch
:
:
:
:The first thing I always do with a dead radio is check the local oscillator with another radio. This can be done with a hand held transistor, and requires no connections to the radio under test. Can you hit the FM-AM switch with contact cleaner? A good shot of de-ox and a little clicking of the switch might have you in business. Other than that, I'll have to look at a schematic for more ideas.
:Lewis
::
:
:
If the BC and SW are working i think that maybe the oscillator is working. I can try the transistor radio as i have in the past. The push button contacts have been cleaned with contact cleaner and then de-ox.

After the cleaning all of the bad noise and static in the switches went away, now the BC and SW is very clear with great sound, just no FM stations.

Mitch

8/2/2012 6:02:16 PMEdd

Sir Mitch. . . . .

Since the AM-SW- and FM are all sharing common audio and IF circuitry, the “real happening” for the FM aspect

of the sets operationality is either the ECC85 tube circuitry or , yet a FURTHER closer evaluation of proper

bandswitching contacts action . . . specifically the switches sectors of:

5---ABC

6---AB

10—ABC

9---CDE

9---IKL

10---IK

9---FGH

And the audio switching of

10---EFGH

My included schematic, points out those contact sections with a switch sector ID diagram at far left center

position on the schematic.

Additionally pull out the ECC85 and peripherally SCRAPE clean all of its 9 pins. Concentrate on the oxidized area

near the glass to pin interface.

Then plug the tube back into and out of its socketin 10 or 12 times

‘Den we sees wha’ hoppens ?

Next procedure would be to dump a 10.7 modulated IF signal into the FM if strip.
Or even just an AM signal at 10.7,

as you can rapidly "wobbulate" the tuning knob of the generator to create a varying "whish" of received audio signal

output, confirming FM strip demodulation operation . . . pointing yet, back again to the prior mentioned fallacies.

F.I.O. Aside:

DO take additional note, that BOTTOM LEFT CORNER on the schema, that those smart and considerate

'Chermans, additionally, even done showed you'se hows to wind (rewind) yer own audio output and power transformers !

2077 Schema Referencing:

73's de Edd

Two rules of success in life: 1. Don't tell people everything you know.

8/3/2012 11:39:37 AMMitch

:
:

:
:
:
:

:
:
:
:
:
:
:
:Sir Mitch. . . . .
:
:
:Since the AM-SW- and FM are all sharing common audio and IF circuitry, the “real happening” for the FM aspect
:
: of the sets operationality is either the ECC85 tube circuitry or , yet a FURTHER closer evaluation of proper
:
: bandswitching contacts action . . . specifically the switches sectors of:
:
:
:5---ABC
:
:
:6---AB
:
:
:10—ABC
:
:
:9---CDE
:
:
:9---IKL
:
:
:10---IK
:
:
:9---FGH
:
:
:And the audio switching of
:
:
:10---EFGH
:
:
:My included schematic, points out those contact sections with a switch sector ID diagram at far left center
:
:position on the schematic.
:
:
:Additionally pull out the ECC85 and peripherally SCRAPE clean all of its 9 pins. Concentrate on the oxidized area
:
: near the glass to pin interface.
:
: Then plug the tube back into and out of its socketin 10 or 12 times
:
:.
:
:
:‘Den we sees wha’ hoppens ?
:
:
:
:Next procedure would be to dump a 10.7 modulated IF signal into the FM if strip.
:Or even just an AM signal at 10.7,
:
: as you can rapidly "wobbulate" the tuning knob of the generator to create a varying "whish" of received audio signal
:
: output, confirming FM strip demodulation operation . . . pointing yet, back again to the prior mentioned fallacies.
:
:
:
:F.I.O. Aside:
:
:
:
:DO take additional note, that BOTTOM LEFT CORNER on the schema, that those smart and considerate
:
:'Chermans, additionally, even done showed you'se hows to wind (rewind) yer own audio output and power transformers !
:
:
:
:
:
:
:
:
:
:
:
:
:
:2077 Schema Referencing:
:
:
:
:

:
:
:
:
:
:
:
:73's de Edd
:
:
:
:
:
:
: Two rules of success in life: 1. Don't tell people everything you know.
:
:
:
:
:
:
:
:
:

:
:
:
:
:
:
:::Does this set have a ratio detector tube(6T8)? You should check it and the bias conditions around it. Also check for any bad electrolytics around the chassis.
:::
:::Lou
:::
::::Hello everyone,
::::
::::The radio does play BC and SW with very good selectivity and sensitivity and volume control after i cleaned the push buttoms.
::::
::::I tested the tubes and they test good, the weakest is the EF89 but there are no shorts or leakage in any of them.
::::
::::On the FM band there is no static or noise, just the tone from the radio. I do have limited access to the chassis from the bottom of the radio, the complete chassis is still mounted in the cabinet. I will also have to modify the AC cord if it is necessary to remove the chassis.
::::
::::Any ideas or thoughts on what to check for first is appreciated.
::::
::::Thank you,
::::
::::Mitch
::::
:::
:::
::The radio does have a EABC80 (6T8) and it does test good.
::
::Mitch
::
:
:
Thank you to all,

The problem was in the switch assembly. The FM switch was being pushed beyond the contacts and had to be readjusted to make good contact. Then some more de-oxit.

All bands play now.

Mitch