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-   -   Grundig 5399/u/s (https://www.vintage-radio.net/forum/showthread.php?t=184533)

Vecher1 7th Oct 2021 4:04 pm

Grundig 5399/u/s
 
Having a issue with AM.. No signal present even when hooked up to Signal Generator.. All other band work although not great but receives signals..

Audio is very low I am using 3.2 ohm speakers All tubes check good..

Has anyone worked on this model??

Thanks

Skip

simpsons 7th Oct 2021 5:32 pm

Re: Grundig 5399/u/s
 
Hi Skip

This is a very well specified radio with the potential of excellent sensitivity on both AM and FM bands.

The schematic is available online and the first question must be how confident are you in finding your way around a circuit diagram. It isn't the end of the world if it's outside your comfort range but using a test meter is a must.

The circuit uses Grundig's well engineered and familiar design for a range of models together with easily obtainable parts.

The first check will be the HT voltage and then to work back from there applying some logic to the fault finding.

One thing, do you have a another AM FM radio to hand to see just which stations should be heard where you live and to maybe help in fault finding?

Good luck

paulsherwin 7th Oct 2021 6:12 pm

Re: Grundig 5399/u/s
 
As with all 50s radios, all the capacitors between 0.001uF and 0.1uF are suspect.

Have you cleaned all the switchgear with something like Deoxit?

Joe_Lorenz 9th Oct 2021 7:39 pm

Re: Grundig 5399/u/s
 
Hello,

owning a 5299 by Grundig I can tell that there were a lot of capacitors that had to be replaced. The "brown candies" and the wax-paper types are always suspects and often guilty. Yes, cleaning contacts of the keyboard is helpful, too, in many cases but it does not repair leaking capacitors.

Regards, Joe

Vecher1 10th Oct 2021 5:04 am

Re: Grundig 5399/u/s
 
Joe, How did you get to the contacts for the BC band? Seem to be buried under another board..

Skip

PS BC Osc is not working..

Skip

Vecher1 10th Oct 2021 9:12 pm

Re: Grundig 5399/u/s
 
Ok Found problem One of the wires from the BC OSC coil was off Very hard to reattach But was able to Now radio works on BC band.. Next Alignment..

Also I am using 3.2 ohm speakers the back of radio says 5 ohm.. Audio is low.. especially on FM. Do they make 5 OHM speakers?

Skip

Mr 1936 11th Oct 2021 8:15 am

Re: Grundig 5399/u/s
 
Hi Vecher 1

The loss in audio output power due to using 3.2 ohm loudspeakers instead of 5 ohm should be so small as to be almost unnoticeable.

I'd suggest the low audio fault lies elsewhere.

simpsons 11th Oct 2021 10:34 am

Re: Grundig 5399/u/s
 
Alignment? Why? Has someone been at the dust cores before?

I might be speaking out of turn but the Grundig Radios I have repaired have not had AM alignment problems and unlike many, are not just peaked but are set for a particular passband. The FM IF passband is doubly important.

Glad to read that the broken wire has been fixed, how on earth did it get broken? But may I suggest that you take note of decoupling capacitor issues mentioned by Paulsherwin and of course that the dc levels are correct.

Last but not least, how were the tubes checked? By substitution or emission?

This radio has an additional common IF for both AM and FM which is why I asked about a second radio for reception comparison. It should be very sensitive.

Is a stereo decoder fitted?

Why are 5 ohm speakers mentioned? Is the radio incomplete? Or do you only have the chassis?

Chris

Vecher1 11th Oct 2021 1:46 pm

Re: Grundig 5399/u/s
 
Ok A little history on radio.. This was giving to me by a Antique dealer that has me fix ,repair get working any radio he gets in..as arrived by me it was without speakers..my guess is the radio had the broken wire when i received it.. after replacing the filter caps radio was powered up.. that's how i found it did not work on BC band.. I hooked up 2 speakers 3.5 ohms only ones i had for testing purposed. the stereo decoder was present but had a coil broken off so its not hooked up..tubes checked by emission on tester..

so i will hook up a couple of antennas . I noticed a loop antenna in there it has a broken wire also I think I can fix it.. question is what is the loop for AM(BC) or FM/

I will look at coupling caps next..

Thanks

Skip

Mr 1936 11th Oct 2021 3:34 pm

Re: Grundig 5399/u/s
 
In answer to simpsons, this is a stereo radio which was (unusually) designed for two separate outboard loudspeakers. Grundig in their wisdom specified these as 5 ohm types.

If the loop antenna has one big single turn it is likely to be for the FM/VHF band. If it has multiple turns it is probably intended for the AM/BC band. Usually the plugs and sockets differ for FM and BC antenna inputs to prevent misconnection, but this may not be the case.

Vecher1 12th Oct 2021 3:41 am

Re: Grundig 5399/u/s
 
Ok replaced 4 coupling caps feeding the output tubes.. radio now has good sound on BC, and the SW bands.. But on FM the sound is extremely low I can hear stations but barely audible..

So where do I look for problems in FM Not at all familiar with FM circuits..

Skip

simpsons 12th Oct 2021 9:23 am

Re: Grundig 5399/u/s
 
Hi Skip

Many thanks for the background information, you were a brave man to take this job on.

Before passing on tips on FM fault finding, when you removed the stereo decoder you did link the audio in- out on the socket? No offence I assure you.

Secondly, your signal generator. Is it AM/FM or AM only. Should it be the latter, then is the EM87 tuning indicator bright enough to use as a signal level meter. An AM modulated audio signal presented to the FM ratio detector is just the opposite to what the ratio detector expects. It is designed to reject AM modulated signals.

As the IF for AM and FM is common, although emission tested, my first task would be to replace the ECC85 or at least make sure it works in another radio. Opening up the FM tuner can to check voltages or decoupling capacitors will test your good nature to to its limit!

Chris

simpsons 12th Oct 2021 10:20 am

Re: Grundig 5399/u/s
 
I forgot to add that the stereo decoder schematic is also available from Electrotanya. Search for Grundig Stereo Decoder 4.

It includes the pinout of the 9 pin decoder socket which indicate pin 4 is the audio input, pins 3&2 stereo output. Pin 1 is shown to have 200 vdc, if this helps.

By the way, which coil is broken on the decoder?

Chris

Vecher1 12th Oct 2021 1:22 pm

Re: Grundig 5399/u/s
 
No i did not .. i will have to look at board to see what coil is broken off.. I guess i have to jumper some pins if not using the decoder? what ones?

Skip

Ps I can take a picture of board

Vecher1 12th Oct 2021 2:41 pm

Re: Grundig 5399/u/s
 
here are pictures

https://live.staticflickr.com/65535/...a1179c37_c.jpg

https://live.staticflickr.com/65535/...c79f50f0_c.jpg


Skip

simpsons 12th Oct 2021 2:43 pm

Re: Grundig 5399/u/s
 
Hi Skip

On the decoder socket link pins 2&3 together, these are the stereo out and connect both to pin 4 audio in. This will bypass the decoder circuit.

So that you are counting the right way, pin 1 has 200 Vdc on it to supply the decoder. Pin 9 the earth for the ECC81 heater.

Chris

Joe_Lorenz 12th Oct 2021 7:04 pm

Re: Grundig 5399/u/s
 
Hello,
referring to the low level on FM I'd suggest to check there is no oxidation having built up resistance on valve sockets, ECC 85 tuners can be quite sensible as well as following stages. I also have had Grundig anode resistors gone up in value so the ECC was operating on much too low anode voltage. According to the schematic, measurements of voltages are no impossible job.
You are very brave digging so deep!
Regards,Joe

simpsons 12th Oct 2021 7:17 pm

Re: Grundig 5399/u/s
 
Joe

Your advice regarding the low FM is very useful but hopefully will not be needed.

From what Skip has said, when he removed the stereo decoder from the radio chassis, he didn't link the now open connections on the B9A socket to the audio amplifier. This, and I am sure speak for all of us, do hope once the connections are made full volume will result although of course in mono.

If it doesn't then being brave will be only one of his challenges!!

Chis

Vecher1 12th Oct 2021 7:33 pm

Re: Grundig 5399/u/s
 
Well unfortunately there is no way to get to the fm circuits.. i have replaced all the other electrolytic's that i could get to..

Skip

simpsons 12th Oct 2021 8:45 pm

Re: Grundig 5399/u/s
 
Skip

Your photo of the pc board and broken coil are just what was needed.

It looks as though the coil can be re used BUT you do need to download the schematic for the Grundig Stereo Decoder 4 stated earlier. It doesn't matter if reading a circuit diagram (schematic) is not one of your skills, we can walk you through this as follows.

Please skip the following if necessary.

The coil is shown on the circuit diagram is part BY 9235-103. The coil has a beginning and an end and is called the primary. The start of the primary, is connected to the plate of the ECC81, pin 1 and the finish to the ht supply. These connection are also made to capacitor C3. It so happens that the capacitor C3 is clearly seen on the photo you have taken, connected across the coil former. This should help you identify how the coil was orientated on its former.

Once you have identified the primary, the other coil, known as the secondary is similar to the primary in that it has a start and finish but importantly the centre of the coil is brought out to make a connection. This is known as the centre tap.

The centre tap is connected to another coil part BY 1225-104 as shown on the schematic. This you must locate.

The start and finish of the secondary are connected to pairs of diodes which are connected back to back. That is the cathode of one is connected to the anode of the other and then joined connections one pair of diodes to the start and the other to the finish of the secondary. I can see the diodes clearly in the photo.

Hopefully, the tail ends, the wires still poking out from the coil former will make it all come clear.

After "super glueing" the coil back onto the former, make good the connections using new single core wire soldered onto the pins, then being careful not to break the enameled wire solder it accordingly.

Sorry to be pedantic but making a mistake will cause no end of issues.

Chris



The secondary


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