EL3516 no sound

[Phantomrose1999]

Hi

This unit worked for a few minutes and then lost sound. Left it for a week and seems to play for few minutes and then dead

I can get audio when driving the final, all voltages are there but high. Common for 220 bolt units running in 240

Odd observation.

The two anodes of the ecc83 are around 270v, no where near the 100v.
When signal applied to grid of the ecc83 before the main amp, nothing.

Looks like the ecc83 is not drawing any power hence the high anode voltage. But it’s high on both anodes. Both 220k resistors have been replaced previously and are measured to be good

Can’t measure any voltages on the grid of either half of the ecc83

Greatly appreciate any suggestions before I order a new ecc83.

[Phantomrose1999]

The anode voltage of the last stage of the ecc83. Supposed to be around 100v but way higher as I suspect it’s not drawing any current.

[Andrew2]

Are the heaters lit?

[Phantomrose1999]

Think it’s fixed. As you were trying I was investigating the ecc83

It has a metal shield on it. Had to remove it to see the ecc88

At first power on, I noticed only half of the heaters seemed to be working. See photo.

After a few minutes I then saw both filaments come to life. At that point the sound was working and the anode voltage dropped to 107v

Will be ordering a new ecc83. They are more expensive than the $20 unit.

[Andrew2]

Before you get your wallet out, have you tried cleaning the valve base and the pins? It could be a simple bad contact.

[Phantomrose1999]

Yes. I will be doing just that. It’s currently working and 5m in the belt broke. Lol.

[Phantomrose1999]

Any kind soul have a main drive belt ? Happy to pay.

[Restoration73]

Is a 12AX7 any cheaper out there - that will work.

[Phantomrose1999]

Lots of 12AX7s here. May even have some in the shed. Finding them is another story.

I really need a belt ? Anyone have one pls ?

[Phantomrose1999]

Back again.

The recorded audio is very low when played back. Even though the magic eye is showing close to maximum.

If it max out the input via mic input the magic eye is almost solid and while the playback is louder it’s obvious distorted

Any suggestions why I would have a low recorded audio ? I did have problems with the ecc83 but after resetting it, the unit plays.

Could it be a weak output ecl82 ? As it’s the oscillator ? All old black caps and most resistors have been replaced. Main supply voltages are good.

[Phantomrose1999]

I recorded a track on my Grundig tk1 and played it back on the Philips and the volume is great. So playback is good. But recording on the Philips is very weak when played back

[Phantomrose1999]

I don’t understand the recording part of this circuit. Am used to Grundig’s which have their own oscillator. Any experts on this model around ?

[ms660]

Apart from the fact that the oscillator coils are all part of the erase head there's nothing out of the ordinary about the circuit, the 2nd schematic in the manual in the link that was posted shows the circuit in record mode, the triode of the ECL82 is just used a diode in order to obtain the -ve voltage from the record signal to feed to the grid of the magic eye.

Lawrence.

[DMcMahon]

If you erase an existing recording (with no input signal to record) is the original recording fully erased ?

Do you have an oscilloscope to monitor the Bias Oscillator signals ?

David

[Phantomrose1999]

Hi, unfortunately working away from home. Oscilloscope is at home 2000 kms away.

I tried recording with no input and the tape is 100% erased. Not a whisper. So looks like the oscillator is working

Given I had trouble with half the ecc83s heater not lighting until I removed and reinserted it, perhaps it’s weak and not able to drive the audio while recording

But what confuses me is the playback and record uses the same circuits.

[Phantomrose1999]

The side input for R or L is dead. Only the RCA socket on top is working as an input.

Maybe I need to trace the input from the side input as maybe the input is being attenuated ? Before getting to the 1st valve

[vidjoman]

Could be poor switch contacts. Old machines often have corrosion on switches causing loss of signals.

[ms660]

You've said that it erases ok and you also said that there is a good record level being shown by the level indicator, so for no recording at all that leaves the switch contacts, open circuit connection, R6....or no/low bias voltage or poor head to tape contact for a weak/distorted recording.

Relating to the above the relevant switch contacts are record switch SK2 contacts 21 & 22, and contacts 24 & 26.

Lawrence.

[Phantomrose1999]

I removed the valve chassis and thoroughly cleaned the two big sliding switches, with lots of isopropyl and a blade screwdriver along the slider. Then I separated the input switches on the side and cleaned them with sand paper. Then I replaced the ecc83.

At first power up had lots of him like the input was open. Banged around the volume and it moved the sound. So resoldered the volume pot wires. Just came good at the next power up and playback is good but record is still very low.

I can only get the magic eye to move using the rca socket on top. The left two L and R have zero effect on the magic eye when recording

https://youtu.be/qL9I-3oHtMk

Posted a video.

The signal seems to be weakened after the magic eye and before the record head

[Phantomrose1999]

You can hear there is no distortion in the YouTube video. Just low output like the input was turned down. But the magic eye is maxed out