Klemt Echolette S...(cont.)

[oc disorder]

Well , so far so good we or you know a lot more than we did in the beginning. The fact that you measured 7 volts means it's partially working and we can count on that being a good indicator.... i.e. the meter can read DC ok !
Usually this means the tube or the components immediately near/around it must be faulty.
I saw where Mickey mentioned that normally the stryoseal caps are unlikely to be faulty but we should be thorough and methodical and check these after replacing the tube. There isn't much else that could go wrong apart from a dead conductive moth or bug or spider across the tube socket - it does happen !
Re reading your notes , while you are waiting for parts we should look at why the Magic Eye is not Magic at the moment.
Possibility could be just the tube. I'll have a look and think about it.

I re read your notes from the earlier thread and I see the Magic Eye is working but only on the live signal (no Echo indication).

[Mickey]

Hi,i'm back to the "gold cage"
First i wanna Thank you guys again for all your advices,and guiding a beginner like me trough this piece of machinary..

This is a recap of our work since the begining:
troubleshooting the Echolette NG51s with no echo.

The visual indicator does respond when the signal is applied

TUBE READINGS:

Tube n°1:
Pin1&6=230V
no ohms readings on the other pins
Tube n°2:
Pin1=199V,Pin2=162K,Pin3=992ohms,Pin6=290V
Pin7=990ohms,Pin8=343ohms
Tube n°3:
Pin1&6=136V, no ohms readings on the other pins
Tube n°4:
Pin1=202V,Pin2=1000k,Pin3=988ohms,Pin6=227V
Pin7=1000k,Pin8=2k20
Tube n°5(ECC82):
-without tube: Pin1&6=300V,Pin2=100k,Pin3=470ohms
Pin6=300V,Pin7=100k,Pin8=470ohms
-with tube pluged in:
Pin1&6=230V,Pin2=100k,Pin3=470ohms+7V,
Pin7=100k,Pin8= 470ohms+7V

TAPEHEADS
-I measured 1k14 ohms for each except the erasehead that seems open

* with the reverb control fully clockwise i touched the head gap of the replayheads with a screwdriver as suggested Mickey
and i can hear no sound coming from the amp

-I measured the trim caps
"The voltages you measured are for record head 3 & 2. You only need to measure where
the head connects to the variable capacitor.For head 3 you measured 45 volts .. (according to Kazooman) this should be 120 volts AC @ aprox 60kHZ.
For head 2 you measured 30 volts this should be 90 volts AC @ aprox 60kHZ.I suspect head 1 ('s) reading (which is hard to get to under the rectifier) would be lower 10 or 15 volts so
I guess the oscillator is low on the output.Oc Disorder"


-stange thing is i got AC on trim caps but i can't find any 270V AC on the osc coil..
-i Have 7VDC at pin3&8 of the ECC82 with the tube pluged in.

I'm still waiting for the parts and the new ECC82, i will replace the 0.1uf (C18) but we're not sure it's gonna solve the problem.

Cheers Nick

Hi Nick,
From your above list I think there are a few discrepancies.
If the visual indicator closes and overlaps when driven strongly I would forget about valves 1 & 2 for the moment, as it appears that their circuitry is working as designed.

Valve 3 pin1 should read approximately 75V with the valve plugged in
Valve 3 pin 6 should read about 75V with the valve plugged in.

Valve 4 pin 6 should read about 100V with valve plugged in.
Valve 4 pin 1 should read about 200V with valve plugged in.

Is there approximately 300V coming from the power supply rectifier and have you bridged any/all filter caps?

If an anode voltage is considerably higher (eg 175V instead of 120V) it indicates that the valve is not drawing current, if the voltage is very low (eg 120V instead of 175V) this indicates that the valve is drawing higher current.

Check if there is a +ve voltage on either pin 2 or 7 of valve 4, but before you do re-check the anode voltages. A positive voltage could indicate a leaky coupling capacitor.

I would suggest that you have valves 3 & 4 working correctly before going any further. With care you can touch the grids with your finger (via a screwdriver) and you should hear a buzz in your amplifier. You would need to turn up reverb control (nachhallstarke) and work your way backwards from right to left on the schematic.

Let us know your observations.

Mike

[notea]

Hi Mike i've got good news from the readings that you've suggested,
Valve3: Pin1&6 =70V when tube pluged in
Valve4: Pin1=74V and Pin6=167V it's a bit low but could be a matter of tweaking some pots perhaps..
-I've got 290VDC from the power supply rectifier and 213V AC.
-there is no voltage at Pin2or7 of Valve 4!
-I touched with a screwdriver Pin3&8 of each tube with reverb control fully clockwise and i can't hear no buzz at all coming from the amp

Oc, the magic eye seems to respond to the signal even on echo mode.
But something happen with this preset:
with reverb control turned up, and the head 1 button at zero.
At this point i've got a sort of ugly metalic overdriven sound with a bit of wobble (not sure with the word) as i play with the reverb duration button. And the magic eye is clipsing.
As i slowly turn the head 1 button clockwise the magic eye stops clipsing and i lose this "wobble overdriven sound", and the reverb duration button doesn't respond anymore.
This "thing" occurs only with the head 1 button, the second and third doesn't do anything.
I'll study the schematic carefully but it's confusing at my level, i didn't have the chance to build an audio probe test yet but i soon as i have, i'm not sure if i'll succed to trace the signal
in this narrow jungle of wires..

Nick

[Mickey]

Hi Nick, If you trace the signal from your amplifier backwards you can see from the schematic that it travels back to anode of valve 4 via C5,R65,R57,R50(REVERB CONTROL),C31 to pin1 on valve 4. This valve is driven by the other half of valve 4 via C22 and R29. The signal can then be traced back to valve 3 via C9, R16 and R15 and to it's input grid from the tape head, pin 2 on this valve (valve 3).
So working backwards and touching each grid as you go along you should be able to get a buzz in your amplifier which should get louder as you reach pin 2 on valve 3.
Check to see if this part of the circuitry is working and then we'll go from there. Don't do anything else until this section is working reasonably well.
This is also easily seen on the Echolette S detailed schematic I sent you
Mike

[notea]

Hi Mike, the only thing i could say for the moment is that there is no noise when taping the pin2 on Valve3, i got a slightly scrachy noise on R65 of valve4 but after it's to hard for me to see, get in or even recognize the proper component..
it's harder than i expected..

cheers Nick

[Mickey]

Hi Nick, First of all let's get the right schematic. If you have a very early non-printed circuit board NG51 your schematic wouldn't have an R65 which is the anode resistor for the first half of valve 4. That resistor would be R30. Although the circuits are very similar and will make it a lot more difficult if you and the other contributors are working from different schematics. That R65 you refer to would be 200K and would have HT on both sides.
Again I think it is easier if you pull a valve out slightly and then measure or touch (whatever) the appropriate pin.
Did you get a reasonably loud signal on the output din socket (pin 3 on this socket) from which the signal goes to your amplifier? As I noted previously, once you have ascertained that buzz then work back to valve 4 and then to valve 3. Just be a little careful that you don't short pins together and that your other hand doesn't touch the chassis. The grids are always either pins 2 or 7.
Let me know what signal you obtain working backwards and touching the pins with your finger via a small screwdriver. If for instance you get a good buzz on pin 2 of valve 4 but nothing on pin 7 then there is a fault in this part of the circuit. If you don't get a good signal on either grids of valve 4 swap valve 4 with valve 1 or 2.
Cheers,
Mike

[notea]

Hi, great progress here!
You're right i don't have the right schematic it seems that this unit is an early one.
Mike i followed your procedure first i checked the output din socket and no buzz at all, then i checked valve 4 pin 2 and i was happy to here that buzz!, then nothing on pin7(valve4).
I moved to valve 3 and i got a loud buzz on each pin (2&7)

The faulty components could be C8? C9? (i found an another schematic but in bad quality, too pixelized i can't hardly see the label of the components)
I know that the resistance is ok cause i measured 1000k on pin7

what i doesn't understand is why i've got the signal from the guitar but no buzz on the output Din socket?

Thanks Nick

[Mickey]

Hi Nick, Are you telling me that you can't get a buzz in your amplifier when you touch pin3 of the Ausgang din socket of your echolette? I believe it is a "pink" wire, and if this is the case then you have a faulty lead or maybe C5 (.01) or C35 (.0022) has shorted, but I would think that you aren't locating pin 3.
Fix this issue first and then work backwards.
Now that you have established the right model for your echolette do you have the right schematic, should be available on the net.
Cheers,
Mik

[notea]

Hi Mike, i 've got a buzz on pin 5 of the output din socket according to the schematic, hope i'm right..
the order on the schem is like this:1-4-2-5-3 clockwise

i've soldered pin 2 and 3 on the din plug as i read on the internet, but that doesn't explain why i can hear the guitar signal trough the amp..
what do you think?

cheers Nick

[Mickey]

Hi Nick,
Just remembered a point, you will need to have the echo button switched on (first button on bank of 4 white switches).
Now if you remove your din cable from the echolette locate the pin which provides a buzz through your amp and then find the corresponding connection on the din output socket of your echolette. If you look at the schematic pins 4 & 5 should hav the direct non-echo signal coming from the input srage of the echolette, and pin 2 should be ground. Pin 1 would be a lower level output signal.
You have to find the signal going from the echolette to your amp before we go any further.
Cheers,
Mike

[Mecaso]

Hello

I own an Echolette NG-51 S, but i am not sure of the tape heads location.

For record heads, i think , when going from right to left, we have 3,2,1 heads.

But, my doubt is for playback heads!

After record head n°1, (always from right to left) is it head n°4 or n°5? Please?

My Echolette was modified by the previous owner, & i am

not sure that heads 4 & 5 are in the good order...

If any one could inform me, thanks to him!

Best greetings from France.

[oc disorder]

Hi Nick ,
Couple of diagrams that may be useful. See if your Echolette is the same layout as the one I'm working from.
Although this one has a different style motor and originally had din input sockets from your photos I think they are the same.
The tube the ECC83 as you know has 2 identical halves .. well its a dual triode. Sometimes pins 1,2 & 3 are transposed/swapped
with 6,7 & 8. Once you find the heaters pins 4 & 5 it makes it easier.
On the schematic I show the pathway for the guitar signal to pin 3 of the output and also the pathway for the echo sound from the tape head.

On the "layout" diagram with photo I included the 3 schematics for tube 4 I had with their respective titles from the schematics.

Although the component numbers can change the actual values and pin numbers remain the same .. well most of the time !

[oc disorder]

Hello Mecaso


see #4 here (a gif)

http://music-electronics-forum.com/t37002/


Wiedergabe Köpfe = Playback heads
Aufnahme Köpfe = Record Heads

[Mecaso]

Hello Mecaso


see #4 here (a gif)

http://music-electronics-forum.com/t37002/


Wiedergabe Köpfe = Playback heads
Aufnahme Köpfe = Record Heads

Hi, oc disorder.

Thanks for your answer, but....., sorry, i don't see where tape heads n°4 & n°5 are located.

I see the playback heads, of course, on the left of the diagram, but not which is the

n°4 or the n°5.

When the "nachhalldauer" button is pushed, is it the playback head near the record head n°1 which works, or is it the playback head near the plastic guide roller which reads the tape?

This is my doubt...

[oc disorder]

Hi Nick ,
Here's a picture and rough layout of where the playback heads terminate. You should be able to check the resistance here.



Mecaso

The normal or logical order of heads would be
----- >[ERASE] [REC 1] [REC 2] [REC3] [PLAY4] [PLAY 5] ---->
I would count from erase in the direction of tape travel.
Yes No 5 playback head has a shorting switch on it.
It is a pull switch on the Reverb Duration control "Nachalldauer" .
This diagram for Nick should help you too.