Klemt Echolette S... (cont.2)

[notea]

this is the part 2 of the thread talking about troubleshooting (for beginner!) the Echolette Tape echo NG51,The Gold Cage, with no echo sound .

Mickey, Oc, Mecaso i start an other thread here cause i can't reach our last posts..

With the Nachhall reverb on,reverb control fully clockwise, i tried to trace back the signal as Mickey suggested me.

-First i check the output din socket pin 3 and i can't hear no loud buzz trough the amp when taping the pin with a screwdriver.
I can hear a tiny buzz when i touch the pin 5&4.
I soldered the pin 3&2 on my din plug, so it seems that the dry signal is passing trough pin 3 but without producing a buzz when taping on it..

- then, still with the Nachhall reverb switched on, i move to valve 4 and with the tube slightly pull off i touched the pin 2&7 and there was no buzz
- I came to valve 3 and the same, no buzz at pin 2&7..

Oc, i looked at your diagrams and it seems for the valve 4 that i got the schem on top right of your pic,
but when i look at your picture of the valve 4 which i guess is the E 51, they look the same to me..
i tried to measure the playback head thanks to your diagram, and don't know if i succeed, but i've got oscillating readings sometimes toward infinite on playback 5
and a "1" on playback head 4 so an error reading.

Mecaso, lucky for me the tape is in the right position with the join faced out but this is a good thinking!

cheers guys

Nick

[oc disorder]

Hello again Nick

Yes , I am having problems too reaching the last posts.
A while back someone suggested emptying the cache and making sure at the top right
of our posts "Display v" is in Linear Mode.

I think that there may be a misunderstanding in translation re your din lead/cable .
When you write "joined pins 2 & 3" I thought you meant join them together i.e. to one another
Now I think you mean made the cable din to jack & joined pin 3 to tip and the shield ground to pin 2.
Joined pins 2 & 3 to their respective places.

Anyway... when you hold the din plug in your hand and touch pin 3 it hums.


The output could be shorted .. check that 220k resistor that goes under the din socket near the motor
between pin 3 the output - and - pin 1 a reduced output.
in the Klempt I have here that resistor has no insulation (sleeving) and could touch on the chassis.

I re-used your photograph and can see the 10K also connected to pin 1 , the other end of the
10K connects to ground. So thats definitely Pin 1.

Again from your photo there is no C5 between the remote control pin 1 and the famous pin 3 output.
That is exactly the same as mine.

On the older schematic diagram (with my green notes) Echolette S Type NG 51 it is C23 with
the same value of capacitance 0.1uF. (the other schematic has a 10k resistor in series)
It goes to 4 places - 1. the sound from the tape heads via a 100K* resistor going to the wiper of the reverb intensity pot.
2. Remote control f/s which just shorts it to ground when plugged in ! (choice of 2 - all mute - or just echo/rev mute)
3.Another 100K* brings in the direct sound " * mixing resistors".

I will try to find where the 0.1uF lurks in the gold machine . (c5 c23)

Re tube 4 ......Pin 3 to the left of the heaters p4&5 (filaments) on mine goes to 2 resistors.
it would be either that or 1 resistor and 1 capacitor.

oh and attaching an idea for a test probe from bit and pieces from a radio socket or similar
but could cause shock which is why capacitor is there.

used a bic of course ...

[notea]

Hi Oc,

thanks for your tips & diagram, i understand a bit more everyday..
Sorry for the story of the Din jack plug sometimes i can't explain well in english what i'm doing.
-Yes when i hold the din plug in my hand and i touch the pin 3 it hums, and when it's plugged in, it doesn't,
but i hear my guitar so the signal is passes somewhere and it has to be pin 3..
- i checked the resistor and i measured a perfect 220k
- the attached pic show the valve 4 and i've got the 2 resistors on pin 3.
- tomorrow i have to find a small radio or speakers with mono in to build this audio test probe.

but thinking of this, if i understand correctly, i will have to test the signal path in purple on your diagram that
corresponding to the echo signal path, but the echo signal is produced by the playhead, so in theory i must have an already recorded tape to play on if want to hear something during the test?

cheers Nick

[oc disorder]

- tomorrow i have to find a small radio or speakers with mono in to build this audio test probe.
but thinking of this, if i understand correctly, i will have to test the signal path in purple on your diagram that
corresponding to the echo signal path, but the echo signal is produced by the playhead, so in theory i must have an already recorded tape to play on if want to hear something during the test? cheers Nick

Using the probe to put ("sound") an electrical signal in .. the arrows on the diagram ? mean to the headphone socket ,
not the signal direction.
The tape head makes a small/tiny electrical signal so we want to put an "outside" electrical signal that we know works in ,
(inject) , at various stages of the "tape head" electrical pathway to the output (can test it on pin 3 in plug).

By working backwards from the amplifier and correspondingly reducing the output from the radio
(cass. walkman etc) an old broken earphone lead may give you a "test lead" but hard to solder.
It may be too loud i.e. too much signal maybe a small 1K resistor at the earphone end across the output .
You may have to experiment .. that is why I scribbled a 50 k potentiometer - to turn it down ..

"I've got the 2 resistors on pin 3." so the person that drew the schematic did not check which set of pins were used !

But yes , the probe can also be used the other way round (in reverse), to "listen" to various parts of the circuit.

and.. you are explaining very well .. in Aust they could say...

" well I got the bloody thing , pin 3 wos 'ot , checked 'er out-- hummed like a shit house so shees a goer "

[oc disorder]

Couple of simplified diagrams which should help. Could try test probe onto reverb pot R50 that should work !

[notea]

Hi ,i built the bloody thing!, with a .001 uf/630 VDC cap
thanks for your diagrams very helpfull, so i pluged the test probe to an old cell phone where there was this old Gram Parsons 'song playing in repeat..
And so far i could hear this old Gram at various points in the unit with Nachhall reverb switched on "long", reverb control fullt clockwise:
- first at pin 3 of the output din socket with not so much volume.
- at valve 3 i "injected" Gram at pin 2&7 and that worked, sound was pretty clean at pin 2 but scratchy at pin 7.
- i tested the playback head 4&5 lugs, and it worked a part for one lug in the middle but i'm not sure if we are suppose to hear something here, see the attached pic.
- i moved to valve 4, i've got a loud and clear sound on pin 2&7.
- on the reverb control pot and reverb duration, i could hardly hear something behind a loud hum..
- on the Tone control pot, the sound is loud and clear.
- i'm not sure if i'm supposed to test R73/ R72/R71, but i tried anyway and i couldn't hear any sound.

may be there is something that doesn't work properly between Valve 4 and reverb duration control?
I will do more test and i 'll try to understand better what i'm doing
Cheers Nick

[oc disorder]

Hi Nick
That sounds good so far ..wonder "Gram" didn't overload tube 3 !!

Seems to me we may have open playback heads (fine wire broken) although this part is fiddly and tricky.
We also may have a low sound due to a faulty bias oscillator.

Check these points
The direct sound pathway works fine - is good.
The playback sound pathway works from head 5 at pin 2 but sounds scratchy at pin 7 which we assume is head 4.
When you took those resistance readings at the head termination one appeared to be a short circuit from memory.
I know this is difficult but we need to know the exact readings. The short circuit may have been due to the switch being shut.
There are also a few components around the input to tube 3 which could be faulty.
The scratchy sound could also be a bad connection.
The capacitors (22nF) on the grids of valve 2 should keep the heads isolated for a good resistance reading.
They should measure open circuit and have identical readings.
If you can measure around all components ie Pin 2 to Ground , Pin 2 to the junction of 10k ,10m and 22nF.
The junction of 10k , 10M , & 22nf to ground. Across the 22nF and of course the head + wire to ground..the heads resistance.
You should be able to find the switch that shorts head 5 , it will be either shorted (switch closed) open circuit (no resistance broken head)
or hopefully about 1K "'ish" with the switch contacts across it open.
Then the same for the other side with pin 7.
Staying clear of the duration etc at the moment. Want to get it going in its simplest form.
"test R73/ R72/R71?" No .. you might get a bit of sound leaking back but they are for the signal levels to the record heads.
You would need a loose guitar pick up on a lead or one of those old "radio shack style" little suction cup telephone pickups that may magnetically pick up the signal at the record heads.

If head 5 is ok I would rewire it to head 4 position but not move it physically at the moment.

Delicate operation so leave to the end .. maybe try testing the head this way below.

EDIT : Just thought an old style tuning fork vibrating in front of the playback head will induce into the head as will a small speaker
1 inch or approx. 2 cm or earphone/earbud from a radio,mp3 player phone etc. May help to find the switch or perhaps another clue.

[notea]

Hi Oc,

well i tried again measuring playback heads again and it's the same, "error or infinite" for the PH4 and oscillating reading for PH5 see the attached pics how i proceeded,
-i measured between valve 2 pin 2 and ground and i have 152k

Hi Nick
If you can measure around all components ie Pin 2 to Ground , Pin 2 to the junction of 10k ,10m and 22nF.
The junction of 10k , 10M , & 22nf to ground. Across the 22nF and of course the head + wire to ground..the heads resistance.
You should be able to find the switch that shorts head 5 , it will be either shorted (switch closed) open circuit (no resistance broken head)
or hopefully about 1K "'ish" with the switch contacts across it open.
Then the same for the other side with pin 7.
.

sorry Oc but i can't find for the moment the junction of10k etc, i 'll dig into this.. the same for the switch story..
at this time i can see those wires connected to playback head 5 but everything is so tightened and i can't see where they ended..
-i tried to put an earhone close to the heads but nothnig happened

i'll dig into this but so far it's seems like a playback heads problem..
cheers Nick

[oc disorder]

Yes seems like the playback heads are open circuit which is a known common problem.

The bare wires of the two 10K resistors going to the tag strip will do.
The point here is to see if the two identical circuits (ignoring the switch) measure the same ... have identical measurements.

If you are convinced they are faulty i.e. no sensible measurements or no resistance readings with your meter I would suggest,
to remove them, to send to Bobby.. cut the tiny wires close to the tag strip with sharp cutters.

The Germans did an excellent job of securing/terminating the wires physically by wrapping 1 or 2 turns around the tag strip lug/terminal before soldering !!!

It was probably one of the first parts to be soldered .
I thought the risk of damage was more trying to unwrap the fine soldered wires.

Of course you will kick yourself if you find that the heads loose on the table measure 1.1k ... so double check
before you remove them.

[notea]

hello,

well it seems that we've found what's wrong with this unit.. For now i'm hesitating if i only send to Bobby the faulty playback heads or the entire unit..
I know the price will not be the same but it might be safer to send it all and if he does a complete check.
while i take a decision i would like to thank you Oc and Mickey for the great job that you did, you were the brains while i was the hands
and it's been a great experience to me, i learned a lot and i feel a bit sad that it's finished.. unless i only send to him the playback heads!

just a quick thought, do you think i can desoldered playback head 4 as you said and try play with just 1 playback head left?

Cheers Nick

[oc disorder]

"and try play with just 1 playback head left?"
I think both heads are not working unless you get a reading about 1k.

Yes it's a complex machine to learn on and there could be some other minor problems that someone familiar with the machine would recognise.

[Mickey]

Hi ,i built the bloody thing!, with a .001 uf/630 VDC cap
thanks for your diagrams very helpfull, so i pluged the test probe to an old cell phone where there was this old Gram Parsons 'song playing in repeat..
And so far i could hear this old Gram at various points in the unit with Nachhall reverb switched on "long", reverb control fullt clockwise:
- first at pin 3 of the output din socket with not so much volume.
- at valve 3 i "injected" Gram at pin 2&7 and that worked, sound was pretty clean at pin 2 but scratchy at pin 7.
- i tested the playback head 4&5 lugs, and it worked a part for one lug in the middle but i'm not sure if we are suppose to hear something here, see the attached pic.
- i moved to valve 4, i've got a loud and clear sound on pin 2&7.
- on the reverb control pot and reverb duration, i could hardly hear something behind a loud hum..
- on the Tone control pot, the sound is loud and clear.
- i'm not sure if i'm supposed to test R73/ R72/R71, but i tried anyway and i couldn't hear any sound.

may be there is something that doesn't work properly between Valve 4 and reverb duration control?
I will do more test and i 'll try to understand better what i'm doing
Cheers Nick
[ATTACH=CONFIG]33534[/ATTACH][ATTACH=CONFIG]33535[/ATTACH]

Hi, have been following your conversation, all good. When you say that you have good sound on pin 2 of valve 3 but poor sound on pin 7 that would indicate a shorted head, but you think the head is actually open circuit. Have you tried another valve? If you look at the schematic you will notice that both anodes are connected together which can result in part A affecting part B of that valve. Is there any voltage difference between pin 7 and pin 2?
You only need to have one head working (either one) to ascertain if signal is being detected from the tape. I would probably remove head 4 to measure it's resistance. If you're very carefull you can snip it's connecting wires about 10-15mm from the head which will allow you to resolder if necessary, but be very carefull. If the head is faulty and you send it to Bobby he will attach new long wires to the repaired head.

[notea]

Hi, i checked the voltage on Valve2, pin2= 0.70 VDC and pin 7= 0.68 VDC,
i removed PH 4 and measured it on the table and i still got this "1" error or infinite, so she's dead. I got more space now to measure PH5 and i've got a 0.6 ohms so it's pretty low isn't it?
- i switched on the unit and put the reverb on, try one at the time Nachhall long and short and still no echo..
- may be the resistance of PH5 is too low so it doesn't catch any sound?
- i've got a silly question now... but are playback head and record head the same? so i could replace the playback head left with one of the 3 record heads?
Cheers Nick

[Mickey]

Hi, have just measured the resistance of 3 Klemt heads that I have in stock and they all measure approximately 1K ohms. Two of these were rewound by Bobby and as far as I know there is no difference between recording and playback heads. Can you measure the resistance of your recording heads as they may also (very likely) be faulty, so swapping heads may not prove anything.
Pity you live so far away and that postage is so expensive otherwise you would be welcome to borrow one or more of my stock heads.
Please consider carefully the cost if all of your heads need replacing and your Echolette also requires other repairs, the total cost may be a lot more than the unit is worth. There was another person on this forum who had purchased a faulty Echolette ( transformer missing?) maybe if he is closer to you a compromise on parts could be a possibility.
If you do send your heads to Bobby could you please let me know what his current charge is to recondition a head.
Good luck, Mike

[notea]

Hi Mike, the recording heads are ok, 1k14 each, i'll send an email to Bobby and see how much it 'll cost for reconditioning 2 heads and i'll let you know how much he charges.
Cheers Nick