Klemt Echolette S

[oasisbluenose]

Thanks Mike. I am working off the schematic online at present which is a little grainy so any improvement is useful.
I'm getting a good signal at all three heads measured at the junction of the 100k/150pf . Have tried to see on scope with and without the bias engaged. Shows up well both ways.
Have tried to get the signal to the tape(same stuff I use for the copicats) with each one of the heads in turn two and then three. Still no joy. Then tried with the playback head disconnected and reconnected to just the scope. Nothing showing. Cheers

[Mickey]

Hi Steve, just a quick thought, have you measured the bias signal at the record heads? Head 1 has 160V, head 2 has 120V, head 3 has 90v but these could be reduced by up to 20% evenly across the three. The erase head should have about 90V. Also check that the bias signal is very close to 60Khz. Cheers, Mike

[oasisbluenose]

My scope does 10v per cm. 5cm +\_. Off the scale on all three. Have had a bit of a fiddle with the 150pf trim pots which did change the voltage of it. Haven't measured the frequency yet.

[notea]

Hi Mike,

this one is a point-to-point wiring,really crowdy in there..
I followed your procedure, i touched the wires in white circles on the the picture attached,
not sure for the input of the valve 4 it's pretty hard to see it..
hope i've done well, if yes, no loud buzz were coming from the amp as i touched those wires.

-Strange thing is since yesterday, the sound gets really distorded as i turn on the reverb control clockwise

-in the configuration as follow, something is goin' on, i get a sort of fuzzy sound with a bit of oscillation as i :
- switch on the Nachhall buttons "long or"chort"
- Head 1, button at zero
- reverb control button at, 1/1.5 before it's get too much distorded
- reverb duration at 5

that's mean almost one playhead is working?

Nick

[Kazooman]

The bias voltages I got from Bobby are 60, 90, and 120 on heads 1, 2, and 3 by his numbering. The erase head should be 70 - 80 volts. Be certain to use a non-conductive screwdriver when adjusting the trim capacitors to set the voltages.

If either or both of you send me a personal message with an email address I can send you a pdf of the schematic and a pdf of the manual (in English).

[tboy]

notea, could you try uploading your attachment again? Apparently you didn't complete the process of adding the attachment to your post. Here's a thread from another forum that explains the problem:

vBulletin 4.xx, Stop Attachments Getting Deleted - the Invalid Attachment Problem

[Mickey]

Hi Nick,

I can't download your attachment. I have a better schematic which I'll happily send to you so can you please send me your email address.

Cheers

Mike

[Mickey]

Hi, the service schematic I sent to Nick also show the voltages as 60,90 & 120V AC. My other notes that I have from a previous repair show the voltages a lot higher so I believe that any adjustment requires a difference of about 30V from one head to the next. The oscillator frequency needs to be 60Khz +- 5% and the erase head requires approximately 80V AC, and from memory a quick check is to measure the voltage coming from the oscillator transformer feeding the record heads. This voltage needs to be approximately 250V AC. Regarding the CRO it may be a good idea to invest in one of those probes which have an inbuilt attenuator which will reduce the input by a factor of 10.
If the output (what there is) is severely distorted it may be worth bridging all the power supply filter capacitors, and also long ago I found valve 2 cathode bypass capacitor to be defective but I don't remember the effect it had.

[notea]

Hi, sorry for this and thanks for the link i try again

[notea]

Hello everybody,
here in attachement i found a problem,

when i turn on de reverb control button, and with the head 1 button at zero the "magic-eye" gets distorded. And when i turn this button clockwise it's not..
it looks like a double pot.

could it be a dead or open?, how could i test it (without scope), and where is it on the schematic?
If i build an audio test probe, could someone show me the test points on schematic or name them?
sorry a lot of questions..

cheers Nick

[oc disorder]

Some schematics and discussion here NG 51 S and E 51

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

[notea]

hi, thanks to this link and schematics of Kazooman and Mike! I might found the test points but i need your approval..
Please see the attached pic;

i read 45 AC, 17,30 and 13 from right to left

Are they correct values?

Cheers Nick

[oc disorder]

Hi Notea

I've attached some diagrams which may be helpful.

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.

The connection from the oscillator coil to the lower center lug of the trim caps is on that bakelite (almost) square tagstrip
mounted on the coil almost just behind the 12AT7/ECC82 .
Facing the front of the unit with the transport face down for me it's the top left terminal as per my picture .

There should be aprox 270 volts AC here at about 60kHZ. I'ts important to use a good multimeter here that won't load down
the supply which is probably why Kazooman mentioned using an oscilloscope if possible.

You need to make sure the 270 v AC supply is there before tweaking the trim caps.

There is a clue on the E51 schematic at pins 3 & 8 of the ECC82/12AT7 - the cathodes.
11 volts DC should be across R79 , that 470ohm cathode resistor (on S NG 51 it's 500 ohm R37).

In other words between Pin 8 or 3 and ground if the oscillator is working ok there should be 11 volts.

Likewise the main power supply should be supplying 290v DC to both anodes of ECC82/12AT7 , pins 1 & 6.

[notea]

Hi, yes indeed very helpfull! thanks a lot for those pics, i'm not use to schematics so i feel confident when i visualize components.

I did the measurements, got something strange:
-C14 is oscillating between 40 and 60 AC
-On the Osc coil test point (see attached) if i got it right i have the same something oscillating between 40 and 60 AC
- i got nothing on pin 3 and 8 of the ECC82, pin 1 is 190 V DC and pin 6 is 214 V DC


could it be a bad cap? perhaps the one of 0.1 uf of the osc coil?

Cheers Nick

[oc disorder]

Hi Notea

I'll have to check to suss out what terminal is what on the osc coil.
I suspect that 0.1 on top leads to the erase head.
Before delving into capacitor change check that the 470/500 ohm
cathode resistor is intact from pins 3 & 8 of the ECC82/12AT7 to ground.
You're allowed to cheat here - stick one end of the ohm meter probe
in either pin 3 or 8 on top and the other to ground.
EDIT2:While you are there - check there is aprox 100Kohms to ground on both pin 2 and pin 7 , the grids.
Make sure the psu is discharged .. it could be concealing a nasty shock!
If the osc tube/valve is ok I suppose the next candidates are the caps around the coil.
C19 & C21 200pF 500v and C20 1000pF or 1n 500v.

EDIT: You can measure the heads for continuity here where the 100k , the trim cap. and the head join.
Should be less than 2K ohm.