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.
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?
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.
Last edited by oc disorder; 03-02-2015 at 07:05 PM.
Thanks Oc disorder,
-I got this values from ECC82: pin 3 = 989 ohms, pin 8 = 2k20, pin 2 = 1Mohms, pin 7 = 1Mohms (this is strange we expected to have 100k..)
-good thing is i measured 1k14 for the 3 record heads
We're making good progress here!
Pins 3 & 8 should be joined together and not have different readings 989Ω -220kΩ ???????
Double check the pins again pin numbering clockwise from above .
The 1 meg readings from pins 2 & 7 are consistent ! I would expect them to be different if the two 100k's had gone high.
Try reversing the meter probes and measure again.
Maybe some residual DC is affecting your multimeter readings.
If the 470/500Ω cathode resistor is open circuit it would explain the fault.
I haven't measured around the ECC82/12AT7. It's very hard to get to. Perhaps the osc. coil could be carefully removed to gain
access to the ECC82/12AT7 tube/valve base and then placed back?
I'm glad the heads are ok.
sorry i did the readings anti-clockwise, corresponding to the number written under the socket.
- So clockwise we've got Pin 3 = 995k ohms, Pin 8 = 996k ohms, Pin 2 = 2k18, Pin 7 = 989 ohms
- i checked the voltage on Pin 8 and we've got 22V DC, nothing on Pin 3, Pin 4 is 224V DC and Pin 9 is 196V DC
Pin 1 and 6 is zero..
Hope i did good..
It still seems to me the readings are not right . If you look at the diagram pin 3 and pin 8 are joined.
You get a reading of 995k ohms on 3 , more or less identical on 8 996K ohms (contact resistance) which shows
(if they are the right pins) they are connected but you only measure 22volts DC on pin 8 and not on pin 3.
Those readings if correct show the resistor has gone "high" nearly 1 megohm .It should be 470 ohms... I would put a 1 watt there.
Pin 4 and 9 (and 5) are the heater or filament connections. The 12 in 12AT7 shows it can run on 12 volts however they provide a centretap at pin 9 which allows the two "halves" to be in parallel and run on 6.3 volts. Pins 4 & 5 are joined together and 6.3v AC
is applied to pin 9 and (4+5). For practice you should be able to measure that pins 4 and 5 are joined and between that and pin 9 there is approx 6.3v AC.
Pins 1 and 6 are the anodes and the high voltage (H.T.) should be there.
After we solve the measuring system I would get right into the base of that tube/valve and find the actual resistors and measure them. I think you will have to remove or move the coil to gain access ..make sure you label or name the wires so it can go back to where it lives !! Do you have another ECC82/12AT7 ? We may need one later if this one is no good.
Last edited by oc disorder; 03-03-2015 at 09:55 PM.
first i want to apologize cause the tube was not at his right place, i measured the n°4..
Sorry about that and thanks Oc Disorder for your patience, as well as for this schematic very usefull.
So i measured the good one this time and we have:
- Pin1= 0V DC, Pin3= 100 k + OV DC, Pin5 = 5V AC, Pin6= 0V DC, Pin8 = 100K + 0V DC
-On pin 4 and 9 my multimeter is going mad, oscillating between 600 and over 1000 V AC!
- i checked the Nachhall reverb button behind the front panel and i've got the 300 V needed.
Do you think C19-C20-C21 are shorted?
That's good !
"Do you think C19-C20-C21 are shorted?"
Not yet.. :-) but I think the 300v is not getting to the osc coil
and the 470 ohm is also bad at pins 3 & 8 ... 100k is too high
we would expect that on pins 2 or 7.
On the above diagram post #79 "bias-osc-klempt-Echolette.jpg"
on the left is a 470 ohm resistor going from the switch to a capacitor
1uF 350v and then goes to the center tap of the osc. coil.
I forgot to label these components.
On the osc. coil bakelite "tag strip" are all it's connections.
One of them is the power in (probably about 295volts DC).
Although the tube is not oscillating at the moment the D.C. supply
to the coil should be there.
One of the terminals should measure nearly 300 volts DC.
I'm not sure which is which ??? but with the multimeter
set to DC volts you should be able to find the DC between one
of the terminals and ground.
If not we may have another faulty 470 ohm , this time between the
switch and the coil.
Please be careful with the high voltages , if you suddenly stop posting we may get worried !!
I'm back to this beast, and i did the reading anti-clockwise this time of the ECC82, and it's seems that we've got the proper values here except that there is no DC at pin3&8.
Pin 1= 300V, Pin2= 100K, Pin3= 470 ohms+ 0 DC, Pin 4&5= 5V AC, Pin6 = 305V, Pin7= 100K, Pin8= 470 ohms+ 0 DC, Pin9= 0 AC
can't explain why there is no DC at pin 3&8?
sorry you gave me the answer at #73..
If there is no DC at pin3&8 of the Ecc82 it's because of the osc coil that doesnt' work properly.
-So i checked the lug of the 0.1 uf cap and there is no voltage at all,
-so no voltage on L2 and 300 VDC on L1, that's mean the cap is dead right?
- i don't know where the test point is on the osc coil for the 270V AC so i checked each lug and i got nothing except where there is the DC coming (i read 600-650 AC)
Hi again Notea
I am having trouble reaching the "last post" on this thread so will start a new thread
shortly called "Klemp Echolettes...(cont.)".
In the meantime some suggested French links to capacitors
| Farnell element14
and some related entertainment:-
Further reading on things that flip back and forth (oscillator)
Astable Multivibrator (Oscillator)
C U soon !
Hi Nick, a bit off the beaten track but the photo of the bottom of the motor indicates to me that the end retaining plate is missing. If this is the case you will damage the motor when turned on.
There is usually a plate that is held by screws which screw into the four holes that you can see in your picture and this plate keeps a ball bearing in place on which the motor shaft rests.
Did you remove it?
Hi Nick, to measure the heads unsolder them carefully (one at a time) where they connect to the level adjustment variable capacitors which are located on the LHS just near the motor. They should read about 1k ohms, actually you don't have to unsolder tham as they are in series with the variable capacitors.
Have you measured the heads? This can be done without unsoldering by just measuring across the leads to the heads where they come from the variable adjustable capacitors.These are on the LHS just near the motor and each head should read about 1K ohms. Cheers, Mike
Mickey .. In post #75 Nick measured the record heads at just over 1k.
I think there are two types of Motor .. if you look closely at Nicks photo you can see a circlip and it appears there is a nylon cover on the bottom of the motor shaft.
The other type of motor has different ventilation slots. And... he has measured a healthy 300 volts going to the coil
and on both anode connections.
I put some fuzzy pics of Kazoomans motors for comparison beside Nicks which happen to be the same type.
Greetings! I just received my Echolette NG51 S, which I bought on eBay from Germany. It seems that I'm in luck! The unit sounds like the demos I have heard on YouTube, and all the knobs are reacting to my turning on them. I need a new tape though. I easily changed the old powerport to a new IEC-connector, fired it up and tried to record my vocals. I used a DIN y-cable to split the dry and wet signal, so I can blend it in when I'm producing my vocals later on.
Three small problems with my unit:
1) The light behind the on/off and reverb knobs has gone out.
2) The tape motor is also making quite a bit of noise, especially when I choose the fast reverb mode.
It will bleed into the recording if I stand too close.
3) The rubber mounts that holds the two tubes on the left is dissolving.
How can I fix this? Thanks in advance!
You can hear a quick test here. My chain: Shure 545 > Echolette (fast setting - I increase towards the end) > Soundcard.
I have then gated, EQ'ed and compressed both signals. I'm quite happy with the result and it bodes well for future use!
Last edited by pfrost89; 05-11-2015 at 09:50 PM. Reason: Added third problem
Hi, the rubber tube mounts are a pain, I usually replace them with small rubber grommets(the ones that allow wires to pass through metal chassi) but the lower tube Ro3 is probably beyond your competence. There is a small eyelet inside the rubber mount through which the retaining screws pass which is required when fitting a replacement grommet.
I remove the screws and eyelet, then pull out all of the rubber mount and fit the grommets using contact glue to keep them in place. The grommets won't be as flexible as the original rubber but I haven't experienced any issues.
The biggest problem that I usually encounter when doing this type of repair is the damage to wiring etc that I cause because of the limited access. So be careful!
The light bulbs are screw type bulbs and their sockets are held in place by a single screw which you can see on either side of the switch bank. The bulbs are a 7 volt variety but can be replaced with a standard 6.3V type.
The motor noise could be caused by a dry bearing on the bottom of the motor. This can be accessed by removing the small white retaining plug after removing the internal circlip. I use graphite or molybdenum grease. Resetting the screws which hold the motor to the chassis may also be beneficial as sometimes these have been un-evenly tightened.
Have just got one of these units on the workbench for a complete overhaul, should be fun!!??
Thank you for your reply! Since my post to this thread I have looked a bit more into my unit. I found out that the noise, which I thought came from the motor, is coming from the pinch wheel (andruckrolle). The wheel has become very hard, and every time the splice on the tape is passing, it makes a loud noise. I have now removed the pinch wheel and everything sounds fine. I have found a replacement on eBay for the ridiculous price of 33 GBP. Any advice for a cheaper replacement? I will look into fixing the light!
The outer size of the pinch roller is not that important and I have seen pinch rollers from tape recorders being used successfully. The diameter of the inside bearing of the roller would of course have to be the same as that of the spindle on the Echolette.
If your tapes are home made they may be contributing the excess noise, I stopped making my own tapes after I compared them to the superior tapes I could buy on eBay for only a few dollars.
As a side I have just received a later NG51S ( the printed circuit board model) for an overhaul. It has had previous repairs done but appears to be in reasonable condition for it's age. May post on progress with this overhaul.
Yes You are 100% right. By the time I realised my silly mistake it was too late to edit and correct.
I MUST remember
12AX7 = ECC83
12AU7 = ECC82
12AT7 = ECC81
I MUST remember
12AX7 = ECC83
12AU7 = ECC82
12AT7 = ECC81
I MUST remember
12AX7 = ECC83
12AU7 = ECC82
12AT7 = ECC81
Hopefully I wont do it again.
You indicate Bias voltage on record heads, (60v for head one, 90v for head two, 120 volts for head three) on an Echolette NG 51-S.)
Please, how mesuring these voltages. I own only a METRIX 462 E, and, with HF voltage, i find about 1000volts.
Thanks for your answer and thanks, too, for ECC82=12AU7....
I think your Metrix 462 E is not able to measure high frequency A.C. voltages.
You should be able to measure the bias voltage at the coil aprox. 270v ~ 300v AC .
Most of the info is already here how to connect to measure.. I would just be repeating myself.
Attaching this picture again .. I can't really improve on this.
Thanks to Oc Disorder.
But, my question was not correctly written.
I wanted to say: " With what to make the measures? "
(And I had understood well in which place it was necessary to make them.
This is the problem of my aprroximate english...)
A good quality multimeter ... if you could borrow one from a friend ?.. I don't know brand names for you .. there are some good ones not as expensive
as a Fluke but you had better get local advice on a good one.
Anyone reading this who can suggest a good reasonably priced meter in Europe that will measure high frequency AC please post suggestions.
Thanks again, Oc Disorder....
I have an other problem.
On ECC83/12AX7 n°4, DC voltage seems to much low.
A2 Voltage is, on my NG51S about 210vDC, but, on the side of R58 (47k ohms) connected on ECC83 n°4,
i have only 130vDC. This voltage, when i put the motor "ON", for echos function, starts about 170v DC,
and after, a half hour of working, it stabilizes on 130v DC.
Of course, echo level is lower after a half hour of working than it is just after starting.
I verified all the components connected to this ECC83, I revealed nothing of abnormal.
It would be a component, that with the rise in temperature
changes of value??????
I also replaced the tube ECC83 without more success.
I don't know where is the problem! Perhaps do you have an idea....???
Last edited by Mecaso; 01-27-2016 at 10:48 PM.
R58 (47k ohms) could be going high under stress/load. (ohms increasing ..going up ) ???
C30 (10uF) capacitor faulty ?? "It would be a component, that with the rise in temperature"
R61 (2k) faulty ??
Possibly only change value (go kaput / go faulty) when conducting. When you measure when off (no power) seems OK.
The E51 and the 51S are slightly different in this area.
Some voltage readings on E51 may be useful.
The valve/tube pins on the 51S may be different .. as "two triodes" are in the one glass envelope.
ie P6 = P1 , P7 = P2 , P8 = P3 Mentioning this as can get confusing , designers can use whichever half they like in circuit.
Hope that is some help..
R58, 47K: i have changed it.
C30: i'll change it, but, on "Off" mode, seems OK.
R61: i have changed it.
Voltages on E-51 are higher. And, on E-51, R61 is different (330ohms instead of 2,2k).
I 'll try to be inspired by tensions and differences of E-51 for
apply them to my NG-51S.
I think i have found the reason of the problem.
It was C28 which varied with temperature.
I have changed it, and, now, when starting echo function, voltage on the
point with R58 & ECC83 plate is about 195v DC.
And, after one hour, it is again about 195v DC.
For finding the reason of the problem, i had idea to blow hot air with an
hair dryer on C28, and, then, i have seen voltage falling down.
Sorry, i did not had this idea yersterday....
Thanks again for your help...
As seen above, I managed to rehabilitate a Echolette NG- 51S I bought
on ebay for cheap.
Now , for fun, I 'm trying to rehabilitate the one I used in my orchestra in
On this NG51S, i meet the following problem. the signal recorded by the
head #3 is erased by the heads 1# & #2.
When in "echo" function , if I take away the tape from heads 1# & # 2,
the signal recorded by the head #3 is correctly read by the heads #5 and
I had replaced the heads #2 and #3, but the problem persists.
I tried to adjust to different values capacitor for
premagnetizing heads #1,#2 and #3, but it changes nothing .
As soon as the magnetic tape is in contact with the head #2,
the signal of the head #3 is completly deleted.
This problem is much less sensitive with the head #1,
but, it erases a few the signal recorded by the head #3.
I should mention that the heads #1, #2 & #3 are recording correctly .
I must also say that I demagnetized heads #1 to #5 .
I confess , I don't know what to do to try to fix the problem.
That is why I called for help on this forum.
Sorry to request you again , and thank you in advance for your ideas....
Last edited by Mecaso; 02-06-2016 at 06:51 PM.
Can anyone measure the double capacitors in the power supply? It seems that I have such capacitors (NOS) and being frankly I don't need them. I'd be happy to give them to guys who restore Echolettes - they are doing good job.
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