Klemt Echolette S

[TransLucid]

I would appreciate learning about any sites/vendors/etc who deal with the Echolette S tape delay machines.

I just got a fixer-upper and I suspect I may need parts (rubber parts, maybe heads, etc).

I apologize if this repeats an earlier thread - I looked and found one thread with the schematic, and several sites that sell the manual, but nothing too comprehensive.

Bob

[Kazooman]

Welcome to the club! I have four Echolettes. I don't think that you will find anything "comprehensive". The manual does not have much technical information other than the schematic and you have already found that.

Here is a place that can rebuild the rubber roller: Terry's Rubber Pinch Rollers & Wheels

I do not know of a source for heads. You can buy tape loops on ebay or just make your own.

These are very difficult to work on since the chassis is very crowded with parts. I have replaced all of the caps on two of mine to reduce some distortion and it is not an easy job. I still do not have what I could consider a properly working unit.

Here's a pic:

[TransLucid]

Tnx - I found you post before. I think I can handle all the electronic issues (I've had lots of experience with analog tape recording), but, as you know, lack of mechanical parts can kill the whole project.

I'll post again once I've had a chance to look it over...

Bob

[doctor]

Tnx - I found you post before. I think I can handle all the electronic issues (I've had lots of experience with analog tape recording), but, as you know, lack of mechanical parts can kill the whole project.

I'll post again once I've had a chance to look it over...

Bob

May be this link (Echolette documentation) will be useful
Untitled Document

[TransLucid]

Chapter 2: I'm partway through, but I've learned some interesting things along the way so far...

1. I took off the front panel and the underlying metal plate so I could get inside the chassis. Then I started tracing the circuit. I got through the input amp, record amp, and output mixing stage. The bias oscillator circuit (the ECC82) is behind the bias transformer, so I couldn't see it. Everything looks fine so far.
2. There are only two electrolytic caps inside the chassis, both cathode bypass caps (c8/c30). One is easily accessible, the other isn't. I haven't replaced either yet.
3. I plugged in the bias oscillator tube and slowly brought up the line voltage. I could see oscillations at the transformer and at the adjustment caps, and no smoke. There was bias everywhere, so I turned it off (Nachhall Aus switch).
4. I changed input 1 and 2 to 1/4" jacks. Since the stage is grid-leak biased, you must wire the 25n cap from the input to the 10M resistor, then to the grids. The jacks should not be grounded to the chassis - use insulating resistors. The grounding scheme is a little strange - I measured 0.3V between the chassis and the internal ground buss. I also changed the output to 1/4" - again, do not ground the jack to the chassis. Also, I added the attenuator (200k/10k) so the output is low level.
5. Next, I ran signal through it and got signal at the output and at the record calibration pots, but with very high 120Hz noise. I looked at the rails and saw over 25V p/p of nasty ripple. Subbing in a new cap, things looked normal. So, the filter caps were shot. I took them out (surprisingly easy) and mounted a couple of terminal strips next to the power transformer, then used regular axial caps to rebuild the supply filters. Fired it up again, and the noise is much lower.
6. Next up, the playback chain. I'm going to inject signal at the heads and see what happens. If all looks good, as I suspect, the next step is to roll tape.

More to come later...

[Kazooman]

Sounds like great progress. I know what you mean when you say that one of the caps is not easily accessible. Sometimes you need to lift one end of several components to clear a path to work in. Maybe we need some of those probes that arthroscopic surgeons use to repair knees through a tiny incision ;-).

I have tried to find replacement cans for the filter caps without success. The only ones I have found are too large in diameter (Antique Electronic Supply). They might squeeze in but only after enlarging and moving the holes in the chassis. I did disassemble one of the original cans and pulled the guts out, but I haven't found any suitable caps that will fit in the can to keep the stock look.

Keep us posted on your progress. I am very interested to hear how your project turns out.

[TransLucid]

Not much to report this week (I was busy editing my Guitar amp book for reprinting):

1. I made some tape loops with prerecorded 500Hz/5kHz tones (at 3.75 IPS). Loaded one on, after cleaning and demagnitizing the heads and tape path. Pulled the bias oscillator tube so no erasure or recording. Does anyone know the tape speeds of the Klemt?
2. The first thing I noticed was that the motor wouldn't start spinning without some help. I'm assuming the cap is bad (like the PS caps). Does anyone know anything about this cap (I'm assuming it's nonpolarized, since it handles AC). Maybe I can use 2 100ufd caps back-to-back.
3. Then, no output. It seems to be the playback circuit. Unfortunately, that tube is way back in there and hard to get at.

Anyway, my next step is to troubleshoot the playback circuit. Hopefully, next week.

[Kazooman]

All I can say about the cap is what I read off the can (and schematic). It is marked as a 48 uF 42V Bipolar cap. I am not an expert about this, but from what I have read about bipolar caps they constructed of two polarized electrolytics in series in opposite polarity. I would need to do more research on that before I actually tried it! A assume that they need to use electrolytics to get that high a capacitance and needed to go bipolar for the AC. It sounds like your idea to use two 100 uF caps in series (with opposite polarity) would work fine.

Bummer on the no output.

[TransLucid]

Update: I'm still working on the playback circuit. I was able to inject signal at the inputs to the playback amp and see it at the output, but when I played the prerecorded test tape there was no output. I measured the resistance from the input cap to ground to see if the heads were ok: infinite resistance at both inputs. I moved the test point to the leads from the heads, and on one channel saw 1.1k ohms (seems reasonable) and on the other still infinite. So, in spite of the fact that everything looks ok, there's a break somewhere between the head and the input cap.

My next step is to disassemble that part of the circuit and recheck the heads, then resolder everything and make sure the heads are really connected to the input.

To be continued...

[TransLucid]

Looks like one of my playback heads is bad - I removed both, and one measures 1.1k ohms, which seems reasonable, while the other measures 1.5M ohms, so I'm guessing that head is more or less open.

Kazooman, have you measured the resistance of your heads? The playback heads are the two on the left, and they connect at the lower RH corner of the back panel. You can clip on to the coupling caps and, assuming the caps are good, measure the resistance in-circuit. I'd be interested to know if your heads measure around 1.1k ohms...

That still doesn't explain, though, why the other head didn't produce output. I'm on that next...

[carrejans]

Hi guys,

I'm also in the possession of a Klemt Echolette NG51S. Happily, I only had to replace a broken power supply. It sure looks like hell, working on this beast, it's very crowded inside.
To be honest, the sound isn't excellent. But I notice a lot of trimpots on this machine, that I don't know the purpose of. (I count 9 of them) Do you guys have a manual of this machine?
Another thing I'm curious about, is the Din connector for a remote control. What can be controlled with this? Only on-off?
Also the output is pretty quiet. Could there be an impedance problem?

TransLucid: if you could tell me exactly where to measure the first two heads, I would be happy to help you out. Is it possible to measure without taking this machine apart? (the big chassis is removed)

Best regards!

[Kazooman]

PM me with an email address and I can send you the manual and schematic.

[carrejans]

Aaaahhh, crap. Just bought a manual of ebay.
Nevertheless, you can e-mail it to me; then I can start reading.
Thanks

[TransLucid]

You will see the functions of most of the trim pots from the schematic. There are 3 records heads, each with its own bias and level adjustment (on the side panel). There are also a few other adjustments on the top (with the heads) and back (with the tubes). The ones on top are labelled, so you can find them on the schematic. The one on the back is echo/input balance, The internal pots are also on the schematic; I'd leave them alone, especially since some are in series with other pots.

The DIN remote connector can switch the echo off (by grounding pins 2 and 3) or can mute the output (by grounding pins 1 and 2).

There is a low level output (from pin 1) and a high-level output (from pin 3) of the output jack.

The playback heads are soldered way inside the chassis, near V3 (the playback preamp). You can measure their resistance to ground there, but it's not easy to get to. The playback heads are the two outside heads; the three inside heads are record heads.

I've got a new problem now - the unit passes signal, but the level indicator doesn't show any signal (the tube is good). Plus, the signal looks like the bottom part of the waveform is soft clipped. I'm going to fix that before moving on the the playback circuit...
You need to adjust the bias for the tape you're using to get flat response, and adjust the record level trims for equal output from each head.

[carrejans]

Thank you for this great explanation. I'm starting to think that this machine is just too complicated for me.
I think that it's best that I don't open up this thing. Sorry.


My main problem at this moment is oscillation. I know it's normal that these machines can oscillate; but mine starts when the "Reverb Control" is at level 1! Any idea how I can prevent this?

Another problem: I think the levels of the 3 playback heads aren't equal. I suppose that when I turn the 3 knobs to level 5, there should be 3 echoes with more or the less the same volume?
If I understand correctly, I can adjust this with the 3 trimpots at the right side of the machine?


Thanks and good luck!




Also Kazooman, thank you very much for the manual!!