problem with Melos Echo Chamber

[spy]

ok you were right, the problem were the cartridges and head's angle

...and the previous owner who has done a mess up with the heads!

Anyway, I placed the original heads back, I inserted a cartridge with new felts and I was playing with the angle of the record head. Then I heard a repeat!

Thanks for the support!

[TVLand]

Just found a non working Melos with 3 cartridges. They look like Dictaphone but I'm not sure as there's nothing written on them.

Hello! I am looking for a cartridge for my Melos Echo Chamber. Could you spare one of yours? I will buy it from you!

[spy]

Hi, I repaired it so I need them!

Are you sure you have a dead cartridge? Read the thread, maybe you have the same problem.

[TVLand]

I don't have any cartridges! I have bought a Playtape off ebay, and tapeloops in Holland is going to re-furbish it for me. I will have to shave some plastic off the Melos for the Play Tape to fit.

[spy]

Hey, try eBay. You will find some!

[corkyburger]

Not enough feedback on my Melos Echo Chamber!

I recently won a Melos Em-150 on an auction and after a bit of fiddling got it working. (tape heads were slightly out of position, needed a refurb on the cartridge).

So I'm now getting echo but what I'm not getting is the continuous feedback when I turn the Echo Repeat dial up full. I know it can do this because before I got the tape cartridge refurbished I tried putting some cassette tape in and was getting plenty of continuous feedback.

Any ideas why I'm not getting this now?

Thanks in advance
Corky

[oc disorder]

Hi Corky and welcome..

From what you're saying the first thing that springs to mind is the cartridge
we refurbished with the wrong type of tape eg chrome or inadvertently wound with the wrong side facing out.

If the cartridge hasn't been rewound perhaps the tape has shredded its oxide.
As you are not getting enough level to tape there is not enough signal picked back up to regenerate hence fading away rather than building up.

As you know the alignment is crucial to getting maximum signal to and from tape.
Make sure the little felt pad in the cartridge is gently pushing the tape onto the head.

There is a possibility there is a amount of residual magnetism in the surrounding metalwork (were any of the tools ,screwdrivers etc magnetized before adjustment?)which acts as an eraser but from what I can remember this has a very small effect on the signal compared to alignment problems.

A demagnetiser can be useful perhaps even a degausser used sparingly you have to make sure the melos is off and discharged as the induced ac signal from demagnetiser will totally overload the sensitive heads magnetic input and possibly burn out some of the electronics. A degausser was/is used to demagnetize cathode ray tubes - old tv's and computer monitors, although its using a sledgehammer to do a tack hammers job !
Just thought that these may be more common in junk sales etc.

Anyhow "demaggin" is really icing on the cake I think alignment and type of tape will be all that's necessary as well as cleaning the heads and tape path with isopropyl alcohol .

Have a 'oogle for azimuth & adjusting tape heads to get a better picture of the geometry involved e.g. one side up and down tilt forward and back ..what you are trying to do is have the tape perfectly flat and straight on the head.
It strikes me as I write this that two junked cassette decks built into one would make a great echo unit. A lot of the mini cassette motors have inbuilt speed adjustment - a mini preset pot on the base which can be extended into an external adjustable pot although the extremes of travel could burn out the motor however I digress.
good luck !

[corkyburger]

Thanks for your advice. You were absolutely right about the head positions. The screws that hold the heads in place are missing which means they aren't being held perfectly in place. With a little bit of fiddling, moving the playback head slightly forward and down, I am getting more feedback. It feels like its nearly there but the playback from tape is very muffled. Now obviously I know its not going to be sparkling clarity but I'm sure it should be brighter than it is.

Do you think this could be the tape?

Thanks again
Corky

[oc disorder]

Hi Corky
Well it could be the tape but now you mention the screws were missing I presume
the mounting tension springs have gone west as well!
I think there may be more adjustment required although if the tape looks worn
it may be contributing to the dull sound.
The two heads should be attached in the middle with a stand off.
If I get time I may draw a rough diagram as it may be hard to explain.
The heads have mounting flanges either side.The inner flanges(mounts) use 1 fixed threaded bolt in the center which after having passed through the flanges pass through a hollow standoff and screw into the chassis.This standoff determines the average height of the heads i.e. the center part of the head should be right on the tape.
The two outside mounts also have a threaded bolt but after having passed through
the flange pass through a spring before threading into the chassis.
That means as you tighten or loosen the bolt the head goes up and down on the outside edge as the spring is pushing up onto the mounting flange thus changing the angle. Kinda like a capital T where the top of the T can curl up or down on the outside edges. The face of the head should be at a right angle to the chassis normally
there is no adjustment for this it relies on the flange mounts not being bent.
If they were it would lean back or tip forward.Undo it if necessary to flatten them out if they are bent.
With the springs in place (or even tiny rubber tubing) it should be easy to wind the head position up or down in tiny increments.
You will hear the "highs" when you pass into the optimum area and they disappear
when you leave it. If any of your tools are magnetized this may magnetise the surrounding metal work which can also reduce highs so demagnetizing the heads and surrounding areas may help.
Cleaning the heads will help too !
I'll attempt a basic diagram !

[corkyburger]

Thanks so much for you help with this. Yes indeed the springs are missing. The center bolt is in place though. I'm not quite sure how to go about attaching springs to these outer holes. I have a nut and bolt store that might be able to supply the parts so will try and get some.

To be honest I'm not usually very good with this kind of thing but I determined to get this working!

I will have another look at your diagram and see if I can get my head around it. I'm just not quite sure how the springs attach and not fully conversant in the technical names for everything.

Corky

[oc disorder]

I'll attach another diagram to attempt to show what I mean.
You may be able to use springs from retractable writing pens although it may take some experimentation to get the right (write? {joke!}) length.
I have found hobby shops stock small screws/bolts etc the ones that sell balsa wood kits for planes and small fuel engines ,glue together battleship replicas and mini paint tins etc.
Although these stores are harder to find there's still a few about and they sell copper tubing (fuel lines)and other odds and ends that can be helpful in some situations.
My local hardware stores only seem to have the big stuff and not a good range of threads etc.
The spring has to push up on the tape head mounting flange..again small rubber tubing (medical?) sometimes used on pickup mounts in guitars so you can raise or lower the p/u,(the r. tube mounting between the scratchplate and the p/u mounting flange) may work as well as a spring.
Matter of experimentation until you get a solid mounted head with up and down adjustment.

(called compression spring)