Electrocompaniet original 25 W needs help

Hi

I got an original Electrocompaniet 25 watt 'The two channel audio amplifier' This model was made by Norse Ecosse Electronics. This amplifier was badly tweaked. The job was really butchered. I want to restore it in it's original condition. I need the power supply and protection circuit schematic with the parts list for the Norse Ecosse Electronic model.


Thanks a lot

Marc Legare
 
Bonjour Marc,

Do you still need the Electrocompaniet 25 W schematics?
I saw somewhere else that you are looking for the Ampliwire II schematics too. Is it still the case?

For the 25 W I do have some schematics but they may not be complete.
I have a link that brings you to the site of a former Electrocompaniet employee. The site is filled with under construction links but some are still working. Especially the one on how to troubleshoot the 25 W.
http://home.online.no/~tsandstr/AudioStartsHere.htm

As for the Ampliwire II, I pretty much have all the schematics and service notes that have been published for this one.

Salutations,

Michel
 
Marc

I have three of the Electro 25's. ( I had a fourth but that was stolen when I lent it out one night to a local dance - yes the electro does produce a lot of power for a 25 watt amp ) You will have already guessed that I think they produce good music.

Each of the three is slightly different. You should find what you need on the two web sites already provided. However I also completely rebuilt two of the electro's that I have and did schematics from these.

The main changes I made to the amps was to change all the electrolytics and the resistors on the output stage from 1 watt to 5 watt. Later I also increased the size of the capacitance bank and then added a fan - these amps do run hot in summer.

The normal cause of failure on these amps was the output resistor overheating. Also beware that the bias on the amps may drift and all the amps I bought had different bias settings. From memory I set mine to 2.5/3 amps. I will check my notes.

Do you have a model number for your amp?

Hope this helps

Don
 
Electro 25 schematics and grief

I have two pairs of Norse Ecosse 25s. The first pair are very early small heatsink, no handles version, built as bridged. The others are the later ones with handles (colour squared not shiny round) and heatsink wings. The second pair was bought, allegedly working, to relieve the frustration of unsuccessfully trying to get the first pair repaired. Several hundreds of pounds later I have three Electros, none of which work properly and the one Electrocompaniet smashed (sent it back to me in a box without wadding!) gutted for some Vellman boards and transformers, just so I can listen to music. My desire is to get the remaining old one remade as a stereo unit and the other two bridged units repaired and simplified, even if it means making them single ended units. I have not got the engineering skills and knowhow to do it and I have not got the funds to keep trying to find someone who can fix them by trial and error. I have some old schematics from Glenrothes but they are rough and difficult to follow. I miss them and would like to find a way out of this if you can suggest a solution...
 
Hi

I got an original Electrocompaniet 25 watt 'The two channel audio amplifier' This model was made by Norse Ecosse Electronics. This amplifier was badly tweaked. The job was really butchered. I want to restore it in it's original condition. I need the power supply and protection circuit schematic with the parts list for the Norse Ecosse Electronic model.


Thanks a lot

Marc Legare

I'd really like to see pictures of the internals of the original Electrocompaniet 25 watt amp if you happen to take some.
 
Hi PB2. I too would like to see Don's schematics if he is happy to share. I am determined to try to get these amps working again but imagine the solution is beyond my own untrained capabilities. I have a private web site which I have assembled to try to gather all the info in one place. It is a work in progress but there are photos there and you are most welcome to go and have a look if you want: Hi Fi
 
Schematic Electrocompaniet 25W designed by Lostroh and Mati Otala

is this the schematic of the showed amp front from the picture?
 

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Hi Drew,

Having posted here before regarding this amplifier and had no luck finding any photo's of the amp internals, I like to say thank you as I've just downloaded the pictures for the amp.

I have restored the preamp and reversed engineer the circuit and I also have some photo's if you would like to add them to your web site.

With regards to the amp it seems like a never ending project many of the parts have been lost.
I've most of the case, front panel and transformer and two rebuilt amp boards one is working the other went up in smoke and the biggest problem is finding the transistors. :(

I'm also hoping shortly to get the missing parts for the case re manufactured and have another case made at the same time. :)
 
Hi Drew,

Having posted here before regarding this amplifier and had no luck finding any photo's of the amp internals, I like to say thank you as I've just downloaded the pictures for the amp.

I have restored the preamp and reversed engineer the circuit and I also have some photo's if you would like to add them to your web site.

With regards to the amp it seems like a never ending project many of the parts have been lost.
I've most of the case, front panel and transformer and two rebuilt amp boards one is working the other went up in smoke and the biggest problem is finding the transistors. :(

I'm also hoping shortly to get the missing parts for the case re manufactured and have another case made at the same time. :)

perhaps this threads help a lot:
http://www.diyaudio.com/forums/soli...istor-families-audio-power-output-stages.html
http://www.diyaudio.com/forums/solid-state/165528-best-drivers-bjt-output-stages.html
http://www.diyaudio.com/forums/soli...ver-stages-high-power-amplifier-overview.html
The use of dual transistor for first and second stage like
http://www.datasheetcatalog.org/datasheet/philips/BCY89.pdf
isn't necessary. Selected discrete transistors (same Ube threshold voltage and hfe) is fully compatible.
and much more cheaper than dual BjT like BCY87 available there:
http://www.williges-elektronik.de/a...enteaktiv/transistoren/53042398e007aef46.html
 
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I have two pairs of Norse Ecosse 25s. The first pair are very early small heatsink, no handles version, built as bridged. The others are the later ones with handles (colour squared not shiny round) and heatsink wings. The second pair was bought, allegedly working, to relieve the frustration of unsuccessfully trying to get the first pair repaired. Several hundreds of pounds later I have three Electros, none of which work properly and the one Electrocompaniet smashed (sent it back to me in a box without wadding!) gutted for some Vellman boards and transformers, just so I can listen to music. My desire is to get the remaining old one remade as a stereo unit and the other two bridged units repaired and simplified, even if it means making them single ended units. I have not got the engineering skills and knowhow to do it and I have not got the funds to keep trying to find someone who can fix them by trial and error. I have some old schematics from Glenrothes but they are rough and difficult to follow. I miss them and would like to find a way out of this if you can suggest a solution...

Hi Drew,

Can you tell us what was wrong with each of these units? Strange noises? Overheating? Smoke? DC offset? Distortion or frequency response issues?

Did you put in the Vellman boards yourself?
 
As I never repaired my 25 W, I looked at web infos today to rebuild mine. It's funny to see that my original post is still alive after all that time.

As my power supply board is in really bad condition I would be glad to buy one from someone who have such an amp he wil not rebuild.

I think I have internal picts if someone wants to see it. I also have many 25 watt different schematics I could share with interested peoples. I think there's more than one version.

This will be a winter project.

As the input impedance of this amplifier is only 1K, i'm a little worried about the load it will be for a preamplifier to drive it. If the preamp has an output capacitor, it should be big.
 
Apologies all for not replying sooner re: EC25

For some reason I was not notified of the new posts. Please feel free to send me pics of the preamp to add to the web site.

I did not install the Vellemans myself. This was the last ditch for the chap who had been trying to repair the other amps.

The catalogue of faults is a complex affair but the main issues are:

A pop hum on one channel, when the amp would start with some rustling noises from the speaker, followed, progressively, by by a sharp hard pop, sometimes a double pop and this would develop to a random, out of the blue, pop followed by a loud hum and the bass cone turning almost inside out. This hum might last a couple of seconds, twenty seconds or not go off at all unless I switched off. Usually when I switched back on later it was still in crisis. There were all sorts of dc anomalies measured at the outputs.

Added to this there was a bad earth hum, originating in the unit and there was a change to the sound after having been worked on and very very bad distortion, making them impossible to listen to, even without the pops and hums.

I had a lot of work done on them and the chap who was doing the repairs said he was stumped. Just about all the electrolytics, many resistors and several transistors were replaces and nearly all the plugged connections were direct soldered.

I have done nothing about them since the last posting as pressures from other quarters have kept me busy but I am keen to get back to them in the new year. On the other hand, if there was someone who really knew his Electros living half an hour away, I would be on his/her doorstep tomorrow. A slight irony when you consider than my doorstep is less than half an hour from where the amps were made.

Cheers. Drew
 
two-channel

Many of my little friends I find butchered :(
What is it you need ? Is it the bcy87/89 ? Because that is the only exotic part in it. It works with bd139/140 and the bd203/204. Cheap :) I do stock a couple of the bcy transistors. But these are spare parts since I use the two channel(s). However, they are quite expensive for such a small part.
I pretty know them inside out and have one advise: If the pcb's have been "slaugthered" and the pcb's are damaged the game is over. You need new pcb's then probably. Most issues are with the pcb's since they are under serious stress (read: heat and lots of current) Keep in mind that the two-channel is a heat factory. I read someone mentioning 2,5-3A as idle current. Well .. I think your amp will work for 2-3 minutes and then go into protection due to over temperature. The idle current for a two-channel is a simple 1c . (eg. 1A). But I have mine running at 750mA which expands the lifetime of the components (less heat) A lot of two-channels were sold with half idle current settings. They live longer that way. Just turn the idle current down until you hear it getting sounding 'different', and then add 50mA. Don't go under 300mA. From all the Electrocompaniets I have, the Two-channel still is the most musical one. That is why I love them and will restore them :)
 
Hello msdin,

I do not know how the tracks looked like on the original pcb but the pcb PSU you posted sure needs some corrections. Connections should never be make along a track that connects a diode bridge to a large filter capacitor. This track is extremely noisy because the high currrent pulses needed to charge the capacitors go through it. Only make a connection to this supply line, after the capacitor. This rule applies to ground tracks too! You have to be extremely careful with those tracks if you do not want to end up with hum, as it happened with some of my earlier designs.

I could not deduce all the external connections going to the pcb but since I was sure of some of them, just for fun, I redrew part of the design to show you some of the corrections, but not all, I would make.
 

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