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Nordmende Isabella 58

M

Mil Mike

New Member
I am new to the AK forum. I recently acquired a Nordmende Isabella 58. The unit works and sounds good. However the FM turner requires excessive turning to change stations and the indicator does not move.. I have not begun restoration. I am assuming it is all original. I have made contact with the Radio Museum and I was told that it may not need to be re-caped. Any thoughts that you may have on the best way to proceed with the restoration would be appreciated.
This is my first restoration project.Any suggestions on which books/publications I should begin with?
Does anyone know the rarity/value of the 58?
Thank You
 
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Well... most of those old German consoles have selenium bridge rectifiers. That will probably need replacing. You probably have a loose tuning string. Those things are a real pain to replace, especially if you have separate ones for each band.

Replacing the capacitors on some of these old German radios is insane.
 
Thank you for the quick reply.
Is replacing the caps insane because of the difficulty, or insane because it is usually not needed?
 
I'll add some general observations:

- 2 aspects of capacitor replacement:
- Safety: Some caps _can_ explode under certain circumstances.
- Audio quality: Other caps in these old units need to be replaced to return the unit to its original sonic quality.

- Difficulty: Cramped, tightly installed caps can be tedious and requires some idea of how to choose caps that are sized to work in such quarters. Good soldering and wire forming skills are essential.

- Test Gear: You'll need a schematic, know how to read and interpret it, plus have at least a DMM to measure values and operating voltages. Metal cleaning chemicals are also needed most likely.

- You also need to be comfortable around high voltage up to ~500v, depending on the amp.

Bottom Line: Choose something a bit more simple in layout and complexity as a starter piece to get some experience. A tube kit will also be an option to get the basics in hand.

Cheers,

David
 
Insanely difficult. I made the mistake of making a German radio one of my first projects. It took forever to fix because at the time I didn't know half of what I was doing. It's a wonder I didn't get zapped. It had relatively long glass, wax sealed capacitors. A number of them were passing DC and almost all of them were leaky. Thirty-eight of them!

The upside- generally most of these radios I've seen are point to point wiring. The downside is that most of the capacitors have short leads, are layered on top of each other, and are in impossible places glued to the chassis.

Nordmende might have switched to the smaller plastic sealed capacitors by that time, those usually test good for me. I have an slightly newer Nordmende that is completely and totally beat but I haven't touched the circuitry, works fine.
 
Many thanks for your feedback.
It seems obvious that this German amp is the wrong project for the novice. I have been gathering info on restoration and I am grossly mistaken on how easy the process is.Can you direct me as to what books that I should start with. Is there a learners "kit" that I can purchase to develop my skills?
I would at least like to fix the tuning problem which seems mechanical in nature. Can the chassis be safely (for the novice) be removed for me to check it out? Are there components that hold a charge that I need to discharge before I can safely handle the chassis? My last stupid novice question is, were can I obtain a service manual and parts for Nordmende?
 
If you know what needs replacing it can pretty straightforward. Most of these radios are held down in their cases with 4 screws and sometimes the dial glass (don't clean it unless it needs it). A few radios just have a panel on the bottom that can be taken off. Sometimes there were multiple dials for different bands. That can make things a little harder.

A good introduction to theory is the "RCA Receiving Tube Manual" which can be found here: http://www.bunkerofdoom.com/tubes/rc25/ The end of the book usually had a lot of little kit projects.

Capacitors will hold a charge (your electrolytic capacitors are probably at least 400v in this radio). You have to short them out with something that's insulated from you.

Try this: http://www.antiqueradio.org/recap.htm

Personally, I wouldn't replace anything except the dial string for now. Radiomuseum.org has lots of schematics but you have to be a member.
 
Thanks for putting me on the right path. I will order my books and starter project kit. The Radio Museum has accepted my application (that group is intensely serious).
Do you have any idea on the rarity of the Issabella 58?
 
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