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#1
07-05-2010, 10:20 PM
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Help with Faulty Speakers
Hey guys..a few months ago I started a thread on an early 60s German Kaiser brand tube radio. The only major problem with this radio is that while the bigger front speaker works, the two side facing smaller speakers do not. I've opened it up and the wiring and soldering seems to still be in good condition so I need some help with what to check next. I've included some pictures of where the wires from the speakers terminate..I'm not sure exactly what part it is...
Picture of the radio: http://www.flickr.com/photos/38242085@N02/4072679760/ Inside..(red wire ends at the resistor): http://www.flickr.com/photos/38242085@N02/4766621888/ http://www.flickr.com/photos/38242085@N02/4766617986/ Maybe the resistor needs to be replaced? Hopefully someone can lead me in the right direction Thanks!
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#2
07-06-2010, 01:02 AM
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Well, have you had any luck finding the model number on that radio? You might could get ahold of some schematics for it and trace your problems a little better. Even without them, I can tell you that the capacitors in the radio will definitely need replacing. From the looks of it, there's a resistor in that picture alongside what look like a couple of weird capacitors. They look a bit fried to me!
Even without a schematic, you can often read the values right off the capacitors in the radio... providing they haven't melted or deteriorated so badly that the numbers are illegible. I would say that those capacitors are the most likely culprit of your speaker problems, far more so than the resistor. The radio may seem to work right now, and replacing those few bits may very well correct your speaker problem. But... keep in mind that that this should tell you something about the other capacitors throughout your radio. If you know how to take your radio apart, put it back together, and use a soldering iron, you can probably replace every faulty capacitor in that radio for less than $15. Capacitors are very inexpensive individually and if you order your parts online, it's likely that you'll find dealers who require a minimum order of $10 or $15. So, you'd be a step ahead by ordering all of the capacitors that you need for the entire radio in one stop. There's a lot of great websites that discuss how to "re-cap" a radio, so if you plan on using your Kaiser on a regular basis, I'd recommend reading up on this and deciding if this is something you'd like to attempt yourself. Naturally, you can always ask for help here! It's always worked for me! Last edited by RitchieMars; 07-06-2010 at 01:17 AM.
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#3
07-06-2010, 01:48 AM
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That radio resembles models made by Grundig and Blaupunkt that commonly used electrostatic panels for the two side speakers. If your radio has these electrostatic panels, the speakers themselves may well be bad. The electrostatic speakers are flat, (usually square) panels.
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#4
07-06-2010, 06:49 AM
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We haven't seen a picture of the speakers in question, but if in fact they are electrostatic tweeters as YahmahaFreak suggests, they may be bad. The attached article tells how to repair several types of them. Before tearing into them, however, you would want to put your DC voltmeter leads across their terminals and see if they are getting power per the article. If they aren't, that problem would have to be addressed first. Note that electrostatics work on high voltage, as opposed to common permanent magnet speakers, so be careful.
http://www.ppinyot.com/electrostatic_tweeter.htm
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Reece Perfection is hard to reach with a screwdriver. Last edited by Reece; 07-06-2010 at 08:55 AM.
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#5
07-06-2010, 05:14 PM
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#6
07-06-2010, 07:26 PM
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Im pretty positive that the speakers are not electrostatic. They are circular and conical in shape and are not flat. Maybe I should give you some info on my technical skills: I can figure most anything out if I have some guidance. The only real experience I have in electronics is partially recapping a mid-70s Pioneer receiver last year. Tube stuff is totally new to me! So thanks for everyone's help!
EDIT: Regarding the model number..I have been unable to find a model number on the radio, unless I'm not looking in the right place. I've looked through a couple of radio websites and there are a couple of Kaiser models that look to be similar but I have been unable to narrow it down.
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If you don't know, come to learn If you know, come to teach. Last edited by sidbartos; 07-06-2010 at 09:54 PM.
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#7
07-06-2010, 10:54 PM
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So are they permanent magnet speakers used as tweeters? A screwdriver attracted near the rear of them would show if they had magnets. There will often be a nonpolarized capacitor in series with the feed to a tweeter like this which passes only the high frequencies. With your ear to the tweeter and the treble turned up, should hear something.
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Reece Perfection is hard to reach with a screwdriver.
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#8
07-08-2010, 10:14 PM
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I've studied the capacitor replacement guide on the "Phil's Old Radios" site, which was very helpful. (love that site) Could someone help me identify what type of capacitors are shown in the pictures I provided so that I can work on finding values on them and finding replacements?
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If you don't know, come to learn If you know, come to teach.
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#9
07-09-2010, 12:37 AM
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The capacitors look like early electrolytics. That much smaller one in the middle is a resistor, and should still be good.
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Sony Trinitron Fan
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#10
07-09-2010, 02:37 AM
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The few Kaiser KG ( Kaiser-Werke ) radios I could find which were similar to your's have model numbers starting with W, like W1636, W1838. These seem to have the number printed on the back of the radio, or on a sticker. Your sticker might have fallen off.
As for your capacitors there, they appear to be WIMA's...a German-brand and almost certainly the originals that came in your radio when it was new. They have rather large figures on there, probably rated in pF's rather than uF's. Looks like one might be 5000pF? with 1000 below it? and rated at 500V. The other also looks like it say's 5000 with a 500 below it. It's very hard to make out, plus I'm not particularly familiar with German radios! You may need to twist them a bit and write down every number you see on there and try and make some sense out of it. Have you taken the whole chassis out to look underneath? There's probably a lot more capacitors like these in there that are just barely hanging on to life. Oh, and Phil's Radios is a great site, btw! I've spent hours reading through his restorations and I learned a lot from it!
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#11
07-09-2010, 02:44 AM
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#12
07-09-2010, 06:55 AM
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I believe the knobs on those radios are "captive" so people can't pull them off and touch the "hot" shafts. I think you pull the chassis screws underneath and then pull the chassis out, the knobs staying in the panel. I've got a K731 in the colonial cabinet that I got for FIVE bucks at an estate sale, still works but needs recapped and refinished and I haven't got to it yet but recall reading about those knobs. The underchassis screws aren't hot because they screw into plastic blocks anchored to the chassis. The chassis isn't technically directly hot but has an interference-reducing cap from line to chassis so you could get a tickle out of it and a bit more if the cap was shorted.
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Reece Perfection is hard to reach with a screwdriver.
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#13
07-09-2010, 09:48 AM
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Please replace those WIMA paper capacitors! they are serious JUNK and often leak badly, modern orange drop plastic film capacitors are suitable replacements for them, keep in mind that if you run your radio with a leaky WIMA on the output tube's control grid you can get a positive voltage on the grid and this will write off the output tube and possibly also the output transformer, power transformer, rectifier and other assorted parts.
You don't need to remove the knobs to remove the chassis, as it will slide out together with the dial glass and knobs, the knobs of some Euro radios are sometimes held on their shaft by means of grub screws located on a collar behind the dial glass be very careful as the glass dials are very fragile, so DON'T attempt to pry the knobs off with a screwdriver This is a fairly expensive radio, so the chassis MAY be an isolated one, with a full power transformer, but you want to make sure it's actually isolated before you touch or work on it while plugged in, also beware that if the coupling capacitor between the power line and chassis ground is a leaky WIMA, it may make your chassis HOT anyway!
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#14
07-09-2010, 09:59 PM
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There's a space for a sticker on the back panel but it is totally blank so I assume it has fallen off over its lifetime.
I'm having trouble reading the values on the capacitors in the photo, but here is what they seem to be: The smaller one on the right: 5000- 500 Du (?) The larger one on the left: 5000 pF 1000V (?) 500 V~ 70 Ns Another capacitor on the bottom side: 250 V 31 Ca There are a couple others but they have so many yellow cracks it is hard to tell what they say.
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#15
07-10-2010, 10:16 PM
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Quote:
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