Hi,
A few years ago I bought a "Concertone 200" on german ebay. It was listed as rare but not working but I liked the look of it and wanted to refurbish it. I blindly disassembled it and then I moved to another town and didnt see it until today. I searched the internet for infos and the only thing I can find is a french thread and a german site called radiomuseum but theres alomst no info at all about this am. I know its from 1986 and was quite expensive back in the day. I would love to make it work again but I'm afraight it will be very hard or even impossible for me without a service manual or someone who knows this amp. So if anyone has infos on this I'd be very happy!!
Thank you!
A few years ago I bought a "Concertone 200" on german ebay. It was listed as rare but not working but I liked the look of it and wanted to refurbish it. I blindly disassembled it and then I moved to another town and didnt see it until today. I searched the internet for infos and the only thing I can find is a french thread and a german site called radiomuseum but theres alomst no info at all about this am. I know its from 1986 and was quite expensive back in the day. I would love to make it work again but I'm afraight it will be very hard or even impossible for me without a service manual or someone who knows this amp. So if anyone has infos on this I'd be very happy!!
Thank you!
Yep, thats the thread that I meant OldDIY...I dont speak french but I asked a buddy who does and he said there is barely any info on servicing etc at all. I spent hours searching the internet for infos on the concertone and also on the thores which seems to be the same amp.
rayma what exactly is a death capacitor?
rayma what exactly is a death capacitor?
I do speak French.
Short answer: do not spend time on it
Slightly longer, and in no particular order:
* it´s not 1986 by any means but late 60's
* all germanium, which is NOT good.
* very poor specs, and I bet they are optimistic.
* very nice and well made hardware, you *might* house something good and modern there
* I bet designers tried their best, but then current Technology didn´t help.
Short answer: do not spend time on it
Slightly longer, and in no particular order:
* it´s not 1986 by any means but late 60's
* all germanium, which is NOT good.
* very poor specs, and I bet they are optimistic.
* very nice and well made hardware, you *might* house something good and modern there
* I bet designers tried their best, but then current Technology didn´t help.
There is a capacitor from the mains neutral to the PSU GND. This is highly dangerous and it should be removed.
More specifically, it is highly dangerous if it is a wax paper capacitor, which are almost invariably leaky as the paper has gone acidic. These days you would be using a Y2 rated safety capacitor in such a spot, no more than about 4.7 nF.
BTW, I'd say this is late '60s at best - by about 1968 silicon was all the rage. We're talking the bad old days of solid state here. BTW, I'd check the rectifier, which might already be silicon but could also be a selenium raggedifier.
BTW, I'd say this is late '60s at best - by about 1968 silicon was all the rage. We're talking the bad old days of solid state here. BTW, I'd check the rectifier, which might already be silicon but could also be a selenium raggedifier.
I guess I'm gonna get rid of whats inside then and install something else. Thanks for your replies, you really helped to decide how to proceed
Thank for the date correction. I was puzzled because it didn't look mid 80s and if it was, I'd probably know it.
As stated, early days of solid state. I own and have fixed a small number of old consoles stereos that are similar and use germanium. The "death cap" is usually leaky and will cause a tingle if you touch the chassis. The amps worked well enough for me. Not the greatest amps on the world, but just fine for TV/console work. Personally I would not scrap it, I'd restore it as an antique, a germanium relic.
As stated, early days of solid state. I own and have fixed a small number of old consoles stereos that are similar and use germanium. The "death cap" is usually leaky and will cause a tingle if you touch the chassis. The amps worked well enough for me. Not the greatest amps on the world, but just fine for TV/console work. Personally I would not scrap it, I'd restore it as an antique, a germanium relic.
That amplifier box must contain a transformer based power supply. You can measure the rails' voltage, and if it is compatible, replace the amplifier circuitry with a chip based amplifier like the LM3886 or build a discrete amplifier which is known to perform well like some well known amplifiers in this forum.
Hey Pano, that exactly was my intension (restoring) and honestly it doesnt even look poorly made. I will check all the transistors and if they're all still ok I will try to restore ist. Its still possible to get all of them from the bay but at 25€ a pop I wouldnt go ahead and do like edbarx said.
Although I want to recap it anyway but can someone point out to where exactly this death capacitor is or how I can identify it so I put the right replacement in ? And could someone tell me how to identify those diodes? the printing on them sais PAE which probly is the brand and then p100 9199. Probly some french brand.
Thank you all so much!!
Although I want to recap it anyway but can someone point out to where exactly this death capacitor is or how I can identify it so I put the right replacement in ? And could someone tell me how to identify those diodes? the printing on them sais PAE which probly is the brand and then p100 9199. Probly some french brand.
Thank you all so much!!
Yeah I have had to replace some germanium outputs, but they were not that expensive.
The so called death cap is the one one the schematic just to the right of the power plug. Get rid of that thing, for sure. If you replace it, you need a Y rated cap. 2.2nF or 4.7nF will do. The rectifier didoes will be connected to the transformer output, then to the big caps in the power supply. In that era they often looked like little silver tophats.
The so called death cap is the one one the schematic just to the right of the power plug. Get rid of that thing, for sure. If you replace it, you need a Y rated cap. 2.2nF or 4.7nF will do. The rectifier didoes will be connected to the transformer output, then to the big caps in the power supply. In that era they often looked like little silver tophats.
Germanium transistors tended to run away with temperature and short or open. Germanium diodes don't typically have the circuit details that will provide the energy to run away thermally.
The problem is in the push pull output stage. 2 transistors there are supposed to run current continuously from + to - rails to avoid crossover distortion from switching on and off. That current can't be controlled effectively with Ge, so mostly amps didn't have idle bias circuits. The designers ~1965 just switched the output transistors on & off every cycle, causing .6 v of vertical edge in the middle of the music waveform. Which is not nearly as bad sounding as the 1.2 v switching edge of silicon transistors. .6 v vertical edges didn't cause a lot of harmonic distortion at rated power, but at low volume of typical music it could be very annoying. I listen at 1/4 W base level typicly in my music room.
Class A is worse, the current it operates at continually tends to wander to dangerous levels pretty frequently. As this is a 15 W amp, it probably is class AB with push pull output, quasicomp generally with a speaker cap about 1965. Class A single transistor output designs @ 1 to 3 watts were very popular in car and portable radios from 1958 to 1965.
I'd eliminate the death cap,from AC power to case or speaker ground either one. Otherwise try to start it up on a light bulb limiter and see if it worked. Listen occasionally, but not continuously the way I do my $60 Peavey PA amp. If not working, I'd salvage the case which looks nice, and transformers, to run something silicon. LM386 boards and TDAxx boards are about E10 on ebay. Apex AX6 25 W version would sound very nice, very low distortion for 6 transistors per channel. If you can make PCB's, they are not for sale.
The problem is in the push pull output stage. 2 transistors there are supposed to run current continuously from + to - rails to avoid crossover distortion from switching on and off. That current can't be controlled effectively with Ge, so mostly amps didn't have idle bias circuits. The designers ~1965 just switched the output transistors on & off every cycle, causing .6 v of vertical edge in the middle of the music waveform. Which is not nearly as bad sounding as the 1.2 v switching edge of silicon transistors. .6 v vertical edges didn't cause a lot of harmonic distortion at rated power, but at low volume of typical music it could be very annoying. I listen at 1/4 W base level typicly in my music room.
Class A is worse, the current it operates at continually tends to wander to dangerous levels pretty frequently. As this is a 15 W amp, it probably is class AB with push pull output, quasicomp generally with a speaker cap about 1965. Class A single transistor output designs @ 1 to 3 watts were very popular in car and portable radios from 1958 to 1965.
I'd eliminate the death cap,from AC power to case or speaker ground either one. Otherwise try to start it up on a light bulb limiter and see if it worked. Listen occasionally, but not continuously the way I do my $60 Peavey PA amp. If not working, I'd salvage the case which looks nice, and transformers, to run something silicon. LM386 boards and TDAxx boards are about E10 on ebay. Apex AX6 25 W version would sound very nice, very low distortion for 6 transistors per channel. If you can make PCB's, they are not for sale.
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