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Does anybody have any info About this french amp?
Does anybody have any info About this french amp?
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Old 3rd December 2020, 12:12 PM   #11
OldDIY is offline OldDIY
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Can be offered on marketplaces with an emphasis on germanium (if germanium is there)
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Old 3rd December 2020, 12:23 PM   #12
Arne Jensen is offline Arne Jensen
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yeah its pretty much all germanium. will have to unsolder and check them first but thanks for the hint
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Old 3rd December 2020, 12:32 PM   #13
Pano is offline Pano  United States
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Does anybody have any info About this french amp?
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.
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Old 3rd December 2020, 01:03 PM   #14
edbarx is offline edbarx  Europe
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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.
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Old 3rd December 2020, 04:18 PM   #15
Arne Jensen is offline Arne Jensen
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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!!
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Old 3rd December 2020, 04:40 PM   #16
Arne Jensen is offline Arne Jensen
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ok I think I found the death cap. 0.01 400volt. The four main transistors checkout fine only thing that puzzles me is the hfe. two are 18, one is 15 and one 54...?
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Old 3rd December 2020, 04:42 PM   #17
tauro0221 is offline tauro0221  United States
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Hi,
Before replacing the capacitors read the voltage with a voltmeter in the AC and the voltage reading should be about zero. Higher voltage means that the capacitors are not good.
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Old 3rd December 2020, 05:33 PM   #18
Pano is offline Pano  United States
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Does anybody have any info About this french amp?
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.
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Old 3rd December 2020, 07:04 PM   #19
Arne Jensen is offline Arne Jensen
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alright, I think I documented every step when I disassembled that thing. would you say the diodes should be replaced no matter what or can I leave the old ones if they test ok?
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Old 3rd December 2020, 09:38 PM   #20
indianajo is offline indianajo  United States
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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.
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Last edited by indianajo; 3rd December 2020 at 09:52 PM.
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