BOUYER AS30 Power Amplifier Repair
This is an antique piece, which I bought from a scrap picker many years back. When I sold many of my electronic scrap and other things to this guy, he showed this to me and asked whether I would be interested. I took it in and switched on and the power was OK.
So, bargained and paid him and added this to my antique collection. Being a set made in France. I was curious to know its contents. Found a lot of dust and dirt inside, which I cleaned thoroughly. Connected speakers by directly soldering the wires inside and the set was working but the audio was having distortions and lacked power. I tried to get a service manual online and could not get it. I chanced to see their website, picked up the contact email address and wrote to them along with the picture of this piece and enquired whether they could help me with a schematic! I was pleasantly surprised when they responded promptly and let me have a schematic! I wrote a thanking reply highlighting their care and concern for the customer! Here was a company, who cared for their customer, by digging into their archives and making available schematic of a piece, which they would have discontinued many, many years back! What a grand gesture!
Looking through the schematic, I traced the defective capacitors and had replaced a couple of them, which made the amp working perfectly well. This was lying with me for many years like that and I used to test Decks and other Devices which require an Amp, through this Bouyer. Subsequently, it developed intermittent sound problems and as I was not having time, I left it like that until the time came now to dispose it off, as a part of my ‘load shedding drive’ to reduce number of sets lying around in the bedroom, clustering the place!
Well, this set is so unique that the servicing is made as simple as it could be, exposing an excellent design. All the PCBs (except the control PCB) were all modules which were inserted into slots like in the case of Desktop PCs. It was a lovely arrangement, which made things easy for a service technician. The fact that the whole Amp could be exposed by removing the top cover, which was fixed only by two long screws from behind and the bottom cover with only four screws, presented an amazing design! The metals used were very heavy too!
I saw Grundig capacitors in use. In the sixth picture above, you can notice that I had replaced the original caps with Keltron capacitors. I am sure you will see how well the components were arranged, though not marked. But the PCBs had numbers on it, which is mentioned in the schematic too.
(I am not sure whether the above schematics would be clearly readable, but perhaps you can download it, expand it and read. It was ok, when I tried.)
The electrolytic capacitors of small value were of peculiar type, which looked like a styroflex capacitor on first sight, but with markings on both sides; red for positive and black for negative:
Since I was not having 6.8uF, I used 4.7 and 2.2 uF 63V each in parallel. I checked all the other electrolytic capacitors this time and found the ESR to be ok and so left it as it was. Put the covers back and tried it for several hours before one of my friends who is crazy in collecting antique pieces picked it up. (I forgot to mention that I had fixed the caps of mosquito repellent liquid as its legs) I collected only the cost and nominal charges towards service.
Now I have only these pictures for its memory! Anyhow, satisfaction had got jumped into the bag twice on this set, when I completed successful repair! And, that’s a solace!
This article was prepared for you by Parasuraman Subramanian from India. He is 69 years old and has more than 30 years’ experience in handling antique equipment like Valve Radio, Amps, Reel Tape Recorders and currently studying latest tech-classes conducted by Kerala State Electronics Technicians’ Association. He has done graduation in BBA degree, private diploma in Radio Engineering and retired as MD of a USA company. Presently working as Consultant to Hospital and other institutions.
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You may check on his previous repair article below: