Bad AM-FM IC Replaced In Philips Radio
TRANSPLANTATION OF BOARD IN PHILIPS RADIO!
This is a story of utter confusion due to miscommunication. This Philips RL118 Radio was sent by one of my technician friends, stating that it needed a replacement of the Gang, as it was found to be defective due to damage of PVC insulations inside. Unfortunately, this was delivered to my home much later, when I was not in station. Though my wife asked the guy to write down his name and telephone number, he just wrote down his name, stating that he was known to me. On my return, I saw this set lying on the table, with a slip, in which a name was written, with his father’s name and the location, but no telephone number. I could not place this guy at all, as my wife forgot what other things this guy communicated. I tried contacting a couple of my regular customers in that area and enquired whether they had sent any Radio for Repair, but got negative replies. I could not relate to whom this set belonged or what the complaint was. I could never connect this to the telecon my technician friend had with me before sending, as the guy who delivered it never mentioned that it was sent by him! Anyhow, I opened the set and found symptoms of previous
opening and meddling. I switched on the set and noticed that it was not picking up any stations either in AM or FM. It used a single IC, with triple power supply, one from the mains, another from rechargeable batteries and yet another from dry cell compartment. The customer can have the option of using any one f these. When the mains are inserted, internal supply is disconnected. An option switch is provided at the rear to use internal or external power, which can be seen on the second picture above. Here are the pictures of the inside:
I checked all the related components including electrolytic capacitors and could not find anything wrong. Bad luck, as it turned out to be, I never recollected or related the complaint on Gang, nor did I check it up visually. There was no need, as the gang turned without any catch. No suspicion normally goes into such a peculiar complaint, if not specified beforehand. As I have had experiences of the IC failing, I ordered for it, but got an IC, the number of which looked same, and the fitting was also proper. When I asked why the prefix was different to the supplier, he told the ICs were same. So, I replaced it and this time, the result was total silence when switched on. Then I searched for the IC Data and knew that this was a different IC. The links for both the IC date are given below:
https://www.seeedstudio.com/document/pdf/ULN2003%20Datasheet.pdf
http://www.ak-modul-bus.de/cat/documentation/CD2003.pdf
You can guess what would have happened to the set by now! I ordered for the correct IC to Aliexpress, as replacement IC was not available locally. I kept the Radio to one side and continued with my other works.
Then one day my technician friend called me and asked me the status of the Radio sent. I was taken aback, but quickly connected the missing puzzle. I replied to him that the IC was defective and I had ordered for it and was waiting for it from Hong Kong. I also told him what his messenger did, of not communicating properly and further that because of inadequate communication, I did not check the gang.
Got the IC. But by this time, the board had become very bad and I could not replace the IC in it. Luckily, for a change this time, I saw a similar set lying with one of the technicians and on enquiry came to know that the set was abandoned by his customer. When I asked whether I can take the gang, he gave the entire set (he had removed the speaker from it). I replaced the IC in it and it worked very well once again! I am giving below details of the Crystals used in this set, which I replaced in the set in my steps of trouble shooting, but later restored back.
I also learnt from the web (I think it was from some service manual of Philips) that if a 10.7 MHz crystal has a Red Dot on it, it is exactly 10.7 else it is 10.75! Something that I never knew before!
But let me tell you one thing, this set is superb in its performance. Very sensitive in Station Pick up and very clear and dynamic sound. Very compact and noise free when operated from battery. Altogether, a good set from Philips that one can buy at an economical price. But one draw back is that the IC is failing and I have had the chances of replacing it in a couple of sets. This statement is supported by my technician friends too. Philips might have to go for a better quality IC!
Another amusing job got collected into my satisfaction bag!
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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https://jestineyong.com/servicing-mercury-smps-kob-ap4400xa/
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Albert van Bemmelen
March 16, 2019 at 6:08 pm
Nice repair report Parasuraman, but I couldn't exactly trace the meaning of the word Gang. I think you mean the mechanical tuner control or something related to it but have no idea why you call it Gang? I found no translation on that subscription that resembles its meaning. The supplier that had send you the completely wrong ULN2003 chip must have been real idiots if you told them about the wrong prefix, especially if they already knew the purpose of this IC!
Parasuraman S
March 17, 2019 at 12:11 am
Ganged condenser is called 'Gang' in short. The suppliers sometimes are so ignorant, if we are not careful, we will have it!
Albert van Bemmelen
March 17, 2019 at 7:24 pm
Oh, I understand now that you meant the variable tuning capacitor as in this video:
https://www.youtube.com/watch?v=fVkRDjrRnc4
Google gave no matching explanation previously of its meaning. It was a unknown description to me.
Parasuraman S
March 18, 2019 at 1:05 pm
Yah! That's right, with the only difference that what I replaced was a PVC Gang Condenser instead of metal. Metal Gang Condensers are generally used in Valve Radios, and in some Tuner Decks. PVC Gang condenser is:
https://www.bing.com/images/search?view=detailV2&ccid=fwG0mT3f&id=015CAC87F2FB834CC88C9AA1B83E71610B045551&thid=OIP.fwG0mT3fkt3JjKRdM8h6nwAAAA&mediaurl=http%3a%2f%2fimage.made-in-china.com%2f43f34j00mNFTqkDGfHoh%2fFilm-Dielectric-Variable-Capacitor-PVC-Gang-.jpg&exph=288&expw=300&q=pvc+gang+condensor&simid=608049243335362752&selectedIndex=1&ajaxhist=0
beh
March 16, 2019 at 10:39 pm
PARASURAMAN
Is not clear for me you have replaced the ic and/ or ic+crystal or just crystal?
by the way have you received the answer of JEREMY from ATLAS co.I sent his letter to you via JESTINE ? JEREMY said if the answer is not satisfactorily you may ask him more explanations.
thanks
beh
Parasuraman S
March 17, 2019 at 12:15 am
I replaced the IC. I had mentioned that I had replaced the crystals in the process of trouble shooting, and later put back the old ones (restored)!
Yes, I got the email! Many thanks for your concern and the clarifications received! The answer is satisfactory. But they should have programmed it better to avoid this confusion.
Humberto
March 19, 2019 at 2:51 am
Great article Parasuraman. Keep on sharing your articles with us.
Robert Calk Jr.
March 20, 2019 at 11:10 am
Good job, Parasuraman.
Yogesh Panchal
April 6, 2019 at 3:59 pm
Good Fault finding sir.
V Krishnan
April 19, 2019 at 9:24 pm
Thanks for a great sharing.
Came across it while I was looking for its diagram.
I am trying to mend the same model for a rural India villager who values his transistor radio dearly.
Figured the mains transformer primary is open. Do not know the secondary AC voltage for it and the markings do not reveal it clearly. Would you know it by any chance? Thanks in advance.
V Krishnan
April 29, 2019 at 3:02 am
I am happy to share that I found the cause of the open primary winding. The mains transformer had a fuse type device embedded within it. I shorted it with another fuse-wire and voila, the problem was resolved. I have a picture if that damaged fuse but unsure how I can upload it here. Bye for now, and thanks to all who share here. Cheers, V Krishnan.
Ishwar Sharan Tiwari
October 10, 2019 at 12:07 pm
मैंने फिलिप्स आर एल 384 का नया रेडियो लिया है जिसकी ट्यूनिंग चलाने पर चर्र चर्र की आवाज़ आती है,
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I have taken a new radio from Philips RL 384, which is tuned to a different sound when running the tuning,
GOUR CHAKRABORTY
December 3, 2019 at 1:53 pm
I am an electronics engineer & hobbyist I have one Videocon SX25 stereo 2 in 1 tape recorder, suddenly it's audio output has stopped no sound is coming from volume control centre point for both the channel spkr is ok. Can any one tell me which IC or driver stage is defective in this stage. { Kolkata }
Parag
December 25, 2020 at 3:27 pm
Hello, It was nice reading this article. I have the same model with me. It powers on but only gives a hissing sound. Does not get tuned to any frequency. Same happens for Internal AA batteries. Need some guidance on how to find the fault in this circuit.