Crystal And Tuning VR Found Defective In Philips Radio Model RL205/94
This radio was given to me by the customer to whom I delivered a TV after repair. The complaint was that the radio made hissing noises, but no stations were picked up in any of the three bands, FM-MW-SW. I checked it in front of the customer and confirmed the complaint and brought it home. As expected, the radio was having a lot of cobwebs and dirt inside:
I dismantled the boards and cleaned them and also the inside of the cabinet thoroughly. In cases like these, the first suspect would always be the crystal, which was a 32.768Hz oscillator.
I replaced that first, upon which some stations were coming in but not what should have. Since the problem was in all the three bands, it was a defect of a common component and the tuning VR was one such. I downloaded the schematic of the SMD IC used in this lovely Radio:
I replaced the only electrolytic cap on the board, 2200/25V as the reading was not proper. As the 100K VR was suspected and showed very low ohms on checkup, I removed it from the board. It was showing around 80K, and the contacts were also not proper.
As this was a concealed VR, a spray of any cleaning agent would not penetrate into the contacts for cleaning. I applied a few drops of CRC 2-26 into the holes found on the back and on the sides of the spindles, along with a few drops of IPA as suggested by an expert reader in this forum. After allowing it to settle in and turning the spindle left and right a few times, when I checked up it was showing around 98K and the reading varied smoothly on an Analogue multimeter.
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Then re-fixed the VR and tried. The radio was found working with stations coming to proper positions on the dial. Then retouched the boards thoroughly as I found a lot of dry solders too. The Radio was found working very well on prolonged tests for two days, after which I delivered it to the customer.
Satisfaction had enough reasons for seeking entry into the bag, which got accepted and was allowed!
This article was prepared for you by Parasuraman Subramanian from India. He is 76 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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Waleed Rishmawi
March 14, 2026 at 4:24 pm
as always, professional work and capacitor replacement that usually pleasing to this article..LOL. have a blessed day my friend. thanks for sharing.
Parasuraman S
March 14, 2026 at 6:16 pm
Glad to get a comment from you, my dear friend! Many thanks for finding time!
Yogesh Panchal
March 14, 2026 at 10:23 pm
Good Fix! Sir,
useful design of torch for rural area use.
Parasuraman S
March 15, 2026 at 8:37 am
Yes, of course! This has a good market! Many thanks for your comments, dear Yogesh Ji!
Albert van Bemmelen
March 15, 2026 at 2:20 am
It often also looks like you started a cleaning service too dear Parasuraman. Reading about removing cobwebs and dirt before fixing bad dry solder. But no doubt it was added time well spent before the repair finally took effect!
Parasuraman S
March 15, 2026 at 8:39 am
Cleaning is a part and parcel of the repair work! Without that, I do not even feel like looking at the boards! It gives us the starting push and a clear mind to work on the problem solving! Many thanks, dear Albert!
Mark J
March 15, 2026 at 2:54 am
Parasuraman another great radio repair and restoration. Thank you for sharing.
Parasuraman S
March 15, 2026 at 8:40 am
Many thanks, dear Mark!
MP
March 16, 2026 at 5:00 pm
Thanks for creating light in total darkness. But could you please shade a little bit more light on the function of the oscillator in relation to the SMD IC its linked to, and also memtion what should be done if a suspected crystal IC has nothing written on it as is often the case. also how to test it. PLEASE BEAR WITH MP, HE IS ASKING FOR TOO MUCH. Okey, please just one more querry. In small chinese origin radios I oftenly come across ic - KT9936M whose connections to the oscillator crystal, vcc, ground, VR middle pin etc, I'm conversant with. But the Philips radio and a few others have different amplifier SMD ICs (what was the ICs number please ?). I`m stuck with a radio whose shorted amplifier IC has no lable at all, its definitetly not kt9936m. It may be the IC I`ve been looking for. Philips, the name rings a bell in my mind, its too familiar, I mean just too familiar.
Parasuraman S
March 18, 2026 at 12:51 pm
1) Value of Crystal: Looking at the circuit, we need to check what crystal is used and rpelace it. 2) How to test crystal: If you give the designated voltage to it as per its original datasheet, it will start resonating and we can check that in oscilloscope 3) Amplifier: You can use any stereo or mono amplifier IC suitable for its power supply, for which ready boards are now available in the market.
Hope this helps! Many thanks for your comments and queries!
Angel Delis
March 18, 2026 at 1:28 am
Hi, I love this web site because I learn a lot, but please what is a VR?
Parasuraman S
March 18, 2026 at 12:52 pm
Variable resistor. Many thanks!
MP
March 18, 2026 at 4:28 pm
Sorry ! I had been having trouble to find out the IC number in the article, later I found its identity as, Si4825A10.
Parasuraman S
March 19, 2026 at 9:20 pm
Oh! I never thought that you were asking for the number of an IC which was already very clearly shown! Sorry!
jose ignacio
March 21, 2026 at 1:33 am
I follow many of your repairs through this page, and it is a delight to see how you express your love for others through your mastery of electronics. Thank you for sharing it.
Parasuraman S
March 21, 2026 at 5:31 pm
We need to maintain universal brotherhood, irrespective of where they are! We need to give only love, love and love to others and everything in this world! Many thanks for your wonderful comments! I loved it!