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Philips AZ1005 CD Radio Cassette Recorder

By on April 18, 2016
philips cassette repair









Recently my youngest sister asked me to look at a Philips Portable CD Radio Cassette Recorder Player of her’s. A Portable Philips AZ1005. Because she and her Boyfriend were moving into a new home they probably had used the player to give them energy while being busy around their new Home. And my guess was that the volume most likely was set to a level that it in the end killed the Amplifier chip inside.

I looked on the internet for a Service Manual but the only one I found was about 6 pages or less of the CD Player circuit of this AZ1005. The other pages of the 33 pages or so were sadly missing. So I had no clue about what chip was used for the Amplifier inside. Which meant I had to open the Player to find out more. The Volume Knob didn’t work anymore and now you only could hear it playing on a very soft level. Almost unnoticeable, no matter what source was selected. My sister warned me that the player could be also a bit dusty from the work in their new Home. And after I had checked the obvious first tests I noticed that also the Headphones gave no significant sound either. So I removed the screws on the back to have a look inside this AZ1005 Player.

philips cassette repairing

The front of the Philips AZ1005 CD Radio Cassette Player. With on the left the Volume Knob that didn’t work anymore. Next photo shows the Inside top view of the AZ1005 after opening.

open cassette player

On above photo, the Board with the Amplifier Chip is on the most left Board. I already removed the four screws that kept the Board in place. Also I removed the 3 plugged in connectors at the bottom of this Board, also removed the Antenna on the back, and the Power connector to better be able to remove the Board with the Amplifier on it.
To be sure that both Speakers were not blown earlier also, I measured both Impedances with the well known Blue ESR tester. And both speakers measured 20 Ohm. So that means they are okay and no problem for the Amplifier Speaker Output Impedance. (As everyone knows that any battery or Power Supply also has an internal Resistance that should be at least equal or lower compared to the attached Resistance of the connected Load. Which means that only in that specific situation the Power given to the Load by the Battery will be at its highest possible value. And in this case the Battery is of course the Amplifier, and the Load is the Speaker. A Battery gives its maximum voltage at its Load when its current through its internal Resistance is lower. Because the Voltage loss is higher over its internal Resistance at higher given currents to its attached Load. Or simply said : The Battery Voltage over its Poles is Maximum when no current flows at all!).
In case that the Speaker Resistance would be too Low for the Amplifier Output circuit, it would likely destroy the Amplifier Chip. And in case that the Speaker Resistance is higher than the Output Resistance of the Amplifier, that would mean less Amplifier Power to the Speakers. (Impedance probably would be in this case be a better description, because Resistance only is used for DC circuits whereas we now in fact use AC frequencies here. Although the Impedance of a Speaker doesn’t have much influence on its Resistance or Real Ohmic Value). Next Photo shows a closer view at the Board with the Cooler removed from the bad Amplifier chip. The Amplifier proved to be a 16 pins UTC2025.

ut2025 ic


Previous 2 photos showed the side view of the Board also showing one of both Speakers and followed by this Board top viewed with the UTC2025 already removed. Next photo finally shows the removed Amplifier chip Cooler.

chip cooler

And removing the UTC2025 only took me about 30 seconds with my new Desolder Gun. Previous Photos showed this recently bought perfect time saving Desolder Gun. After I knew what Amplifier was used, I of course checked the internet to order this UTC2025 16 pins chip.
It was easily found at a low price and Free Shipping. So 5 chips for only $1.67 dollar would mean that my sister could enjoy her Portable Sound System again very soon ! Maybe not a very big repair article this time, but the fact that this Philips AZ1005 CD Radio Cassette information couldn’t be found (at least for free) on the world wide web, hopefully makes this repair nevertheless worth something.
Anyway, what would the World be without Music ! Until another repair.



Albert van Bemmelen, Weert, The Netherlands.

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Note: You can read his previous repair article in the below link:




  1. Robert Calk

    April 18, 2016 at 4:03 pm

    Good job, Albert. Thanks for the article. De-soldering guns are worth every penny! They make life so much easier.

    • Albert van Bemmelen

      April 18, 2016 at 5:32 pm

      You're so right Robert! But only after I found one at a reasonable price I bought one on Aliexpress too.

    • Paris Azis

      April 19, 2016 at 3:18 am

      Hey Robert

      If my left hand thumb, using the hand operated mechanical desoldering sucking pump, had a voice to speak, it would obviously copy Albert's saying..."You are so right Robert"...!! Some times (depending on the count of the pins I desolder) my thumb looks like an inverted J ! You lucky (desoldering) pistoleros!!


  2. suranga bandara, Suranga Electronics

    April 18, 2016 at 4:49 pm

    hello.Mr, Albert,

    Very professional and Nice repair work you have done.
    Congratulation !!

    • Albert van Bemmelen

      April 18, 2016 at 5:38 pm

      Thank you Mr.Suranga. That feels like a great compliment coming from a real professional who owns a Repair Shop!

  3. Parasuraman S

    April 18, 2016 at 8:21 pm

    Good Job! Removing and refixing this type of component system is cumbersome, as I have handled several of such sets and one is pending to be attended to! Which brand of the desoldering gun was that?

    • Albert van Bemmelen

      April 18, 2016 at 9:36 pm

      This is the DesolderGun I bought a few months ago, Parasuraman S.
      I also bought 3 other different matching nozzles too. And a spare
      Heating element.

      From Rose's Machine world. Upgrade from MT-993

      Good luck!

    • Albert van Bemmelen

      May 4, 2016 at 5:47 pm

      By-the-way dear Parasuraman: talking about cumbersome component systems.
      You are right that they are sometimes badly soldered. Seems they were
      using the wrong solderflux or with too much solder fluid on the Boards. Without cleaning them afterwards. And also the Stereo Potentiometers
      for the Volume adjustment are often problematic. Even finding the right Service Manual for this AZ 1005 was not possible. But I found another
      Philips Manual for the AZ 1009 that although uses other parts, still
      uses the same 7 pins Stereo Potentiometer for the Volume Knob. If you
      need this info see here:

      • Albert van Bemmelen

        May 6, 2016 at 2:27 pm

        By-the-way: Although these Philips audio sets have a fantastic sound and use a left and a right amplifier section for both Speakers, nowhere is the word Stereo written on these Boom Box audio sets. But because they do create some special spatial stereo sound they use these very flat ingenious designed stereo Potentiometers for the Volume adjustment. Which therefore needs 7 pins. Sadly replacing them is very though because finding a new one is not possible. And often the Volume knob doesn't work anymore because the 3 middle carbon resistors layers get deconnected from the outer pins 3 to 5.

  4. beh

    April 18, 2016 at 9:36 pm

    Hi Albert
    thanks for article with very comprehensive explanation of parts .by the way if you can help me to find any info about the pin lay out of this ic HX8904TB or any diagram .this is the driver of Samsung LCD panel board

    • albert van bemmelen

      April 19, 2016 at 2:07 am

      Hi Beh, Try this link and see the download button for a file
      about 129.81 KB.


    • albert van bemmelen

      April 19, 2016 at 2:12 am

      And from that same site, this picture maybe is the pin explanation of the chip you were looking for?

    • albert van bemmelen

      April 19, 2016 at 2:30 am

      Beh. Above link gives you the needed information of the chip.

      • beh

        April 19, 2016 at 10:52 am

        Dear Albert
        thank you so much of your info s indeed this is a great help for me.
        best regards

        • Albert van Bemmelen

          April 19, 2016 at 5:37 pm

          Glad that I could Help.

  5. Paris Azis

    April 19, 2016 at 3:06 am

    Good job, Albert. Thanks for sharing it.


    • Albert van Bemmelen

      April 19, 2016 at 1:54 pm

      Thanks Paris. This repair was a fast one. I expected the Amplifier chip
      to be much bigger, but it wasn't.

      Now I am busy with 'repairing' an older SIM CARD READER (SIM v1.03)-
      that had only 2 crystals. It seems to be recognized in Windows with
      an old Huge Pine HL0108 USB to RS232 driver. But the SIM Manager 9.0
      software keeps refusing to see it now. It had worked before though.
      So now I bought another newer SIM CARD READER (SIMC R/W)- to keep my
      Phone Contacts safe, and to be able to copy them. That new reader uses
      3 crystals and works fine with my older SIM Manager 9.0 Program but it
      also can do much more (hack Cards and copy them) but it then uses
      another driver from A-Men Technology. But sadly my Windows USB COM
      ports now seem all occupied after I tried the Prolific PL2303 USB
      driver (that chip is on the new READER pcb). How to undo or reset
      all old USB settings is a real problem. But now I also lost the
      old A-Men Technology USB driver that previously was selected
      automatically by inserting the USB Reader Dongle. Maybe I should
      try Zadig?

      These Windows USB problems are really bugging me !

      Finding and downloading a good matching USB driver is also almost
      impossible without those not free Driver programs that keep
      interfering without solving the problem !

      Maybe Paris, You have a decent solution? (or one of the Jestine Blog

      • Albert van Bemmelen

        April 19, 2016 at 5:34 pm

        The only solution that restored everything to the situation were everything worked again, was a Windows7 System Recovery to a previous date before the Prolific PL2303 was installed.
        Windows and USB drivers are nothing but trouble when this Recovery would not have worked. I guess that is also why many people buy those very costly Apple Notebooks?
        To be safe I will try to copy my working A-Men-Technology USB Driver to a backup file now. So this can be restored later without any System Recovery. (hopefully).

  6. Yogesh Panchal

    April 19, 2016 at 10:42 pm

    Good job! Good tools make our job full of fun.

    • Albert van Bemmelen

      April 20, 2016 at 1:54 pm

      Thanks Yogesh. So true! Especially the previously mentioned DHL-
      from Rose's Machine world is a fantastic new Tool!
      Yesterday it only took me a couple of hours to easily disassemble all
      components from a complete but discarded PC Monitor Board.
      And the price - only about $87.51 dollar - was very affordable! and
      includes Free Shipping.

      • M usman

        June 8, 2020 at 11:29 pm

        I want someone who repair an old tape recorder

  7. Humberto

    April 21, 2016 at 9:30 pm

    Hi Albert, good job. And of course, a wonderful tool. I tried to buy a Electric-Vacuum-Desoldering-Pump-Solder-Sucker, and when I read the comments almost all of them said that the tip was very bad.

    • Robert Calk

      April 22, 2016 at 5:07 pm

      Hakko makes good ones. I've been using mine for years and it works great. I can't imagine electronics without it. I can't vouch for other companies, but Hakko makes great de-soldering pumps.

    • Albert van Bemmelen

      April 23, 2016 at 5:02 am

      I can't speak for other people that use other Desolder Guns, Humberto. But I've tested mine for 4 to 5 hours or so without switching it off and it caused no problem at all!

      Also the Tip is so good I even can use it to solder at the same time when I need it!


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