Tivoli PAL won’t run on batteries unless you plug it in first…

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This is a seasoned Tivoli PAL AM/FM radio which I love for its retro simplicity, great sound, versatility, and clean build.  These things don’t last forever and the years take their toll. For example, when I first got it (lightly used) I had to replace the battery pack with a home build 4-pack of NiMH AA cells soldered together. I removed deteriorating tacky blue rubber finish.   Now, recently, after considerable usage, even if the battery is charged, the radio won’t turn on until the power supply is plugged in. Once it is on, I can unplug the power supply and the radio will play from the batteries.  ???

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I opened it up and found I can jump start the radio without the power supply plugged in by shorting two points on the Tivoli circuit board which I found by following the 7.3 V of the battery B+ and 13.8V of the external power brick. Without a schematic or desire to trace out the circuit I decided on a hack  with a miniature momentary switch that are becoming easy to get and widely used.  Turn the radio to FM (or AM) , short press the switch, and the radio turns on.

A not pretty solution but the radio works on batteries now, and life goes on.

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Soldered #28 wirewrap leads to the two contact points  to and threaded the wires out the hole used for the external power supply.  The two wires were attached to the miniature switch. I borrowed one of the recessed screw tunnels for the switch seat.  Used BONDIC to hold the switch and wires in place.   Done.

Technical note.   I don’t know the underlying cause and did not isolate the bad component.  I suspected the big 2200 uF electrolytic near the  power input jack. One of the  shorting points is connectected to the positive lead of this cap.  Later experiments to replace the cap did not fix the problem.

Below, a better shot of the two leads for jump starting the PAL.  The lead on the right is soldered directly to the + pin of the C11, the 2200 uF cap.  The other lead is soldered to a trace which carries 7.2V from the B+ battery lead.

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B+ and B- connect here (below)…  That 9 pin row above it are the pins from U5 – which so far is unidentified.

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Above – top view of the board.  C11 is the 2200uF cap.

Update 1/23/17 : I unsoldered the 2200 and substituted a new 5500uF low ESR cap using jumpers to the solder pads, but that did not fix the problem.  I reinserted the 2200 to get back to square one.   1/31/17 – another experimenter tried replacement of the 2200 with a new one without result.

Status: no fix yet.

Miscellaneous :  The 7.2v batter pack connects directly to U5, a mystery component.  Some circuit seems to switch in the battery pack when the power switch comes on if there is not charger or external power applied.  The PAL has a fast charging circuit, and a trickle charging circuit which switch in automatically to charge the battery pack from a 12V source.  We’ll have to think about how that circuit works.

Here is a really good site: harrysradios.  Harry did a lot of work and had a serious go at reverse engineering the radio to produce schematics.  The schematic does not include U5 which would solve the mystery of the 7.2V battery circuit.
http://harrysradios.blogspot.com/2012/09/tivoli-pal.html
Unfortunately, no contact information.  Harry are you out there?

Please contact me if you have an idea or solution fix this problem on this very cool radio.

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9 Responses to “Tivoli PAL won’t run on batteries unless you plug it in first…”

  1. Had exactly the same problem!

    You (and Harry) led me to the solution.
    It was a bad cap, the big 2200µF.
    Running without the cap at the moment.

    A fading battery pack with high internal resistance
    can act the in the same way. I know!

    • Thanks Patrik – I should check out that cap myself since I still have the work around in place! Check back if replacing the cap fixed it for you!

  2. I have an iPal which suffers from exactly the same symptom. Which one is the 2200uF cap mentioned in earlier posts ? Is it confirmed that this is the potential culprit ? Thanks a lot !

    • Hi – I updated with a photo of the cap which should help you locate it. It’s still a potential culprit :). Good luck.

  3. Thanks a lot ! I will buy the 2200uF capacitor today and solder it later this evening. I will then post the result.

  4. No better results with new capacitor … I guess some more reverse engineering will be needed.

    • Shucks. Thanks for posting. Please check in if you have any ideas! Looks like the 2200uF cap does not figure into the battery start up circuit. You’re right about more re. The 5V battery goes directly into U5, a 9pin mystery component.

  5. I finally did the same as you. I bought a small switch and mounted it on the rear panel in place of the aux connector (which I unsoldered from the pcb to make some room for the switch without having to drill another hole in the rear panel). It looks and works great. I think I’ll live with that for now. Thanks again !

  6. Heiner Ollendorf Says:

    Had the same issue on a used PAL off ebay and I think I found an easy fix!
    There is a voltage regulator (U4 – for naming and location of parts see Harrys blog quoted above) That one has an ‘error out’ pin, which goes low when the regulator voltage goes slightly low. That low signal is used via Q1 to switch off the FET, which cuts off the power to the radio. That circuit seems to be oversensible. (It is meant to saveguard you from draining the battery too low, I think). To disable it, just cut the (tiny) coppertrace from the upper right pin of U4 to the adjacent resistor R40. Done! It fixed the issue for me.

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