The 'protect light' comes on Fender PD150 Portable Sound System
When we plug in our Fender PD150 Portable Sound System, a 'protect light' comes on and we can't power up the unit. We tried swapping out the fuse but it didn't fix the problem. Any ideas?
Music - Fender - Passport Deluxe 500watt Sound System with Deluxe Speaker...
Answers & Comments
The protect circuit is activated by a current sensing transformer in the *input* of the power supply. If any of the subassemblies of the unit (or all of them in combination) draw excess current then the protect light will illuminate and the power supply shut down to prevent any damage to the system.
The circuitry in the power supply is fairly robust as well as fuse protected so it is unlikely that the power supply itself has failed. More than likely one of your output power transistors has been shorted and it is easy to check this yourself if you are interested in doing so.
Furthermore if you follow a few *simple* precautions you can do this safely and confidently.
Post again on this thread if you are interested and I will spew the details.
-BK
this sounds like the problem I am having. I am interested in the details you have on this.
The protect circuit is activated by a current sensing transformer in the *input* of the power supply. If any of the subassemblies of the unit (or all of them in combination) draw excess current then the protect light will illuminate and the power supply shut down to prevent any damage to the system.
The circuitry in the power supply is fairly robust as well as fuse protected so it is unlikely that the power supply itself has failed. More than likely one of your output power transistors has been shorted and it is easy to check this yourself if you are interested in doing so
Repaired a PD250. The energy storage inductor in the power supply is a bifilar wound toroid. It had overheated and the two windings shorted. I rewound it, and unit operates but the inductor really runs hot. Fortunately the insulation on the replacement wire seems to take the heat.
Although it would be much easier to diagnose the problem if Fender made the wiring schematic more readily available, BKFlorida's response is enough for me to fix it! Just count up how many different circuit the power supply secondary supplies, and start isolating them one at a time by disconnecting, testing, the re-connecting the circuit. When the problem goes away, you've found the defective circuit.
My old band had a similar problem with a different system and we had to return it.
Usually when it does that, it means that there is a short somewhere in the unit and the protect light is a way of preventing the system from overheating and becoming a fire hazard. We kept blowing fuses right before it finally failed.
If your out of warranty, look for electronics repair shops locally.
DO NOT attempt to repair it yourselves and there is more than enough power to stop your heart in there. It's designed to take a small electrical signal and step it up so were definitely talking LETHAL!
Hope this helps,
Simon.
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