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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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UPDATE: Dead Compaq Armada 4210T Laptop (more details)
Hi,
Part of the internal DC-DC inverter (SMPS) is not "running" which I assume powers the drives (HDD and floppy), etc. There are three transformers and using a scope with a pickup loop, one of the three transformers is not "switching" with laptop turned "on". Note: LEDs that are on, cannot be turned off using their related key (eg. Caps Lock). See details in my previous post below. I have searched everywhere for a schematic. I have the "service manual" (.PDF file) for this model, but it doesn't have schematics. I tested (in circuit) the parts in the internal DC-DC inverter and I have not found a defective part. Checked all solder joints. It is possible that an outside "control" that normally activates the SMPS is not functioning. Does anyone know where I can get a schematic for this or a similar model laptop? Thanks in advance, Brad On Fri, 16 Feb 2007 13:58:26 GMT, you wrote: Hi, My brother gave me his "dead" Compaq Armada 4210T laptop to repair. I normally service TVs and other stuff. With fully charged battery, when I turn it on (push power button), almost nothing (no hard disk spin or floppy disk drive noise (with floppy in drive), no "beeps" or lights, no display (even with external monitor)) happens when you turn it on except 4 (power, caps lock, scroll lock, numb lock) of 5 LEDs light up. I removed the battery, but the same thing happens using only the external power source. With the room totally quite, if I put a floppy disk in the drive, I can hear a faint noise when I turn on the power (but floppy drive doesn't run). If I remove the floppy disk, it isn't there. I measured +5 volts (after power turned on) at one of the pin connectors for external keyboard, which tells me that the internal DC to DC inverter is "running". This failure wasn't the result of a power surge, as in a storm. No advance warning of any kind and the laptop wasn't dropped or abused. I thought possibly a static discharge from his body after walking across a carpet, but he said, he doesn't recall that event? I opened the unit and found a tiny 5A fuse, but that tested good (not open). I examined circuits for bad solder joints. Also checked for loose connections of any kind. If you ever had this experience, please tell me what you did to fix it. Thanks in advance, Brad Before you type your password, credit card number, etc., be sure there is no active keystroke logger (spyware) in your PC. |
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