Hello ! I am trying to repair one of these recorders for a College that I am attending at the moment as they are on a tight budget. The Item was repaired a year or so ago by someone else and it only lasted 2 weeks before it stopped displaying again. I haven't replaced anything yet cause I am awaiting schematics, but was wondering If I were to replace R17 with a higher wattage, do you think it will work or do I need to replace other components ie capacitors also ? Thank for any Advice Regards : Owen
Televison & Video - Alesis - MasterLink ML-9600
Answers & Comments
I would first do a reasonable-ness check on that resistor... In other words check resistance value and voltage across it. If this is a backlight problem, MANY of them are indeed 5 volt for the backlight... however IF you are seeing 10.3 then there may be damage to the module. I would trace backwards to the source of the 25 volts and see if that is reasonable. You MIGHT find a three terminal regulator that has shorted and is supplying way too much. MANY devices use +/- 15 volts or sometimes +/- 12 volts and it would be unlikely they would generate 25 volts and then drop it to 10.3. I suspect that a regulator up front may have shorted causing over voltage and burning of the resistor. Power sources USUALLY can be traced without schematics and that is what I would do.
Work from both ends... diodes and caps at the source, and look for regulators checking the in's and out's of those. Trace back from the resistor toward the source...
You didn't specify if the r17 was burning up...but assuming so..replacing the resistor with a higher wattage resistor would be like putting in a higher rated fuse...i would'nt do it...instead I would try to troubleshoot the circuit until you find what is taking out r17...the schematic will be useful in determining the test voltages and such...you can try tracing the pc board trace from r17 to whatever it supplies..but if it's the main +5Vcc then it pretty much goes everywhere in that unit...good luck jc