Help programming an LGB sound module

The wattage rating of the speaker will have had no effect on causing the failure..

I guess it was 'louder' as the speaker was probably more efficient than the little LGB original.

I would check your connections. One may have come loose??
 
It was the smell of burning electrics that made me think I had overloaded the amp. What is likely to have roasted? It started decaying with intermittent audio as I turned the volume up and down. I will re-check everything tomorrow morning (7.30 pm here, dark and cold).
 
Yes, overloading the amp was my first guess, that was the intent of my questions. Sorry about the smoking, but possiby it's only one or 2 output transistors, and judging by the size of that enclosure, it's probably got replaceable parts, i.e. not surface mount components.

I'd open the unit up and look inside.

Greg
 
It has been out of its box for many years. I mounted the board directly into the carriage at the time (I was reckless in my youth). There is nothing that looks fried. I can measure 24ac input. The speaker tests OK. That's about as far as my diagnostics have gone to this point.

Sound Board

Sound Board

  • Media owner Slawman
  • Date added

Chip level repairs are not something I attempt unless stuck on a dessert island.....
 
strange, none of the resistors look burned (from here)... look at the ends of the electrolytic caps (big blue cans) and make sure they are flat, not pushed out in the center.

What's the part number on the large 3 terminal device? It's probably a regulator... no burn marks on the diodes? (the 2 terminal rectangular ones that are a bit bigger than the rest - one is what the 3 terminal socket is "pointing at"... nothing on the back side I assume...

Greg
 
Nothing looks out of order. The caps all look OK, the part number I can make out is 209 and BD698 although the character recognition is difficult.

I have dropped it in to the local electronics shop to see if they can see anything with their gear.....
 
Thanks Greg, I didn't smell it specifically, it didnt look out of order. How would you test such a thing? I will have it back early next week and post if anything is found by the electronics shop.
 
Slawman said:
It has been out of its box for many years. I mounted the board directly into the carriage at the time (I was reckless in my youth). There is nothing that looks fried. I can measure 24ac input. The speaker tests OK. That's about as far as my diagnostics have gone to this point.

Sound Board

Sound Board

  • Media owner Slawman
  • Date added

Chip level repairs are not something I attempt unless stuck on a dessert island.....
Click to expand...
One thing that I would certainly do with the Input Wire is to Tin it with Solder and cut so that no unisulated wire is protruding beyond the screws or Terminal Block. This may sound a little anal, but it is amazing how a proper installation can save problems later.
 
As others have commented there seems to be no visible sign of damage, somewhat surprising if it emitted a fair volume of smoke.
This leads me to suspect that the speaker may be the problem.
Do you have access to a known good speaker of 8 ohms impedance and at least 2W output? If so it's worth a try before working on the board.
 
Neil Robinson said:
As others have commented there seems to be no visible sign of damage, somewhat surprising if it emitted a fair volume of smoke.
This leads me to suspect that the speaker may be the problem.
Do you have access to a known good speaker of 8 ohms impedance and at least 2W output? If so it's worth a try before working on the board.
Click to expand...

Hi Neil, It didn't emit any smoke that I could tell, just a smell of burning electronics. Something was too hot briefly. I have tested it with the old 8 ohm, 2w speaker which tests fine with other sources so it is not the speaker which has failed per-say (although the replacement 3w speaker may have overloaded the output in the first place).

dunnyrail said:
One thing that I would certainly do with the Input Wire is to Tin it with Solder and cut so that no unisulated wire is protruding beyond the screws or Terminal Block. This may sound a little anal, but it is amazing how a proper installation can save problems later.
Click to expand...

Good point Dunnyrail, agree completely.
 
Sorry to report the advice back from the electronics shop is that the primary chip has failed. No cause found but nothing to do with turning the volume up and down. Apparently all of the obvious componentry tested OK.

Thank you to all who responded. Not all stories have a happy ending.....:(
 
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