DBX 3BX LED Troubleshooting

[JSMATT]

A quick anecdote on DBX 3BX troubleshooting. I am new to this, as will soon be seen.

Purchased a unit and most yellows lights and some red lights were not working. My original unit was my 'control' for observing what the behavior should be.

Having read posts here and elsewhere, focused my attention on the three LED boards (and the ailing DBX sounded fine). This led me to focus on the 3083 for the yellow lights. Replaced it using a 16 pin mount, so future efforts would be easier (notwithstanding the potential downside of using a socket, versus simply resoldering).

After hours of swapping 'fixed' boards with working LED boards from my 'control' and using the DMM to check voltages, resistor values, etc., I concluded that the yellow lights on the 'repaired' board should absolutely be working.

One point I did not yet share is that I had swapped LEDs from yet a different, non-functional 3BX, into the LED boards of the unit being repaired.

And, then it dawned on me that maybe the LEDs have a polarity. Hmm...

Problem solved at that junction with (i) the 3083 replacement and (ii) orienting the LEDs properly. PO'ed and elated at the same time!

I have had a few of these types of moments in other pursuits from time to time, but this was a good one in this area, especially as I continue on my troubleshooting.

So, a few comments. The LED boards can be used between the two generations of DBX 3BX gen 1 (those with and without daughter boards.) They have some slightly different components, but otherwise are interchangeable (at least that was my experience).

 

[shelly_d]

You clearly learned that diodes have polarity. Definitely a good thing. It sounds to me like there are large gaps in your knowledge of electronics. Here is a website that can help you fill those gaps and teach you a great deal to boot:

http://www.compatt.com/Tutorials/NEETS/NEETS.html

Good luck in the future.

Shelly_D

 

[JSMATT]

You clearly learned that diodes have polarity. Definitely a good thing. It sounds to me like there are large gaps in your knowledge of electronics. Here is a website that can help you fill those gaps and teach you a great deal to boot:

http://www.compatt.com/Tutorials/NEETS/NEETS.html

Good luck in the future.

Shelly_D

Shelly:

Thanks for the link! To call them 'large gaps' is an understatement, but am working on reducing that and that link will help.

The incident also showed that I need to think a bit more - like there is a reason why there is a "D" in LED and it is not simply called a "LE" (Light Emitter)!

John

 

[w1jim]

I’ve fixed many of the first gen dbx 3BX units, that doesn’t mean I fully understand what’s going on in those.
BTW, I usually replace the LEDs with new ones, the old ones aren’t very bright.

You had what I call a Eureka! moment, there will be more to come.

 

[shelly_d]

Shelly:

Thanks for the link! To call them 'large gaps' is an understatement, but am working on reducing that and that link will help.

The incident also showed that I need to think a bit more - like there is a reason why there is a "D" in LED and it is not simply called a "LE" (Light Emitter)!

John

LED = Light Emitting Diode. They are, at their heart, a diode, passing current in one direction and not the other, just as any other diode does.

Shelly_D