Bass Cube LED not illuminating, LED good

[neurokrash]

Greetings,

On of the Bass Cubes here is not illuminating the LED, but the problem is originating on the Bass Cube itself. The remote and cable test fine with another BC. Can anyone suggest what to look for on the BC in order to repair this? Does anyone have schematics?

Thanks!

[thedeal7235]

did u try switching the connector to the led; sometimes i found that connection to be backwards and led not light up-worth a shot???!!

[Jacampb2]

Greetings,

On of the Bass Cubes here is not illuminating the LED, but the problem is originating on the Bass Cube itself. The remote and cable test fine with another BC. Can anyone suggest what to look for on the BC in order to repair this? Does anyone have schematics?

Thanks!

John,
First, I still have not gotten your remote out. I appologize, but I am still pretty damn sick. I will get is out ASAP.

As for your question, open up the bass cube, and check U16, it is a 78L05 +5V voltage regulator. It is responsible for regulating the +15V rail down to 5v to power the remote, as well as provide a 5v reference for some of the subsonic filter section of the cube. I would venture a guess that it is likely bad. The cube itself will still power up w/ it bad, but the subsonic section wont work correctly, and the remote will not work, basically rendering the cube useless.

I would guess that someone, somewhere along the line, plugged something that did not belong into the remote port. This is why I keep telling people not to plug shit into them just because it fits. You'd not believe the stuff people told me they "tried" because it "had the same plug". I am surprised no one has told me that they plugged a phone into it yet to see if they could use the house phone mobile!!!

There is no good way that I am aware of to check a voltage regulator. If you check with a DMM from V_out to Ground, and there isn't 5V present, then pull it and replace it. They are cheap, and can be purchased at radio shack. You could wire it up on a bench, out of circuit and check with say a 12V wall wart to see if it will regulate down to 5V, but it isn't worth the time.

If you test it in circuit, and find that there is 5V there, then follow the trace from V_out to pin #1 on the modular jack in the cube. Inspect it for any breaks. Check for 5V from Pin#1 (+5V) to Pin#4 (Ground) if it is not there, then check both the ground connection (trace to pin 4) and the power trace again for breaks. If you still don't see anything, carefully inspect the modular jack for bent pins, or broken/missing pins. The mod jacks are fairly cheap too, so replace it if you have too. If you do this soon, and find it needs a replacement jack, PM me and I will send you a spare with your remote. Actually, if you need a 78L05, I can hook you up with one of those as well (I think, I would have to make sure I have some hanging around).

Good luck,
Jason

[thedeal7235]

You'd not believe the stuff people told me they "tried" because it "had the same plug". if theres a will, theres a way-( i couldnt resist man)
told me that they plugged a phone into it yet to see if they could use the house phone mobile!!!

[neurokrash]

Greetings,

It turns out that the cable was the problem, as one of the pins was intermittant (tested okay upstairs, but was bad by the time the cable was run in the car).

No hurry on the replacement BC remote - the other BC unit that someone sold us was apparently attached to power incorrectly by the previous owner, which caused horrible damage inside. At least 8 components look fried, and I'm not sure it will be possible to repair. The (third) BC that I am going to install looks good, but I won't be putting it in for a few weeks.

In other words, get well soon, and don't worry until you're feeling better.

Regarding a voltage regulator, the only way I was able to troubleshoot these on one of my keyboards was temperature. At least for that device, the bad ones were quite a bit hotter than the others. I learned this the hard way, and let me be the first one to say that your finger is not a good tool for testing electronic components! After burning my fingertip quite effectively, I ordered a temperature probe for my meter, which allowed me to (painlessly) find the components that were much hotter than normal. If I had a lot more money, I would get one of those infrared laser non contact temperature probes. I don't know if this approach would apply to troubleshooting the BC.

Thanks!