Velodyne CT100

[tdlunsfo]

Need a schematic for this powered subwoofer. No response from Velodyne, shot in the dark hoping someone else has worked on this. Found a CT120 but the drivers are completely different. Need the preamp board as well.

[Jazz P Bass]

I do not have that particular schematic. But>>>>
Honestly, the amp does not look that complicated.

The preamp has 1 LM339 and 2 LM384 opamps.

The power output is a STK4040II.

The power supply is a linear design.





STK4040II.pdf

[Jazz P Bass]

mailto:service@velodyne.com

[tdlunsfo]

Hmm this looks a lot different than mine. I am dealing with BA4886's and a upc1298v. Ouputs are 2sc3519 and 2sa1386. I emailed them last week. Do you know if the service phone number is still active?

[Enzo]

Dial it and find out. Phone contact is always better than email. At least if they are going to say no, you hear it right now.

[Jazz P Bass]

According to a gent over at AudioKarma, there are two versions of this amp.

[tdlunsfo]

Ahh..that explains it. The customer service number that I have is still good. Will try that monday morning. This thing has been a tough one..

[Jazz P Bass]

upc1298v
Aack.
Hold old is this unit?

BA4886
Never heard of it.

[tdlunsfo]

I haven't looked at the age but the hot spots on the board tells me it got some use. Sorry I meant to say ba4558 not ba4886..not sure where that came from. I replaced the outputs as they were shorted but for some reason the preamp board lights up the dim bulb when connected. I still have some power amp board issues as it will not produce sound with a signal injected. Voltages all look right but without a schematic I am shooting in the dark to some degree.

[J M Fahey]

I replaced the outputs as they were shorted but for some reason the preamp board lights up the dim bulb when connected.

Not too likely.
The preamp board can´t even be connected by itself to mains, so look at it and describe what IS connected.
Meaning:
* is power transformer connected?
* is power supply (basically diodes and capacitors) connected?
* is power amp connected?

any of these has muscle enough to light a series bulb, wimpy preamp does not.



I still have some power amp board issues as it will not produce sound with a signal injected.

[tdlunsfo]

The on/auto on, volume, crossover network, inputs and outputs all reside on the preamp board. It is feed voltages directly from the power supply +-15v, 40v and 60v.

[tdlunsfo]

Here are some pics to get a reference. I can connect the power amp/ power supply board without the preamp board and it will fire up and the relay clicks. When the preamp board is connected the dim bulb lights. My first goal was to get the power amp to pass a signal then tackle the preamp board. I am at a point where I need a schematic to help me trace and develop troubleshooting tests.

[J M Fahey]

If it uses a upc1298v then you have half your problems solved, I bet they use the straight datasheet example, what else?
Maybe with very minor variations or tweakings, compare that schematic to what you have in your own, should be real close.

[tdlunsfo]

Thats what's maddening..I feel like I am close as well but all the parts are testing good. Hopefully velodyne will come through and the schematic will help.

[J M Fahey]

Ok, even if tweaked, upc1298 + IN is still Pin 4 .
It will some 10k to 100k resistor to ground, and most probably a coupling capacitor.

At the same time, 1 of the input ribbon connector 7 pins is the Audio Input.

So there must be some path leading from connector to Power Driver
It might not be straight, I see a JRC4560 in the middle, it *might* be an active lowpass to feed the subwoofer ppower amp.
If dead, no signal will reach power stage.
So check it has proper +/-15V on pins 8 and 4 respectively, that you do not have more than a few mV DC on outputs, pins 1 and 7, confirm that one track leads to one of its inputs from input connector (with maybe some capacitors and resistors in the path) , that another track (same thing) goes from one of its outputs to power amp driver, etc.
You see there is a couple things to test even without the proper schematic.

Try injecting some audio (even fingertip buzz) straight to driver IC and listen at "a" speaker, any spare speaker you have around.
If no sound, the Power Amp is NOT repaired yet (IF relay clicks, of course)
If you hear something, move backwards towards input until you find a dead zone.
Please report results.

FWIW I live in Argentina, very little information and no access to original parts ... yet stuff gets repaired