Strange Shark Problem

I'm having a problem with my new blue shark. It arrived today, and I've fitted the wires, and checked continuity (only continuity is battery neg to LED neg.....I assume thats correct). I connected my 3 P4's (series wired total Vf 9.75v) and turned the pot to middle position (couldn't remember which way was max). The output was disappointing to say the least. I turned it up to full, but no real change in output, and turning it down only killed the output totally. The battery is a 4xC cell pack, but is kicking out 5.3v after a fresh charge, so it should be OK (input current to shark about 2 and a bit amps). I know the battery is good for about 3.5amps draw, as it usually runs an 18w xenon.

Trying to figure it out, I measured the voltage across the LED's at 7.8v on full power, so decided to try a few different batteries and voltages. Outputs as follows:-

Vin pot open Vout initial pot closed 2.64 7.53 5.25 2.59 3.92 7.74 5.42 3.87 5.33 7.83 5.58 5.27 6.62 7.9 6.36 6.54 7.89 7.9 7.45 7.8 9.26 8.7 8.73 8.88

Vout initial was at about half power. Voltages are so low that I'm only getting all 3 LED's to light at6.6v and above.

I looked at the resistances too, which are as follows (some might be x10 out, can't remember which setting I was on on the meter):-

r1 91.5k r3 cannot get a reading r4 3.45k r5 22k r6 16k r7 14.5k
Is R7 (trim pot) a bit too low? I thought it was meant to be nearer 20k. Not sure why I can't get a reading off of R3, but I just seem to get a "1" appear on my meter, so its either above 200Kohm, or I'm doing it wrong. If R7 is the problem, can I check this by shorting across the 2 terminals visible from the side of the board (did I read somewhere that it will just output at the 980mA max setting)? I'd give it a go, but don't really want to fry my board or LED's.

Thanks in advance for your help.

Storm Monkey Phil

In your first paragraph are you saying it's drawing a bit over 2A with very low output voltage?

It sounds like a bad Blue Shark. If the Shark is not doing anything one symptom is Vout tracks Vin. I'm not sure if Vout could be less than Vin for the Blue Shark.

Can you make your list of numbers into a table. I don't understand your list of numbers. Thanks.

Wayne

Yeah, sorry, reading through it's a bit unclear, and I swear the data was in a table when I posted!

The 2 amps (nearer 2.3A) refers to the max draw I expected from the fully charged 5v source, neglecting reductions for less charge etc, at the time of test, it was within the max 3A for the shark. I was just trying to rule out too low a voltage source as a problem.

The test voltages are as shown below, with close Vin tracking with the pot at min, with less of a correlation as the pot is opened more. I'm putting the slight differences in positions where the graphs are very close to each other (e.g. higher v in) to measuring tolerances.


The numbers are:-

Vin Vout
pot open(max) half open pot closed (min)

2.64 7.53 5.25 2.59
3.92 7.74 5.42 3.87
5.33 7.83 5.58 5.27
6.62 7.90 6.36 6.54
7.89 7.85 7.45 7.80
9.26 8.70 8.73 8.88

Resistances measured as:-

R1 91.5 kohm
R3 too high for my meter, or I'm doing it wrong!
R4 3.45 k
R5 22k
R6 16k
R7 14.5k (the pot!)

From other threads the 14.5k for the pot seems low, and should be nearer 20k. Could this be the culprit

Thanks,

Phil

Can you provide us your order number. We will send you a replacement. That is not how it should be working.

With no load Vout should go to voltage limit which is set around 32V.

Wayne

The results above were with the 3x P4 load, however I just checked the no load Vout and it's about 16V.

The order number is 15679.

Many thanks.....

Phil

The blue shark appears to have an assembly problem.

The problem appears to be IR reflow temp inconsistant around the IC causing failure to fully solder some of the pads of the main IC.

Starting a week or so ago I have been inspecting every blue shark before the copper C is installed and I have been rejecting more than 50%. Not sure if the ones I rejected were actually bad, but, I'm not taking any chances. Anything that was rejected I manually touched up the suspected bad joints and put them back into stock.

This I believe has resolved many of the blue shark issues and it the root problem is the 2oz copper PCB. 2 oz copper takes more heat/time and I don't believe they dialed in the IR reflow oven to take the 2oz pcb into account. I believe it was run as 1 oz standard pcb process. Also, it is unknown where they were in relationship to location on the panel. Finding the pattern before they depanelized could have identified the actual IR temperature profile and could have been compensated for.

Anyway, the rest of the blue sharks in this batch will be inspected and touched up as needed.

Wayne