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I bricked my Synguider


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Just a word of warning really...

A few days ago, I accidentally plugged in the wrong (12V) power supply to my synguider. I normally use a 5V battery pack but I got the leads mixed up in my excitement to start imaging. After a few minutes I noticed the unmistakable smell of burning electronics but didn't put 2 and 2 together. After another few minutes I heard a loud pop and noticed the synguider screen flashing.

I opened the guider up this morning and this is what I found...

Notice the burned out capacitor. I may try to fix it myself some day.

Anyway...I ordered a new synguider (the newer version) and it should be arriving today so I should at least get 1 night of imaging done!

Dan

Synguider_PCB.jpg

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I thought they were designed to work on 6-16V PSU??? Hence the 7805 regulator on the circuit board... the only thig that should happen is that the volt regulator should get warmer on the higher voltage.... 

Maybe the wrong 12V adapter polarity was reversed from the power that the SynGuider was designed for????

 

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3 minutes ago, MarsG76 said:

I thought they were designed to work on 6-16V PSU??? Hence the 7805 regulator on the circuit board... the only thig that should happen is that the volt regulator should get warmer on the higher voltage.... 

Maybe the wrong 12V adapter polarity was reversed from the power that the SynGuider was designed for????

 

I know...the manual mentions the voltage range but 5V is recommended. I have also read other people using 12V and not having any problems.

Just checked the 12 Volt lead and it is tip positive so that wasn't the problem.

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24 minutes ago, dph1nm said:

Mine never works with 6V, I always have to put at least 9V through it.

NigelM

Weird...my 5V battery pack normally gives out ~4.8V (using 4x 1.2V rechargeable batteries) and the synguider worked well. I wonder how my new syngider 2 will behave.

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Oh no, you let the smoke out, so now it won't work. :crybaby2:

Hopefully, that capacitor was the only casualty.

Generally, different voltages have different sized jacks.  What happened here?

Seriously, back in my electronics lab days, I had breadboarded a circuit and was pushing 5v into a logic input by accident and noticed a faint odor.  After disconnecting the power supply, I touched each DIP to find the hot one, blistering my finger in the process.  Amazingly, the DIP was undamaged (TTL logic).

In another case, a bring-up lab technician messed up the heat sinks on several flip chip mounted ECL logic ASICs and fried a bunch of them nearly instantly when power was applied.

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OK, I'm going to attempt a repair...The C66 capacitor (I think it's 4.6uF) popped and I have read that the original capacitor can be replaced by connecting the +ve and -ve outputs of the regulator with a similar rated capacitor (see the pic). A larger Aluminium electrolytic capacitor was suggested as a better alternative than the original. I will then remove the original tantalum capacitor (crossed out in the pic).

You you think this world work???

Synguider_PCB_repair2.jpg

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If I am right, the 7805 voltage regulator (big silver/black chip with the three pins) has voltage in (left pin) ground (middle pin) then voltage out (right pin). A capacitor connecting voltage out to ground will allow AC current (like ripple/fluctuating current) to pass safely to ground but DC current cannot pass the capacitor and will be allowed to continue to the rest of the circuit.

As for the old capacitor, I checked it with the multimeter and it seems to show high resistance so I could just leave it there...not sure though (I'm not so steady with the soldering iron!)

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You could try to do some continuity checks to see if it's a dead short (~0 ohms) between the regulator pins and the corresponding pins on the burned out cap.  This would indicate a board trace connecting them together.  If so, connecting at the regulator leads should be equivalent to replacing at the cap's original location as long as the original cap shows high resistance.

Caps sometimes have a preferred polarity, so make sure to figure out what that would be before soldering if applicable.

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Why not you just replace the blown cap to be safe? Is not hard to desolder those, and you dont have to worry about damaging it since it's already blown. If you don't have a hot air station, just add a nice blob of leaded solder on each side and put the iron quickly on each side (I desoldered a lot of soic8 chips like this), make sure to use some wick (and flux) to clean before soldering the new one.

The cap is probably 4.7uF, never seen a 4.6 one, and rated 25 or 50v.

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Thanks guys, I have removed the burnt out capacitor and checked the connections, turns out the burnt out capacitor was letting current through some how so I couldn't be sure which side the regulator pins were connected to. Now I am sure the ground (middle pin) is connected to the left side of the capacitor (-ve end) and the right side of the capacitor goes to the left pin (voltage in).

16 hours ago, Louis D said:

Caps sometimes have a preferred polarity, so make sure to figure out what that would be before soldering if applicable.

This is true, I am assuming that the positive end attaches to the V_in and the negative end goes to ground...I'll check this when the new capacitors arrive.

43 minutes ago, wok said:

Why not you just replace the blown cap to be safe?

I could do, but I was thinking of replacing it with a better component, something with a better lifespan.

44 minutes ago, wok said:

The cap is probably 4.7uF, never seen a 4.6 one, and rated 25 or 50v.

My bad...4.7uF is right and the capacitors I have ordered are rated to 50V.

 

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46 minutes ago, spaceman_spiff said:

Well, I got the Aluminium capacitors (4.7uF) today and I soldered one onto the board. All is working and I have no intention of testing it with the 12V power supply even though it is rated to 50V.

Chicken!!!! :evil:

giphy.gif

 

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1 hour ago, spaceman_spiff said:

Well, I got the Aluminium capacitors (4.7uF) today and I soldered one onto the board. All is working and I have no intention of testing it with the 12V power supply even though it is rated to 50V.

You could desolder the regulator and test it outside the circuit with 12v to make sure its giving out the correct voltage. Maybe that's whats not working correctly and killed the first cap.

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3 minutes ago, wok said:

You could desolder the regulator it and test it outside the circuit to be sure its giving out the correct voltage. Maybe that's whats not working correctly.

That's a good idea, if the new capacitor pops that's the first thing I’ll try!

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Tantalum capacitors have a habit of going short-circuit when they fail. 

I'd suspect that the capacitor was at best a 16V rated one, and eventually gave up the ghost.

If it is now working and you usually use it at 5V then I'd leave it all alone. If you accidentally connect 12V again it will probably be okay.

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