Xenon Strobe Repair, troubleshooting the circuit

Hello,
I have an old xenon strobe (disco light) that had been stored for a very long time and when I tried to turn it on recently, it no longer worked. I first assumed it was the xenon tube bulb so I replaced it but it still does not work.

I opened it up (circuit was inside wood box) to try and measure voltage at different points to see if I could determine any current interruptions but as soon as I plugged it in, there was a point on the back of the circuit that lighted up (burning) and even some smoke came out. I immediately unplugged it.

Searching information on this I found this topic: http://www.aaroncake.net/Circuits/strobe2.asp , and it seems like my circuit is very similar. The burning came from one of the terminals on what seems to be the 4KV Trigger Transformer (see red arrow on attached photos).

I am no electronics expert (I do own and can operate a multimeter), and that is where I would greatly appreciate any support on this forum, is there a way that I can troubleshoot this circuit to get it working again? Any suggestions or ideas?

Thanks on advance for any comments.


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Standard "Radio Shack" strobe

First, clean that arc with a brush and acetone. Then dremel into the board and get rid of all the carbon or it'll arc over again.

Second, replace the electrolytics, they'll be dead by now.

Finally, give the pot a squirt of control cleaner.

Cheers!

yeah ... looks like arc-over from the hv trigger .
there may have been some crud on the board or a "dead engineer" .
clean the board up , maybe back-fill with some epoxy ... and as geek said : replace the electrolytics .

Thank you for the suggestion. I remember getting this at one of those Spencer Gifts stores that are in shopping malls, back in the 80s. I assume that Radio Shack had or has something very similar.

Can you please describe which ones are the electrolytics? Is there a way that I can test them to ensure they are bad? Would there be any other element that could most likely be bad?

Thanks,

Thanks!

The big gold things.

22uF @ 250V is a standard value. A local TV repair shop is likely to have them.

Axial is rare nowadays, so you'll probably have to use radial (ones with leads on the same end) capacitors.

They are old and been in storage... trust me, they're dead or dying.

Maybe, but the caps are the most likely suspects.


Cheers!

^ Replacing an axial with a radial might look like this:



Stick one lead in the board, run the other back to the other side. If your capacitor doesn't have long enough leads (as mine didn't -- the original was long!), you might need a pigtail wire (red) to extend it.

Tim

Oh and mind the polarity as you replace them. Reversing the polarity turns them into nasty little explosives

yep ... tell me ... about 6" from my head ...
not my fault (directly) , the guy that borrowed my meter (analogue) swapped the red and black leads .
i checked a power supply and went by what the meter indicated for polarity .

@ OP :
post back with the electrolytic caps that you want to use as replacements .

Thanks for the warning!

Ok, I scraped away the carbon area between the lines and even put some nail polish on it (I read somewhere that this was a good insulator - ???). I placed the xenon tube back in and powered up. The arcing burn is no longer there! ...however, no strobe flash.

So, I got rid of that issue (thanks again for the advice!), now I just need to get the circuit to flash that tube again.

The current electrolytic caps on the circuit read: 22 uF, 250 WVDC

As replacement for the electrolytic capacitors, I found these online from a local store:

Electrolytic Capacitors
The specs are:
- Radial
- Aluminum
- 22 uF, 250 Volts
- 13 x 29 mm.

I assume that these will do the job, right? Or, is there anything else that I should consider when looking for the replacement?

Thanks!

the voltage and uF is correct ... no telling who made them or the specifications .

about the only thing i would question is the "duty cycle" of the replacements .
the original caps are the sprauge brand ... and if memory serves me correctly that particular variety was made to withstand considerable loading/discharge/high ripple currents .

install the new caps , run it for a minute (hopefully it fixes the no-flash bit) at a high rate , shut it down and feel the caps with your finger ...
if they are warm ... your replacement caps are not adequate .

Thanks, I will try that and report back.