Wheelock 7002 Strobe Issues

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VibratoneKing
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Hi there, got a quick question.

Picked up a Wheelock 7002-24 a couple weeks ago to dump into the collection. Grabbed a couple 9-volt batteries and gave it a quick run, but to my dismay, strobe's not firing and the horn's not skipping; the horn does sound though. Replaced the capacitor as it had a discolored bulge on it-figured it'd died, plus it didn't seem to be holding a charge. Still nothing though, honestly not even sure where to probe on the strobe circuit to check. Anyone happen to have a schematic on the strobe circuit or have any suggestions where to start troubleshooting?

Thanks!

Photos for reference (apologize for the quality)

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Simplex 2903-9101
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One of the first things to do is try it on three nine-volts rather than two. If a 7002 or 7002T hasn't been powered up in a while, the strobe will take a long time to charge (5 to 7 seconds). It'll take even longer if you're underpowering it.

The first time I bought a 7002 (a newer version), I thought it was broken for the first three seconds before it started flashing at the normal rate. Here's an older one that flashes slow and took REALLY long to start flashing:



If simply waiting doesn't work, then you'd have to defer to one of the circuit wizards on the forum.
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VibratoneKing
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Simplex 2903-9101 wrote:
Thu Jul 30, 2020 10:50 pm
One of the first things to do is try it on three nine-volts rather than two. If a 7002 or 7002T hasn't been powered up in a while, the strobe will take a long time to charge (5 to 7 seconds). It'll take even longer if you're underpowering it.

The first time I bought a 7002 (a newer version), I thought it was broken for the first three seconds before it started flashing at the normal rate. Here's an older one that flashes slow and took REALLY long to start flashing:



If simply waiting doesn't work, then you'd have to defer to one of the circuit wizards on the forum.
I was running it on three, although I will definitely try to cycle it and give it some time! I'm not too familiar with strobes and I especially wasn't aware it may take a fair bit of time to charge 'em up. I highly doubt this horn has been used in a while.
"We were fortunate to be there a day or two before 'the big bang' and then we got the heck out of town."

-Scotty Moore
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VibratoneKing
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Cycled it for a solid 30+ seconds and got a strobe fire and a skip, but nothing else. With the lens off, I cycled it and found that the large component below the strobe tube (gray colored glass(?) tube, somewhat to the left) is internally arching every time the strobe should fire. I'm not exactly sure what that component is? It reminds me of a very small vacuum tube; I imagine it's not supposed to be arching. Any thoughts?
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Simplex 2903-9101
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If it looks anything like the tiny bulb on the back of the 2903 strobe plate, I wouldn't say it's not supposed to arc.

Because of how the 7002's strobe works, the strobe frequency is semi-dependent on the horn frequency. If your horn is low-pitched and you're okay with it going a bit higher, it might help a bit to tighten the volume screw until you get up to about a "B" note.

There IS a way to change the flashrate independently of the horn, but I'm not entirely sure how.
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VibratoneKing
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Simplex 2903-9101 wrote:
Mon Aug 03, 2020 10:59 pm
If it looks anything like the tiny bulb on the back of the 2903 strobe plate, I wouldn't say it's not supposed to arc.

Because of how the 7002's strobe works, the strobe frequency is semi-dependent on the horn frequency. If your horn is low-pitched and you're okay with it going a bit higher, it might help a bit to tighten the volume screw until you get up to about a "B" note.

There IS a way to change the flashrate independently of the horn, but I'm not entirely sure how.
Interesting, didn't know frequency played a role in the horn's function. If I recall correctly, I believe my horn is actually higher pitched than a B note, albiet just slightly, so I'll have to play around with it and see what I can get. I figured I could go through and replace every piece in the strobe circuit, although I dunno what half of the components on the board are. I do have a 7002T-24 sitting around-I don't know if there are major differents in the circuitry between the 7002 and 7002T, though I may see about swapping out the entire strobe circuit if everything lines up.
"We were fortunate to be there a day or two before 'the big bang' and then we got the heck out of town."

-Scotty Moore
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