I can dig out a good deal of Whelen history, but when it comes to the technical/electronic aspects @RS485 is your guy. He has saved several of my supplies and provided the most detailed info I have ever found on strobe power supplies.
I love that they gutted a senior rotabeam/deputy and added an aircraft strobe. The more this thread continues the more it really shows how Whelen products (both strobe and otherwise), and all emergency vehicle strobes in general, were born from the aviation industry.
I believe its the black with yellow potting (bottom-right in your pic)...sorry I didn't show one of those in the pic 'cause I don't have one
Ah! Okay -- fingers-crossed, that it! Note the "H0574" on the Hutson HS44 SCR -- I believe that means it was mfg fifth week of '74!
So in the end, were the only things wrong, the disintigrated diode and dirty connectors? Or did you need to mess with the caps? (also, was there any difference in behavior between the first diode you put in and the harvested/correct one? If so do have a part number on that first diode you used? Thanks!
. On closer inspection the very faded band does say 5200, not 3200. It is a single head later 5200 on a cast base. It has a power supply from between the "traditional pie pan" and last gen "edge on a pie pan". It has a date of 1986, which makes perfect sense. It defaults to high power and the purple wire puts it into low power. Here are some pics of the supply, a video is in the works.
it is interesting that Whelen used modified edge supplies for several different generations of these beacons. I suppose that makes sense, why have multiple different components when you can reuse working tech.
This is what I was starting to wonder after you explained the inverter cut off. There is a little variation in between the "two clear sides", but I agree it is pretty close to being engaged or not, i.e. two basic rates. Thanks for clearing that up. I am amazed it came back to life, but you have shown me enough tricks to try that I will continue shocking myself in a variety of flash patterns for years to come.I do see what you mean, that it does change the FPM but still, that dial controls the point at which the inverter is turned off (based on cap charge level).
You can hear up to a certain point, it has no effect (because the flash discharges the caps before they ever charge up enough to cause it to kick in). But then at some point, it kicks in and starts to clip and at that point, the more you turn, the sooner it kicks in and clips.
Ideally, it shouldn't clip unless the tube is no good.
Matter of fact, to my ears there's only two different FPMs there....one when clipping _is_ kicking in, and one when its not.
Thanks for posting the vid for me to see what you're seeing
BTW: Kudos to you for bringing those caps back to life! That was cool!
That capacitor was leaking everywhere or at least had been so I'm going to swap it out. It's not on the picture of the board I'm going to upload here. But I believe you may be right about the transistor. I'll do some more digging
Yes, the cycle is a tad longer and voltage higher. I replaced the capacitors too just in case. They seem to loose voltage very fast for having not fired...even the new ones.
So listening closely to your vid, I hear a pattern of "thumps" (not "clicks") that would seem to be in-line with the flash triggering. If this is accurate, it tells me the AEI-219 is sending the SCRs timing pulses so we don't need to worry about the timing. The only thing left is triggering.
