Whelen power supply buzzing like angry bees

[ur20v]

Earlier this year I was able to get my hands on a mini Advantedge strobe bar. Aside from being dirty, the bar was in pretty good shape, but when I went to power it up, the power supply just buzzes. Seeing as it's almost 30 years old it doesn't surprise me, but I'd like to repair it or get it repaired if possible. I have a couple Whelen Competitor Series power supplies and was going to try and verify the tubes weren't bad, but the gender of the power cable in the bar is opposite of the gender on the CPS690... The tubes look pretty good for being made in 1994! (The reflectors are a bit dusty because I've had the domes off the bar for months)

Any suggestions about what to do to test or repair the power supply, or common problems to start with?

 

[RS485]

The VPPS6C is potted, right? I don't think there's much chance of repairing it, unfortunately.

 

[JohnMarcson]

The VPPS6C is potted, right? I don't think there's much chance of repairing it, unfortunately.

Agreed. When the one in my fluted dome dual 360 strobe responder did this it was a paperweight. If the tubes aren't bad then this supply needs to be replaced.

 

[ur20v]

Oh well. I didn't realize it was a sealed unit.

 

[JohnMarcson]

Oh well. I didn't realize it was a sealed unit.

Yeah, it was a bummer when they started doing that..

 

[ur20v]

I found a NOS replacement on fleabay for $30. Hopefully the capacitors are still "elastic"!

 

[Pete L.]

When you get it, don't forget to power it up first time without any tubes plugged in.
It was probably sitting for awhile.

 

[Nolines]

When you get it, don't forget to power it up first time without any tubes plugged in.
It was probably sitting for awhile.

Not to sound stupid on this and I probably forgotten the reason why but can you post the reason why to do that Pete??

 

[JohnMarcson]

Not to sound stupid on this and I probably forgotten the reason why but can you post the reason why to do that Pete?

In theory people have said powering it on when not under load is easier on the system if the capacitors need conditioned. I have heard this before but can't really see how that would work. Seems like just powering it up with known good tubes should be fine. I always test power supplies on known good tubes and never have a problem.

@RS485 , any thoughts on "dry firing" a lower supply with no tubes the first time you power it up?

 

[RS485]

Quoting from page 45 here:

https://www.csobeech.com/files/WhelenInstallManual.pdf

"WARNING: Strobe light power supplies are meant to be used, not to
remain in an inactive state. Use them at all times, this will improve their
proper functioning. Any strobe light power supply that has been out of
service for a long period of time is subject to failure because the elec-
trolytic condenser loses the polarity formation. A strobe light power
supply not having been used for one year or longer is vulnerable to
failure, applies to 1993 & older units.
If this is the case, it is recommended to start operating the system on
a voltage that is reduced by 25 percent for 10 to 15 minutes before
putting the power supply into normal service. This will prevent over-
heating of the condenser while they reform. If the power supply, after
a long period of non use, is operated at full voltage immediately, there
is an excellent possibility that the condenser will become overheated."

I would not run the PS (tubes or no tubes) for any length of time without a meter measuring cap voltage.

 

[Pete L.]

I remember seeing those exact words posted here on ELB but that was a few site upgrades ago.
I was heavy into Edge 9000/9M bars at the time so I think it saved me some money and frustration.

 

[RS485]

I remember seeing those exact words posted here on ELB but that was a few site upgrades ago.
I was heavy into Edge 9000/9M bars at the time so I think it saved me some money and frustration.

Perhaps you were remembering @dmathieu's post here?:

Question about older powersupplies

Hi there! I wonder how often old powersupplies should be activated when they are unused for a long time ?? I have heard that they should be activated every now and then so that they don´t stop to work... I have many lightbars with quite old powersupplies inside and is wondering if I can...

elightbars.org

It does state that flash tubes should be removed but it looks like Whelen changed that part of the recommendation at some point (they also added the qualification of, "applies to 1993 & older units")

I think the key part common to both iterations of the recommendation is running at 25% reduced supply voltage no more the 15 minutes.

Also, that part about, "1993 & older units" seems to imply any PS made after that point should be immune to this problem.

 

[JohnMarcson]

I had seen the "use it or loose it" warning before, and I certainly have advocated for running power supplies frequently... I had never seen the "with no tubes attached" part (that was later deleted). I assume that applied more to older supplies since it was later dropped. I still can't figure out how that would matter. It's interesting... Any thoughts?

 

[RS485]

I had seen the "use it or loose it" warning before, and I certainly have advocated for running power supplies frequently... I had never seen the "with no tubes attached" part (that was later deleted). I assume that applied more to older supplies since it was later dropped. I still can't figure out how that would matter. It's interesting... Any thoughts?

I'm using:

https://www.nichicon.co.jp/english/products/pdf/aluminum.pdf

as a source of information.

It states, "The DC voltage that is applied to the foil to oxidize the anode foil is called "Forming Voltage". The thickness of the dielectric is proportional to the forming voltage and measures approximately 1.3X10-9 〜 1.5X10-9 m/V"

I take from this that under laboratory conditions, discharging the cap (flashing the strobe) is extraneous to the process of re-forming the cap.

However lets consider this case - we have a "really old" PS with no cap-voltage sensing/clipping.
Unbeknownst to us, the caps are in pretty good shape. We follow Whelen's advice as of '81, remove tubes but forget to run the system at %75 supply voltage. What are we doing? We're _overcharging_ the caps.

I'm guessing Whelen deleted the advice of removing the tubes for protective or defensive reasons.

Under ideal conditions, flashing the tubes doesn't help the reforming process...but just letting the tubes flash might avoid problems in certain edge-cases.

 

[JohnMarcson]

I'm using:

https://www.nichicon.co.jp/english/products/pdf/aluminum.pdf

as a source of information.

It states, "The DC voltage that is applied to the foil to oxidize the anode foil is called "Forming Voltage". The thickness of the dielectric is proportional to the forming voltage and measures approximately 1.3X10-9 〜 1.5X10-9 m/V"

I take from this that under laboratory conditions, discharging the cap (flashing the strobe) is extraneous to the process of re-forming the cap.

However lets consider this case - we have a "really old" PS with no cap-voltage sensing/clipping.
Unbeknownst to us, the caps are in pretty good shape. We follow Whelen's advice as of '81, remove tubes but forget to run the system at %75 supply voltage. What are we doing? We're _overcharging_ the caps.

I'm guessing Whelen deleted the advice of removing the tubes for protective or defensive reasons.

Under ideal conditions, flashing the tubes doesn't help the reforming process...but just letting the tubes flash might avoid problems in certain edge-cases.

Really good point. It absolutely sounds like something that from a lab standpoint would make sense but from a practical field standpoint doesn't.

 

[Nolines]

Yeah but how do you run them at 75% power if you don't control the power to it You just hook up 12 volts flip the switch or plug it in and it does the rest..

 

[JohnMarcson]

Yeah but how do you run them at 75% power if you don't control the power to it You just hook up 12 volts flip the switch or plug it in and it does the rest..

I always took this to mean 75% input, i.e. 9vdc. I'm not sure if that's right though. I tried it with a few power supplies and the old ones came to capacity (measured at capacitors) slowly and eventually fired. Later ones either work normally or don't work at all. That would correspond with the fact that the literature stopped recommending the procedure.

I would say running your strobes every so often at normal voltage is the easiest and best practice. When I get a new to me old supply I generally just start at 6vdc and slowly turn the voltage dial on my bench supply up. I also have a thermal camera and I watch for overheating if it's a valuable one. I will also say that power supplies are usually working or not. About half the non-working ones are bulbs, and most of the rest need a component already.