Reviving old flashes

Fast14riot · Oct 2, 2013

I remember reading an article outlining a generally safe procedure for easing a long dormant flash back into life so as to not fry the capacitor right from the start. I think it was on Strobist, but I completely went through the article index and couldn't find it. Google searches were equally unhelpful.

If someone has either a link to a good article or has experiance with an idea of how to handle this that would be a great help.

Thanx in advance.

-Xander

Tom1956 · Oct 2, 2013

I think a lot of that talk is nonsense.Not entirely though. I'd say to put some older batteries in it and run it a little, let it sit, run it some more, and repeat several times till one time when you see the ready light, and turn it off to sit. It ought to work out OK. If the capacitor is that weak, may as well find out now.

Gerald C Koch · Oct 2, 2013

Some years ago I looked into fixing a beloved flash unit. The problem I encountered was trying to get a capacitor that would fit in the space of the old one. The ones that would work electronically would not fit geometrically. I came to the conclusion that it was just not worth the trouble.

BTW, even the charge in a weakened capacitor can be very dangerous. All the is necessary to stop your heart is a few milliamperes of current propertly delivered.

wombat2go · Oct 2, 2013

Hi Xander,
You are referring to a method of "reforming" the dielectric of old electrolytic flash capacitors.
The method has merit but in the case of old flashes, might not be worth the trouble.
I have lots of old flashes going back 35 years, so far never a failure.
The old flashes have little value, pulling them apart is no fun and it is likely to result
in consequential damage like broken wires ( or worse a fracture that does not quite break till later)
or lost parts.
If you want to treat a capacitor gently, use a partially discharged set of batteries initially,
"blip" the on switch - off and wait a few minutes, repeat over an hour or so till the neon is on.
I never bothered to do this, but i do run all my old flashes every 3 months or so.

Fast14riot · Oct 2, 2013

My main concern is I am acquiring a Leica with a leitz/braun flash. It isn't very old age wise, but probably hsnt been used in years. I don't want to just fry it right from the start so looking for more of a soft start routine just to play it safe.

I really have no intention of opening the flash to start off, I'm not comfortable enough with safe handling of caps, but just want to try the option of a safe start.

I appreciate the responses guys! I will try with an old but not dead set of cells to start and ramping up the time on the cap for a while.

-Xander

Truzi · Oct 2, 2013

A camera flash that isn't going to have enough amperage to kill you, but it can bite pretty hard (been there). If you get shocked by it, you might swear off working on it again - and you will probably swear.

It is easy to short a cap to discharge it, and then you will be safe.

The worse part would be trying to de-solder the capacitor, then solder a new one in, without damaging the unit with the soldering iron. I've not fixed a flash, but there is not a lot of room to work with.

That said, I'd just load some batteries like you intend. There is a good chance the unit will be fine.

wombat2go · Oct 2, 2013

Truzi said:
It is easy to short a cap to discharge it, and then you will be safe.
.

No, any of the higher energy capacitors should only be discharged though an adequately rated resistor
Both to protect the operator, and the capacitor's life.
For an average flash capacitor, let me say a 10,000Ohm 20 Watt resistor , or similar, commonly available eg at radio shack
with insulated leads, let it remain connected directly across the capacitor till dc voltage is less than 12 V, and wait 1 minute longer.

Truzi · Oct 2, 2013

I was going to mention a resistor, but would have been too tempted to go down the path of the resistance of human skin, etc.
Oops...

Fast14riot · Oct 2, 2013

Good to know ^^ but, again, I have no intentions of opening it up. I have plenty of other flashes I could use, but I just hate to potentially ruin a flash by throwing new batteries in there and just firing away.

Other flashes I have that were purchased after 4-5 years of non use have always fared fine, but there's a good chance this one hasn't been used since the late 90's.

-X

MattKing · Oct 2, 2013

New batteries aren't likely to hurt the flash - as in damaging it where old batteries wouldn't.

They are just unlikely to help it if you are trying to nurse it back to operation.

I would have different advice if you were talking about a flash that uses a high voltage, over the shoulder battery pack.

Mike Wilde · Oct 3, 2013

Low tech solution if it is a battery powered flash - turn it on with fresh batteries, and leave it on at first without discharging the flash immediately.

I would suggest 20 minutes on standby, pop the flash once on manula, reduced power if there is a way at first, then shut it off and repeat this for a few days.

This is a low tech way to reform electrolytic capacitors.

I have a poweredful older line powerd studio flash, a Speedotron 2401.
With it you can actually hear little arcs and snaps from time to time for the first 20 minutes of conditioning, if the flash has not been used for a while.

I am not super diligent, but I do try to condition the studio flash pack every three months if it has been otherwise idle.
The power packed into the big caps in thia unit can leave a a lot of havoc behind when they blow. I have seen some fried examples at the repair depot over time.

Mike Wilde · Oct 3, 2013

To further Matt's comments , bigger flash do well by slowly building the supplied DC voltage to them if they have been idle for a while.

Fast14riot · Oct 3, 2013

That's good to know too, I have some studio strobes that haven't been used in a while, I'll be sure to do that.

This has been a very helpful thread! I understand that this won't really wake up a dead cap, but its good to know it won't hurt an old one.

-Xander

mr rusty · Oct 3, 2013

Please treat flash caps with caution. Once I shorted a flash cap with a screwdriver expecing just a little spark. The bang was something else. Sure won't be doing that again in a hurry.

Mike Wilde · Oct 4, 2013

I have a straight bladed screwdriver with one corner that has been vapourized away. It dissapeared with a sound akin to a shotgun being discharged right next to my ear.
I keep it in the tool bag as a reminder to not be so stupid again

The next time I serviced a flash I was sure to bleed off the cap by shorting it though a 1 megohm resistor for a few seconds.
The one that blew the screwdriver and my hearing temporarily had been powered off overnight.

wombat2go · Oct 4, 2013

Mike Wilde;1554109 by shorting it though a 1 megohm resistor for a few seconds. .[/QUOTE said:
That will hardly begin to discharge a typical flash capacitor of 250 uF charged to 300 Volt
(See my earlier post)
The way it works is, Time constant [seconds] = Resistor {ohm] * Capacitance [Farad]
The capacitor will still have 33% charge (say 100V) after being discharged for one time constant so you have to leave the resistor on for about 6 times longer

Take care!

Steve Smith · Oct 4, 2013

wombat2go said:
For an average flash capacitor, let me say a 10,000Ohm 20 Watt resistor

On valve (tube) equipment with similar voltages, I usually put a 100K bleed resistor on one of the capacitors. It only needs to be about 1 watt rating.

Steve.

wombat2go · Oct 4, 2013

Steve Smith said:
On valve (tube) equipment with similar voltages, I usually put a 100K bleed resistor on one of the capacitors. It only needs to be about 1 watt rating.

Steve.

Typical Flash 250 uF 330 V Nom initial discharge power = V^2/R = 330 *330/100000 = 1.1 Watt
1 Watt might be OK for tube Hi Fi etc where the voltage is lower.

i prefer the wirewound with safety factor and posts so the insulated leads last longer before breaking off
a 20 W resistor is OK right up to 1 kiloVolt ( I work with industrial capacitors too)
The high potential capacitor testers usually have an inbuilt discharge which is safer than messing around with clip leads etc.

Fast14riot · Oct 12, 2013

Well to give an update. I received the flash and loaded an old set of cells in it. They wouldn't even get the cap to make noise at first, so a good thump or two got it going. The cells were further drained than I had thought, wouldn't even bring the flash to ready, so I just left it for 30 minutes to sit. It finally got enough juice for one last flash. Switched the batteries out for a fresh set from another flash and it ramped up pretty good but again not right away. After doing the flash and sit routine for half a day it seems to be just fine now with fresh cells!

Its not a very advanced flash, manual push/pull zoom, decent power range and 180 degree pan/tilt head. The bounce reflector is something I haven't dealt with before, its clear with a matrix of silver ovals on it. The color cast is quite nice though. It'll just be another working piece of kit now.

Thanx all for the help!

-Xander

vsyrek1945 · Oct 12, 2013

Reforming Speedlite Capacitors

Some time in the distant past, when I was still buying new gear, I read the owner's manual for a Vivitar unit [could have been a 283 or 285] that had a section devoted to reforming the unit's main capacitor after a long idle period. As I remember, the procedure was to load fresh batteries, switch the unit to manual and full power, power on, let the unit light its Ready lamp for thirty seconds before pushing the Test button, and repeat for a total of five cycles. The first charge cycle could take long enough for you to get real antsy, holding the unit close to your ear to be sure the voltage multiplier oscillator circuit was working, but by the fifth time around, the unit would be recycling in a much more reasonable time.

I just took delivery today of an 'AS-IS' Sunpak 611 that was marked 'won't power up' and ran through the procedure after running an emery board across the battery cover contacts. The unit needed a few more than five flash cycles before lighting up its 'FULL' indicator lamp, but it looks like it will be OK for use.

Best regards,
Vince

Tom1956 · Oct 12, 2013

vsyrek1945 said:
Some time in the distant past, when I was still buying new gear, I read the owner's manual for a Vivitar unit [could have been a 283 or 285] that had a section devoted to reforming the unit's main capacitor after a long idle period. As I remember, the procedure was to load fresh batteries, switch the unit to manual and full power, power on, let the unit light its Ready lamp for thirty seconds before pushing the Test button, and repeat for a total of five cycles. The first charge cycle could take long enough for you to get real antsy, holding the unit close to your ear to be sure the voltage multiplier oscillator circuit was working, but by the fifth time around, the unit would be recycling in a much more reasonable time.

I just took delivery today of an 'AS-IS' Sunpak 611 that was marked 'won't power up' and ran through the procedure after running an emery board across the battery cover contacts. The unit needed a few more than five flash cycles before lighting up its 'FULL' indicator lamp, but it looks like it will be OK for use.

Best regards,
Vince

That 611 is a great flash. I've had mine since '76.

Steve Smith · Oct 13, 2013

wombat2go said:
Typical Flash 250 uF 330 V Nom initial discharge power = V^2/R = 330 *330/100000 = 1.1 Watt
1 Watt might be OK for tube Hi Fi etc where the voltage is lower.

1 watt is enough because it's 100K rather than 10K in your first example. The voltages are similar.

Steve.

vsyrek1945 · Oct 14, 2013

[Some] Old Flash Units Never Die . . .

Tom1956 said:
That 611 is a great flash. I've had mine since '76.

I didn't know the 611 went back that far - I thought it was mid-80s vintage. Mine came without the clamp and bracket, so it'll be a while until I get to shoot with it.

I find it interesting that a lot of thyrister-based units from that era are still going strong after 35 or more years: in addition to the OEM lines, units from Achiever, Starblitz, Sunpak, Vivitar, Metz, and other brands [as well as some off-brands] that have slipped my mind are proving to be virtually bullet-proof as long as they've been used periodically and stored without deteriorating batteries fouling up their contacts.

TBN · Oct 14, 2013

The Strobist article can be found here:

http://strobist.blogspot.dk/2013/06/how-to-keep-your-old-flash-from.html

Reviving old flashes

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