RESTART OLD BRONCOLOR PULSO

[angelo_photoworkers]

I own several pulso 2-4-8 generators that for various reasons have not been utilized for decads.
I would like to know what procedures should I follow to start them up again re-forming the electrolytic capacitors.
I was thinking to give them a slow start, beginning with the lowest power level to increase it gradually to the maximum.
Therefore I contacted Broncolor-Swiss, they told me:
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Start in slow charge mode, with the lowest power and increase it to the maximum.
When you start the unit on the lowest power in slow charge mode, you have to stay at this level for about 1 hour, than make a few flashes about 10.
Then increase the power 1 f-stop and do the same procedure as on the lowest power until you are on the highest power level.
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Do you agree with them?
Another question for pulso users:
How can I set "slow charge" and the lowest output-power?

I guess the best procedure is:
- insert the plug into the wall socket
- press "slow" pad
- press "-" pad to set the lowest power (display shows 6)
- press "on/off" pad to start the charge of the capacitors

Obviously this procedure assumes that "slow" pad and "-" pad will work AFTER INSERTING THE PLUG AND BEFORE SWITCHING ON THE UNIT WITH "ON/OFF"PAD.

If this is is not true I am afraid that the charge will start in fast mode and that the output-power is not set at the lowest level.

Thank you in advance for your kind advice.
Angelo

 

[Leigh B]

Hi Angelo,

The failure mode for vintage electrolytics is well-known and very predictable.

Internal electrical leakage generates heat, causing moisture in the electrolyte to turn to steam.
Steam pressure builds up over a short period of time until it blows the safety vent.
At that point the cap is dead and must be replaced. It cannot be re-formed

To re-form a cap that's not yet failed, apply power for short periods, short enough that the pressure doesn't rise.

The process I use is as follows, done every day at noon for a week.
Power the unit up for one minute, then off and leave it off until the next day.
For the next six days, double the ON time each day, i.e. 2, 4, 8, 15, 30, and 60 minutes.

At the end of the week, the re-form will either be successful or the cap(s) must be replaced.
If at any time the fuse or circuit breaker blows, the cap(s) must be replaced.

If multiple caps are used in parallel, they must all be replaced with identical units.
You cannot replace just one or two in a set.

Re-building works because the insulating layer rebuilds itself when power is applied.
This process takes time. It's not instantaneous. As the layer rebuilds, leakage current decreases.

Be very careful when working with high-voltage equipment.
The fact that you mentioned re-forming indicates that you are at least somewhat familiar with this activity.

- Leigh

 

[angelo_photoworkers]

Hi Leigh,

thank you for your accurate reply.
the process you use seems me fine!
an information: after each capacitor-charge, do I have to fire the flash?
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I wrote for infos to Bron (IT), they told me:
after this long period of inactivity
- avoid to charge the power packs using mains current (220V in Italy)
- connect the generator to a voltage variator starting from low voltage and increasing (very slowly) to reach 220V.
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Therefore I suppose they don't open the generator and don't re-form each capacitor,
I think they simply give the generator currents of increasing voltage.
Do you know what are the best steps to increase the voltage?
I supposed that the generator don't work if it was connected to very low voltage...

Do you think it is better to start in "slow charge", beginning with the lowest power level?

Thanks in advance.
Angelo

 

[Leigh B]

Hi Angelo,

No, I do not recommend firing the flash.
All flash power supplies have internal bleeder resistors that will discharge the capacitors if you simply turn them off.

A variable voltage source would certainly be desirable if you have one.
Here in the US those are known by the brand name Variac, which was invented by General Radio.
I'm sure there are comparable devices available in Europe. You could use a 220-volt Variac if you can find one.

The procedure Bron suggests is an alternate method of re-forming the capacitors.
It may well be preferable if you don't mind spending a lot of hands-on time with the equipment.

The really correct way to do it is to monitor and limit the charging current going into the capacitor(s).
I designed a constant-current source to do this. It supplies 1 milliamp of charging current regardless of voltage.
Here's a schematic: http://www.atwaterkent.info/Images/CapFormerSchematic.pdf

Doing the same thing by hand can take a long time.

Unfortunately, any of the "proper" re-forming methods require you to take the capacitors out.
Then you can hook them up to a proper test jig and power supply, and monitor voltage and current.

- Leigh

 

[pdeeh]

It seems you've been given very clear information by the manufacturer themselves.
It occurs to me to ask, Why do you think anyone here would have more accurate information?

 

[Leigh B]

It seems you've been given very clear information by the manufacturer themselves.

In fact, the instructions from Bron are quite incomplete.

The critical factors in any capacitor re-forming operation is the magnitude of current flowing into the capacitor.
Bron did not mention that at all.

Using the Bron method without that measurement can blow up a capacitor.

And your experience with the re-forming activity is what?

- Leigh

 

[angelo_photoworkers]

Hi Leigh!



I appreciate a lot your procedure to monitor and limit the charging current going into the capacitors.
Great your equipment supplying the constant - current source (1 milliampere!)

Frankly having no experience in disassembling power packs, I prefer don't open the generator (having Pulso8 6400 Joule…) and work with each capacitor…
Therefore I'll prefer a re-forming methods not requiring that I take the capacitors out.

I 'll use your procedure, but I have some questions:
1)is it better use 220V source or use a variac before the generator?
2) if you prefer to use the variac,
- will the Pulso generator start at low voltage?
- at what voltage will you start the procedure?
- can you tell me every step (voltage, time, etc.)?

Thanks in advance for your competence and kindness.

Best
Angelo

 

[Leigh B]

Hi Angelo,

I'm afraid I'm not familiar with your Pulso equipment, and have no schematic of it.
So I can't answer whether or not it would work at reduced voltage.

You can try it. If it doesn't work, that should be obvious.

If i does work, I would start with half voltage for the first two days (1 minute and 2 minutes).
Then go to full voltage for the remaining days.

I don't think it will make any difference, but it does not hurt to be cautious.

- Leigh

 

[ced]

How many lamps can be connected to the Pulso and if more than 1 does it need the same amount of capacitors as there are lamps?
Then do all the lamps need to be connected to do the recapping?

 

[angelo_photoworkers]

Hi Leigh!

Thank you for your reply.

you told me:
"If it does work at reduced voltage, I would start with half voltage for the first two days (1 minute and 2 minutes).
Then go to full voltage for the remaining days."
OK!

you told me:
"The procedure Bron suggests is an alternate method of re-forming the capacitors.
It may well be preferable if you don't mind spending a lot of hands-on time with the equipment."
Frankly I think that the procedure Bron suggests is a faster and a more commercial one (not better than yours)…
I prefer yours…

I agree with you:
"The really correct way to do it is to monitor and limit the charging current going into the capacitor(s)."
Unfortunately I prefer don't take out the capacitors to avoid any accident…(having Pulso8 6400 Joule…).
you told me to start with half voltage (working with unopened generator):
in this situation is it important give a constant-current the to power pack?

Bron made two Pulso of different voltage (220V and 110V).
Do you think that the electronic control-system (microprocessor working probably at 5V) will work if the power pack is connected at a lower voltage?
in other words: is it better
- to connect to 220V (having microprocessor working)
- or to connect to lower voltage (having microprocessor working or NOT…)???

You know that a capacitor is in a "short circuit" condition at starting therefore and I'm afraid for the dielectric if intensity and voltage are not OK...
what do you think is the best procedure? (variac or no-variac?)

Thank you in advance for your expert advices.
Have a happy new year!
Angelo

 

[Leigh B]

Hi Angelo,

I doubt that the microprocessor and related circuitry would work properly at half voltage.
Those circuits are normally powered from a supply that includes a transformer to reduce the line voltage to a suitable level.
If the line voltage is halved, the transformer output will likewise be halved, probably below the working voltage for the circuit.

I do not know (and cannot know) how the circuitry would react to a significantly reduced supply voltage.
I would not recommend running the equipment for any extended period of time under those conditions.

If that control circuit is involved in setting the charge voltage for the capacitors, then it's unlikely you can re-form them in situ.

- leigh

 

[ced]

Hi Lee can you look at my question prior to the last one by Angelo please? Thanks!

 

[Leigh B]

Hi Lee can you look at my question prior to the last one by Angelo please? Thanks!

I saw that post.

I did not reply because I don't know the answer.

- Leigh

 

[ced]

Leigh, thanks!
Angelo, how many lamps/capacitors does the Pulso have and if more than one does this recapping get done for all or just one capacitor?

 

[angelo_photoworkers]

Hi ced!

Pulso generators have four symmetric connector.
I don't know how the capacitors are connected therefore I couldn't give you a reply.

Angelo

 

[ced]

Angelo Thanks! So you think connecting the head to one of the 4 ports that this will do the recap on all capacitors how ever many there are(10)?

 

[angelo_photoworkers]

Hello ced!

Leigh says that is better don't flash any lamp after charging capacitor(s).
therefore I'll connect no-flash-head to power-unit.

best
Angelo

 

[angelo_photoworkers]

Hi Leigh!

do you think there is any risk in following your procedure?
any explotion of the capacitors or dangerous voltaic arc?

Please, can you read too
(there was a url link here which no longer exists)
thank you in advance for your advices.

Angelo

 

[wiltw]

Angelo Thanks! So you think connecting the head to one of the 4 ports that this will do the recap on all capacitors how ever many there are(10)?

'symmetric design' indicates that all connectors are wired in parallel to each other and the available power is divided among the number of heads plugged in...so whether you plug a single head into A or B or C or D does not matter.
Also, one does not need to exercise a capacitor (to store and then discharge)...it mere needs to rejuvenate the insulating layers within the capacitor(s), so storing and holding the charge (once the layer is re-formed) is what it is all about.

For 'assymetric' power packs it is not necessary to re-form each channel independent of re-forming the other channel...you re-from/charge both channels in a single operation. You do not plug a head into Channel A, re-form channel A, then move the head to Channel B and re-form Channel B.

 

[Leigh B]

do you think there is any risk in following your procedure?
any explotion of the capacitors or dangerous voltaic arc?

Hi Angelo,

There's always a risk when working with power supplies that have not been used in many years.
Parts can deteriorate due to many factors. The resulting problems may or may not be obvious.

I routinely work on radios from the 1930s, over 80 years old.
Many of them actually work fine after replacing the electrolytics.
Some manifest various types of problems due to parts just getting old.
Your power packs are newer, but may have similar problems.

The only way to evaluate the packs is to open them up and do some visual and electrical testing.
Guesses about their present condition are just guesses.

- Leigh