Bowens

[andreas_holmstr_m]

Hi guys!

 

I have used studio lights seldom, and now I have bought a used Bowens

400 E with a 100cm softbox, IR reciever/sender, and I wonder if you

could give me any hins on this model, regarding use, service and function.

[garry edwards]

There isn't really much to know. They are a good basic light (very old now) with 5 adjustments settings.

 

The modelling lamp can be on, or off, or can be set to go off when the flash if fired and comes back on when it has recharged, so you know when it is ready to use again.

 

Like other old Bowens units, it doesn't have a slave sensor. A separate slave sensor can be plugged into the top of the unit (the most sensible place to put one) or, as in your case, you can fit an IR sensor instead.

 

The only unusual feature of this unit is that it charges up very slowly when you first switch it on, about 30 secs I think.

 

Hope this helps

[andreas_holmstr_m]

What about startup/warmup?

[iain_b]

I have a couple of these lights along with some 200D's, they may be basic but they are good solid workhorses, and they can actually be repaired fairly easily and cheaply.

 

It takes abut 30 seconds for it to "warm up" - the "slow charge" light will be on, when it goes off, you can fire away.

 

The weakest point is the power changing switch, which whilst it can be replaced, Bowens no longer stock the parts, so you have to find an alternative. To save the switch, do not change the power setting and fire it at the same time, it damages the switch, same goes for changing the switch whilst it is charging up.

 

Remember to dump excess power by firing the flash once or twice after turning down the power, I am not completely sure if it is necessary, but it is a worthwhile precaution for most older flashes

 

Apart from that, they are as good as any of the more modern monoblocks, but watch out for the massive sync cable voltages, they will kill all Canon's especially the digitals could damage most other cameras excapt the mechincal trigger like in the MF cameras. Buy a radio trigger or a safe sync.

[hans_p._strobl]

Here are a few specifics: The Bowens Monolite E was last produced in 1982 and was replaced by the Monolite D. It does not have voltage control. The power supply consists of a voltage-doubling circuit which charges the storage capacitors up to a value 2x rms of the mains. At 220 VAC line voltage this is theoretically 644 VDC, practically this comes to approx. 610 VDC due to the current-limiting resistors and losses in circuitry.

In practical work this means wide-spread differences in light output if you make one exposure right after the ready light comes on (Bowens factory setting of the ready-light threshold is 500 VDC, which is attained after approx. 2 seconds), another one after - let?s say 6 secs or longer - when the unit has had a chance to charge up to the full 610 VDC.

Take this into consideration when using a flash exposure meter. Don?t take a reading after the unit has had a chance to load to the max when your actual working cycle is much less. For half-way precise work, pop the unit first, then wait for such length of time which corresponds approximately to the interval between shots you plan to take, before you pop the flash for metering purposes. Other than that, I see no reason to trigger the flash needlessly. If you think you can get away with up to 1/3 f-stop differences in exposure, forget what I said before.

The storage capacitors always get full charge. The various power settings are obtained by discharging through a resistor bank with tabs connected to a rotary switch, which connects the corresponding resistor sections in series with the flash tube, resulting in flash durations between 1/500th second at full power and 1/150th at 1/4 power. You read right! Partial power will get you longer flash duration on Monolites 400 E and 200 E, remember that these units fire through resistors in series with the flash tube, so the storage capacitors take a longer time to drain off. The 800 E behaves the opposite way, but thats another story!

 

 

The contacts of the rotary switch are sometimes a problem with the Bowens Monolites, like Ian Burgess mentioned before.

(image 1)

 

To prevent arcing on the contacts you must avoid firing of the flash tube while switching the power setting.

 

The following advice may be helpful in the future:

1. Do not hit the trigger button while turning the power setting switch.

2. Do not turn the power setting switch while the unit is reloading.

Wait for the ready light to come on.

3. Remote trigger systems, especially the ones based on infrared can be triggered sometimes by IF generated thru the flicker of fluorescent

lights, modelling lights etc. Turning on fluorescents will surely

trigger the system when using older IF remote trigger systems.

 

If one day the power switch should fail, and no substitute is possible, do not junk the unit, just have an electrician put a jumper wire on the switch (image 2).

 

This way it will still be useful on occasions, although limited to work on "full power" only.

 

As to your Bowens I.R. remote trigger system, make sure you never plug it into the sync jacks of any 200 or 400 Monolite with gray housing, because the sync-voltage of these old models is 220 VDC.

Your I.R. receiver works fine with the sync-voltages of 35 VDC of the Bowens Monolite ?E? and the ?D? series.

I.R. receivers produced later than March 1982 have a Zener Diode ( BZY 88 C12 ) fitted to the Receiver P.C.B. (see image 3) to protect against high sync voltages.

 

 

The receiver is equipped with an auto-shut-off circuitry which senses the collaps of the sync-voltage when the flash unit is turned off.

 

The sensitivity of the I.R. receiver has been factory set. However, I sometimes find the setting way off, resulting either in reduced working range or otherwise in uncontrolled firing of the unit.

The sensitivity adjustment can be tuned through a hole, which is covered by a plastic stud, in the front of the case. Adjust the trimming-resistor so that the unit triggers at approx. 50 ft from the transmitter.

 

Greetings from Wuerzburg (Where the Hensel flash units come from), Germany.

 

Hans P. Strobl<div></div>

[hans_p._strobl]

Here comes image 2<div></div>

[hans_p._strobl]

dito Nr. 3

[hans_p._strobl]

Sorry about the quality. But I am sure you recognize the modification of the added ZENER DIODE BZY 88 C12 top left<div></div>

[hans_p._strobl]

Forget "Dumping the excess power by flashing off after the power setting is reduced ". It just is not necessary with any of the Bowens units, and it never was. On the Monolite 200 and 400 series all the storage capacitors are electrically bunched together and dump their power jointly into the flash tube, the various power settings are obtained by switching-in different sections of a resistor bank (for technicians: a 6.8 Ohms wire wound on ceramic body, 3 taps, dividing into 4 sections (1.7 Ohms each).

The Monolite 800 model is featuring bank switching of the storage capacitors via section separating diodes; only the 1/8 power setting uses a 2.2 Ohms resitor in series with the flash tube. Again, no need to dump excess power. By the way, the look-alike Hensel Varios of the 80s have to be flashed-off when reducing power. But that is another story!

As to the slow charge circuit, it is a feature that makes the storage capacitors of the Monolite 400/400E and 400D "last forever". When the unit is first turned on, an additional limiting resistor( 500/910 Ohms) is in series with the main limiting resistors to give a gentle charge of the main capacitors in case they may have deformed due to non-use.

[robin_arnold]

Hi people :)

I wish I had found this forum earlier and seen the excellent article by Hans Strobl, re the burnt switch.

I was given a Bowens 400E to repair recently.

Unit was totaly dead - found and fixed a faulty fuse holder - powered it up and it went.

However, after a few flashes, it died again.

Found one of the high voltage charging diodes had "shorted" - replaced it - unit went again for a few more flashes, then died - had to replace the other charging diode. (used 1N5408 diodes-(Si. 1000v @ 3 amp.)

Unit went again for a lot longer period.

This is great thought I, switching the power-switch back and forth and triggering the flash.

Next thing, there's a loud pop and a big flash from INSIDE the unit, then it would only go on lowest power setting. :(

Switch looked just like the one in Hans's picture, only more blackened.

I guess life is a constant learning curve.

Great forum/site - cheers guys :)

[jun_cordero]

<p>Thanks for the info.</p>