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Photographer
David Gerard
Posts: 10
Kyle, Texas, US


I just picked up a Norman 200B last night.  The battery is dead but I've got an adjustable 0-15V @ 35A bench power supply.  It draws nearly 20 Amps when the starts charging depleted capacitors.

Anyway, sometimes the tube stays lit, which I've heard is called afterglow.  There is supposed to be circuitry that quenches the tube after it fires and it apparently degrades over time.

Does anyone have a service manual or schematics for it?  Or know anyone that does?

thanks,
david
Sep 28 12 06:36 pm  Link  Quote 
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Photographer
GPS Studio Services
Posts: 34,616
San Francisco, California, US


The circuit you are talking about is called the "Hangfire" circuit.  I have a LOT of Norman equipment including 200B's.  I have no idea what you are talking about when you say "degrades?"  The hangfire circuit is basically a timer.  What it does is shuts down the charging circuit so that the caps don't start to re-charge until the flash tube has quenched.

Essentially what happens is that the unit senses the discharge of the caps and then activates the hangfire.  If the hangfire fails, what happens is that the caps begin to recharge, and dissipate right to the tube.  That causes the afterglow you are referring to.  We also call it a "blossom."  Basically, as the caps charge and discharge, it causes the ignition to be protracted.

I don't have a schematic for the 200B.  Heck, they are just about impossible to get for any Norman light.  They are protective of them.  In most of their lights, they just use a "555" timer along with a timing capacitor.  The cap is more likely to be the problem.  I really haven't looked inside a 200B though to see if they use the same chip.  It really shouldn't be hard to figure out though.  The 200B is a very simple device.
Sep 28 12 08:09 pm  Link  Quote 
Photographer
Alfred Mathis
Posts: 183
Tyler, Texas, US


I'm a bit of a fit-it-myself kind of guy, too, but I generally don't mess with my Speedotron packs because of the voltages involved.  I see that you're in Texas.  You might contact these guys to see if they have suggestions or can fix it for you.

http://www.flashfix.com/

They're in Dallas.  I'm pretty sure they used to be across the street from Competitive Camera on Irving Blvd.  Very knowledgeable, they definitely know what they're doing.
Sep 28 12 08:22 pm  Link  Quote 
Photographer
David Gerard
Posts: 10
Kyle, Texas, US


There is no 555 timer...  There are three 741's (all with different mfg'rs), three TIP-29's (TO-220), two 2n3771's (TO-3s), and two TO-220 parts that don't have a recognizable number (SCR's?). 

All the rest of the components are passives.  I have not pulled the controller board off and looked below the shield at the toroid transformer or the caps and whatever else is under there (http://graywolfphoto.com/journal/2009/0 … eeds-work/)

By degrade I meant to say a commonly seen failure mode, something that is known to go after time on these units.  He said it was a handful of components that would not cost more than $15 in parts.  Shipping and labor, though, would likely bring it up to $90-100.  I'd prefer to attempt to fix it myself before spending that much.

All that said, one of the 741's may be the timing circuit...  There are two pots at one end of the board, next to one of the 741s, the top end of http://www.powersource.org/powersource/ … bpack.jpg.
Sep 28 12 08:58 pm  Link  Quote 
Photographer
Andy Pearlman
Posts: 3,411
Los Angeles, California, US


when you give up, call Silvino. He's very nice and might be able to answer your question over the phone or by email.

Silvino's Strobe Rx
937 N. Cole Ave. #1
Hollywood, CA 90038
323-962-7076

He's the best Norman repair guy in LA, he used to work at the Norman factory when it was in Burbank. He may be able to talk you through it, or ask you to send it in.
Sep 28 12 11:48 pm  Link  Quote 
Photographer
David Gerard
Posts: 10
Kyle, Texas, US


Well, I've not given up yet...  As it does not exhibit the afterglow with every pop, I don't think it worth the money to send in for repair.

I've traced out most of the board circuitry.  I know which transistor enables the inverter to charge the caps.  The voltage goes up to about 490V on the first charge up after switching on the power and then settles in to around 485.

It looks simple enough to rework the trigger circuitry in the head and convert it to an IGBT trigger which would allow fully adjustable power.  And by default, the afterglow would go away because the flash tube can be completely disconnected from the cap.  If I get really creative, I can simply insert between the head and pack and not rewire anything inside either...

What I find simultaneously interesting and disconcerting is that the 200B has a battery positive chassis/ground.  I have only ever heard of that, never seen or touched it...
Oct 12 12 10:34 pm  Link  Quote 
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Photographer
GPS Studio Services
Posts: 34,616
San Francisco, California, US


Sundays Child Snapshots wrote:
Well, I've not given up yet...  As it does not exhibit the afterglow with every pop, I don't think it worth the money to send in for repair.

I've traced out most of the board circuitry.  I know which transistor enables the inverter to charge the caps.  The voltage goes up to about 490V on the first charge up after switching on the power and then settles in to around 485.

It looks simple enough to rework the trigger circuitry in the head and convert it to an IGBT trigger which would allow fully adjustable power.  And by default, the afterglow would go away because the flash tube can be completely disconnected from the cap.  If I get really creative, I can simply insert between the head and pack and not rewire anything inside either...

What I find simultaneously interesting and disconcerting is that the 200B has a battery positive chassis/ground.  I have only ever heard of that, never seen or touched it...

Two things, first have you checked the flash tube?  That can also cause the symptom you are exhibiting.  I should have mentioned that in my first post.

Second, the 200B is part of the Norman 450 series.  The reason it was discontinued and replaced by the 500 series is that it is a positive ground system.  There are safety issues and design issues. That is also, in part, why the 450 series was always transformer based.

Before you start to design new circuitry, you should keep that in mind.  My guy worked on the 450's quite a bit and the positive ground always became an issue every time he designed modifications for it.

Oct 12 12 11:11 pm  Link  Quote 
Photographer
David Gerard
Posts: 10
Kyle, Texas, US


ei Total Productions wrote:
My guy worked on the 450's quite a bit and the positive ground always became an issue every time he designed modifications for it.

Who is your guy?  I looked back but don't see a reference.  The man at Dasaga said that it was the pack or the flash tube but that more than likely it was the pack.

I understand the issues with the positive ground - it's upside down from everything I've seen, and that includes everything Harold Edgerton's strobe book. There's not even an interlock that cuts off power when you open the case. Long gone are those days...

The board seems somewhat inextricably entwined with the inverter toroid because the feedback transformer appears to be on the board (the hockey puck thing).  Conceivably, I could just gut the whole thing and then use a small microcontroller to drive the existing inverter parts (the power transistors and large toroid).  Then it is a relatively simple matter to convert everything over to a negative ground and IGBT triggering.

It all remains to be seen how ambitious I end up being... Conversion pretty much precludes any future possible sale of the equipment unless I save the old parts to convert them back. 

I just purchased two more packs and 3 heads from an older photographer that has not used them in years.  I can at least swap flash tubes from that bunch once it all arrives.

Oct 13 12 04:33 pm  Link  Quote 
Photographer
Don Olson Imagery
Posts: 291
Eugene, Oregon, US


When all else fails give Hal a call.
541-689-0046

He keeps my 2 going strong and right. Including making batteries, twin heads etc. They aren't rocket science just a damn nice strobe.
Oct 13 12 04:42 pm  Link  Quote 
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Photographer
GPS Studio Services
Posts: 34,616
San Francisco, California, US


ei Total Productions wrote:
My guy worked on the 450's quite a bit and the positive ground always became an issue every time he designed modifications for it.
Sundays Child Snapshots wrote:
Who is your guy?

My guy is a close personal friend that is a retired electrical engineer.  He tears these things apart and works on them as a hobby now, he is a photographer.  Between us, we've torn apart dozens of Norman packs along with a lot of other gear.  Unfortunately, he isn't available for hire and he has some health issues.  I wish he could help you out, but it isn't going to happen.

I do wish you good luck.  I will tell you, he's done a lot of modifications, some worked out, others did not.  We've even designed some of our own replacement parts from scratch and had circuit boards etched.  The guy amazes me.

The positive ground on the 450 system has always been a frustration.

Oct 13 12 06:06 pm  Link  Quote 
Photographer
David Gerard
Posts: 10
Kyle, Texas, US


Your guys sounds s lot like my grandfather:  He's the reason I tinker and work as an EE. He used to bring me to his shop where he'd fix radios and tvs.  He had the big old GE orange and gray travel case stuffed with replacement tubes and a whole kit of stuff he'd bring on location to fix tvs.  He built a frequency counter from scratch using nixie tubes.  I've made boards myself but I don't like to anymore because the chemicals are such a hassle.  I'd love to meet your guy, though I know it's not possible, and not even to talk about the Norman... 

Last night, I tore the unit I had apart all the way, completely emptying the box.  Because of how they wired the big toroid, there's no way to reuse it as is and still convert it to negative ground. 

Digikey sells small tic-tac sized Allegro parts that do flash capacitor charging and IGBT trigger driving.  The current limit is really low in comparison (1A max) compared to the 30A max of the TO-3 transistors of the 200B.  If it was to drive an external power FET (I found a 40A one last night for $0.67 in single quantities), all that remains is finding a flyback transformer to handle the current and step up the voltage appropriately.  That and I'd need to have a board made, since these little parts are extremely small and have no leads at all...

I had hoped to just replace the board with another board that plugs in the card connector as-is with no further modding, but that does not look like it will be the case.  And it still may never happen since I've dreamed big grand plans like this before that never come to fruition...  It's fun thought experimenting but in the end, if I can buy something for the cost of building my own or less, it's not worth building my own.  But I do seem to keep learning that lesson over and over again.

In the end, all I want is a fairly powerful (stronger our SB-900), bare-tube strobe to use at home and something small and compact to take out on location to fight against the sun.  I was going to use it yesterday when we went out doing some test shots but the high voltage seemed to kill the cheapo optical trigger I was using on it to test (it's got 100V at the sync port) and I did not want to kill a second one, so I left it at home.  That and it kept after-glowing.

I have to believe, after tracing through the schematics, that when after-glow occurs in a 200B, it can be the tube but it's also the time delay after a pop before the inverter starts charging the capacitors again.  If the tube is still conducting when the inverter kicks on, it's just going to keep the tube glowing rather than charge the caps back up.
Oct 14 12 05:29 am  Link  Quote 
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Photographer
GPS Studio Services
Posts: 34,616
San Francisco, California, US


Sundays Child Snapshots wrote:
I have to believe, after tracing through the schematics, that when after-glow occurs in a 200B, it can be the tube but it's also the time delay after a pop before the inverter starts charging the capacitors again.  If the tube is still conducting when the inverter kicks on, it's just going to keep the tube glowing rather than charge the caps back up.

The tube can cause it, but, alas, you are back to that darned hangfire circuit again.  There is also a small chance, btw, that you are getting arcing on the cable connector.  I have a couple of LH2400's that are blossoming on P2000's right now.  They are socket dependent, so in my case, it is an arcing issue.  On the 200B, you only have one socket but you might consider cleaning the pins and the socket to see if that helps.

At least on the P2000's, sometimes when there is increased resistance, the hangfire doesn't detect that the gas has extinguished so it allow the capacitors to recharge rather than triggering hang time.

Oct 14 12 08:55 am  Link  Quote 
Photographer
David Gerard
Posts: 10
Kyle, Texas, US


Is there any chance that you could point me to the components on the board that are part of the hangfire circuit? 

I've drawn up most of the board but as I went the route of material science instead of EE in college, I missed out on op amp theory, so the full function of the three op amps is lost on me.

What's the best method to clean the contacts?  And what do they look like when they're dirty?  Are there marks from arcs?
Oct 14 12 09:10 am  Link  Quote 
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Photographer
GPS Studio Services
Posts: 34,616
San Francisco, California, US


Sundays Child Snapshots wrote:
Is there any chance that you could point me to the components on the board that are part of the hangfire circuit? 

I've drawn up most of the board but as I went the route of material science instead of EE in college, I missed out on op amp theory, so the full function of the three op amps is lost on me.

What's the best method to clean the contacts?  And what do they look like when they're dirty?  Are there marks from arcs?

Ya know what, the one thing we have never been able to get is schematics for any of these things.  We've figured these things out over time, asking questions, looking online.  We've worked on the 200B but nowhere near as much as other Norman products.  They aren't very expensive to have fixed.  Why don't you just send it to Silvino or Holly Enterprises (or Silvino's sister up here in the Bay).  I really doubt that it would be a very big thing to fix.

Oct 14 12 09:21 am  Link  Quote 
Photographer
David Gerard
Posts: 10
Kyle, Texas, US


I've since acquired an additional two dead packs (with three heads and 4 tubes, too). 

I now have two fully functional packs.  The original board has a popped op amp on it, which is why the afterglow occurs.  The op amp output on the other two boards toggles after a pop but the original one does not.

A second pack had a broken wire on the toroid because the foam they put in originally did not immobilize the toroid and it broke loose from movement.

The third pack is still not working yet but I've not gotten a chance to get it back together after completely pulling the caps and toroid out.  Pulsing current in the toroid's primary makes something happen on the HV secondary but maybe the windings are shorted - still have to re-assemble it all.  That or maybe the caps were not charging after sitting so long unused.

In looking at how the secondary of the toroid is not connected to the primary other than on the PCB, and the ground point for the battery positive is at the big connector, these may still conceivably be changed to negative ground.  Rolling my own controller board would easily allow switching it to negative ground as well as switching the trigger to IGBT for variable power control rather than switched power, but I'm not sure it's worth the bother.

They'd all be better used to make photos than be engineering experiments - I originally bought the first one to do hemispheric bare tube lighting...
Oct 18 12 05:46 pm  Link  Quote 
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