Strong Switcher "Main Mod" Error Failure Mode

[Ryan Gallagher]

Thanks Tony. I think I'm leaning towards caps/fuses first repair attempt. We have 3 functioning and 4 with issues. If I can get up to speed servicing these we may be good for a while for our single screen.

I was already headed down your advice path in my datasheet comparisons for replacement caps. Size and leg pitch seem to be the gotchya to avoid, all the rest is easily searchable on Digikey etc.

As far as the fuses in these. Are they generally slow-blow or fast-blow ceramic fuses? I'm guessing fast-blow based on the ceramic look... but minimal markings on mine other than the rating.

[Tony Bandiera Jr]

Thanks Tony. I think I'm leaning towards caps/fuses first repair attempt. We have 3 functioning and 4 with issues. If I can get up to speed servicing these we may be good for a while for our single screen.

I was already headed down your advice path in my datasheet comparisons for replacement caps. Size and leg pitch seem to be the gotchya to avoid, all the rest is easily searchable on Digikey etc.

As far as the fuses in these. Are they generally slow-blow or fast-blow ceramic fuses? I'm guessing fast-blow based on the ceramic look... but minimal markings on mine other than the rating.

For fuses, the 3 character marking (AGC, 3AG, MDL, etc.) will tell you if it is fast acting or slo-blow.

In the 1/4 x 1.25 inch fuse sizes, ceramics marked ABC are fast, and MDA are slow. (Cooper fuses) Other manufacturers may use different markings.

[Mark Gulbrandsen]

This is the very first switcher I worked on back in 2004. It's very important to use the exact same fuses in a switcher that were originally in it. Exact equivalent fuses are also ok. Having repaired hundreds of them from all over the US, most issues are blown transistors and switching transistors. I NEVER had a single control board failure. There are also diodes on the inside area between the heat sinks that fail. It is important to check all of the semiconductors on those two boards. The most that fail are the 1 to 3K switchers, later de-rated at the top end to 2.5 kw. Theaters still ran 3kw lamps in them. The larger rectifiers are the same, there are just more switching and rectification modules in them. If you have any V-1 switchers throw them in the trash. Semiconductors are NLA for those. You will also usually find burnt up wiring in them. See Photo.

Also write which color transformer lead goes to which terminal, up on the heat sinks, or take pictures. If you hook em up out of phase and turn it on, Austin will no longer exist.
You may see a crack in one or more of the semis as in the picture. No worries. Be sure to replace All OF THE heat sink mounted SEMI'S, and use brand new insulators with a very light schmear of decent heat sink compound on both sides of the insulator! ! !
Also, be sure SG-405 inrush current limiters are installed. Some older units have other types that eventually fall apart or crack. Check all the PCB mounted diodes on the boards that are behind the heat sinks. Occasionally one or more of those can short out. I never had a unit with bad capacitors. Replacing all of them will be expensive, but I always tested them with a meter for shorts. Lastly... The first turn on should be done from at least three blocks away just for safety's sake. If there is no mushroom cloud, then you may approach the rectifier.... Just kidding.... They have always worked fine after a rebuild.

[Ryan Gallagher]

I can get to most everything except maybe the diodes under the heat sinks, is there a way to check those in circuit from behind without removing the sinks and their associated semis?

if not, I guess the more complete tear down is advisable. Would allow more thorough testing of the ones affixed to the sinks too.

[Mark Gulbrandsen]

So which version are you working on? A picture or two and model # would help. As far as checking inaccessible stuff, you just have to figure out which traces on the bottom of the board they are soldered to. On the 6000 series switchers, there were no parts located under the heat sinks except the PCB. Seriously, if you are working on one of the older ones, put it straight into the dumpster. Semi's are NLA for it, and they are a fire and smoke hazard..

[Tony Bandiera Jr]

So which version are you working on? A picture or two and model # would help. As far as checking inaccessible stuff, you just have to figure out which traces on the bottom of the board they are soldered to. On the 6000 series switchers, there were no parts located under the heat sinks except the PCB. Seriously, if you are working on one of the older ones, put it straight into the dumpster. Semi's are NLA for it, and they are a fire and smoke hazard..

Mark, go to post#10, I think that is the one he's trying to fix. IT is a black case Version 1 unit, manufacture date of 12/98

Ryan, please confirm if that is the one you're working on. If so, as Mark said, parts are NLA for it. IF you get really bored, you COULD possibly try to dig up the old semi's data sheets and try to match up to a modern replacement...but it would be risky. You are working with high currents and voltages and it will go boom in bad way if mistakes are made.

Too bad I am so far away, I have time and could try to repair it if shipping wouldn't be so expensive. I have repaired a few in the past (many years ago) but they were the first of the grey case models.

[Ryan Gallagher]

Mark, go to post#10, I think that is the one he's trying to fix. IT is a black case Version 1 unit, manufacture date of 12/98

Ryan, please confirm if that is the one you're working on. If so, as Mark said, parts are NLA for it. IF you get really bored, you COULD possibly try to dig up the old semi's data sheets and try to match up to a modern replacement...but it would be risky. You are working with high currents and voltages and it will go boom in bad way if mistakes are made.

Too bad I am so far away, I have time and could try to repair it if shipping wouldn't be so expensive. I have repaired a few in the past (many years ago) but they were the first of the grey case models.

Yes it is the 6280107 pictured earlier in the thread. How does one tell the version 1 other than the dates? I have others too but they may be similar period. I did notice some of the semis were out of production when looking up data sheets. Some of those semis are in old stock form on ebay though.

in fact alll ours may be that era, will check date codes when back in booth.

[Tony Bandiera Jr]

Yes it is the 6280107 pictured earlier in the thread. How does one tell the version 1 other than the dates? I have others too but they may be similar period. I did notice some of the semis were out of production when looking up data sheets. Some of those semis are in old stock form on ebay though.

in fact alll ours may be that era, will check date codes when back in booth.

They have V1 on the labels just as yours does. Later models will be V2, V3, V4, etc. It is almost always on the paper label only, IIRC from V3 on I think (but not sure) it is also on the engraved plate.

Also, any of them with an "R" after the numbers is a rebuilt by Strong unit.

[Mark Gulbrandsen]

Strong redesigned them for a good reason. A. They were likely alerted that the Semi's were nearing end of production life. B. The things are rats nests and difficult to service. C. They can be a hazard as shown in the one picture. D. For what it matters, they still produce the later version, or possibly even a newer version of the updated units, because Strong follow spots are still made.

[Ryan Gallagher]

Strong redesigned them for a good reason. A. They were likely alerted that the Semi's were nearing end of production life. B. The things are rats nests and difficult to service. C. They can be a hazard as shown in the one picture. D. For what it matters, they still produce the later version, or possibly even a newer version of the updated units, because Strong follow spots are still made.

I knew they still made some for smaller follow spot applications, but I was unaware if they still made ones suitable for Super-80 lamphouses lamped at 4K (without calling). They very well could as their online catalog is horrible. Digging into their Gladator IV and Super Trooper IV series manuals online, at least one of them was updated in 2024, and both accepted 4K lamps. So yeah!

Last time we were worried about supply spares our TD started investigating iREM. (That was when I got our existing spares into a functional state wired for manual/spot operation). At least one of which popped rather quickly (like 2 months in service). I'll check the version numbers on all in the booth and consider how serviceable any of these still are considering outdated semis and make a recommendation.

I still enjoy the tinkering, but I'm not considering this V1 unit officially in the repairable camp anymore. Thanks for the clarifications.

[Mark Gulbrandsen]

The Strong Souper Trooper follow spots I am familiar with used the Lume-x lamp house with lamps up to 2500 watts. The Gladiator and it's accompanying rectifier can go to 4KW, There is also a Gladiator 2 and Gladiator 3. Back in the Carbon days, there was one even larger than the Gladiator, but I don't remember the name of it. It used the largest Strong Carbon lamphouse in it. They used those in big Stadiums. I saw a couple of them in the Chicago Stadium many years ago. They used them for the Ice Capades and other similar shows.

Also, there are manuals and some schematics at this site...