Elation DP-DMX20L Popped!

[JD]

F.Y.I.

Just popped a channel on one of these nice little packs. (They really are kind of nice for what they are.)

THE FOLLOWING IS FOR QUALIFIED SERVICE PERSONNEL ONLY!

Having spent 20+ years servicing things, I was surprised to find the BTA16B triac being used on a dimmer rated at 10 amps. (The BTA16 is a 16 amp triac which is a little too low of a safety factor) The BTA24 is a 25 amp version of the same device in the same package. (Mouser part number 511-BTA-600BW Cost $1.84)

I will let you guess what I am doing. Note: This is a solder in part, not a job that should be attempted by non-qualified personnel.

[mbandgeek]

I am not 100% sure on how a dimmer works, but i understand the theory.

If you are doing what i think you are doing, I would check the specs on the other components in the pack to make sure they can handle the increased amperage.

best of luck to you,
KN

[JD]

There would be no increased amperage as the channel fuse is what sets the limit on any dimmer (or breaker, or both as the case would be.) The fuse is "suppose" to be the weak link. All parts in the circuit must be able to handle the fuse rating. Actual current load is determined by whatever wattage load you have on the dimmer, up to its rated load. In the case of the DP-DMX20L, the per channel rating is 1200 watts per channel (10 amps) with a pack maximum of 2400 watts due to the 20 amp limit of the power cord. In no case should a person try to increase the power rating by changing fuses ect. as all other components would then be underrated. In most cases, you want a safety factor on your thrysistors (SCRs or Triacs, SSR, IGBT) of 4 to 5. (For example, a 10 amp dimmer really should have a 40 amp triac.) In this case they saved 16 cents per channel by going with a devise that only had a 1.6 safety factor. Even a 2.5 (using a 25 amp triac) is low by "theater" standards, but would be a step in the right direction. Once again, this was an FYI post about parts, and should not be considered by people outside of the dimmer service industry. In the case of this unit, a 40 amp triac would not be an option as they are not available in the TO-220 iso case which the unit is designed to accept. One last note, the last DP-DMX20L that I serviced used the BTA24 as the OEM part. Not sure when they changed to the cheaper part.


BTA16 600BW > 16 amp, TO-220 iso case, 600v, 50ma gate current, STMicroelectronics manufacturer.

BTA24 600BW > 25 anp, TO-220 iso case, 600v, 50ma gate current, STMicroelectronics manufacturer.

EDIT: I remember a recent post about failures on newer Leviton D4DMX dimmers which look suspiciously the similar in case design. I wonder if the vendor on that changed to the BTA16 as well. (again, info intended only for fellow servicers.)

[n1ist]

I have worked on some of that type of shoebox dimmers. I love the 20A ratings that don't take into account the 14ga cordset, 10A AC inlet, 6A switch, and 10A triacs... I asked tech support; they had no clue.

[David Ashton]

I think it may be that they are designed as 240volt 10A units for the civilized world and then modified to sell in the US.

[JD]

Originally Posted by allthingstheatre

I think it may be that they are designed as 240volt 10A units for the civilized world and then modified to sell in the US.

Very funny!
Actually, this unit at least does have a 12/3 power cord and omits the 10 amp input connector. It is what it is, club/DJ stuff. Other then the 16 amp triacs, it's built pretty well, but emphasis on "for what it is!"
I hate when the bean counters get in there and wreck what the designers intended. I have a couple of their rack mount dimmers. Nice piece, 40 amp triacs for 10 amps. But even there, when you look at the the blade style power mods, the PCB is laid out for back to back SCRs, and there is even a place for the second device, but there are just hardwire jumpers and the single triac mounted. Oh well!

[Benchtech]

Yes I found the same 16 amp triac in both models. I guess if you figure 16 cents times 4 triacs times 5000 units, somebody made $3200 bucks! But I digress, I totally agree with the increase to a larger triac especially since the gate is rated the same. That way the linearity should be pretty close (if it makes a big difference.) Both are imports and at first glance they look pretty close but the circuit boards are different although the programming is almost identical.

[lightman02]

What do you think about Lightronics dimmers?? I have 4 AS42D packs and they have been though alot and have never failed me and are about 8 years old. They have been rained on, snowed on, kicked, scrapped, overloaded and not one failure. I just picked up the XC 42 series and they have some pretty nice features such as dimmer curve settings, channel limiting and soft patching.

[church]

I have a number of these and the DP415 which is the 600W per channel unit and they both use the same TRIAC. I have only blown one TRIAC in normal use and it was an easy fix - 500W lamp failed. I have experienced this type of failure on other makes of dimmer in the entry to medium level price range.

I had one customer knock a Manfrotto stand over with a DP415 mounted on a T bar. Came down from 12 feet onto concrete. The impact caused two TRIACs to break in two. I replaced the two broken TRIACs and the unit still works great after 18 months. I also had another customer accidently connect phantom power into the DMX input via the sound snake - destroyed the SN75176 - the chip actually caught fire and burnt the board. Amazingly the only damage was the SN75176 the PIC was fine even though there was no optical isolation after the transceiver. Replaced the chip and the unit continues to work. I can't complain they are not bad for the price.

I normally replace the TRIAC with the highest current version I have that will fit when I change them on any dimmer.

The build standard is pretty good for the money and the parts are good quality - Texas Instrument etc.

[Benchtech]

I have used, sold and installed a lot of their products and have had very good experience with the company. Good stable products, great factory support and pretty innovative applications.