DCM TimeFrame 600 Crossover Revealed

Up until tonight, I had no clear picture in my head of what a TF 600 crossover looked like. It dawned on me that some of you were probably in the same boat so I am posting these pictures for a good view.

This all came about when the system in my den/workshop started to sound wrong. Upon isolation I came upon some odd situations. I determined that the Kenwood KR 8010 has a strange anomaly. Somewhere inside the wiring is switched so that the output from the left input appears on the right output and visa versa. Trying to figure out what was switched was surprisingly confusing. This however was not the issue with the sound.

The pair of JBL LX 600s are controlled by my Toshiba SA 620 and were missing the mids on the left side. I pulled the driver and it checked out OK. I pulled the crossover and it checked out OK. I put it back together and the speaker was functioning correctly. I hate it when that happens. I have no idea what was wrong or how I fixed it.

The TF 600s are attached to the KR 8010 and had been running reversed L to R since I first hooked them up, but that has now been figured out and made correct. The big issue was I had no highs on the right speaker. I pulled it tonight and got the crossover out. The crossover is very similar to the one in my TF 400s including the well recognized lamp/fuse. The addition to the crossover, that I do not remember from my TF 400s, is the self reseting circuit breaker. My problem, luckily, was a blown fuse/lamp. I had a difficult time getting the crossover out of the speaker because the lamp was stuck/melted to the fiberfill inside the cabinet. When I replace it I will trim the dacron back to keep it away from the lamp. This will hopefully allow more heat to dissipate and keep the fuse from blowing or degrading as easily.

Here are the pics. I hope it helps someone out there.





This pic show the grey circuit breaker.

Thank KB!

Hopefully I will never have to reference this thread for problems with my 600's..
Does anyone know if the 350's had a similar fuse?

My 350s did not have a fuse.

I do not think that is a fuse. I believe it is used to keep the tweeter from blowing when used with too high an input. Yes, it will blow if abused too much but that's not the application. This should be wired in series with the tweeter's part of the crossover.

It is actually a light bulb. Since the filament's resistance will rise when it starts getting warm, an input signal through the filament will begin to heat it. Then, as the signal gets louder/bigger, the filament's heat increases the resistance inline with the tweeter and its crossover circuit. This reduced the amount of power applied to the tweeter and, hence, its volume.

Hopefully, the light bulb's filament properties are matched with the tweeter's in such a way that the bulb will self-destruct just before the tweeter does. Other companies like Bose and UREI used this same technique and, I'm sure, made up the extra cost in a far lower warranty cost to the company.

Cheers,

David

Hi KingBubba.

I am thinking about buying some TF-600s. I don't know if they have any problems, but like Wolverine said, I hope I do not encounter any crossover problems. Thanks to your great info, I know where to come for help.

Great post KingBubba!
Rome

Dshoaf, I'm no expert about this particular subject, but, if I am correct, the resistance of a filament in a lamp remains constant. In series it is acting just like dim bulb/poor mans Variac setup. The filament burning through would be the same limiting factor as a fuse blowing. I don't see how resistance can change as a lamp filament warms up. As simple as Ohm's law appears to be, it eludes me, especially with AC voltage. Can anyone else clarify this for all of us?

Anybody know the value of the NP electrolytic?

Interesting - thanks for sharing the pics! (They didn't spare the hot glue, did they? )

I've never gone into the crossover on my TFM-700s. Anyone know if they are similar?

Lamp filaments

The lamps used in speakers are very close to ones used in car dome lights.
As long as the lamp is not pushed to it's wattage, the resistance does not change much.
Once it is taken beyond that, they do indeed increase resistance. Then they act like a load. If the current is increased enough they over heat and the filament breaks. Older Chryslers like to pop dash lights when the voltage regulator would stick on.
At least by what we seen when I used to work on cars. Also happens with head light bulbs. To the point if there is any resistance in the circuit(corrosion) that point instead of the bulb will get crispy. I've replaced many connectors.
On GM LH jetronic fuel injection, the computer depends highly on filament resistance change. Inside the mass air flow sensor is a filament that has a steady, measured amount of current applied to it. By watching a DVM or scanner you can change the resistance just by blowing into it. These replaced the Air flow meter on older(mostly japan)L jetronic. Those notoriously had a lag when first stepping on the gas. The a.k.a Hot Wire Mass airflow sensors did away with the lag. Some earlier models even had a burn off feature. When you first turned the key on, it would send the filament some extra juice to cook off dust. This was before they improved air filters.

Near room temperature, the electric resistance of a typical metal increases linearly with rising temperature, while the electrical resistance of a typical semiconductor decreases with rising temperature. The amount of that change in resistance can be calculated using the temperature coefficient of resistivity of the material

Click to expand...

http://en.wikipedia.org/wiki/Electrical_resistance_and_conductance

relay

anyone have any idea where i can get a replacement for that culver 17a-50 relay? Also I imagine if Im going to replace one I should also replace the other right? For the sake of them sounding the same. One of the speakers was cutting in and out, at the moment I am running an alligator clip across the leads of the relay and it seems to have fixed it, temporarily anyway.