DCM TF600 crossover question

Dabutcher

The four rear firing tweeters do not work and I assume it is the soldered in fuse on xover? Do I just unsolder and put in a low blow auto fuse? Any suggestions on replacement for it? I have never soldered boards before but am willing to try? Thanks. D.

Dabutcher

Mr. Bubbles

The fuse can be checked with an ohm meter to verify your suspicion.Replace it with same type as removed. Vintage DCMs used dome lamp style fueses in many of their designs.

In my experience the tweets go out more often than the fuses. Kind of a pain to work on with the socks and glued in tweets, etc. But a very nice sounding speaker. I currently own 3 pair. Considered by many to be the sweet spot in the TF line. Good luck.

Dabutcher

I can physically see the break in wire (melted )inside glass fuse. I have already pulled both outer socks down to inspect four drivers condition. Inner socks are going to be removed and MDF painted flat black. Where can I source this type of fuse? I was thinking of installing a fuse holder? Thanks. D

[Deleted User]

Hello,
That might not be a fuse, but rather a lamp or bulb used as a tweeter protection device. At certain current levels the lamp begins burning, acting as a "safety valve" for the tweeters. Usually these types of lamps can be found at automotive supply stores.
Regards, Ken

Mr. Bubbles

As Ken says automotive supply stores are prob the best bet. be careful though sveral of those lamp style protection devices look similar but have very different electrical characteristics. Try to clean all solder off and look for any identifying numbers.

I forgot to mention earlier that I beleive ( though I may be mistaken) that the rear tweets are in series with each other.

Good luck.

[Deleted User]

In checking further it seems to be a "1.4 Ampere welded filament bulb" according to the speaker's schematic. This is similar to what is used in car interior lights.

Mr. Bubbles

I found a schematic for that model in my files. It calls for a 1.4 A welded filament bulb. I'm trying to figure out how to attach it here.

Mr. Bubbles

Mr. Bubbles

positioning of this bulb in the schematic would cause ALL tweets to fail. Niot just the rear tweets. For a specific rear tweet issue I would focus on the resistor and or the tweets in that circuit. This assumes that this schematic is accurate.

For the record i have solved isses in these due to oxidation, mouse damage, loose crimps, etc. As well as seeing many blown tweets with only a few blown bulbs.

Dabutcher

The center of the bulb is melted. I will start with that. Thanks for the help. Outer sock is great condition. Inner sock is rotting apart. My idea is to remove inner and paint flat black. Is this a good idea? D

westmassguy

The Fuse Lamp, AKA Festoon Lamp, should have a number on it. Some are 12 volt, some are 24 volt. It's critical the replacement be the same.

Mr. Bubbles

The inner "sock" does indeed have a function; it helps control diffraction. It is simply automotive headliner material. It is not recomended to remove it all together as this does effect the sound characterisitcs of the speakers. Some people have done so and been satisfied with the results while some have not. Completely your call, but I would not remove it on mine. If it's rotting, I would replace it with like material or felt. Felt will actually control soundwaves slightly better and also help keep the aesthetics of the cabinet nice. If the under material is not used any non smooth edges or surfaces (except baffle) will show through the grille cloth.

Mr. Bubbles

I looked at your pics again as i enlarged them this time. i can see the numbers on the bulb and also that it is indeed blown. It appears to be a 12V 1.4A. you should verify that and as Westmass says; be sure to use the same when replaceing.

feuer

The internet rocks, and you specifically, Mr. Bubbles. I have been a fan of DCM timeframes for some time now and I accidentally blew my rear tweeters on my 600s with a faulty amp. I got into the crossover and couldn't find the issue. Fuse was good, cap good, front tweeter worked, but rear ones would not. One rear tweeter measured fine with multimeter, but one was completely dead. Couldn't figure it out to save my life why they wouldn't work. Then I read mr. Bubbles comment about the tweeters being in series. I hooked two good tweeters up simultaneously and BAM! It worked! Thanks a million...... (yes I know this thread is ancient).