Altech lansing pc speakers and subwoofer RIP? coil ohm values.

[gretter74]

Altech Lansing pc speaker system gave in after 10+ years. A few pops in the sound and then... gone.
...but I love them.

I've opened up the subwoofer and looked in side. No mechanical problems, no weired smells or apparently blown caps.

Meassuring resistance on a fuse gives
2 ohms.

There's a transformer.
Primary side 800k ohm
Secondary side 0.9 Ohm.... that seems wrong.

Is it possible for anyone to confirm that, That seems to be the problem?

There are no specifications on the transformer.

[jiroy]

Re: Altech lansing pc speakers and subwoofer RIP? coil ohm values.

Why don't you measure the resistance directly between the minus and plus of the speaker ? , it should give between 4Ohms to 16 Ohms , depending on specific designs . This way you can narrow the culprit .

[Khron]

Re: Altech lansing pc speakers and subwoofer RIP? coil ohm values.

Primary = 800k? That sounds awfully close to "open" to me. Does the transformer have a thermal fuse in series with the primary, perhaps?

Secondary sounds about right (relatively low voltage, relatively high current, which is to say, not many turns of thick-ish wire).

[budm]

Re: Altech lansing pc speakers and subwoofer RIP? coil ohm values.

+1
That primary winding is gone, you are probably reading your body resistance.
Right now you probably do not have DC Voltage from that power supply.

[gretter74]

Re: Altech lansing pc speakers and subwoofer RIP? coil ohm values.

Thank you guys.

There's no power from the supply.

The speaker is ok. 4 ohms.

I'll look around for a new transformer. The only identification is a number '0237'. I dont suppose that's enough to go on. Perhaps I can find a diagram some where.

[momaka]

Re: Altech lansing pc speakers and subwoofer RIP? coil ohm values.

Forget the transformer and its markings. Just see what IC(s) are used for driving the speaker and what is the rated voltage of the filter caps - that should give you a good enough clue of what to use for the power supply output. You may even get away with a cheap switchmode adapter/PSU (like a laptop adapter) - or at least for testing. As far as current rating for the adapter/transformer - worst case scenario would be if you have a BTL chip driving the speaker. In such a case, take the input voltage and divide it by the voice coil static resistance, then add 25% to that value for safety margin. If the speaker has dual voice-coil, the current would be two times that amount.