I have two dead ones from Dynaco A25's, can these be repaired or toss into the trash bin? Both measure open.
If they can be repaired I might put them on ebay cheap, I hate to see once good stuff go into the trash. If they can be fairly easily repaired DIY by me with no experience messing with drivers I might give it try. One was DOA which I replaced other just died in the Dynacos, odd too as the recently replaced cap (film) and resistor are fine.
If they can be repaired I might put them on ebay cheap, I hate to see once good stuff go into the trash. If they can be fairly easily repaired DIY by me with no experience messing with drivers I might give it try. One was DOA which I replaced other just died in the Dynacos, odd too as the recently replaced cap (film) and resistor are fine.
I would check if the coils are burnt first. If not, a likely fault is a broken wire between voice coil and face plate, near the surround, which is subject to flexing.
If the tweeter cannot be repaired, it can be replaced by a Seas Prestige 27TFFC (H0881), according to Seas:
Speaker Replacements: Madisound Speaker Components
If the tweeter cannot be repaired, it can be replaced by a Seas Prestige 27TFFC (H0881), according to Seas:
Speaker Replacements: Madisound Speaker Components
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The external leads look ok, I tried gently moving them as it played trying to see if it went intermittent but no luck.
You can carefully dismount the backs (magnets), by removing the screws on the front, to look at the condition of the coil.
They are easily disassembled, a step needed to remove the grill (after which it sounds better).
dave
dave
Well not that easy. For future tweakers: besides the Dynaco snot all over the tweeter and the years of galvanic corrosion right along the seam, the magnet case and dome parts are stuck together with a double stick tape gasket. It'll only come a part with a nice sharp 1/2" wood chisel and hammer, carefully tapping and moving around the seam. I used two strong spring clamps on either side to hold the tweeter steady and upright along the edge and left the grill in place but the screws loosed a turn to keep it from flying apart once the halves separated.
Pretty scary first time you try it and have no idea what will happen. Once it cracks apart remove the screws and grill then carefully to pull the dome/coil straight up to not nick the bobbin. Use a mat knife to cut back any the double sided tape that resists as you lift the dome away.
The thing is built like a tank, and apparently no ferrofluid. The expensive ALNICO part will last forever though it might demagnetize a bit. Too bad you can't just order up a new dome/coil these days. The current SEAS Exotic T35 X3-06 costs $375 😱
Here's the good part, I tested the dome/coil once it was apart and I got continuity and about .4 ohms resistance which I believe is correct. Put it back together and still got continuity 🙂 but WTF. Gotta love electronics, it's almost like these things are organic and alive. The other one still in the speaker decided to play again after I showed I cared. Maybe they were both under the weather and are now feeling better. Now I have a spare. Glad I asked and didn't just hunt and pay for another off Ebay. I'll try and post some picts on what it looks like apart for anyone else trying this.
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I have not ever run across any (i’ve done dozens) that have sticky tape. Time can make them a bit tricky to remove, not hard, you just have to be careful.
It should be at least some 10x that, you have a shorted VC.
dave
It should be at least some 10x that, you have a shorted VC.
dave
Yup, shorted. I figured the voice coil might read like a transformer winding with a different reading for the impedance rating and resistance on a meter, but yes it should read around 5 ohms. I thought continuity was a good sign but it is obviously shorted across the windings. Pity the alnico section goes into the trash. Have to get my all vacuum tube time machine finished so I can order up a new voice coil.
Here's some picts for some future explorers. Oh and don't set the dome side downwards touching anything, like a table, whether it was always sticky or the coating got that way over the years, it'll stick hard enough to the table to freak you out if your voice coil is good, on a hot summer's day anyways.
Here's some picts for some future explorers. Oh and don't set the dome side downwards touching anything, like a table, whether it was always sticky or the coating got that way over the years, it'll stick hard enough to the table to freak you out if your voice coil is good, on a hot summer's day anyways.
