About the four 291's I won...

[thinking]

From experience, Bill really doesn't like to have to deal with the problems associated with corroded drivers. One of the problems is that any rust particles are pulled into the gap, and rub on the coils until they wear through the insulation on the wires, and then short them out, causing premature failure that you then want to blame him for.
By way of prevention, I have concluded that often corrosion is caused by changing temps. The room air temp can warm up much faster than the huge chunk of metal, and consequently it condenses moisture internally, leading to corrosion. Then they are sent to Ebay, where there is no way to verify their condition before purchase. (more voice of hard learned experience here,)

[Richard C.]

Thinking

I think you are probably correct about condensation inside the driver. I have never opened up a good driver to look inside, and I don't plan to. These 291's had the voice coils locked into the gaps with rust. I have nothing to lose, but the time it takes to clean them up. I think the clear lacquer will help in the future.

I need an easy way to display pictures here...

Richard C.

[Richard C.]

Here are some pics - Who wants to jump right in and make me an offer to buy???

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<font color="#FFFFFF" size="1">[ December 28, 2007 10:43 AM: Message edited by: Richard C. ]</font>

[Audio_by_Goodwill]

Originally posted by Richard C.:
Here are some pics - Who wants to jump right in and make me an offer to buy???

<font size="2" face="Verdana, Helvetica, sans-serif">Wow!! Hmmm, I'll give you million dollars each, I bet I can triple my money on Ebay :-)

Seriously, that's beyond what I think condensation would do, unless some situation caused the condensation to happen repeatedly.

[Richard C.]

This one was a little worse than the one I cleaned up, but it will clean up. I demagnetized the magnet and ALL the steel parts with a bulk tape eraser. Once I got everything demagged, the pieces pretty much fell apart. Individual pieces can be cleaned up easier. I will post the after pics soon. I compared the gap to the "one" nice driver and I can't measure a difference, so I think they will be OK.

Richard C.

[valhallax]

truely..the patience of a saint. thats quite a project you've undertaken. look forward to the follow up

[thinking]

Yes, those would be closer to the 604E's that I got on Ebay, that when I stood them in edge, had water seeping out of the magnet structure, but I've had ones that were much better that still were almost past rescue. I'ts a question of cost mostly. If you have the resources and patience they can be salvaged. In a couple of cases I've taken them apart and had them re-plated, but that opens up a whole new set of problems. Basically you have to be working with something that has either collector value, or is not replaceable to make it feasible. If GPA has it available new, it's generally not going to be worth it.