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Just bought a pair of Model 15's for a good price. However, when I opened up one of the 802-8G's it was pretty rusty. I knew that the diaphram was not working but I wasn't expecting this. The other one is just fine.
I've sprayed with WD40 but can extract the entire diaphram.
What are the next steps? - Junk??, sand blast and send to GPA for re mag?
Thanks
http://i976.photobucket.com/albums/a...e/P1070120.jpg
I'd be tempted to disassemble it completely and send it to GPA as a kit. The other option would be to soak it in Evapo-Rust. It's not an acid, so it won't hurt the base metal when soaking for several days.
Hey Matt,
i'll give you a call tomorrow. Busy with the car.
I would soak it as well, but I wouldn't hold out much hope.
Gads, looks like it was underwater!
Ron
The rusty face will clean-up with a brass wire brush and some hand-sanding.
If there are no broken-off threads in the screw holes these holes can be cleaned using a re-tapping tool(best) or a correct size screw.
Light rust in the voice-coil gap can be lightly honed with a piece of folded fine wet-or-dry emery paper.
Blown air to clean away the removed material.
Apply WD40, or similar, and let dry.
Check VC gap and clean with folded sticky tape.
You may be able to get the Tangerine Phase Plug off by levering it gently.
I'd toss it, or shelve it as a reminder that they're not waterproof.
It's too deeply pitted, will be missing too much metal after all the bad is removed.
With a little thrifty shopping, you should be able to pick up a clean 802G/808B body for less than GPA is going to charge you for a new front plate. I suspect the polepiece under the phase plug is probably ruined as well.
The surface rust is easy to clean.But if the gap is real rusty and pitted ? I would junk it as well. Send it to Bill and see what he says after examining it apart.But I personally wouldn't hold out much hope on it.It needs to be demagnetized to be cleaned properly. I also would be looking for a cheap single on the bay. Is the diaphragm still usable ?
Looks like it was installed in a Yellow Submarine.....
AB, it looks to me like the coil and the former are still in the gap. Note the lead in ribbons sticking out of the gap 180 degrees apart at 12 o'clock and 6 o'clock.Quote:
Is the diaphragm still usable ?
I see them now ! Yeah OOuchh ! Thanks B ! I just sold a single 802-8G (Less Fram) for $75 locally unfortunately.But I now see you have a pair.Quote:
Originally Posted by bowtie427ss
That's a peach hun!
I would think that as along as the pole piece and the top plate near the gap aren't too deeply pitted it would be fine once cleaned up. Even if pitted it may sound fine. There's no way to tell without actually cleaning it up. The camera can exaggerate the way it looks at the moment, and it's tough to know even looking directly.
I will try the cleaning solution and see how that works. Luckily, I have 2 other 802-8G's sitting on the shelve so I can get the system up and running.
I'll put some effort forth to see what I might be able to do. I'm curious to what extent I might be able to potentially get it working - although very concerned that the internals are rusted extensively also.
Learned my lesson - always open up and inspect both diaphragms.
One of the things Altecs are famous for are their very tight manufacturing tolerances. One of those tolerances is width of the magnetic gap. I see no possible way that enough corrosion could occur to tightly lock the voice coil in place without a loss of material that will put the gap dimensions out of spec, and cause significant deviation from proper/expected parameters. We're talking just a couple thousandths here.Quote:
I would think that as along as the pole piece and the top plate near the gap aren't too deeply pitted it would be fine once cleaned up. Even if pitted it may sound fine. There's no way to tell without actually cleaning it up. The camera can exaggerate the way it looks at the moment, and it's tough to know even looking directly.
Another problem area that we cannot see without dis-assembly is the surface where the front plate meets the magnetic return pot. This surface as well as the mating surface of the return pot need to be a smooth even finish in order to provide an even/consistent magnetic circuit. The same conditions also apply to the surface where the polepiece meets the magnet slug. To resurface that part of the front plate would probably take it below the minimum thickness spec by the time any pitting is cleaned up.
IMO&E, salvaging that driver beyond an exercise in determining the exact extent of damage would be an exercise in futility given the availability and value/cost of replacements. I think it's best use is as a conversation piece, or door stop.
Certainly it could be salvaged, even to the extent that the return pot, front plate, and throat/polepiece were all replaced with GPA modern production, using only the original alnico slug and 11 slit tangerine.
But, i don't think it could be done for the ~75 bucks or less that a replacement assembly can be sourced for.
It'd be interesting(but probably not practical) to actually clean this one up and try to return what's there to a "working" condition. My curiosity would be to see how obvious any audible differences would be as well as the degree of measurable variation beyond what i think is quite predictable from a simple visual inspection. I think you'd immediately notice reduced sensitivity and quite possibly rolled off HF.
Just my .02...........................
Whether it's salvageable or not, I want to see it disassembled and cleaned up just for forensics sake. I have cleaned up rusty water pumps and such by just submersing crap in pure Muratic/ pre-diluted hydrochloric acid. Find out what the magnetic gap is, and cut/ grind down a feeler gauge to form a slim pick to clean out the crud. A stainless steel cup rotary drill wire brush should work great.
It'll make a dandy door stop. : /
An acid will remove some good metal, Though. It would be better to use something like Evapo-rust. It's more expensive than acid, but safer for the driver, and safer to handle.Quote:
Originally Posted by VolvoHeretic
Quote:
Originally Posted by bowtie427ss
Good Advice B ! :wink2:
With some good cleaning and some work with a wire brush, I actually got it working!
I used some WD 40 extensively, and a thin razor blade to clean out the gap. I then used some paper speaker shims and compressed air to clean it out even more. I then used a wire brush to clean the rust off of the plate. Here are some before and after pictures:
http://i976.photobucket.com/albums/a...e/P1070132.jpg
http://i976.photobucket.com/albums/a...e/P1070134.jpg
I installed a diaphragm and hooked it up and got good sound out of it. I had another standalone 802-8G and hooked it up (both outside of the speaker box) and they sounded about the same. Definitely not a final test but getting closer to potentially saving this driver.
Question: do you think that I should still use the Evapo-rust?
If the gap is rust free you can probably skip it.Quote:
Originally Posted by mattvandyke
Did you clean all the WD40 off, and out of the gap? I'd probably clean it with soap and water and then blow it out with air....... or maybe alcohol (the 90+% stuff) in the gap, and then blow that out with air.
Disclaimer...... I've never worked on a HF driver, I'm just tell you how I would approach it, given my experience in cleaning other things.
WOW! Great work!
I am impressed. I think you may have salvaged it after all, at least good enough for a working spare. That looks a LOT better than i would have expected, especially in the gap. I was really afraid the oxidation would have eaten away some of the edge of the crown on the polepiece.
That said, i still couldn't sleep at night knowing it was bolted to one of my horns. It'd have to find a new home.:D
I agree, great job ! But I also can't help to think with all that cleaning that the gap getting filled with crud. If you can get the gap totally clean then you will be Golden !
Nice Job Matt. There's a will there's a way eh ? :wink2:
Liquid metal-filler(available in small tubes) and some fine sanding would make those pits disappear. Use JB Weld if you need more toughness. Great job.
If you say it sounds as good as your other ones I wouldn't F with it just run it. :D
Good job! I have an old driver in similar shape that I may try to clean now. I'm curious how you got the phase plug out and what you used to reattach it?
The tangerine phase plugs are merely superglued in. Very easy to re-attach.
I have had a few fall out on their own!
ron
Thanks Ron, I'll give it a try!
I'm going to tell you that I cheat though.
I have a good microscope that I use to help me carefully remove the old glue from the phase plug.
If you don't remove the old glue it won't sit perfect when you glue it back in.
Working in the microelectronics industry has spoiled me. Besides, I'm old and can't see that little stuff anyway!
I've installed a couple of tangerine phase plugs, clean with wire brush lightly, use super glue and you'll should be OK.
Going to do some more testing this weekend so stay tuned. I think that all of this hard work might actually pay off.
Wow! I finally got around to assembling everything today (woofer, horns and driver, crossovers, etc.) put it all together and it works wonderfully. I'm really surprised. I spent about 30 mintues listening to Doobie Brothers (what were once vices are now habits) and it all sounded great. Pictures to be posted tomorrow.
Touchdown!
Really? With my (your) 414's?
Real Nice Work Matt..Quote:
Originally Posted by mattvandyke
I'm looking forward to those Pics ! :Big smile:
It's all up and running and I'm a little surprised that it worked out as well as hoped.
Here is a recap of what I did.
Removed 802-8G. One was good - one was extremely rusty
Sprayed WD-40 on bad one and let it sit. Started cleaning with a small wire brush. Then moved to wire brush on a drill.
Worked on cleaning out the gap that had a stuck diaghrapm. Used a small utility razor blade - spent approx 1 hr on it. Used vacume and air compressor
Used paper speaker shim's to clean out the gap more extensively - spent another 2 hours +
Clean all with hot water and soap
Cleaned and polished 32B horns with Armorall
Installed diaghrapms that I had sitting on the bench
Refished cabinets with Howards
Installed 414C (purchased from member Ron locally in the Portland area)
Removed and cleaned crossover network.
Installed all items
Plugged in and she rocks.
I let it run for awhile and then cranked it up a little. All sounds good. Still have some work to do as I think that I'm going to move the speaker connections from underneath to the back of the speaker cabinet. Additionally, I think that I have to replace one of the LPADS.
Here is a summary of the pictures.
http://i976.photobucket.com/albums/a...e/P1070120.jpg
http://i976.photobucket.com/albums/a...e/P1070133.jpg
http://i976.photobucket.com/albums/a...e/P1070134.jpg
http://i976.photobucket.com/albums/a...e/P1070138.jpg
Thanks to all for your support on this project. We all learned together.
Nice job! Glad they sound great. What is the Howards product you use? I might do my Model 19's and 14's this spring--they could use a little oil (or whatever that Howards stuff is--I think AB recommended it once in a thread here too). I was also wondering, are you using the Model 15 crossover in it's "stock" configuration with the 414's or did you customize it at all to compensate for switching the stock woofers with 414's. Or was no tweeking to the crossover necessary--did it just sound great as is with the 414's?
Howards Restor-A-Finish and Howards Feed-N-Wax Great Stuff BTW.Quote:
Originally Posted by voice of the theater
Nice to see my old 414's put to good use! Only had them sitting around for 15 years or so.......
The 15's look great!
Ron
I used the Howards Restore-A-finish - Walnut. It came out a little darker than I expected but did a great job.
Yes, the 414C are not stock for this Model 15 and I'm using the stock xover configuration. I've built Xover replacements for my 604's (Jeff M's version) and my model 19 (Zilch 19's) and those were a definite improvement.
I'll do a little research and see if there are any xover recommendation for the model 15's with 414c. I've found a couple of instances stating that the 414c were used in some of the later model 15's. Wondered if Altec did a modification to the cross over network then?
I also need to do some more detailed listening on the Model 15's and move them from my garage to my dedicated music room to see how good then sound. More data to follow.
http://www.hostboard.com/forums/hbmc...2012/03/29.jpg
Wow! those are stunning !
Beautiful job on your restoration.
:)
PS : I never knew the so-called 13" ( original ) woofer shared the same baffle cutout size, as the 414 . :Thumbs up:
Yeah, the Model 15 and the Model 9 both use the same 13 1/2" frame woofer (different than the 13 1/2" frame Model 14 woofer). That did work out great for the 414 substitution!Quote:
Originally Posted by Earl K