84B Restoration - update-Touchdown! - Printable Version
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84B Restoration - update-Touchdown! - klondike98 - 10-09-2014
Picked up an 84B the other day. Cabinet is not in bad shape but will probably refinish it… but that’s another thread. Chassis is relatively clean but the speaker cone is very fragile and crumbly and the spider is broken. I’ve seen Bob Andersen’s re-cone video (It was on a 60) but his spider was intact.
Question 1: Has anyone repaired one of those 45 rpm adapter type spiders?? Is it better to try and re-glue the broken arms on the spider or make a new one? It looks like the material is like that of a manila file folder. Thanks for any advice on how to do this!!
[Image: https://www.dropbox.com/s/cy20ov6dullmky5/84B_speaker.jpg?raw=1] [Image: https://www.dropbox.com/s/5v0zagg9hrmsr5x/84B_spider.jpg?raw=1]
Question 2: The 3 wires going to the speaker which were originally green, white and green/white (schematic) have deteriorated and need replacing. (they've all faded to umber now) [Image: https://www.dropbox.com/s/abpfzzk9vemeok4/84B_speaker_wire.jpg?raw=1] Has anyone found a wire source for these (particularly the green/white). I don’t see anything quite right in AES, Radiodaze or Sundial. Perhaps I’ll just have to use green, white and yellow. Thoughts?
Thanks!!!
RE: 84B Restoration - need advice - Ron Ramirez - 10-09-2014
I can't answer your question #1, but I can answer question #2.
I use 20 gauge lacquered cloth-covered green, white and blue wire from Radio Daze to replace the green, white and blue/white wires.
http://www.radiodaze.com/category/400.aspx
RE: 84B Restoration - need advice - klondike98 - 10-09-2014
Thanks Ron!! Yep, I've looked everywhere and just don't see those mixed color cloth covered wires reproduced anywhere.
RE: 84B Restoration - need advice - morzh - 10-09-2014
The way the spider is, I do not think gluing will work.
The condition the cone is in, I would re-cone the whole thing.
RE: 84B Restoration - need advice - klondike98 - 10-11-2014
Thanks Mike, I do plan on re-coning and have the frame cleaned up to do that but I'm still looking for advice on how to repair/replace the spider. Someone must have done that before but I haven't found a thread on it. If I don't hear otherwise, my first approach will be to try and reattach the old one by splicing the pieces back together. If that doesn't work I'll trim out the bulk of the spider and glue in a new one made of manila file folder paper or something similar.
[Image: https://www.dropbox.com/s/27ee5z8dnsly4om/84B_recone1.jpg?raw=1]
RE: 84B Restoration - need advice - klondike98 - 10-13-2014
I went ahead and attempted to repair the spider. The first photo below shows the spider cut from cone and the center of the spider with the remaining fragments of the spider arms still connected to the center nut of the spider. I forgot to take a picture of it but I glued small splicing extensions to the underside of the existing arms on the center nut so that about 3/16 of an inch of extension was glued to the arm and another 3/16" extended out beyond the torn edge.
[Image: https://www.dropbox.com/s/lr8pkmm1fspe7f3/84B_spider1.jpg?raw=1]
You can see one from the underside looking through the voice coil. The yellow arrow points to the lighter "extension" that was made from manila file folder.
[Image: https://www.dropbox.com/s/hbh67h3vx273un2/84B_spider2.jpg?raw=1]
I glued the 3 extensions one at a time and let each dry before moving on to the next just so I wouldn't mess up one while gluing on the next. After all 3 were dry, I slipped the center nut/arms/extensions into place. I used tacky glue from the hobby store and it was tacky enough to allow me to slide the pieces into place and hold them while I got things aligned. Cleaned off as much extra glue as possible with a toothpick and then used a nut driver to apply a little pressure from the bottom.
[Image: https://www.dropbox.com/s/8wousge4q0f1nqa/84B_spider4.jpg?raw=1]
Once dried, I added a little glue to the top where the torn edges were still visible.
[Image: https://www.dropbox.com/s/bw2txwljzdvxxz2/84B_spider3.jpg?raw=1]
Will have to wait to see if it works (and for how long) after I get the rest of the chassis restored.
RE: 84B Restoration - need advice - morzh - 10-13-2014
Bob
Do the extensions overlap and then glued or simply touch the ends with glue around?
RE: 84B Restoration - need advice - Ron Ramirez - 10-13-2014
Very clever repair!
Hopefully it will hold, and remain flexible...
RE: 84B Restoration - need advice - klondike98 - 10-13-2014
The extensions overlap the tear just like you would splice film with a piece of tape. I'm hoping it will be flexible enough as well as strong enough.
RE: 84B Restoration - need advice - klondike98 - 10-21-2014
I installed the new 8" cone from MAT Electronics, shimmed the voice coil and glued them all together using the Bob Andersen procedure noted in the first post.
[Image: https://www.dropbox.com/s/d4juzrcm47xyb09/84B_speaker2.jpg?raw=1]
After it all dried and the speaker was reattached to the chassis, it was playing like a champ. I'm not sure how long the repair will last but I'm thrilled its working as well as it is. As Bob mentioned in his video, the MAT Electronics cone is almost a drop in fit except for a little trimming of the cone's outer edge and the height of the outer hump on the cone which is about 1/16" higher than the metal frame. I'll use some stand offs so the cone doesn't hit the mounting board.
[Image: https://www.dropbox.com/s/3hbilrq8t8q59y6/84B_restoredchassis-speaker.jpg?raw=1]
The chassis restoration was pretty straight forward with the usual bakelite caps, electrolytic restuff, and a few resistors. The 3 resistors that were replaced are the blu/blk/red, red/yel/yel and the 1meg brn/blk/grn. The wires routed to the speaker needed replacement as well. Here's the before and after(without power cord).
Before
[Image: https://www.dropbox.com/s/ruwv5ylzvyscaw1/84B_underside_asreceived.jpg?raw=1]
After
[Image: https://www.dropbox.com/s/da8a963ey0mpol4/84B_underside_restored.jpg?raw=1]
Touchdown! [Image: https://www.dropbox.com/s/7x6ls4dtjlaojqb/touchdown.jpg?raw=1]
RE: 84B Restoration - update-Touchdown! - morzh - 10-21-2014
Bob
I do not see it here...looks to me like you left all resistors in place and, unless the graphics looks unclear, the caps are also untouched, no?
I know for a fact those big brown resistors are always off, and so are others. Unless you made the new ones.
RE: 84B Restoration - update-Touchdown! - klondike98 - 10-21-2014
Caps are all recapped and I made the three resistors I mentioned. The paint is a little brighter than the original. The others were still in spec. That's the goal, as original looking as I can make it. I use your technique on the bakelite caps.
RE: 84B Restoration - update-Touchdown! - morzh - 10-21-2014
Looks pretty darn autentic, what can I say!
RE: 84B Restoration - update-Touchdown! - jerryhawthorne - 10-22-2014
Bob, very clever work on the spider. Thanks for the post.
Jerry
RE: 84B Restoration - update-Touchdown! - Ron Ramirez - 10-22-2014
Great work, Bob!
