A new AR-3a owner here

[davidro]

Can you now post the serial numbers.

There's no paper stuff left in the back. But the one with unbroken drivers has clumsy hand inscription 61335 while the other bears 61233. Are these serial numbers?

[RoyC]

There's no paper stuff left in the back. But the one with unbroken drivers has clumsy hand inscription 61335 while the other bears 61233. Are these serial numbers?

Those are the serial numbers. Your speakers were manufactured in mid-1971.

The L-pads in your link are physically too large. This is what they should look like:

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=260-248

Before you decide on l-pads, you should examine the original controls (pots) to see if they can be cleaned.

Roy

[davidro]

Thanks Roy that's great information. Those pads actually look pretty cheap. Do you have other examples of the appropriate caps from that site?

[dynaco_dan]

There's no paper stuff left in the back. But the one with unbroken drivers has clumsy hand inscription 61335 while the other bears 61233. Are these serial numbers?

Hi again

With those two serial numbers being so close together it closes the timeline for the transition from one model driver to the next.

I could not say how close they are in sound output, dispersion, etc.

The need of test instruments would be a big help here.

Also all other members have better hearing than I do now.

The test meter you photographed is what we would call an, amp probe, used to clip over live AC wires to detect amperage or current.

It has other features as well.

It would be wise to have such a valuable test meter and also the users manual for it.

[RoyC]

Hi again

With those two serial numbers being so close together it closes the timeline for the transition from one model driver to the next.

Hi Vern,

The back-wired tweeter and mid are legitimate AR replacements, and did not show up until at least a few years later. They match the front-wired versions just fine, and there is no need for the test equipment you are suggesting. The broken faceplates are a problem, however.

Roy

[RoyC]

Thanks Roy that's great information. Those pads actually look pretty cheap. Do you have other examples of the appropriate caps from that site?

http://www.parts-express.com/dayton-metallized-capacitors.cfm

or

http://www.parts-express.com/non-polorized-electrolytic-capacitors.cfm

Kent's post above discusses caps, and the 3a restoration guide contains much information as well.

Roy

[davidro]

The broken faceplates are a problem, however.

Roy

Roy, do you have any suggestion for the broken faceplates? I don't have all the broken pieces. Ones photographed are all I have.

http://www.parts-express.com/dayton-metallized-capacitors.cfm

or

http://www.parts-express.com/non-polorized-electrolytic-capacitors.cfm

Kent's post above discusses caps, and the 3a restoration guide contains much information as well.

Roy

Since shipping is involved I'd like to order everything I need from parts-express subject to their shipping rate to Australia. The Dayton polypropylene caps look desirable as per the Guide. I can see 5.6uf (close enough to 6uf?) 50uf but no 150uf though. I'll also check out our local store (Jaycar) but often times they don't have what I need.

Re L-pads, do I also need to buy matching faceplates?

Thanks for your help!

Cheers

[davidro]

I think my restoration project will involve:

1. Replacing caps
   
2. Replacing pots with L-pads (or just cleaning the pots)
   
3. Repairing faceplates of some drivers (no idea how to achieve this)
   
4. Bleaching exsiting grille or get new fabric.
   
5. Refinishing the cabinets
   

I wonder if I can just seal the broken faceplates with some putty/blu-tack etc?

I have rudimentary soldering kits and drivers. No machine drills. Oh yeah no skills whatsoever though!

The followings are the items I think I will need for my restoration project:

1. Fibreglass stuffing if it's rock-wool inside.
   
2. Latex gloves and a dust mask.
   
3. x2 6, 50 & 150 uf polypropylene caps (voltage matters?)
   
4. x2 0.27-0.33 ohm, 10 watts non-inductive resistor for 6uf caps.
   
5. x4 0.27 ohm, 20 watts non-inductive resistor for other caps (may not be needed if I go for NPE caps).
   
6. Cable tie brackets
   
7. Gel contact cement?
   
8. x4 L-pads (3/8" Shaft 8 Ohm) - watts matter?
   
9. x4 25 ohm, 10 watts non-inductive resistors
   
10. Speaker gasket tapes (size?)
    
11. Some 3m strip caulk?
    

I would appreciate some inputs here. Thanks a lot.

[JKent]

Are all L-pads of same size and specs?

No.

This is what you need. 15 watt 8 ohm mono

http://www.parts-exp...tnumber=260-250

or

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=260-248

Kent

[JKent]

Roy, do you have any suggestion for the broken faceplates? I don't have all the broken pieces. Ones photographed are all I have.

Since shipping is involved I'd like to order everything I need from parts-express subject to their shipping rate to Australia. The Dayton polypropylene caps look desirable as per the Guide. I can see 5.6uf (close enough to 6uf?) 50uf but no 150uf though. I'll also check out our local store (Jaycar) but often times they don't have what I need.

Re L-pads, do I also need to buy matching faceplates?

See post #22 re face plate repair.

Use 6.2, not 5.6. It is certainly close enough to 6.

For 150uF combine a 50 and a 100 in parallel. Bear in mind that comes to about $43 USD each. Or just use 150uF NPEs for less that $3 USD each. They will sound just as good but in 30 years your children may have to replace them.

No need for faceplates for the L-pads

Kent

[davidro]

No.

This is what you need. 15 watt 8 ohm mono

http://www.parts-exp...tnumber=260-250

or

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=260-248

Kent

See post #22 re face plate repair.

Use 6.2, not 5.6. It is certainly close enough to 6.

For 150uF combine a 50 and a 100 in parallel

No need for faceplates for the L-pads

Kent

Thanks Kent.

The problem with repairing the faceplates is that I don't have all the broken pieces. SO I might need to fill in the gaps. Would you be able to recommend any particular material? Cheers.

[RoyC]

Roy, do you have any suggestion for the broken faceplates? I don't have all the broken pieces. Ones photographed are all I have.

Since shipping is involved I'd like to order everything I need from parts-express subject to their shipping rate to Australia. The Dayton polypropylene caps look desirable as per the Guide. I can see 5.6uf (close enough to 6uf?) 50uf but no 150uf though. I'll also check out our local store (Jaycar) but often times they don't have what I need.

Re L-pads, do I also need to buy matching faceplates?

Thanks for your help!

Cheers

-The l-pads do not need faceplates...3/8" shaft/no faceplate works well.

-If you go with Dayton caps use 6.2uf for the tweeter, 50uf for the mid and (2) 75uf 0R (1)50uf and (1)100uf (wired in parallel=150uf) for the woofer, per cabinet. Voltage is not an issue in the links provided above.

-Your era 3a's will have fiberglass, not rockwool, so that will not need replacement.

-Given your limited experience, I would not bother with the .33 or the .27ohm resistors. You will not notice the difference. 25ohm resistors will be needed for the l-pads however.

-Parts Express 3/8" wide (by 1/8" thick) gasket tape for the woofer and mids. It is too thick for the tweeters...OR you can use putty for everything. This works as well as the 3M stuff if you can't find it:

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=269-300

I have no other suggestions for your broken faceplates.

Roy

[JKent]

Thanks Kent. The problem with repairing the faceplates is that I don't have all the broken pieces. SO I might need to fill in the gaps. Would you be able to recommend any particular material? Cheers.

Again--read post 22 and the link to my KLH Restoration Guide. It's all spelled out AND illustrated.

You were typing while I was revising. Consider NPE for the 150uF. MUCH less expensive. Not that I take my own advice. You can see my 3a restoration, with Dayton poly caps, here:

http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=6284

You can bank on anything Roy tells you about the 3a. Take his advice above all others (including mine)

Kent

[davidro]

-The l-pads do not need faceplates...3/8" shaft/no faceplate works well.

-If you go with Dayton caps use 6.2uf for the tweeter, 50uf for the mid and (2) 75uf 0R (1)50uf and (1)100uf (wired in parallel=150uf) for the woofer, per cabinet. Voltage is not an issue in the links provided above.

-Your era 3a's will have fiberglass, not rockwool, so that will not need replacement.

-Given your limited experience, I would not bother with the .33 or the .27ohm resistors. You will not notice the difference. 25ohm resistors will be needed for the l-pads however.

-Parts Express 3/8" wide (by 1/8" thick) gasket tape for the woofer and mids. It is too thick for the tweeters...OR you can use putty for everything. This works as well as the 3M stuff if you can't find it:

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=269-300

I have no other suggestions for your broken faceplates.

Roy

Thanks Roy. I'll check with our local store first as to availability.

Again--read post 22 and the link to my KLH Restoration Guide. It's all spelled out AND illustrated.

You were typing while I was revising. Consider NPE for the 150uF. MUCH less expensive.

You can bank on anything Roy tells you about the 3a. Take his advice above all others (including mine)

Kent

Thanks Kent. I think I'll go for JB Weld as the other product doesn't appear to be available in Australia. I guess I can use the JB Weld to fill the void rather than removing what's left and make the whole thing? Cheers.

[JKent]

Plas-t-pair is sold by radiodaze.com, tubesandmore.com, and mcm:

http://www.mcmelectronics.com/product/20-1090&CAWELAID=240969448

MCM also sell capacitors, L-pads etc like Parts Express.

But as I said, it may not work on your plastic.

Q-bond is an automotive product, based on cyanoacrylate:

http://www.google.com/products/catalog?q=q-bond&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&tbm=shop&cid=17202651332200391257&sa=X&ei=swdXTob8IqPs0gGQr7yVDA&ved=0CCAQ8wIwAQ

If you use JB Weld make a mold as I described and make sure there is a good mechanical "grip" since the epoxy does not weld to the plastic. Rough up the plastic and let some epoxy flow on the front of the faceplate. Not on the back because that has to be perfectly flat.

Kent

[davidro]

G'day all

I've just been to our local store. No l-pads. 6uf pp cap (i.e. 3.3.+2.2+1.5 uf) will cost about $18. I think I should just order from MCM along with the l-pads and Pla-T-Pair). I'll get 47 (no 50uf at MCM), 150uf caps NPE. I'll live more than another 30 years I think but anyway.

I'm having difficulty locating 25ohm, 10W resistors for the l-pads both locally and internationally though.

The caulk...I assume I can use it for the tweeters? Our local store didn't have that either. So I'll have to order it from MCM.

So here's my shopping list from MCM:

Can I use this for sealing drivers?

I really appreciate the continuing help!

Cheers

[JKent]

Hi David

Did you test the plastic as I suggested to see if Plas-T-Pair will work? If it won't, no need going with MCM. There is more selection at Parts Express and they have resistors that would work: Dayton Wire-wound or Dayton Non-inductive. And they have the right sealant for your drivers: http://www.parts-exp...tnumber=269-300 (3 feet. Like original caulk. Probably need 3 or 4 of these)

Kent

[davidro]

Hi David

Did you test the plastic as I suggested to see if Plas-T-Pair will work? If it won't, no need going with MCM. There is more selection at Parts Express and they have resistors that would work: Dayton Wire-wound or Dayton Non-inductive. And they have the right sealant for your drivers: http://www.parts-exp...tnumber=269-300 (3 feet. Like original caulk. Probably need 3 or 4 of these)

Kent

G'day Kent

Unfortunately My girlfriend don't do nails and I have no nail polisher at home. I'm a bit reluctant to buy a $11 bottle of acetone just because I need a drop to check if the piece is plastic. But will a bottle of nail polisher work anyway? It's not 100% acetone I note. Mixed with alcohol, moisturiser(!) etc.

From its texture and look I think it's gotta be plastic though. I might have found an alternative for Plas-T-Pair though. Please have a look at this. A bigger size has more description to it and it seems very similar to Plas-T-Pair. What do you think? If it's the same or similar stuff perhaps I could just forget about l-pads and fix my 3a even tomorrow. Caps can be had locally although I might need to find out about parallel arranging. Sealant can be a challenge though. I might use this for the woofers and perhaps this for the other drivers?

[JKent]

The thing about Plas-t-pair is, it's a solvent. The solvent only works on some plastics (like polystyrene) but not on others. Do they sell old-fashioned airplane model cement in Oz? The kind derelicts sniff to get high? That's basically what's in Plas-t-pair. If the plastic does not soften when the solvent is applied, you may as well use JB Weld as long as you roughen up the surface a bit. I don't know about that plasti-bond stuff. Maybe. Might be worth a try.

That woofer gasket looks fine. Don't think the gasket goo is the right thing. What you want is something like window putty. A product sold here, called duct seal is perfect. It's sold in electric-supply houses or in the electric dept of big home centers. It is dark gray and pliable--you roll it out with your hands to make a long snake of the stuff. http://www.google.com/products/catalog?q=duct+seal&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&tbm=shop&cid=16798276072157716551&sa=X&ei=EfRYToLWMqbq0gGSwajHDA&ved=0CEQQ8wIwAA

Connecting caps in parallel is easy. Just place them side by side, twist the leads together and solder.

Kent

[davidro]

Thanks Kent. Regarding Plasti-Bond I'd like to give it a try as it says it takes only 20 mins to have it hardened. I guess I'll need to buy an electric drill so that I can drill in the screw once that's done. Wonder if a cheap one can do the job.

When I shape that Plasti Bond thing I guess I'll need something to keep the base flat as you highlighted. The product description says it will not adhere to polyethylene, polypropylene or Teflon. I wonder what material I can use then to keep the base flat? Supposedly something that's made of either polyethylene, polypropylene or Teflon?

Thanks for your continuing help. I really appreciate it.

Cheers

[JKent]

Thanks Kent. Regarding Plasti-Bond I'd like to give it a try as it says it takes only 20 mins to have it hardened. I guess I'll need to buy an electric drill so that I can drill in the screw once that's done. Wonder if a cheap one can do the job.

When I shape that Plasti Bond thing I guess I'll need something to keep the base flat as you highlighted. The product description says it will not adhere to polyethylene, polypropylene or Teflon. I wonder what material I can use then to keep the base flat? Supposedly something that's made of either polyethylene, polypropylene or Teflon? Thanks for your continuing help. I really appreciate it. Cheers

You should drill holes for the screws in the repaired faceplates but use a screwdriver to drive the screws. I believe they are "machine screws" (bolts) and there are metal inserts in the speaker cabinet.

You can use anything for the flat part of your mold. Just cover it with wax paper or even plain paper or masking tape. The filler will not adhere to wax paper, and if it adheres to plain paper just tear it off (or leave it on for that matter). The point is to get the BACK (mounting surface) perfectly flat. You could make a form using cardboard under the broken parts. Make sure there are no gaps on the back. Use tape to get a tight seal there. Use masking tape to form a lip around the perimeter, then pour your Plasti-Bond into the mold you have made. If it is liquid it should level off. If it is paste-like you will have to spread it and form it. It should overlap a bit on the front of the speaker flange to provide a good mechanical grip. Wouldn't hurt to drill a couple of small holes in the good part of the flange to provide anchor. Just keep it away from the screen on the mid or the paper covering on the tweet. This method would work with JB Weld also. After the patch is thoroughly cured, you can file and sand it if needed to get the shape right, and paint the repair black if you want. Then drill new holes for the screws. Be sure to position the new holes accurately and when you finally reinstall the drivers use putty/caulk to seal them and just snug the screws down tight. Do not over-tighten or you may break the faceplates again.

Be VERY VERY careful with the delicate leads for the drivers. Unsolder them before removing the tweeter or mid.

Kent

edit: I just checked to see if the solvent in Plas-T-Pair has any effect on the faceplate of my AR11 mids. It does not. The 11 mids are exact replacements for the 3a mids, so "assuming" the plastic used is the same, I'd say Plas-T-Pair will not work.

[davidro]

Thanks Kent

Now, I want to be very careful about removing the mid range and the tweeter. I note the problematic speaker has the terminal strip covered in black paint sort of thing. How can I unsolder the leads from it? I have solder sucker ready.

[JKent]

you want to make note somehow of which wire goes to which terminal. I'm pretty sure you can just heat & suck. The paint will burn off. Don't inhale it.

Kent

[davidro]

G'day I've checked out local store and just wasn't happy with the capacitors they had. I think I'll order the caps from Parts-Express subject to their shipping charge. Re 25 ohm 10W non-inductive resistors for the l-pads is this the right one? And I'll need 4 of this? Cheers.

[JKent]

or this

http://www.parts-express.com/pe/pshowdetl.cfm?Partnumber=004-25