Recapping Wire Recorder...easy to do? hard? Help!

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Unread postby Perisphere » Thu Jan 15, 2009 2:24 pm

Steve E. wrote:
Perisphere wrote:My hunch is, the speaker is faulty.
BINGO! External sounds great, it turns out. yayyy, I successfully recapped after all!

Perisphere wrote: Dad's machine had such a buzzy quality when I was young, and through the 1970s it got eventually where there was no real sound from it. By 1980 it did not produce sound at all despite the voice coil showing continuity. No big deal as I had cables that permitted me connecting it to other equipment.
Are you talking about your Dad's Webcor machine? If so, it this basically my best option for fixing this speaker? What to do?


Yes, I did that 'transplant' to Dad's recorder. It wasn't practical to buy another 5 1/4" speaker to fit to the machine, because Dad's machine uses a field coil speaker as part of the B+ circuit, not a PM speaker.

I think the 180 I have in storage has a PM speaker. Whether your 288 has the PM speaker or the field-coil speaker, it's not too expensive having it reconed. (Voice coils are not sold separately from replacement cone assemblies.)

One recone facility I know and recommend is Freeman-Tuell Speaker Service, 7911, Ferguson Road, Dallas, Texas 75228. Phone: 214 324 1132. Low prices, excellent service, fast turnaround.
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Unread postby Steve E. » Thu Jan 15, 2009 4:05 pm

What is a PM speaker?

Interestingly, I tried hooking up the Model 288 speaker to the Model 80 to test it. No sound at all. (I didn't try a vice-versa). But I did hook up the 288 to my regular stereo system and it presented the same exact problem.

I am guessing that the Model 80 used a different impedance? No way to tell from the schematics, though they were different part #'s.
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Unread postby Perisphere » Thu Jan 15, 2009 6:40 pm

Permanent magnet.
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Unread postby cuttercollector » Fri Jan 16, 2009 3:32 am

In the days before they could make very big permanant magnets or very big capacitors (called condensers in those days) someone came up with the bright idea of making a speaker with a voice coil as we have more or less today and a DC field coil that served as the magnet (not permanent)
for the speaker and as a choke to go with the small capacitors to filter hum from the power supply for the tube plates.
So, if the speaker has more than 2 wires going to it, it probably has about 350V DC on 2 of them for the field coil/choke and the other 2 are normal audio. I don't know what the voice coil impedance of electromagnetic speakers is or was but probably in the 4-16 ohm range. I think there were a few 600 ohm speakers produced very early but they got away from that quickly. The output transformer might be mounted on the speaker too. Some manufacturers did that.
I now have to take apart MY wire recorders and see what is up with them.
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Unread postby emorritt » Fri Jan 16, 2009 3:21 pm

Field coils weren't limited to loudspeakers... I have one of the old Western Electric 'rubber line' cutters from the late '20's and it uses a field coil. Never seen a cutter set up that way before. The unit has an advance ball and even with the field coil isn't very heavy; nowhere near the weight of a stereo head.
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Re: Recapping Wire Recorder...easy to do? hard? Help!

Unread postby Steve E. » Tue Feb 13, 2018 12:46 am

I'm revisiting this old thread. i now have need to USE this 288 wire recorder, and dang, I'd love to get that speaker working. Can any suggest my best options for having it repaired or replaced?
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Re: Recapping Wire Recorder...easy to do? hard? Help!

Unread postby Voxster1965 » Tue Feb 13, 2018 4:56 am

I would contact Rob Squire at Pro Harmonics in Adelaide, South Australia. He has repaired and restored a few.
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Re: Recapping Wire Recorder...easy to do? hard? Help!

Unread postby markrob » Tue Feb 13, 2018 11:19 am

Hi,

Did you determine if the speaker was a field coil type?

If not, then you should be able to find something to replace it. Measure the location dimensions of the mounting holes. That should point to a decent replacement.

For example:

https://www.tubesandmore.com/products/speaker-jensen-vintage-ceramic-6-c6v-20w

Even if its a field coil, you can still use a PM speaker if you either salvage the field coil from the original speaker or purchase a similar stand alone choke.

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Re: Recapping Wire Recorder...easy to do? hard? Help!

Unread postby Steve E. » Tue Feb 13, 2018 2:45 pm

E7ADE770-12BE-4F3C-9CDF-96443DA34755.jpeg
E9D59C80-B2EC-494B-8F33-32FCA994BE36.jpeg
i can't tell. Can you? It had only two wires going to it. I'm guessing field coil simply because the recording wire shows no attraction to it when it its vicinity.
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Re: Recapping Wire Recorder...easy to do? hard? Help!

Unread postby markrob » Tue Feb 13, 2018 5:43 pm

Hi,

Its a standard PM speaker. No field coil. Can you measure the speaker cone diameter. From the photo, looks like a 4-5"??

On a quick search of Parts Express, I found this:

https://www.parts-express.com/visaton-r10s-4-full-range-speaker-8-ohm--292-596

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Re: Recapping Wire Recorder...easy to do? hard? Help!

Unread postby Steve E. » Thu Feb 15, 2018 11:39 pm

Thank you!!

Yes, the specs say it is a permanent magnet. it's 5.25 inch.

http://reel2reeltexas.com/vinAd50Webster288.jpg
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Re: Recapping Wire Recorder...easy to do? hard? Help!

Unread postby markrob » Fri Feb 16, 2018 11:50 am

Hi Steve,

This looks like a good start on a replacement

https://www.parts-express.com/grs-5pf-8-5-1-4-paper-cone-foam-surround-woofer--292-405

If you can, try to measure the dimensions of the mounting studs for the speaker. Normally, they are specified as a radius or diameter from the cone center, but in this case they may just be the vertical and horizontal spacing. Parts Express usually has dimension drawings for their speakers. In this case, they are not listed. If you call, them, they may be able to supply them. Make sure you check the depth. Also, if the bad speaker voice coil is not open, check the DC resistance with an ohmmeter. This should give you a clue as to the actual impedance. The DC resistance will always be lower than the impedance (e.g an 8 ohm unit will measure 6 ohms or so). You may not find a perfect match, but in many cases you can find something that can be made to work. You might have to construct a mounting adapter that converts the current stud pattern to the replacement speaker.
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Re: Recapping Wire Recorder...easy to do? hard? Help!

Unread postby Steve E. » Fri Feb 16, 2018 12:15 pm

this is wonderful. thank you so very much!!!

and the reason the model 80 speaker didn't work.... well that one IS a voice coil speaker! one mystery solved there.
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Re: Recapping Wire Recorder...easy to do? hard? Help!

Unread postby Steve E. » Fri Feb 16, 2018 1:48 pm

One more question:

It appears that back when i recapped this, i didn't replace two ancient, silver-colored .01 µf capacitors, presumably because of an additional grounding wire which doesn't show up on modern capacitors. Right now I'm operating on the "if it ain't obviously broke..." line of action after a near disaster yesterday (from an unrelated dumb wiring mistake).

But i am wondering how I'd know if these particular capacitors weren't functioning properly, symptom-wise. Are these just there to reduce AC hum, or switch pops, or are they doing more? They are C7 and C8 in the schematic (attached), and they seem to go between the record/play switches and the 6SC7 tube on the far left mid-page of the attached schematic.

And, if i were to replace them, are there good resources/demonstrations on how I'd do a modern-style grounding of a capacitor?
Attachments
websterchicago 288.pdf
89E19016-BC9D-4743-9920-882EE74F14CC.jpeg
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Re: Recapping Wire Recorder...easy to do? hard? Help!

Unread postby markrob » Fri Feb 16, 2018 2:39 pm

Hi Steve,

On the schematic, they are audio coupling caps. They should be replaced with modern units. I wouldn't worry about the shield ground on the case. Just replace them with the same style film caps that you used for the rest of the re-cap and you should be fine. If you find that they now pick up some hum without the shield, you can get some braided wire of the right diameter and slip it over the new caps to make a shield. The new caps are probably smaller in diameter than the current cap, which will make it easier to find. If you go that route, just be careful not let the shield touch either lead of the caps.

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