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 Post subject: Re: 3M Germanium Transistor part numbers
PostPosted: Apr Fri 28, 2017 6:26 pm 
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Posts: 9227
Location: Santa Rosa, CA
Quote:
If this was the case why did so many manufacturers choose to continue the use of Germanium transistors?


By 1965, Germanium was nearly as dead as a door nail. Westinghouse phased it out around 1960. No one was designing new equipment with Germanium transistors (except maybe in Japan). I am sure there were "legacy" designs out there that lasted into the 1970s, but no one had any serious interest in Germanium transistors by 1970. Germanium diodes continued on as detectors for a long time and are probably still made today in Asia or Russia. There was a small company called Germanium Power Devices that was still active in the 80s making replacement parts. They still make exotic optical devices: http://www.gpd-ir.com/index.html

More info at the Semiconductor Museum: http://semiconductormuseum.com/Historic ... _Index.htm

Rich


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 Post subject: Re: 3M Germanium Transistor part numbers
PostPosted: May Tue 02, 2017 5:20 pm 
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Simple to find when you have multi-million dollars worth of parts accounts.... :mrgreen:

Attachment:
3M.jpg
3M.jpg [ 34.29 KiB | Viewed 1961 times ]


Looks like it's a Delco 2n1535... NTE121 is the replacement if going with an NTE....

Please don't tell my employer....... :oops:

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"Capacitor Cosmetologist since 1979"
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 Post subject: Re: 3M Germanium Transistor part numbers
PostPosted: May Wed 03, 2017 1:29 am 
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Findm-Keepm wrote:
Simple to find when you have multi-million dollars worth of parts accounts.... :mrgreen:

Attachment:
3M.jpg


Looks like it's a Delco 2n1535... NTE121 is the replacement if going with an NTE....

Please don't tell my employer....... :oops:


Wow incredible! :o :o

So you are either one of those 3M guys that archives everything, or this is a Delco Database or both? I was tolt (yes I meant to use the 't') by 3M that all of this information had been "divested" as of 1988. Or maybe at least the service docs were.

Sometimes hoping for the best really does turn out great. :mrgreen:

P.S. I had to remove some smiles. The board has set 6 as the limit per post. :mrgreen:

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 Post subject: Re: 3M Germanium Transistor part numbers
PostPosted: May Wed 03, 2017 3:48 pm 
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Location: The Old Dominion VA 23518
Monarke4 wrote:
Findm-Keepm wrote:
Simple to find when you have multi-million dollars worth of parts accounts.... :mrgreen:

Attachment:
3M.jpg


Looks like it's a Delco 2n1535... NTE121 is the replacement if going with an NTE....

Please don't tell my employer....... :oops:


Wow incredible! :o :o

So you are either one of those 3M guys that archives everything, or this is a Delco Database or both? I was tolt (yes I meant to use the 't') by 3M that all of this information had been "divested" as of 1988. Or maybe at least the service docs were.

Sometimes hoping for the best really does turn out great. :mrgreen:

P.S. I had to remove some smiles. The board has set 6 as the limit per post. :mrgreen:


I work for a company that is half-part broker and half-logistical support, mostly for military, military contractors, and some foreign military sales. Some parts databases (all subscription based) are available to me, for company use. Most of the data is gleaned from support and service contracts, cross reference guides, and competitor cross reference data. It usually is accessible online or via email support (result is a .rtf file..) and has data for most every industry - Agriculture to X-ray. I dunno the exact source, but it appears to be a snippet from the Wollensak parts catalog (we use a later one, but your part wasn't listed..).

Odd that every Hitachi industrial device part number ever made is in the database, but close-to-home/USA manufacturers didn't publish any data, or greatly limited it's distribution. Kodak, 3M, AMF, Allison, Singer, Teledyne, and NCR all held their cards close, and most went under. Perhaps there is a lesson here (are you listening Apple??)

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 Post subject: Re: 3M Germanium Transistor part numbers
PostPosted: May Thu 04, 2017 7:33 am 
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Findm-Keepm wrote:
I work for a company that is half-part broker and half-logistical support, mostly for military, military contractors, and some foreign military sales. Some parts databases (all subscription based) are available to me, for company use. Most of the data is gleaned from support and service contracts, cross reference guides, and competitor cross reference data. It usually is accessible online or via email support (result is a .rtf file..) and has data for most every industry - Agriculture to X-ray. I dunno the exact source, but it appears to be a snippet from the Wollensak parts catalog (we use a later one, but your part wasn't listed..).

Odd that every Hitachi industrial device part number ever made is in the database, but close-to-home/USA manufacturers didn't publish any data, or greatly limited it's distribution. Kodak, 3M, AMF, Allison, Singer, Teledyne, and NCR all held their cards close, and most went under. Perhaps there is a lesson here (are you listening Apple??)


Now if only someone somewhere has the service document(s) gathering dust somewhere for the 3M Model 94BG "Cantata 700" it would save me from trying to re-draw the circuit diagram from the PC board.

I do not expect to get hard copy of the service docs or a high quality scan for free. I'm willing to pay a reasonable amount for said information.

Concerning Apple, I service some equipment for a company which is now 95 years old. They are in the electronic Carillon "musical bell instrument" business. The company has also worked in real Cast Bell instruments too. The son runs the company and has for decades. He is probably in his early 70s to early 80s.

The digitally controlled products have never had service docs available for technicians or the public. Though I am sure they do exist. Documentation for older equipment is spotty. I have managed to purchase some docs for products from decades ago, and helped to fill in the gaps for the manufacturer. They are one of the very few companies which keeps original paper records in addition a database. Paper records dating back decades takes up quite a bit of room.

On the other hand rebuilding a Rauland audio amplifier from 1979 and to only be able to provide a one year warranty when a new audio amplifier from Grommes-Precision has an 8 year warranty is kind of foolish.

Apple is very different from a Carillon manufacturer. When I need information or help, they always try to provide it. I also can't complain as when I have needed something like a switch or a lamp for an much older system, the owner would pull it from a parts bin and say, here "no charge".

When working in a business that can be very "cut throat" sometimes you have to keep certain information out of the hands of those who are out to damage your business.

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 Post subject: Re: 3M Germanium Transistor part numbers
PostPosted: May Fri 05, 2017 7:51 am 
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I received the 1500SS service manual yesterday.

I don't why I thought the amplifier in the 3M Cantata 700 and the Wollensak 1500SS would be similar. They do share the same pre-amplifier and AF transistors. The early version uses (Delco) DTG110 output transistors. The late version uses one NPN 2N2148 and one PNP 40466 RCA output transistors.

Seems that 3M Mincom (professional tape recorder division) decided not to hide these part numbers of transistors with house numbers. 3M Duplicating Products Division (Cantata 700) it seems did.

I believe the 3M Cantata 700 amplifier was a much older design than the 1500SS even though they were manufactured during the same time period.

From references I found the 1500SS was introduced in 1966, and was still being manufactured in 1968.

Useless information....I know.... :P

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 Post subject: Re: Germanium Transistors (3M Cantata 700 Amp) Update
PostPosted: May Sun 28, 2017 6:21 am 
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I replaced all capacitors, resistors and the rectifier diodes. This leaves the original transistors.

With a Variac and a 25 watt dim bulb tester in series I brought it up to 115VAC input at the power transformer. Surprisingly there was no indication that either one of the output transistors is shorted.

With a little math I calculated that the amplifier consumes approximately 16.8 watts. At 120 AC voltage input the current consumption is rated at .44 amps. The motor is rated at .3 amps. This left a remainder of .14 amps.

With a compact disc input and at approximately 1/3 volume it plays cleanly. The output transistors warm slightly with one hour of music programing input. The driver transformer does not have any noticeable warming. The output transformer heats up very slightly.

I allowed the amplifier to play with a musical input for a full two hours. It appears to be a success.

I'll have an image to post of the rebuild amplifier a little later.

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 Post subject: Re: 3M Germanium Transistor part numbers
PostPosted: May Sun 28, 2017 6:43 am 
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Here is an image of the completed amplifier.

The PC board had a crack in it which I repaired with Loctite 2 hour Marine Epoxy. Great stuff!


Attachments:
File comment: Rebuilt 3M Cantata 700 amp board
amprebuilt1.jpg
amprebuilt1.jpg [ 197.68 KiB | Viewed 1758 times ]

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 Post subject: Re: 3M Germanium Transistor part numbers
PostPosted: Dec Tue 26, 2017 6:06 am 
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Hi Donald,

I am curious if you made progress with the mechanical parts of this machine? It is so complicated that I am loathe to disassemble mine before becoming more knowledgeable about its inner workings. I read somewhere it also has a timer inside to start and stop it every 20 minutes.

In the meantime I discovered a few things. I took the tape out of one cartridge (which required repairs in any case) and tried playing it on an auto-reverse reel to reel. Interesting that even though tracks are laid out the same as regular 4-track, they are reversed in direction — music was playing backwards on all four tracks. I wonder if that was intentional to prevent playing on unauthorized machines? (In the end I made a MP3 of a portion of the tape, then used a program to reverse it. Sound is pretty good, for 1-7/8 ips in any case).

The auto-reverse works by using different pinch rollers on the same, clockwise turning capstan. The reel drive too always runs in the same direction. Which reel turns in which direction is controlled by the capstan. Reel turntables — inside the cartridge — sit on felt slip pads and depending on which way the tape is being pulled by the capstan, take-up reel turns with the drive, the supply reel slips against it.

In any case I would love to hear of your experiences.

AE - New York City


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 Post subject: Re: 3M Germanium Transistor part numbers
PostPosted: Dec Wed 27, 2017 4:01 am 
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I have had to place the project aside as of my last posting since I the amplifier was finished and working, thanks to many here and some from the Jukebox list.

The Cantata 700's mechanism never stops until you power it off. The timer feature operates a potentiometer which "fades-out" (or mutes) the music. At an approximate time through which is governed by the mechanics (which may not be an exact number of minutes) the volume "faded-in" again to the previous volume setting. There is a potentiometer mounted on the mechanism chassis with 3 yellow wires which connect to the amplifier board.

I have a tape which I purchased from eBay which had been successfully spolled off and recorded from a reel to reel deck. It's possible you wound the reels in the incorrect direction. The wind on the 3m Cantata reels are "oxide out" (B-Wind) where as on most reel to reels machines it is "oxide in" (A-wind) (except for very early machines). If you have the oxide side away from the tape heads it will sound quite muffled with a much lower volume. You may also get "tape squeak" from the glossy side of the tape rubbing against the heads. You will most assuredly get contamination of the tape pressure pads (oxide accumulation on the pads) if your reel to reel machine is so equipped.

Considering the quality of the audio, "it's all relative" when you compare it to the quality of compact discs (or half track) for instance you will hear a great difference in audio quality. However when something like this and/or PCM quality recordings are played through Quam 70.7v ceiling speakers it all sounds close to the same.

Grabbing the specs from the Grundig TS-1000 Reel-to-Reel (semi pro) machine they are as follows:

Frequency response :

20Hz - 12,5Khz (4,76cm/s) 1.785 ips
20Hz - 16Khz (9,5cm/s) 3.75 ips
20Hz - 20Khz (19cm/s) 7.5 ips

The low end frequency spec. seems a bit "liberal" to me as most 1/4" track R2R machines cannot record frequencies below around 30Hz (which may also be quite high).

For Musak quality of tape recordings from the 1960s would be closer to that of a 8" Quam w/whizzer cone of:

AUDIO SPECIFICATIONS
Average Sensitivity: 92 dB SPL, 1W/ 1M
Loudspeaker Power Rating: 20W RMS, EIA 426A Standard
Calculated Output: 99 dB SPL, 5W/ 1M
Magnet Type & Weight: BeFe Ceramic, 10 oz. Nominal
Frequency Response: 60 Hz - 12 kHz EIA 426A Standard
Nominal Coverage Angle: 90° Included Angle, -6 dB / 2 kHz, Half space


Vinyl Jukeboxes as well as those which play compact discs are purposely rolled off on the low end at 80Hz.

45 rpm records have a peak/bump at 160Hz.

A 45 rpm record Jukebox upper end at about 12-13Khz, with perfect vinyl or styrene records of no where. if I remember correctly polystyrene records start to degrade terribly after about 18 plays with a heavy stylus. It can be seen as there will be "white dusting" on the surface.

I do not know what the specification of a "Downloader" (so called network Jukebox) is but it's probably a lot lower (for the purpose of quickly downloading files) than 320kbps. As a reference Compact Discs on average have a 1141kbps data rate.

Maybe more than a nickel's worth.... :wink:





Tiptop wrote:
Hi Donald,

I am curious if you made progress with the mechanical parts of this machine? It is so complicated that I am loathe to disassemble mine before becoming more knowledgeable about its inner workings. I read somewhere it also has a timer inside to start and stop it every 20 minutes.

In the meantime I discovered a few things. I took the tape out of one cartridge (which required repairs in any case) and tried playing it on an auto-reverse reel to reel. Interesting that even though tracks are laid out the same as regular 4-track, they are reversed in direction — music was playing backwards on all four tracks. I wonder if that was intentional to prevent playing on unauthorized machines? (In the end I made a MP3 of a portion of the tape, then used a program to reverse it. Sound is pretty good, for 1-7/8 ips in any case).

The auto-reverse works by using different pinch rollers on the same, clockwise turning capstan. The reel drive too always runs in the same direction. Which reel turns in which direction is controlled by the capstan. Reel turntables — inside the cartridge — sit on felt slip pads and depending on which way the tape is being pulled by the capstan, take-up reel turns with the drive, the supply reel slips against it.

In any case I would love to hear of your experiences.

AE - New York City

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 Post subject: Re: 3M Germanium Transistor part numbers
PostPosted: Dec Wed 27, 2017 9:24 am 
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Hi Donald,

You say, “It's possible you wound the reels in the incorrect direction“ — I thought about it but I do not think so. I have the oxide facing in and I cannot think of how else I could have got it wrong. When you have the four tracks as:

————>
<————
————>
<————

the only way to have the tape wound wrong is like you suggested, backing facing the heads and I am pretty sure I have that right, it looks right and the sound is clear. That, I believe, leaves the recorded tracks being laid in the opposite direction to normal reel-to-reel as the only explantion. Tell me if there is another way?

Incidentally — and co-incidentally — I was playing the tape back on a Grundig TS 1000.

Ali


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 Post subject: Re: 3M Germanium Transistor part numbers
PostPosted: Dec Wed 27, 2017 10:08 am 
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Tiptop wrote:
Hi Donald,

You say, “It's possible you wound the reels in the incorrect direction“ — I thought about it but I do not think so. I have the oxide facing in and I cannot think of how else I could have got it wrong. When you have the four tracks as:

————>
<————
————>
<————

the only way to have the tape wound wrong is like you suggested, backing facing the heads and I am pretty sure I have that right, it looks right and the sound is clear. That, I believe, leaves the recorded tracks being laid in the opposite direction to normal reel-to-reel as the only explanation. Tell me if there is another way?

Incidentally — and co-incidentally — I was playing the tape back on a Grundig TS 1000.

Ali


If you play the tape on a machine that does not have independently switchable tracks like a Teac A-3340S...... But then again.... no 1.785 ips. If you play it back on a stereo reel to reel machine one of the two tracks should play the correct direction. The operation of the machine is as you have indicated above. The operator's manual leads you to believe that it plays adjacent tracks as it switches directions.

Ooops....

I pulled the mechanism down sat it on the bench and manually turned the head cam marking with a felt tip pen along the guide post where it rests when locked into position.

It is as follows. Track 1, Track 4, Track 2, and Track 3.

I assumed.... and you know what happens when one has assumptions.

It makes an *ss out of you and me! :mrgreen:

I know the TS-1000 has a removable head block which uses a plug in connector. If the heads themselves have slip on connectors, you could possibly temporarily flip the wiring in order that it will temporarily play 1,4, 2, 3... There was also auto reverse head block for the TS-1000, for which it and the additional card for the capstan motor is rather rare.

From thevintageknob.org

A semi-professional deck, the TS1000 could be used as a 2TR or 4TR deck with its interchangeable head-blocks.

The 4TR head-block allows for a switchable auto-reverse playback facility, the direction selector being located on the block itself.

I also own a Grundig TS-1000 which I bought from a seller in Poland for which it was shipped Los Angeles, California about 5 months ago.

Incidentally the seller did an excellent job of double packing it. It arrived in 5 days UPS air saver without a scratch.

It is sitting on my table, haunting me. I haven't had a chance to go through it yet. :oops:

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 Post subject: Re: 3M Germanium Transistor part numbers
PostPosted: Dec Wed 27, 2017 9:00 pm 
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You say, “There was also an auto reverse head block for the TS-1000 (...) it and the additional card for the capstan motor is rather rare.”

Well! I have the auto-reverse head block, three others, the extra card, two remotes and a bunch of other accessories. The TS 1000 is a wonderful machine, just not the most attractive and a bit plasticky.

What chooses between the two separate direction heads is a tiny solenoid, inside the head block. I should just add an outside control to the solenoid to play the Cantata tapes.


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 Post subject: Re: 3M Germanium Transistor part numbers
PostPosted: Dec Fri 29, 2017 7:08 am 
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I am just listening to a recording of Mozart’s Don Giovanni made by someone off a Texaco Met Opera FM broadcast back in 1990, which I bought on eBay. It was taped with DBX noise reduction. Playing on the Grundig TS-1000 it cannot possibly sound better. The TS-1000 has Dolby but no DBX, for that I have an external decoder.

I highly recommend that you unpack your TS-1000 and put it to use. I cannot imagine there is a better-sounding, more user-friendly tape machine ever made.


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 Post subject: Re: 3M Germanium Transistor part numbers
PostPosted: Dec Fri 29, 2017 8:22 am 
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Tiptop wrote:
I am just listening to a recording of Mozart’s Don Giovanni made by someone off a Texaco Met Opera FM broadcast back in 1990, which I bought on eBay. It was taped with DBX noise reduction. Playing on the Grundig TS-1000 it cannot possibly sound better. The TS-1000 has Dolby but no DBX, for that I have an external decoder.

I highly recommend that you unpack your TS-1000 and put it to use. I cannot imagine there is a better-sounding, more user-friendly tape machine ever made.


That is another item I have added to my long list of wants. The dolby B card which plugs into the backplane of the TS-1000.

It is unpacked, and dusted off. Currently it has a cloth cover over it to keep dust off of the exposed parts.

I too have a external DBX A box. Originally I thought that I might need it for older Cassette Bell Music Tapes Verdin had produced for one of their elderly products.

My list (like many others I'm sure) of wants and projects keeps getting longer. Unfortunately business comes first, and without a steady flow of business I cannot invest in parts and accessories I might need for my own personal projects.

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 Post subject: Re: 3M Germanium Transistor part numbers
PostPosted: Dec Sat 30, 2017 7:29 pm 
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The auto-reverse head block is tricky because there is a PCB in there plus switches, the relay and so forth. But it does turn up on German eBay from time to time.

Getting the Dolby and auto-reverse cards may prove to be a longer wait. But they are also much easier to make. They are small PCBs with not that many parts on them.

I have a Braun TG 1000 tape player also. It had a quadraphonic playback adaptor. I have never come across one in 20 years. Yet making one from scratch took no time.


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 Post subject: 3M Cantata
PostPosted: Jan Sun 28, 2018 9:43 pm 
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Hi, after investigating the Grundig TS1000 schematics over a few weekends I figured out that a pin in the headblock is what decides the rotation of the capstan motor. In “normal” headblocks, that pin is tied to ground, so 0VDC, whereas the — unnecessarily complicated — circuitry in the auto-reverse head applies 4.7VDC to it.

Since I need something unusual for playing the Cantata tapes — tracks running in opposite order to normal — the auto-reverse cannot and does not provide what I need.

So I found a DC source in the head connections, lifted the reverse pin from the ground and instead provided the requisite 4.7VDC to it. It works perfectly, like I am dining at the NYC Four Seasons restaurant with Roger Sterling and Dob Draper circa 1965. Sound is faultless but probably tops out around 8kHz, which may suffice for this kind of music.

I am convinced that 3M must have done this reversing the order of tracks business to stop people from playing their tapes on ordinary reel-to-reels. With each track playing 7+ hours turning the reels over once a night would not have been a major issues.


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 Post subject: Re: 3M Germanium Transistor part numbers
PostPosted: Feb Sun 04, 2018 2:57 am 
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Tiptop, That is great.

Unfortunately cold season has found me. Five days of the music trade show six hours of sleep a night, helping promote Hammond USA and thousands of visitors has paid it's toll.

Concerning the roll-off point, 7.510Khz with no harmonic content would be AM radio quality. It's possible that so much of the highs are rolled off that it doesn't sound tinny. I found images of a Cantata 700 extension loudspeaker. No 70 volt transformer but a selector switch with too many resistors. Seems a bit odd. Cost's less than a 70.7 volt transformer and a potentiometer, I suppose?

I did capture the images. Unfortunately the cabinet has seen exposure to water, it's almost destroyed, (and the price seemed excessive) but interesting none the less.

Attachment:
File comment: 3M Cantata Speaker 78-8477-5007-8 Front
78-8477-5007-8,1a.jpg
78-8477-5007-8,1a.jpg [ 249.59 KiB | Viewed 669 times ]


Attachment:
File comment: 3M Cantata Speaker 78-8477-5007-8, 2 Volume control front.
78-8477-5007-8,2.JPG
78-8477-5007-8,2.JPG [ 237.39 KiB | Viewed 669 times ]


Attachment:
File comment: 3M Cantata Speaker 78-8477-5007-8, 3 Volume Control and inside enclosure.
78-8477-5007-8,3.jpg
78-8477-5007-8,3.jpg [ 241.35 KiB | Viewed 669 times ]


Attachment:
File comment: 3M Cantata Speaker 78-8477-5007-8, 4 Right Corner.
78-8477-5007-8,4.jpg
78-8477-5007-8,4.jpg [ 250.91 KiB | Viewed 669 times ]


Attachment:
File comment: 3M Cantata Speaker 78-8477-5007-8, 5 Left Corner.
78-8477-5007-8,5.JPG
78-8477-5007-8,5.JPG [ 236.05 KiB | Viewed 669 times ]


Attachment:
File comment: 3M Cantata Speaker 78-8477-5007-8, 6 Back with cover.
78-8477-5007-8,6.JPG
78-8477-5007-8,6.JPG [ 230.93 KiB | Viewed 669 times ]


Attachment:
File comment: 3M Cantata Speaker 78-8477-5007-8,7 Bottom back.
78-8477-5007-8,7.JPG
78-8477-5007-8,7.JPG [ 191.62 KiB | Viewed 669 times ]


It wouldn't develop much bass with that shallow enclosed back. Unless of course you take advantage of the laws of physics and hang it in a corner, approximately 12" out.

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 Post subject: Re: 3M Germanium Transistor part numbers
PostPosted: Feb Thu 08, 2018 1:53 pm 
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Hi,

Yes, I saw that on eBay but decided to let it go...one more ugly speaker, dameged too, as you say.

Someone on German eBay has a home-made version of the auto-reverse PCB;
https://www.ebay.de/itm/Grundig-TS-1000 ... SwdTJabdro

Not pretty but probably works. Of course you would also need the little direction switch I mention in the above email.


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 Post subject: Re: 3M Germanium Transistor part numbers
PostPosted: Feb Fri 09, 2018 9:15 am 
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I didn't want to mention the "Bay" without getting into trouble. That TS1000 auto-reverse re-make board actually looks fairly clean. Too bad it doesn't have the part designations silk screened onto the board. I do hope it includes a parts's list.

As I look at the zoomed in images the traces are a little rough. It also should be completely washed of flux too. Or maybe the back was sprayed with polyurethane (or equivalent) to seal everything.

Unfortunately, my cash flow has stopped while being sick. Hopefully it will still be there and/or the seller has manufactured a run of several.

But as I read the description the seller will not ship the USA.

Too bad eBay's auto saved searches don't also include international sellers.

I with I still had that kind of ambition.

---------------------------------

To try and get back on topic... there was another 3M Cantata like product on Ebay. The Message Repeater.
Maybe you saw it.

It sold for $50

https://www.ebay.com/itm/302629330894

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