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 Post subject: Tape Recorder Head question
PostPosted: Mar Sun 24, 2019 4:19 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1077
Location: Canton,Ohio.United States
Hi
Not sure which forum I should post this in , Audio or phonographs, but when in doubt......
Anyway, I have an old 1951 dual track open reel Pentron recorder that was dad's, where I recently acquired a set of heads for it, finally.
My question is: Since they both look identical, Can an erase head be used as a Record/Playback head? They use a 30KC signal to erase. I don't do any recording on this recorder, but would like it to play ok. It works now, But the heads are worn and sound frequency has really gotten bad.

Thanks
John


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 Post subject: Re: Tape Recorder Head question
PostPosted: Mar Sun 24, 2019 4:55 pm 
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I would not assume they are the same----if you have the old heads, how about measuring the inductance and DC resistance?

Do you have service information for this unit?

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"Measure voltage, but THINK current." --anon.


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 Post subject: Re: Tape Recorder Head question
PostPosted: Mar Sun 24, 2019 5:34 pm 
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I thought erase heads were different and had wider gaps than playback? But we are talking vintage machines maybe so I don't know what they did. ON any modern solid state recorder I have had, the two types of heads were different.

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 Post subject: Re: Tape Recorder Head question
PostPosted: Mar Sun 24, 2019 5:53 pm 
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Location: Omak,wa,usa
Hello John,
to answer your question no erase heads my look the same but have different coils inside .
As wazz said in solid state units they are different it does not matter if it's a tube unit or solid state they are different the record and playback heads .
What make and model of reel to reel

Sincerely Rich


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 Post subject: Re: Tape Recorder Head question
PostPosted: Mar Sun 24, 2019 5:54 pm 
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Location: Gold Country, (Stanislaus National Forest) California 95235
It would be unlikely that you would get any sound out of an erase head and if you did with the gap being so wide it would probably be severely muffled and muted - like playing a tape with the oxide facing away from the head.

Not to mention when you put new heads on it you have to start off fresh and do the rack wrap height azimuth and zenith completely over from scratch - for which you will need all the necessary supplies and tools.

There are several threads on here that go step by step and a number of websites have other similar guides that may prove useful.

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 Post subject: Re: Tape Recorder Head question
PostPosted: Mar Sun 24, 2019 8:16 pm 
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Joined: Sep Thu 23, 2010 6:37 am
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Location: Powell River BC Canada
Pentron recorders are common. Post the model number and I
will try to find the generic replacement specs.
Attachment:
Pentron  rph.jpg
Pentron rph.jpg [ 101.48 KiB | Viewed 854 times ]

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 Post subject: Re: Tape Recorder Head question
PostPosted: Mar Mon 25, 2019 2:13 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Canton,Ohio.United States
Hi Guys
Thanks for the replies!! You gave me loads of info.
Mark, I took the readings and yes, you are right. The playback looks like 600 ohm, while the erase is 200 ohm. I do have all the info for this recorder. My dad had ordered a service manual in early 60's. Also ,I was able to get more info on Ebay. This recorder has thousand of miles on it. lol.
I managed to scrounge a belt for takeup and had a cousin sew me a few rewind belts from material.

Rich and Radiotechnician:
The model is a 9T3C. Had to be the first generation of this recorder. The tape goes from right to left, so it records the bottom half. The heads are not like they are today. They have a protruding piece that extends out that the tape passes over. Those extended pieces on mine are loose and they shouldn't be. They push in toward the head itself when you hit play, and I have had to pull them out with a small screwdriver. Now they are so loose where I have to move them every time I play it. I was able to get some used heads from a pull on Ebay and hope they will work.

Radiotechnician,
Your chart shows the heads on the first entry. Does Nortronics still exist? Wish i could have gotten new ones.

Aligning the heads shouldn't be too much an issue. Put them in and play a tape while fiddling with the screws, and just hope to get a clearer sound and a louder output than I'm getting now.

Thanks
John


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 Post subject: Re: Tape Recorder Head question
PostPosted: Mar Mon 25, 2019 2:48 am 
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Follow the alignment instruction from service manual.

The 9 T C 3 uses a Nortronics 3000 r/p 1 Hy @ 1 kHz, 6300 ohm Z , 610 ohms DC. Record current 20 microamps, output 4.5 millivolts, 12 dB down
at 10 kHz.,6300 micro inch gap.

Old heads can be lapped to get more life.

I think Nortronics is around somewhere supplying heads for
old industrial special applications.

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 Post subject: Re: Tape Recorder Head question
PostPosted: Mar Mon 25, 2019 3:03 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Canton,Ohio.United States
Thanks for that info Radiotechnician.
I am not sure these heads can be recoated. I did hear of that process, just didn't think it applied to this type of head. I will check up though.
As far as aligning the heads from a service manual, that info isn't present. I don't think they expected an owner to do that back in those days. The manual is more for the mechanical adjustments.
Thanks again
John


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 Post subject: Re: Tape Recorder Head question
PostPosted: Mar Mon 25, 2019 7:28 am 
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Joined: Sep Thu 23, 2010 6:37 am
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Location: Powell River BC Canada
See if the below is of use. From cross- cross back through
Nortronics using the same retro head to another later Pentron.
Attachment:
Pentron TR 5 i.jpg
Pentron TR 5 i.jpg [ 153.39 KiB | Viewed 756 times ]
Attachment:
Pentron TR 5 iii.jpg
Pentron TR 5 iii.jpg [ 286.51 KiB | Viewed 756 times ]

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VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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 Post subject: Re: Tape Recorder Head question
PostPosted: Mar Mon 25, 2019 11:32 am 
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As a heads up, basic troublehooting does need to be done with this unit. It will need the electronics fully serviced also, capacitors replace, tubes checked stuff like that.


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 Post subject: Re: Tape Recorder Head question
PostPosted: Mar Mon 25, 2019 12:36 pm 
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Location: Ohio 45177
Normal type tape heads can be re-lapped by hand, but that is usually dependent on the depth of wear. Each time you relap the frequency response can change as the gaps are closer at the surface of the heads and widens inside so the gap will usually increase as they are lapped down. But it is worthwhile up to that point, in the case of expensive tape heads.

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 Post subject: Re: Tape Recorder Head question
PostPosted: Mar Mon 25, 2019 4:05 pm 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 11632
Location: Powell River BC Canada
The OT service date is CM 4 (changer manual) but changer manuals
(Sams) had mechanical but not electronics data in some cases.

Also the description of what the sound of the old machine is
can be a puzzle. With tape recorders, especially very old ones
you need to hear them to to know if the problem is
in the amplifier, or the mechanical side. Even worse with wire
recorders.

Also old tape was somewhat different

I remember, (when I smoked) accidentally
dropping hot ash down on a transport
spooling an open flange of paper backed
tape. It burned through the tape passing
through the Ampex heads. I spliced it, and
because it was some old music at 15 IPS
it wasn't a big issue. (some old archive
session) I'd hidden far bigger mistakes :D )

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VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
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 Post subject: Re: Tape Recorder Head question
PostPosted: Mar Mon 25, 2019 7:17 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1077
Location: Canton,Ohio.United States
Again Thanks for the good info.

About 3 years ago, I went and replaced the caps and out of spec resistors.. This, being an early recorder,does not have great fidelity. However, if a tape was recorded on a newer recorder,then this would play pretty good. The amp is ok, it is the heads. measuring the output on AC meter makes s11ense.
Some of the tapes are from radio in the 60's. Fidelity was always pretty low at 3 3/4. but now I am plugging the output in a transmitter and going over radio. The handicap isn't as noticable

Now, are any of you familiar with this sight? i found it using Radio Techs info..

https://www.surplussales.com/Equipment/ ... -tape.html.

Radiotechnician, they have the head for play and erase. Play being 3000 as you have told me, but I can't quite make out if the erase head is 3600 or 3500. I am willing to try there. , but just wondering if any of you bought there before.
Re-lapping seams like a tough deal to do. I think these heads deteriorated over the 68 years. LOL
\ Thanks guys.
John


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 Post subject: Re: Tape Recorder Head question
PostPosted: Mar Mon 25, 2019 7:28 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 4265
Location: Boston, MA USA
If you measured the resistance of the heads with an ohmmeter now you will have to demagnetize them before running any tape. The DC from the ohmmeter will have magnetized the heads.

-David


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 Post subject: Re: Tape Recorder Head question
PostPosted: Mar Mon 25, 2019 7:33 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1077
Location: Canton,Ohio.United States
Always sumpten.
Thanks for advice. I do have a head demagnatizer. I will do just that.
Thanks David!

John


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 Post subject: Re: Tape Recorder Head question
PostPosted: Mar Mon 25, 2019 9:01 pm 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 11632
Location: Powell River BC Canada
The Nortronics erase head is the 3600. I have not bought a tape
head for my self since 1963. In my work, I would have ordered
tape heads up to the end of the 70's.

Machines like the Pentron, Webcor, Wollensac, were rented out in
places I worked for in the 60's.

However I have bought test gear from Surplus Sales of Nebraska.
( 80's) Glad to see they are still there. They were good people back then

Caution should be used with demagnetizers and especially ohm meters
with tape heads because inductive spikes may short out old fine wire coils.

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VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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 Post subject: Re: Tape Recorder Head question
PostPosted: Mar Tue 26, 2019 12:58 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1077
Location: Canton,Ohio.United States
Hey Steve
I got a call from Nebraska surplus and they have the heads but not sure if I needed a kit or not. I saw one and ordered it and they said they were out. So I ordered the heads anyway. In the meantime, I have a used pair I will try. The demagnitizr I have has 2 prongs. I guess you just wave it over the head.
When I mount them, I will try and use the ear method. I can easily see the heads and how the tape moves over them.
You are right that a Webcor is pretty close to this kind of recorder.
You were lucky your tape was at 15 ips. very little would have been damaged as compared to 7 1/2
my brothers Roberts recorder has that speed.

My dad used Scotch Brand which has really held up. Audiotape was another brand we have. 1200 standard ft size seems to start crinkling and becoming brittle at the ends. 1800 foot rolls seem the best.

Thanks
John


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 Post subject: Re: Tape Recorder Head question
PostPosted: Mar Tue 26, 2019 2:08 am 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 11632
Location: Powell River BC Canada
The demagnetizer is first plugged in and them passed , slowly
advancing, and then retracting around the pole face of he heads, and
other iron parts that contact the tape. When done, draw the demagnetizer
back away from the machine, then unplug it.

Some tape recorders provide automatic head demagnetization
but proper mechanical sequencing of r/p transfer switches
is essential.

Good stuff here:

https://www.americanradiohistory.com/Ar ... 958-06.pdf

Attachment:
pentron q   ii.JPG
pentron q ii.JPG [ 68.14 KiB | Viewed 660 times ]

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de
VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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 Post subject: Re: Tape Recorder Head question
PostPosted: Mar Wed 27, 2019 7:59 am 
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Location: Tucson, Arizona U.S.A.
Be sure to keep tape a good distance away from the demagnetizer!

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