I have an old Sharp MZ80k computer from the (late 70's) which unfortunately needs the mono head replaced in it's built in cassette deck.
I have found a place online that sells mono heads, but they come in different OHM ratings, from 60 OHMS to 400 OHMS. Unfortunately I have not been able to find out any specific info on the original head (labeled KA30 - OE030). And using my multimeter on the dead head gives me no reading what so ever. I didn't realize heads came in different ratings, so now I'm stuck. I was wondering if anyone here would have any advice for me.
Please never, ever use a multimeter on any tape head. Ever. You will magnetize the head or maybe even burn out the coil. Sometimes a digital meter can't read the resistance (I assume that's the setting you used) on inductive parts due to the sampling pulses reacting with the inductance. Can't answer your ohms question, I don't know what it means. Audio heads are usually rated in inductance, probably they are giving the impedance at a test frequency. This is how you test a head, you inject a sine wave with no DC component and check the field. (With another head and a scope if you must.)
Well, I'd try eBay to get another unit, or try a hard-core tape forum like
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to get more info on tape heads in general.
If they are standard audio cassettes, you can play them back on a regular deck and sample the signal on a PC, there's probably software out there for your machine. If the head is worn and you have money, a head can be re-lapped to get a new surface. Unless the head has a tape guide welded to it, I guess.
Wow! Not quite the subject I would expect to elicit such a heated response.
Anyway, to answer some of the questions. When I first got the machine it would not load anything, some probing around, and I came to the conclusion that the cassette board was good, which only left the head as a possible culprit. I had a spare (very rusted up and dead) unit, which I stole the cassette head from, and to my joy, the problem was fixed...for about a month atleast, and then suddenly it stopped loading again, so my assumption is that the head has died (again). After all, these things are over 30 years old.
You can see the heads for sale from the online store here:
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I have also uploaded the schematic for the MZ80's cassette unit here:
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just in case it helps someone diagnose my problem.
On a sunny day (Sat, 22 Aug 2009 09:18:27 -0700 (PDT)) it happened Nama wrote in :
Ha! This uses DC bias for recording, and and DC current for erase. Perfectly valid for a data recorder, would not use it for music. So that remark about not using a multi meter, I have to give Phill right here. But Phill should watch himself, a teenager was convicted to 3 month in jail today for online bullying.... Internet seems to be growing more and more into a politically correct medium. Its primary purpose of communication being replaced by filters and rules, online police, ads, and that making it like most other things in society, a farce of itself.
In a music recorder you _CAN_ magnetise the heads, in such a case use a demagnitiser. I even have tapes that have thump thump sounds in them because of switching a cheap radio-cassette from play to stop, The current caused by the input cap charging when switching it on, also can put an unwanted signal on tape. Good tape recorders were very expensive :-)
Still I do not know the resistance of the OP's tape head... Usually those are cheap and ordering one or 5 would make no difference (relative to the postage), So give some a try perhaps :-)
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