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Reel to Reel Decks
Head wear / Condition of the heads: how to examine / test. & Head re-lapping info
Question: How do I examine the condition of the heads in a reel to reel deck
Answer: As background information: If the machine was not used much and only on occasion, likely the heads are good. If the heads were cleaned regularly (every 10-20 play hours regularly) bu tthe deck was used a lot there is still a chance, that heads are good. If the machine was used for hours a day on a regular basis over years and years and without particularly cleaning the heads much, likely they are worn beyond repair.
Here what to do to actually see and examine head wear: clean all heads thoroughly with a cotton swab and rubbing alcohol (ideally high percentage grade - is it 93%?, not the 70%) until shiny with no signs of contamination (sometimes one needs to rub fairly hard - careful not to scratch the head). Get a good light source and a magnifying glass to examine them carefully. What you are looking for, is the surface of where the tape was running over the head. It should not be wavery in other words ideally smooth and even. Observing reflections on the surface of the heads may help with determining how smooth the surface. Then: Is there a ridge between where the tape touched the head and where it did not - or is there a groove that the tape wore into the head? (also examine the tape guides for wear) The deeper the ridge or groove where the tape was running over the material, the more wear on the head and the more problematic. For wanting to actually test with a bench test asides form optical examination condition of the heads can also be tested by use of continuous tones. In a shop one would play a pre-recorded test tape with tones, but the home enthusiast can test by recording two continuous tones: 1 Khz @ 0 db and 10 Khz @ -10 db (maybe 10-20 seconds each). The tones should be continuos without any variation in level. When playing back the recording in an ideal deck there should be no difference between the recording and the payed back signal.
Drifting in and out in level may indicate worn heads. A vast differecne between the 1 Khz signal and the 10 Khz signal (to 10 Khz almost non existant) may indicate worn out heads: With wear the tape custs into the head and thus the head gap widens, which results in loss of high frequencies. If not having a test tone generator, an electronic organ of music synthesizer may suffice. Use sustained notes without effects - a clean continuopus tone. If not available one still can confirm if there is high frequency by recording quality music ideally form a CD. What you would be listening to is the highs (cymbals). De-magnetize the heads and tape guides with a tape head de-magnetizer ( I have available for sale) before performing a recording test. Also: If possible use new recording tape that was not used previously. If the recording is dull with no highs, or if the music quality drifts in and out, likely the heads are worn, but if physical head examination convinceably lead to beleive, that the heads are good, and the 1Khz is steady, but simply no highs (10 Khz signal) the problem could be in the bias oscillator and/or bias circuitry.
If it is determined that the heads need to be replaced (and cannot be re-lapped or all of them need to be re-lapped), likely $2000 will not be quite enough for a complete refurbishment job on a 3 head quality deck, if the deck is expecte to perform closely to new and produce studio quality recordings.
As to availability of replacement heads: Very very unlikely that available as an original replacemnet part form the manufaturer. There are some small tape head manufacturers that manufacture heads for a few deck used in the recording industry. As expected though: likely covers only a few models of tape recorders and is expnsive. And there are some businesses that serve the recording industry and audio enthusiast with offering head re-lapping services. To note: If a head can be re-lapped is a matter of how far worn: The purpose of re-lapping is: to eliminate grooves cut inot the head by wear by shavign off in the areas that are not worn to create a smooth surface again. But if re-lapping would widen the head gap it will render the head useless (as loss of high frequency - described above). A re-lap tech should be able to tell if it is beneficial to re-lap the head, or if it is worn beyond. Re-lapping is fairly expensive. An alternative: pull used good heads from a defunct parts doner deck of the same model.
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