hifi engine

Marantz mod. 5020 cassette deck erase head.

My Marantz cassette deck mod. 5020 works perfectly in recording and reproduction, but, when recording on an used tape, the sound previously recorded remains audible in the background of the new material.
I have tried to clean the erase head with surgical spirit, but I do not get much result.
Could it be that the head is damaged or worn out, or is it an internal electronical failure that could be fixed without replacing the part in question.
Marantz claimed at the time the resistance of their "super-hard permalloy heads", but this was 35 years ago!
Any suggestion to fix this problem?
Thanks a lot in advance.
Best regards,

mknovak's picture

bad erasing of the old magnetic record

Hi, Hugues.
Your problem is well known to me: trying to make a record on the old pre-recorded tape (bought in the middle of 70-th...80-th and recorded at the same time), I got the same poor results: " the sound previously recorded remains audible in the background of the new material". But when I demagnetized the old tapes (either on reel and in cassette) with the bulk eraser (coil with open magnetic core, producing very strong magnetic fields), the result became perfect - silent background and good quality new sound recording like on the new tape.
This problem is caused by the physical properties of the magnetic layer of the tape (both ferroxide and chromdioxide): the sensitivity of magnetic domains to the external magnetic fields decreases with the time, so the magnetic tape after years of keeping becomes less sensitive to the magnetic fields of both erase and recording heads. The heads of the tapedeck are not guilty and not nesessary to change any adjustments of the heads, but of course it's nesessary to clean them with pure ethyl alcohol.
I have some amount of audio cassettes bought 20 - 30 years ago (some of them are not used up to now), and before recording I "revive" them (even the newly unpacked) with the bulk eraser - the result is very good.

Best regards,

Marantz mod.5020 erase head.

Hi mknovak,
Thanks for your interesting tip: it could indeed be the cause of the problem.
I have a demagnetizer which seems to be working on the heads under normal circumstances. Guess it will not be powerful enough to demagnetize the tapes (?) Would a woofer magnet work for this purpose or does it exist a device specially designed for the job? and where would I be able to find such a device? And how to proceed? Should I rewind the whole tape in front of the magnet?
On the other hand, I managed to erase the used tapes on an other deck, but leaving quite a lot of hiss and background noise, which I can still hear when recording new material.
I am not a technician but I'm always eager to learn!
Thank you for your opinion.
Best regards,

mknovak's picture

Bulk eraser as a remedy for reviving of old tapes

Hi, Hugh!
Of course the head demagnetizer is too weak for this purpose. The bulk eraser is the coil with E-shaped ferromagnetic core with the opened magnetic gap, placed in the plastic box. This coil onnects to the power net (220VAC/50Hz in Russia, 120VAC/60Hz in the USA), producing the alternating(!) magnetic field (don't use the magnet from the woofer! - it's producing only constant magnetic field - the reason of tape noise and distortions). I'm using such device not only for tape demagnetizing, but for demagnetizing of the screwdriwers and other tools that i'm using when repairing and adjusting the tape recorders.
The procedure of the tape demagnetizing is simple:
carrying the tape (both on the reel and cassette) at the distance of 2 - 3 feet from the bulk eraser, switch on the bulk eraser and slowly move it towards the tape, when the tape starts to vibrate in your hands - move the bulk eraser slowly near the tape and slowly move it away then switch it off. The procedure is over!
At first try to search bulk eraser, for example, on a flew market, otherwice look the adverisements at "Electronics World", "Wireless World" and other electronic magazines. I think it's not difficult to calculate and make this device at home workshop, but it's easier to buy it.
Best regards!

Bulk eraser for reviving of old tapes.

Hi mknovak,
Thanks for the detailed instructions.
Will try and find such a device on E-bay or on a specialized HIFI shop.
I will be away for a few weeks, but I surely will get at the problem when I get back home.
Many tks again and best regards.

Bulk eraser for reviving old tapes. Attn. mknovak.

Hi mknovak,
Followed your advice and got a Realistic "high power video/audio tape eraser" mod.44.233A advertised on E-bay.
It is an american model, 120 volts/60 Hz.
Since we are on 220/230V/50 Hz in Europe, can I make it compatible?
I have a transformer which can tranform 220V into either 110 or 150, and I don't know about the Hz difference...
Can I use it and how will the difference affect the equipment and the results?
Many thanks for your opinion.
Best regards,

mknovak's picture

Bulk eraser for reviving old tapes

Hi, Hugh.
Answering on your first question: yes, of course; you can use such american device everywhere, but only with the additional power transformer. There is an important condition: power consumption of the load must be less then maximal power of the additional transformer to avoid of the overheating or even damage of this transformer. Power consumption of the tape eraser may be signed on the label on the device or on it's pack, otherwice it may be calculated; maximal power of transformer may be appointed on its label too or can be appreciated with the formulas:
Pmax~(Sw*Sc)/1,15 for E-shaped core,
Pmax~(Sw*Sc)/0,6 for U-shaped core
(Sw - square of core window, cm^2; Sc - square of core, cm^2; Pmax - max. power from transformer, VA).
If the results of preliminary appreciation are in accordance with above mentioned condition, connect tape eraser to 110VAC output of transformer and switch it on for 1 - 2 minutes to appreciate the transformer overheating and efficiency of tape demagnetizing.
About frequencies 50/60 Hz - sumply follow to the rule: less frequency - less voltage and vice versa.
I saw photo of a Realistic "high power video/audio tape eraser" mod.44.233A on e-Bay and I think that maximal power of an additional transformer must be not less than 150 - 200W.

Successes and best regards,

Bulk eraser for reviving old tapes.

Hello mknovak,
Hip hip Hurray!!! it works!
Plugging the eraser in the 110V outlet of the transformer did the trick, ignoring the frequencies difference.
Tried to erase two cassettes and I get the background noise limited to the minimum possible level.
Many thanks again for your precious help!
Hoping some day I could be able to be of help too.
Best regards,

RE: Marantz mod. 5020 cassette deck erase head.

First, try demagnatise the heads.
Then if this doesn´t work, try adjusting the EQ-rec trimmers (L/R) on the board, because the equalistion of the erase head is not adjusted properly.

Marantz mod.5020 erase head.

Hi fredastaire,
Thanks for your comment. Could you please indicate where exactly I can find the EQ-rec trimmers: are they on the back board (the only adjustable trimmers seem to be the "play FM cal"), or should I get inside the deck to reach them?
Downloaded a mod.5220 service manual from HFE, which looks very similar to 5020, but do not find any reference to equalization of erase heads.
I will try demagnetization again, although I have done it quite recently.
Many thanks again for your tips.
Best regards,

Marantz mod.5020 erase head.

Hi Hugh,

Open up the 5020 (top) and download the 5220 service manual from Hifi engine

(the boards of the 5220 and 5020 are almost the same)
and go to page 21 for the recording eq., goto page 17 for playback eq.
There you will find what is what.

Be sure you´ll use plastic screwdrivers to avoid interference and magnetization.
Be sure to adjust the right ones, there are three different eq´s you can adjust, corresponding normal, CrO2 and FeCr.
testtape to be sure you´ll reached minimum hiss.
so: First clean the heads, second demagnetize them, then adjust the heads-lining if nessecary, after that adjust the playback rec.
ONLY if this doesn´t work , adjust the recording eq´s.

For best results hook up your deck to the soundcard of your PC and record the testtones described in the manual.

good luck.

Marantz mod.5020 Erase head.

Hi fredastaire,
Just got back from abroad and got your last message. Many thanks!
Will try and adjust the various entries, but I also plan to follow mknovak's suggestion, using a bulk eraser to prepare the tapes before recording.
I want to thank you nevertheless for your tips and advices: it is always nice to find support and knowledge from fellow fans around the world!
Best regards,

... sometimes, Marantz

... sometimes, Marantz claimed to be the experience, and - on the other side - it was like these.

.. and now , it´s difficult, to answer every question.

... anyway, I think, the search by cleaning the erase head may be successfull , ...

Marantz mod 5020

Thanks a lot, arctic.
Will go on trying with the cleaning.
Also got a tip from fredastaire, demagnetazing the heads and adjusting the EQ.
Will adv.
Also wanted to upload my owner's manual for you, but the HI FI Engine site is overloaded at the moment. Will try again later.
Thanks again and regards.