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The tape should be in contact with the heads, not just near to them. Perhaps the thing is threaded wrong. Tape drags right across the surface of the head.
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Education is what you're left with after you have forgotten what you have learned. -
yes, of course, it is in contact with the tape, and threaded correctly. There is a section in the echoplex service manual which talks about how to adjust the record and playback heads manually for the most signal to the heads. this was what i was referring to.
thanks again for the help!
3 mostly working echoplexes now!
IAnComment
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SOS on SOS!
Hi Imo,
And what's about your SOS?I'm so curious !
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I don't have that working yet on the plex in question. Juggling a few things over the weekend. I was also working on the mechanical side, trying to lessen the warble of the tape, cleaning everything, etc. I will give it a go again this week.Comment
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Echoplexes Echoplexes Echoplexes Echoplexes
Hi,
Don't forget to demagnetize the tape heads and all the tape path,you could win some of clarity and avoid distortion.The tension pad is very important too,on one model i haven't got much sound,the tape path was ok but the tape level was lower than the others machines.I found that the tension pad was loose and i bent it a bit to apply much pressure on the roller.The sound went at the good level to have enough feedback at three o'clock,good very good ,same as direct level,even more!
I put here some pics from my echoplexes,yes i love them !Attached FilesComment
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http://hyperphysics.phy-astr.gsu.edu...dio/tape2.html heres that link again,I dont know how the other one got there.Comment
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what about when the erase head doesnt erase totally? this is the problem im having with my echoplex ep3.Comment
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depends. Does it erase what was recently recorded but not older stuff on the tape already? Or does it just not erase things in general?
If the vertical alignment of the erase head is not exact to the playback head, then the edge of old tracks will leak through. Make a tapeful of something and start the eraser. Now twiddle it up and down to peak the erase level.
Make sure the bias oscillator is strong, and the erase head drive circuit 100%. No weak transistors, no leaky caps, etc. Peak the oscullator voltage - wwhich is a lot higher than you might think.
The erase head is not likely to be magnetized. If it works at all, I tend to think the head itself is OK.Education is what you're left with after you have forgotten what you have learned.Comment
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I have not worked on a lot of echo units (a few) but I have worked on hundreds of Reel to Reel tape decks and cassette players and at one time was a factory authorized Teac/Tascam tech as well as many others major brands. The first thing I would do is inspect the heads and guideposts. Look for any uneven wear or trenching. Also make sure that the pinch roller is not hard or worn or skewing the tape. The next thing to do would be to align the playback tape path. You will probably have to disable the erase oscillator so it will not erase your test tape. Then you need a calibrated test tape which is generally around 10-12 Khz. You can probably cheat by making one yourself from a known good machine recording with an audio generator input at 10-12Khz. Then put a scope (or even an AC meter in a pinch) on the output and align the tape path for maximum amplitude while playing back the test tape. After that install a fresh new tape and align your erase head and erase oscillator. Make sure the erase head has uniform contact with the tape and is not worn out. This proceedure is generally true for all tape decks. You don't have to worry about phase because it is mono. BTW, thoroughly clean and demagnetize everything before you start and when you finish. Make very sure that you are using the right tape formulation.Comment
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no it donest erase any of it full strength if at all. when i flip the s.o.s. switch the backgroud gets louder(as it should). it seems to sound ok and echos and plays back just erasing like it should maybe not at all. im not sure about breaking loose the glue to be prying on the head brackets as i wouldnt want to make anything worse. what you said about the tail end of the previous recorded music catching the playback head could maybe have something to it. which head would i realign? how can i check the alignment? im kind of wondering about a weak circut. i took an 8 track tape and cart and pulled out enough to feed through the tape path and put cart where it could feed ok. this worked but due to the way the tape came out of housing it warbled but this was just a test to see if the tape made a difference. it did same thing with no change just was warbled. so im wondering if i can elimenate the tape as the cause? but i do plan on getting another tape to have two carts loaded and i plan on getting some tape to reload myself. i was hoping this was a little more simple so i could solve myself(with everyones help) but its turning out to be possibly more than i can do for it since im not quite the electronic engineers some of you guys are, although i want to learn more.Comment
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As I said before, align the playback tapepath first for maximum amplitude and frequency response with a calibrated tape or whatever you can get with the erase oscillator turned off. Then turn on the oscillator and align the erase head as well as adjusting the erase/record bias. Usually the record bias and erase head oscillator are the same thing.Originally posted by rockinrendell View PostComment
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how do i turn off the erase oscillator? will an o'scope and tone generator do same thing or do you have to use a tape? since im having trouble i was planning on taking to a local repair guy who has the scope and tone generator. just so im clear and as sure as i can be? how do i go about aligning the heads? a lot of info ive tried to gather from the various sites dont seem to address the problem of erasure and the lack of. i know im not the first to have to deal with this.Comment
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how do i turn off the erase oscillator? (there is probably a proceedure in the manual witth a jumper wire but I would just probably lift the B+ to that circuit) Will an o'scope and tone generator do same thing or do you have to use a tape? (You will have to use a factory calibrated tape or make a tape off of a known good machine with a tone generator as an input) Since im having trouble i was planning on taking to a local repair guy who has the scope and tone generator. just so im clear and as sure as i can be? how do i go about aligning the heads? (you adjust the angle and hieght of the head until you have maximum outbut and frequency response) a lot of info ive tried to gather from the various sites dont seem to address the problem of erasure and the lack of. i know im not the first to have to deal with thi.. (magnetic tape will not record without bias. Usually the bias and the erase oscillator are the same) At this point I would suggest that you find a qualified tech. Be careful. When it comes to tape technology many know less than you nowadays.Comment
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im suppose to take it in tomorrow. the guy is my age or older. i made sure he has some knowlege and experience with this old technology. which he has, probably hasnt been for while. he does have considerable experience with vcrs which are tape recorders in short too. i will be giving him the info from regis's echoplex page to go by and the links plus i have the service manual downloaded. if him and i cant get it, it may mean a trip to somewhere like orbit or equivilent. any suggestions for reasonibly priced echoplex guys that wont take forever?Comment
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what errors are on the schematic? the person who has my unit is going off the schematics.Comment
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