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Thread: Question about Echoplex EP-3 sustain/repeats/motor..

  1. #1
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    Question about Echoplex EP-3 sustain/repeats/motor..

    First post.

    I have an EP-3 that I'm sort of refurbishing. I've had this one about 2 years (i've owned a couple in the past) and I know my way around them mechanically. When it comes to the electronics on them, I'm kind of a noob. I was supposed to be getting a "serviced" unit, and i guess by serviced they meant SOS head wire cut/deactivated, some weird mods thrown in... you get the idea. I overpaid for it in the condition it was in, however it does work and from what i could compare to, works fairly well.

    Except I feel like I should be getting way more sustain say, around the midway mark of the sustain pot. It definitely sustains, but i just know i've heard better, longer repeats on other units and i'm sure there is something wrong. Before I go on, i will point out that I have re-loaded the tape cartridge with some 1/4" Scotch recording tape since I just have tons of them laying around, but I can't comment on the integrity of the tape. I adjusted the record level, I messed around a little with the sustain and bias trimmers with no real changes.. also I have already re-capped the power section and plan to do the remaining electrolytics. I de-magged the heads and cleaned them thoroughly.

    At this point I'm going to try and get my hands on a friend's EP-3 which i know is in supurb mechanical and electrical condition and try to compare the two and see what's what. But I do remember working on one a while back and getting it to the point where it was working great mechanically but the echoes were fading off real quick. And we had a friend look at it and he changed some components but I can't recall what he changed. I'll have to have a look at the schematic and see what goes where...

    if anyone has any specific knowledge of the EP-3 or this particular issue I'd love to hear.

    The other problem I have is the wow and flutter which i think is actually the motor. I have the solenoid adjusted for the pinch roller but I still get this little flutter. I'm going to put a new belt on it, but Is taking apart these motors safe to do without risk of destroying them or am i better off leaving it alone and / or finding a new one?


    Thanks for any feedback-

  2. #2
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    Welcome to the place.

    You said that there were some mods done to the unit, have these been checked or removed?

    The amount of signal that is recycled to the record circuit can be limited by so many things that you will need to systematically check each part of the record and playback circuits (both electronic and mechanical) to try and optimize the circuit. A failing coupling cap or a misaligned head may cause similar audio symptoms.

    As for the motor, if you have basic mechanical skills and are very careful about disassembly and reassembly cleaning and servicing the bearings and the oil felts should not be a problem. Remember that there will be a raised burr on the main shafts of the motor caused by the fan and pulley set screws. You must remove these burrs before trying to slide the shaft through the bearings or you will damage them.

    Have you checked the rubber idler wheel for roundness and surface condition? I find that most wow and flutter relate to the idler wheel and capstan rather than the motor. The motor rotation is reduced down so much by the pulley and drive belt that unless there is a major problem with the motor, little variation gets to the actual capstan drive shaft.

  3. #3
    Lifetime Member Enzo's Avatar
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    Is your pinch roller hardened?
    Education is what you're left with after you have forgotten what you have learned.

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    Quote Originally Posted by 52 Bill View Post
    Welcome to the place.

    You said that there were some mods done to the unit, have these been checked or removed?

    The amount of signal that is recycled to the record circuit can be limited by so many things that you will need to systematically check each part of the record and playback circuits (both electronic and mechanical) to try and optimize the circuit. A failing coupling cap or a misaligned head may cause similar audio symptoms.

    As for the motor, if you have basic mechanical skills and are very careful about disassembly and reassembly cleaning and servicing the bearings and the oil felts should not be a problem. Remember that there will be a raised burr on the main shafts of the motor caused by the fan and pulley set screws. You must remove these burrs before trying to slide the shaft through the bearings or you will damage them.

    Have you checked the rubber idler wheel for roundness and surface condition? I find that most wow and flutter relate to the idler wheel and capstan rather than the motor. The motor rotation is reduced down so much by the pulley and drive belt that unless there is a major problem with the motor, little variation gets to the actual capstan drive shaft.
    Thank you for that. I haven't removed the mod yet. It's a trimpot and cap that was added. Here's a pic:



    I got brave the other night and pulled the motor out and busted it apart, and was able to get it all cleaned up and re-greased the spindle etc. I was amazed after I put it all back together that it still worked. I thought for sure I would break something, but it works. It's also quieter than before so I'm kind of glad I did that. I'm pretty sure the heads are in good alignment, but I have yet to actually check this with a scope (because, I don't really know how to use it well...).

    What I do want to do is replace the drive belt for sure. I hate to spend ridiculous amounts of money on stuff if it's a "common" type of part. Any idea of a possible substitute for the belt or what would be a close match? I ask this not because I'm cheap, but because I remember fixing an older Tascam 4-track I read that the idler wheels could use common o-rings as replacement wheel rubber, and they worked just fine. So for all I know the drive belt could be a rubber seal for something common and I can find an exact replacement at a Home Depot or something... just putting it out there...

    Is your pinch roller hardened?
    No.. the pinch wheel 'appears' to be in good shape. It wasn't hardened when I got the unit and I promptly cleaned it with the Caig rubber cleaner (I've seen mixed reviews about using this on the roller but I've used it on other plexes that were working fine and nothing changed from using it). I've cleaned it several times and it definitely has some 'bounce' to it.

    As a bonus, I was able to get my friend's Plex in front of me for comparison sake. And it seems as if the repeats are similar on both machines; his just has a little more sustain than mine. I tried his tape in my unit and it was better, but slowly started to flutter a bit more in my unit. I'll have to go pop my tape in his Plex and see the difference just to know if my tape needs to be rewound. He's cart is definitely using a better grade of tape.

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    You know I should also add that removing the pressure pad made the flutter almost disappear. The pad, even when adjusted for light pressure, seems to drag things down more. Leads me to believe I might be on the right track with a belt replacement. I just ordered one anyway. I'm going to see if I can find the felt weatherstripping at the hardware store.

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    So here is something interesting to note.

    I did a full re-cap on my unit, and while I was in there I noticed that, per the schematic, Q1-Q4 should be TIS98 while Q5 should be a TIS58. (I'm looking at the correct schematic for my serial number also). On both units I have here, on the board with what I assume is Q1 and Q2, they're different. And, different per unit.

    Mine are 2N2484:


    And the other, fully working unit is MPS8048:


    But, it doesn't end there, because on the working unit, even the input board is using the MPS8098 trannies in place of what should be TIS98:


    Mine is using TIS98s at least, granted it is an older unit (in fact, the newer unit is an EP3 built inside what appears to be an EP4 enclosure. All the cutouts are there for the parts on the EP4. Or, they just went to using one enclosure for both at that point).

    Anyway, I've been lead to believe that the trimpot on the board with Q1 and Q2 affects sustain, but in the schematic it looks like it might have something to do with SOS, which on my unit doesn't work because of the blown head which would render the trimpot useless in Echo mode. Can anyone confirm or deny that?

    Basically I'm at the point where I want to increase the level of sustain/repeats. I've heard some units that just sound fantastic and have these wonderful repeats that trail off naturally, and mine sorta starts that way and then quickly dies off; at least quicker than I've heard on some other units. I've ruled out the tape after switching out with the other unit. It has a bit more fidelity, but didn't affect the rate of repeats.

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    Old Timer Leo_Gnardo's Avatar
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    Quote Originally Posted by gbkd80 View Post
    So here is something interesting to note.
    I have no answer on the transistors. BUT something strikes me as odd - that board is loaded with orange drops that look as if they are replacements BUT nobody thought it wise to change out those old white Mallory electrolytic caps. Even though Mallory is considered a quality brand name, these white electrolytics seem to have a bad rep. I've encountered service bulletins (Crown for instance since the early 1980's) and tech advice (on MEF, Audio Asylum and other sites) that recommend swapping them out for any other competent capacitor.
    DrGonz78 likes this.

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    Quote Originally Posted by Leo_Gnardo View Post
    I have no answer on the transistors. BUT something strikes me as odd - that board is loaded with orange drops that look as if they are replacements BUT nobody thought it wise to change out those old white Mallory electrolytic caps. Even though Mallory is considered a quality brand name, these white electrolytics seem to have a bad rep. I've encountered service bulletins (Crown for instance since the early 1980's) and tech advice (on MEF, Audio Asylum and other sites) that recommend swapping them out for any other competent capacitor.
    I'm not sure the orange drops are replacements... in fact, both units have them. But, yes I've heard the Mallory complaints also and I did replace all of them the other day (picture was taken pre-recap). Haven't heard any audible difference from doing so but I really didn't expect to. Re-capping in my eyes is always a preventative thing...

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    So - I just got a new belt. Put it on, and the motor won't turn unless I jump start it from the fan blades. It's considerably smaller than the one that was on there, and I ordered this one specifically (not a diy thing).

    Being that I'm pretty confident it's just too tight, could it stand to reason that all I need to do is loosen the motor from the mounts and kinda let it find it's happy place before snugging it back up? I think it might actually be putting too much tension on the motor and pulling it slightly...




    EDIT: well, here's an interesting observation. It seems that no matter where the motor is adjusted, if the flywheel is sitting as it should, the unit won't start. IF I push up on the flywheel and sort of move it up, the motor will start up just fine. As it runs within the first second or two the flywheel will roll itself back down to where it should. Then you turn it on again and it won't run. So I figured this was as simple as oiling the base and cup, which I did, and it made no difference. As it stands, with no belt, that flywheel moves freely with no issue. I'm a little stumped.

    Is it possibly my motor just doesn't have enough juice to start up on it's own unless there is very little tension on it?
    Last edited by gbkd80; 01-26-2018 at 08:31 PM.

  10. #10
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    Is this with the new belt or the old one? Did you clean and service the flywheel bearing?

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    Quote Originally Posted by 52 Bill View Post
    Is this with the new belt or the old one? Did you clean and service the flywheel bearing?
    This is with the new belt.

    However, after some other research and some other advice, I found that it was my fault for "greasing" the spindle on the motor when I took it apart, causing a lag. I ended up taking the motor back apart and cleaning off all grease and oil and put it all back together. After doing that it fired right up with no issue. Serves me right for not following correct instruction, and ignoring the nice little bold statement right on the motor that said "no oiling required"...
    g1 likes this.

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    Lifetime Member Enzo's Avatar
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    One test would have been to take the belt off, and just spin the fan blades - power off. Does the motor spin freely? Or does it turn a few degrees and stop?
    Education is what you're left with after you have forgotten what you have learned.

  13. #13
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    Quote Originally Posted by Enzo View Post
    One test would have been to take the belt off, and just spin the fan blades - power off. Does the motor spin freely? Or does it turn a few degrees and stop?
    You're right, and when I spun the motor previously (after greasing) it did spin... I felt it spun freely. But I guess with the tension put on it the grease bogged it down. Without the grease that thing spins real nice. i should have known better.

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