Repair.IT – Eagnas Plus 8000 Electronic Tension Head

A follow-up to my recent “Review.IT” article is in order. This is the one where the load-cell had a wire pulled off of it. After some inspection of the load cell – that is, after removing the silicone compound that covers much of the strain gauges, I could see that everything else was intact. If I wanted to do the repair, all I had to do is to connect the yellow wire and then put a blob of silicone sealant on it.

Sounds easy, doesn’t it – except that the pads are very small and the wire is very thin. I put it onto a holder that allows the load cell to be held by clips, then positioned a magnifying glass over the load cell. In this way, I could clearly see the pad that I was soldering to, and of course the yellow wire. This was done in due course – then the other three load-cell wires were connected. All joins were then covered in heat- shrink.

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Load cell connected finally!

The other tension head came in as expected – so using this one, I was able to determine the load-cell connections. On inspection, the white goes to green, black to red, yellow to yellow (which was still connected) and red to black. The photo above shows the heat-shrink in place, but not yet shrunk.

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New Eagnas Plus 8000 internals

Here is the load cell and connector mounted back into the tension head with the chain re-attached.

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load cell attached with chain

Here is a close-up of the mounted load cell – I had to replace both of the screws that hold it to the chain and the carriage because the old ones had been stripped – I think because the original screws were not strong enough – hopefully, these ones will last longer.

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The New Eagnas Plus 8000

Now a final photo of the completed unit attached to my test bench ready to have its calibration checked and adjusted if needed.

By the way, notice how the blue gripper assembly doesn’t yet have the gripper installed? The reason for this is that I had to modify the assembly because the fastening screws were bent, by going through a 6.4 degree bend – that is the slope of the assembly relative to the horizontal. The holes drilled and counterbored in the assembly were perpendicular to the assembly, but were not lined up with the vertical holes in the mounting.

I put the gripper assembly into my mill and adjusted it to have a 6.5 degree slope, then used a 10mm end-mill to do the counterbore. This was followed by a 6.5mm drill to ensure that there was a vertical hole going through the assembly at the right angle. After doing this, the mounting screws can now be tightened up properly without having to bend in the middle.

The next tension head to look at is the one that came in, apparently had been smoking – and the transformer looks like it has been cooked, with the varnish having boiled out of it.

20 thoughts on “Repair.IT – Eagnas Plus 8000 Electronic Tension Head”

  1. Moslem says:

    Hi..plz help me to repair plus 8000…I think that my elec board part IC programmes is damages. ?..help me about the problem. ?..Thx

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    • Moslem, you will need to tell me some more information about what your machine is doing. When you turn the power on, does the display show anything? If something does show up, what happens when pressing the +10 button when powering on. This will check whether or not the main microprocessor is working since this is the one that we cannot get replacements for – the factory does not supply it. Anything else can be repaired and replaced, but you need someone who knows what they are doing.

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  2. Pat says:

    Very informative and useful, I’ve read it a few times and hopefully I’ll be able to get mine working again. I bought an used one with many problems, fixed the ribbon cable attaching to the load cell, apparently one wire within had been cut. The 4 wire cable going into the load cell had been repaired before with heat shrink tube and became very stiff and there is a short circuit when the load cell circuit board is screwed on, I’ll be rewiring those wires so your article came in very handing.

    I also do not have power going into the display panel, it was on a bit then went completely dead, there is a transistor/regualtor(?) mounted on the edge with 7805 marking that gets burning hot, I suspect that is gone and maybe some other components in the voltage regualtor circuit as well. If you know what that component, I would greatly appreciate it.

    Also do you know of any circuit/connection diagram for this model?

    Thank you very much!
    Pat

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  3. Pat says:

    I left a comment just now and it doesn’t seem to come up so will have to post again.

    Thank you for the very informative and useful information, I’m in the process of repairing my 8000+, the ribbon cable going to the load cell was smoking which is likely caused by the very still load cell cable when mounted on the load cell unit. The ribbon cable also had a cut on the outermost wire. Cable is patched up and will be fixing the load cell cable using your info.

    The display only came up briefly then stayed off completely, further check found there is no power coming to it. There is a transistor/regulator(?) on the control board next to the ribbon connector that is burning hot, that is likely the cause of the power failure, it’s marked 7805 on silk screening, would you know what component it is?

    Do you know if there is any circuit/connection diagram?

    Thank you very much for your help.
    Pat

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    • Pat,

      Hi. The 7805 is a 5V regulator, taking an unregulated voltage above 7.5V and giving a stable 5V output which the microprocessor and other parts need to run. If it is very hot, then it is either being overloaded or has possibly failed. The only way to check is to measure the voltage. Don’t leave the machine on, when the regulator is very hot. Turn it on briefly to perform measurements. The middle leg of the 7805 is the common, or ground point, so you can measure with a voltmeter/multimeter from that common point to the left leg first, which is the input voltage, then to the right leg which is the output voltage. Also while the machine is off, you can measure the resistance from the middle leg to the right leg – if you get a reading which is low, like a few ohms, then it is likely that there is a short circuit or other component failure on the output side – that may also cause the regulator to be very hot.

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  4. Pat says:

    Thanks John,

    There seems to be something amiss with the 5V regulator, resistance with power off is about 20 ohm which is acceptable. I have removed all connectors except the J2 power connectors(7+6 pin) and monitor the 5V output.

    When powered on, output is about 4.9V, after about 5-10 secs, the output level drops quickly to about 1.6V, there’s definitely a short pulling it down and overheating the heatsink. I suspect there may be a defective capacitor next to the regulator…..

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  5. Pat says:

    Hi John,

    I have done further troubleshooting and perhaps your insights can help diagnosis the culprit.

    The 5V regulator appears to be working. With power off, the resistance is 20 ohm, only when the big 40-pin (marking sanded off) is removed, the resistance goed to infinity. With the chip removed, the 5V output stays normal. When it’s inserted then power on, the output drops after about 5-10 secs from 5v to 1.6v and the beeper sounds continuously.

    I know you mentioned this is the only one that can not be replaced, I’m still hoping to find one, at least to know what kind of chip it is(some kind of micro controller, should be common in its days), your help would be much appreciated.

    Thanks,

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  6. Pat, when power is off, 20 ohms should mean about 0.25A of load, at least until other things start up. Your option at this stage would be to try replacing the 7805 regulator since it may have been damaged and cannot handle the load, or we look for other things on the 5V line that might be the problem – assuming at this stage that it is not the microcontroller. Why I said that the microcontroller is not replaceable is that it is programmed and we cannot read the code to copy it to another one, so even finding the right chip would not help. Let me see on a board that I have here what else might be causing this.

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  7. Pat, I checked a board that I have been repairing, and will most of the connectors removed, I get about 300 ohms on the 5V line, which is rising so probably I am charging a capacitor. It does sound like your microcontroller is the culprit – which is bad news.

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  8. Pat says:

    Thank you very much for the help, perhaps I could find the same microcontroller from another 8000+ machine – I am assuming the code would be the same or I’ll try calling Maxline Eagnas in the US to see if you carry the parts.

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  9. Pat says:

    Hi John,
    Upon further checking, the microcontroller may not be the culprit, even with the microcontroller pull off the socket, the 5V line still drops down to 1.6V, just takes a little longer, approx. 30 secs vs 5 secs(which makes sense since the microcontroller is also draining the 5V line in normal operation). So something is shorting the 5V line but it is not a hard short. Perhaps a capacitor is the suspect?

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    • Hi Pat, I think maybe that it could be the 5V regulator. Alternatively, if the voltage drops, then something else might be taking the power – and if it is, it should be getting warmer or hotter. You can gently touch the other parts on the plastic to see if any are much warmer than the others – that might give you a clue.

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  10. HI john. Thank you for the good repair writings.
    I have a eagnas flash-767e machine. it has some problem since i bougt.
    When i use the machine first time it works well. but after 10~20 minutes the push and pull button don’t work. Only red button(small one) be working.
    And then after about 1 week. the push and pull button can be woring. and then same problem again..

    Please help me. im in korea. there are no repair shop and anyting about tension head.

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    • Hi, it seems that there is something loose inside – maybe to do with the main switch that does the pull then release. The red button is supposed to reverse the gripper – usually if the release button has not turned the gripper enough to release the string, then pressing it should turn one more rotation. In Korea there should be many repair shops – anyone that repairs machines should be able to help you with this tension head. Maybe what can be done, is to slide something like a credit card under the left and right side of the main front switch, then by working it, the switch should come out towards you with six wires attached. I suspect one of the middle wires might be bad, i.e. maybe not making contact or the wire is not crimped correctly.

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      • Thanks for your reply.
        In Korea i alreay asked a repair shop but they said it couln’t fix eagnas model. They said tension head(plastic part )cant be opend . I think that they don’t know how to do it.
        I already looked at the front main switch and there are 6 lines and they are all good.

        My machine repeat the problem with nothing any action maybe 7days term.

        When the machine is good then i pull the racket during 10 mins its occures the problem again.

        Hope me some advice.
        Thanks

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  12. Hi Roger,

    From memory, the case removal is a little complicated, however – here goes. Remove the four screws that hold the case to the base unit – these are the ones on the sides near the bottom. The gripper assembly needs to be removed – three hex head cap screws. Then the front switches – the left red push button switch – you can slide a piece of thin card like a credit card under the sides and carefully work the switch out and leave it hanging out the front.

    Do the same for the rocker switch, however once the switch is out the front – we need to document, i.e. write down the colours of the wires before removing them. The switch has a roman I and roman II marking – and the wires are two rows of three wires. Top row has I wire, center wire and II wire – we must keep the same order when reconnecting them. Do the same for the bottom row. Take photos. I like to tie some string to each group of three wires and this helps also to help get them back through the hole later on when reassembling the case.

    I hope that this helps you and apologise for the delay in responding as I have been quite busy with my new job.

    -John

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    • Shawn, Hi – thanks for leaving a comment. Regarding the motor, all I know about it is that it likely to be a 24V motor. I haven’t had a motor fail, so haven’t had the need to replace it.

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