Mimaki JV3 Plotter - Help Needed

[AndyStobbs]

Hi guys,
Trying to help out a signmaker in one of the units neighbouring my own unit.
Guy has a problem with plotter as in title, the error seems to be a fault on the IF board, which handles all communications with the computer.

It seems its a very common failure point, and is a case of when, not if.
New board is over £1200, and as this one is now junk anyway I offered to cast my eye over it (i'm no electronics wizz - but what is there to lose). I looked at the capacitors for any with a blown vent and found nothing obvious, nor dry joints etc.

Did a bit of googling, and found there are some additional smaller caps I hd overlooked. Around these there does seem to be a deposit on the pcb. When scraped with a blade the deposit flaked off the PCB. This deposit is present in the vicinity of each of four caps which are around the periphery of a large IC.

I plan to obtain some replacements and solder them on anyway (not feeling at all hopeful). They are an odd design (to me), being surface mount and not metal cased. Appear to be made from the same resin type material as chips, transistors, gates etc.

Shouldn't have too much difficulty getting them from farnell or maplitz, but does anyone know their correct name?
And, is this a typical failure mode, for an almost clear deposit to be in the vicinity of the cap?

Thanks

 

[the snooper]

could be polyester film, ceramic, tantalum a picture would have helped

 

[AndyStobbs]

will get a picture tomorrow. Have left the board at work.

Thanks

 

[the snooper]

just google capacitor types under images and you might be able to match them up with a picture

 

[AndyStobbs]

non of the types you mentioned earlier look the same. Nor did polyester. I realise it could just be a different style of case with same innards as another case.

 

[mike 109444]

Take it it's not this one then?
http://www.ebay.co.uk/itm/Mimaki-IF...310?pt=LH_DefaultDomain_0&hash=item35c0433f6e
Maybe more like this one?
http://www.ebay.co.uk/itm/Mimaki-JV...ther_Computing_Networking&hash=item4d0b615e1b
Don't forget surface mount components have a max heat time, much longer and the component is toasted! See component specs

 

[mike 109444]

If you/he gets it fixed or replaced he might want to invest in a ups to filter the mains as if he is in as you say a unit then could be spikes from nearby units say doing welding putting interference on to the local mains. Ups should soak this up and protect it from dips in mains.

 

[MattF]

If they aren't electrolytics, leave them be. Saying surface mount, I assume you're referring to the, (generally), light brown body rectangular types? The residue you see around them is likely just flux.

Btw, electrolytics don't always leak when they go faulty. Leaking is generally the last step before they tend to blow apart. Electrolyte is usually easy to distinguish due to its darkish hue, the fact that it will likely have corroded the lacquer and tracks around it and the rancid fish type smell it'll give when you get anywhere near it with a soldering iron. The caps can go duff well before that point though. Unless you have a capacitance meter or the like, however, the only way to check whether they're knacked or not is to replace them.

 

[AndyStobbs]

Got some pics of the board, have attached them.
The deposit is only present around these four components, no here else on the board - ofcourse it's possible they've already been replaced.

In the last pic you can see them around the big IC.

 

[500e]

Leave it alone walk away.
Without diagrams a. you are guessing b. your depth of knowledge is not enough, working with surface mount is not easy, even if you are set up to do it.
I spend most of my working life now on print boards (mainly RF) & they still bite me.
Is there an dedicated repairer with exchange boards it sounds as if there should be if the level of failures is as high as you suggest ?.
If you damage the board the repairer will not even look at it, the first thing we do is check to see if people have had a go at self repair if so return it.
Remember some components are static sensitive & touching them can either destroy or seriously shorten life.
mike 109444 has a good point regarding spikes anything to remove mains fluctuation is good

http://signweb.com/forum/digital-sign-printing/jv3-160sp-firewire-board-problemhow-to-repair


I would still walk no run away

 

[AndyStobbs]

Remember some components are static sensitive & touching them can either destroy or seriously shorten life.

Kind of irrelavent as the board is already dead.

Have taken the rest on board though (no pun intended), will see about repairers.

Thanks

 

[500e]

http://www.ko4bb.com/Manuals/11)_St...aintenance Manual/160S maintenance manual.pdf

This link downloads service manual takes time be patient in PDF.
The board may not be dead but is faulty, there is a big difference in cost, repair V replacement.

 

[the snooper]

I have to agree with the above that board is very complex and I doubt very much it has anything to do with those components, could be any one of those ic's gone corrupt and each one will contain thousands of transistors, unless you have the specific test data you will never repair it

 

[MattF]

Kind of irrelavent as the board is already dead.

Not really. A simple fault could end up becoming far worse. Saying that, whilst ever the components are soldered in place on the board, the chance of static damage is far less than if you were handling the components directly. Like others have mentioned though, don't even bother. Even if you do download the service manual, for example, it's b*gger all use of you don't have the necessary test equipment, and a board like that is one that few but a brand specific engineer would even attempt, and as 500e mentioned, if you do send it off for repair, any visible form of self repair will likely cause it to be returned untouched.

 

[AndyStobbs]

I only mentioned those 4 caps inparticular because I found a post through a google search. This post suggested that those caps should be replaced as a matter of course if they look at all damaged, and that in early boards the japs even managed to solder them on with the polarity reversed. The american firm offering a repair service seems very cheap at the USD equivalent of £142. Suggests that whatever they do to the boards cant be very costly.
Signman is resigned to a replacement board anyway. I might just go ahead and replace them anyway - nothing ventured nothing gained...

 

[MattF]

The four black ones sat upright? If they're polarised, you can use some tantalums in place of them. Just make sure you get the same uF rating. Voltage rating needs to be same or higher, but keep the rated voltage as close to the originals as possible. Then just make sure you solder them on the right way round.

 

[AndyStobbs]

Went to maplitz earlier as I needed some bits and picked up four suitable caps for the mimaki board.
I can now explain the deposit around the originals on the board, as I began to desolder the first of the black caps sat upright, it became clear those 4 have been added onto the board.
Underneath them, are 4 tiny SM's, the really small ones with no numbers on. At some point in the past it must've been neccesary to create extra capacitance so they've piggy backed onto the orignal terminals. (caps in parallel).
Decided to solder it back on and re-acess the situation.