Linn Kinos repair

[4cx10000]

Hi!

Suddenly I found myself looking at a Linn Kinos system controller that need repair, but ... seems like Linn keep their service manuals real tight in-house. Searched manual to this one everywhere but to no avail... Seems like I have to open the box without any kind of helping document, but I do not like it. Does anyone out there know if it is possible to get hold of any info on this particular gear?

[_Wim_]

Operator manual can be found here, service manual could indeed be difficult:

https://www.manualslib.com/download/524290/Linn-Kinos.html

What problem does the unit have?

[4cx10000]

Hi _Wim_ and apologise for not answering your question until now, really missed your post!

This Linn Kinos has a non functional display. I have been quite busy so I have not done any further investigations. The only thing that can be said is that the owner was able to buy and replace the display board as well, but to no avail - display is still dead. A schematic is really needed for this bastard...

[_Wim_]

No problem for the late reply, I have the same thing also regularly.
If the display board has been replaced, I would check the supply voltages to the display board. Do you see anything appearing on the display when the unit is powered on? Do all other functions work correctly (if it is possible to test that off course without a display)? Typically a display board is only connected with a few wires with contain the power supply and some sort of communication bus. If absolutely nothing is being showed on the display during power-up (not even some blink of flash), I would expect it gets no power. I think it should be fairly easy to check if you have supply voltages coming in (even if you do not know what they are supposed to be, looking for some supplies and nice rounded numbers tells already a lot).
Can you maybe post a pictures of the display board and how it is internally connected?

[4cx10000]

Hi _Wim_! Thanks for reply and helping me out! 

No, there is no sign of life at all - not a single blink. The display is a VFD and there was no filament voltage AC or DC nor anode. Expected AC but of course it could be one with DC filament, but there was nothing. The display board itself is feed via a flat flex cable from one of two main boards. I will have to take it apart and hopefully the flex cables are long enough to make it possible to run uncle Kino and be able to measure around. Bottom side of the pcb, the mainboard where the flex cable from display board enter, is pointing upwards the cover, that is why the cables truly must be long enough to turn it over and then gain access to upper side. I will open Mr Kino again and see what I can do and take some photos I will post later.

A pass along one photo I took of the display board, really not much to see, when I tried to find data sheet for the controller, but search on the webb ended up with nothing...

[_Wim_]

That picture is not so clear, but could it be that TR1 is used to generate the high voltage for the VFD? If that is the case, it should be ok, as the display board has been replaced. But it could well be that the entire display board gets no power, so check what is supplied via the flat flexes.
I cannot see it in the picture, but does the display board also contains buttons or other devices? Do these work ok?

[4cx10000]

Hi _Wim_ and thanks again!

Well ... yes, that picture was not much to see because the photo angle did not left much over for enough light, focus or other components then the controller IC.  Yes, I also think that they have the step up – which most probably includes TR1 – for the 20 volts or so on the display board. I also think, as you wrote, that the display board does not get proper power feed from one of the motherboards and that is why I want to turn over the PCB if lengths of the flat flex cables allow me to. When I get there I will see all components, take a picture and hopefully be able to measure when it is powered. The owner told me that everything works ok except for the display and there are six buttons, among them power on. Owner will bring me the old display board tomorrow, which probably work, and during the coming week I will open up Kino again.

Thank you _Wim_ for being with me 

[4cx10000]

Well ... got the display board from the owner but sadly, the VFD itself was cracked. However, I was able to heat all glass pieces, which more or less looked like a puzzle, that where secured to the PCB with double adhesive tape. Luckily i managed to read out the model and found data sheet, did not expect such a high Vdd as max 65 volts tough.  Seems that they use a Cypress MB3800 switching controller as can be seen in the picture. HV and filament voltage (AC) is supplied from TR1 and of course HV rectified. Now I know where to start measure. Power is supplied from the upper PCB in Kinos via the flex cable to pin 24 & 25 on display board. There is test points close to a linear 5 volt SMD regulator LM2940. Next step will be, depending on what my measurements will show, to turn the upper board upside down and continue investigate.

What do you think _Wim_?

MB3800 http://www.cypress.com/file/236381/download
VFD MN12832E  http://www.noritake-itron.com/Specs/MN/MN12832E-04.pdf

[_Wim_]

I would have a look at the primary side of TR1. My guess would be that the DC voltage is missing there, and that this voltage comes directly from the main PCB (so a second power rail). So I would probe the primaray side of TR1 and check if this is connected to the flatflex, or work my way back from this point. If you have a scope available, you could check if you see any switching at all...

[4cx10000]

Hi _Wim_ and thanks!

Yes, I back tracked from the primary of TR1 to the flat flex cable connector yesterday and it goes to pin 24 & 25 as I mentioned in my previous post. Same power rail feeds the 5 volt linear regulator which make me believe that your assumption is correct about still another power rail that feeds the controller from the main board, because, as the owner said, everything except for the display works. I will be backs as soon as I have time to open up Kinos again. Thank you _Wim_!

Here is my setup at work 

[_Wim_]

Nice setup 

[MrTea]

Hi,
My first post here, but i'm in a similar predicament with a Linn Kinos that I've been asked to take a peek at and am trying to decide the best next step to take.  Any advice would be greatly appreciated.

I was given the unit to look at because "it wouldn't power up" and to see if there was anything i could do as the Linn repairs were prohibitively expensive.
I noticed some damaged caps on the PSU module (heat damaged) so started by replacing those.  I then got some solid (+/- 17 and +/- 6 volt) outputs from the PSU.
The Kinos then starts to power up and i get a 'Loading Operating System' message on the display (which is very very dim).  So, i'm making progress I think...
With it perpetually 'Loading OS' i then scoped around the boards looking at power rails.  I found 3 that didn't appear to be in spec (i.e. had 3V ripple on a 5V rail).  Suspecting the electrolytic caps again i replaced them and the rails snapped back into spec again.  More progress i thought...
After a few cups of tea the Kinos suddenly sprung into life and worked, it worked repeatedly every power-up  . I went to try it out again the next day before boxing it back up and the damn thing didn't work again (stuck loading OS).  It looks lke its trying to do some internal checks (internal status LED's flashing) then gives up.

As a last resort I borrowed MrsTea's hair dryer and warmed the boards up gently... The Kinos then sprang into life again.
It also still has a very dim and pixelated VFD display.

I'm thinking that some internal power rails are not in spec so the Kinos is failing some Built-In-Test checks. 
I've seen thermal instability related to faulty IC's but warming them up usually made them fail not work!, hence me suspecting the caps...

On the boards there are about 65 surface mount electrolytic capacitors, mostly around voltage regulator IC's.  My thought is to replace them all but this sounds quite drastic, what do you think?

I think the dim VFD is possibly another fault so i'll take a look at that once i can get the Kinos to reliably power up without the aid of a hairdryer!

[_Wim_]

Did you try with gently flexing the pcb? Could be a bad solder joint somewhere that make contact again when the pcb expands due to heating? That could also be the reason why after assembling the unit it stopped working again. I would not expect something like this to be related to caps.

[MrTea]

Hi _Wim_
That's a good point, i'll start with the board that responded to the heat-treatment the most and see what I can find.  Time to get my good eye loupe out... Suppose I should be glad there are no BGA's!!

Thanks for the advice, I'll post progress in a bit.
Cheers