Repair Siglent SDS1102DL

[Bigfoot]

The silicon I'm referring to is on the small PCB stuck to the back of the LCD panel which has two connectors one is the end of the ribbon cable coming from the main PCB and the other is a socket for the Mylar (clear orange) flexcable which goes into the TFT display itself. This small PCB looks to be a bridge between the grey ribbon cable and the orange Mylar flexcable. The problem had nothing to do with the grey ribbon cables.

There's no tape on any of my  cables. There appears to be copious amounts of white (neutral core) silicon used. Quite a bit of it around the legs of a group of electrolytics on the Power Supply board (probably for HV insulation). I know this stuff shrinks with age and realistically I can see why this would cause a problem on the specific socket due to the construction. Once you pick off the silicon the socket latch comes away at 90deg to the cable, it's the hinged variety.  I didn't get a pic of this as the scope is all sealed up now.

There's a possibility this will occur with other units.  Very strange how the display was reversed though.

Anyhow I thank you all for the suggestions.

Bigfoot.

[tautech]

The problem had nothing to do with the grey ribbon cables.

Gotcha. Thanks for the explanation. 

Quite a bit of it around the legs of a group of electrolytics on the Power Supply board (probably for HV insulation).

In many Asian products you find this.
More for mechanical reasons than electrical IMHO.

[tautech]

I have to say that a simple thread like this says a great deal about Siglent and tautech. I would have suggest to Siglent that they post a disclaimer (do at your own risk) but regardless, two thumbs up on the just do it attitude.

It's more than that pickle, don't you just love a good mystery too.

@ Bigfoot
This was a very unusual fault and your fault finding efforts/skill certainly helped. 

Guys, I've asked Siglent (Jade) to refer this thread to R&D as it appears there might be a rare issue with the retaining silicon and the LCD connector.

Maybe it will never happen again. 

[Bigfoot]

It did look like a hardware issue rather than firmware and fortunately it was only a cable. Overall these scopes look pretty well constructed (apart from that power switch location )  I would buy another.

@tautech: A question for you, what are the chances of getting a new power switch from Siglent?

Cheers,
Bigfoot.

[tautech]

AFAIK it is part of the PSU and unlikely to be available as a separate item.
I'm sure I've seen mention of similar breakages in past threads and mention of suppliers for them. 
Maybe it was a Rigol. 
It's getting late here and the brain is starting to fog up, I'll sleep on it.

E14 or RS is where I'd go looking for one.

[Bigfoot]

All good. I sourced a couple on eBay UK. The switch manufacturer part no is KDC-A11 type 303. It'll be as good as new in no time at all.

Bigfoot.

[Roman Nartov]

Dear friends, please I strongly do not scold-how to communicate with you through translator. After reading your topic I think I encountered the same problem. Purchased on aliexpress SDS1102 Siglent CNL, received the goods at the post office brought it home and Oh include a screen around the perimeter gives some sort of red tides ( like stripes but with smooth contours ), these bands change their shape, e.g. press the menu button, each menu item with a right-to-left in the background more red tide, off the menu instead of black background get reddish. Advise something, a huge request to you friends that if you need to replace please provide a link to ebay or aliexpress if you want to do something with the device then please tell us in an expanded form on the fingers and if the photo will attach I will be very grateful to you. I enclose for your attention a video of my misfortune, probably will be clearer. Thank you for your precious time and understanding!

https://youtu.be/XWv7_psA75k

[tautech]

Welcome to the forum.

The serial # indicates it was made in March 15 and is still in warranty.
Do you have a Siglent dealer near you for assistance?

I have not seen that same fault before.
Normal recommendation from Siglent for screen faults is to re-seat the LCD ribbon cables. There are 3 connections, motherboard, and a socket the adapts the ribbon cable to the LCD panel flex PCB.
Re-seat all 3 connections.

Let me link Siglent to this thread and they should be online in ~5 hrs.
As it is under warranty please wait for their instructions.

[tautech]

@Roman Nartov

Siglent Techical support engineer looked at your post and replied to me:
Hi Rob,

   For this problem.
   Our suggestion is same like you .
   
    Best regards,
    Jexy


Please see these examples of a similar LCD problem and how it was fixed:

I plucked the silicon off the LCD Mylar flexcable that goes directly to the LCD and reseated the cable, booted up the scope and the display is now back to normal see the pic. There you have it the cable socket is a hinged type that lifts off the cable as I discovered under the silicon adhesive so any contraction of the silicon over time is going to reduce conductivity of the cable to socket as it would have a tendancy to unlock the cable.

The silicon I'm referring to is on the small PCB stuck to the back of the LCD panel which has two connectors one is the end of the ribbon cable coming from the main PCB and the other is a socket for the Mylar (clear orange) flexcable which goes into the TFT display itself. This small PCB looks to be a bridge between the grey ribbon cable and the orange Mylar flexcable. The problem had nothing to do with the grey ribbon cables.

There's no tape on any of my  cables. There appears to be copious amounts of white (neutral core) silicon used. Quite a bit of it around the legs of a group of electrolytics on the Power Supply board (probably for HV insulation). I know this stuff shrinks with age and realistically I can see why this would cause a problem on the specific socket due to the construction. Once you pick off the silicon the socket latch comes away at 90deg to the cable, it's the hinged variety.  I didn't get a pic of this as the scope is all sealed up now.

There's a possibility this will occur with other units.  Very strange how the display was reversed though.

Anyhow I thank you all for the suggestions.

Bigfoot.

It seems the white silicon rather than preventing connection problems on the LCD mylar connection is actually causing a connection problem by way of shrinkage, partially pulling the connection apart.

This is maybe something Siglent needs to address with a different more stable product. 

Please report your findings to us.

[Roman Nartov]

Dear friends, thank you for responding! I understand you correctly I need to release the cable from the connector and re-insert it into place? Sorry to ask again but I work with a translator. Thank you for your understanding.

[tautech]

Dear friends, thank you for responding! I understand you correctly I need to release the cable from the connector and re-insert it into place? Sorry to ask again but I work with a translator. Thank you for your understanding.

Yes that is correct. One of the gray ribbon cables is for the front panel keypad and the other is for the LCD.
Note there is another LCD connection hidden behind the LCD. You must check this other hidden LCD connection too.

[Roman Nartov]

Thank you for the prompt information, please tell me where you are hidden behind lcd panel connection? These connections also go through a mechanical connector?
In all the pictures you can see that the ribbon cable goes directly to the screen without mechanical coupling, it is necessary to remove the metal housing from the lcd screen?

Please tell me if it doesn't work then can I change the screen like in this link : https://www.eevblog.com/forum/repair/sds1102cml-lcd-26-pin/msg720299/#msg720299
And do I understand correctly that the model of this lcd screen AT070TN07 ?
Thank you for taking the time and understanding of my problem

[tautech]

Thank you for the prompt information, please tell me where you are hidden behind lcd panel connection? These connections also go through a mechanical connector?
In all the pictures you can see that the ribbon cable goes directly to the screen without mechanical coupling, it is necessary to remove the metal housing from the lcd screen?

See movie @ 0.44.
https://docs.google.com/file/d/0B_dQmKARz4hfSlhtU01yY1dlTXM/edit?pli=1

Yes, the hidden interface connector is behind the metal housing.
To access this connector you must dismantle the scope.