QL not booting if case screwed tight

[t0nyt]

I’ve discovered a problem with the QL I’ve been putting together

It works fine until I screw the case together and then it hangs with black and white stripes (both JM & Minerva)

I’ve tracked it down to the middle rear screws and if I leave them out it works

If I grasp the back of the unit it stops working until I let go

But looking at the motherboard etc. I can’t see why this would be happening

I was wondering if anyone has come across anything similar or has any ideas how I can try to troubleshoot the problem please? (given the case has to be closed to reproduce the issue)

Many thanks

[Pr0f]

almost certainly 'flexing' of the main board is probably exposing a dry connection or a chip not seating properly in a socket.

Remove Ic's that are socketed - clean the legs with a deoxidizer - the stuff people use for their guitar jacks is excellent but expensive and re socket them.

Try the board again - see if that fixed it

if not - you most likely have a dry joint and that will be harder to find - visual inspection can help - look for poor quality solder joints - obvious "leg in a lake" solder blobs around component leads, voids, badly discolored joints - and also check for damaged or broken tracks...


https://learn.adafruit.com/adafruit-gui ... n-problems

[t0nyt]

Thanks, will give those things a try

As a followup though I just tested with the lid off and found I could reproduce the problem by pressing on the RF modulator, though when the case is screwed down nothing appears to be pressing on that, so I don't think it's RF modulator itself. I guess flexing as you say

The main culprit is the rear middle right screw when looked at from the front

Many thanks

[Derek_Stewart]

Hi

Try looking at the back of the QL board to see if there are any soldered joints that have broke their soldering.

The TV modulator, is under a bit of stress by plugging the TV Cable in and out.

Check the soldered joints on the Power Connector, this is another weak point.

Is there anything on the case that is pressing on the board parts.

[t0nyt]

Hi

Try looking at the back of the QL board to see if there are any soldered joints that have broke their soldering.

The TV modulator, is under a bit of stress by plugging the TV Cable in and out.

Check the soldered joints on the Power Connector, this is another weak point.

Is there anything on the case that is pressing on the board parts.

Will do, thanks

(I'm not using the RF modulator, so no cable stress from that)

[t0nyt]

Have desocketed the ic’s and washed the sockets with contact cleaner, just waiting for it to dry

I can’t currently see any broken tracks or bad soldering, but will keep looking (picking up my new glasses Monday!)

[t0nyt]

And we have a winner!

Not sure who though...

I couldn't find any obvious issues with soldering/tracks, though my eye's aren't great

I cleaned all the sockets and made sure everything was very firmly pressed back down and nothing was snagging anywhere

The case seems to go back together better now, rock solid with no sign of any flex

After fitting all case screws the "QL's alive!" (read in best Brian Blessed accent)

I've still got to fit an MDV2, QuintupLer & vMap so will see if it all stays that way with my ham fistedness (I broke a pin off my Minerva board)

Many thanks all

[t0nyt]

Thankfully managed to replace the broken pin on my Minerva/TK2 board

Luckily it was probably the easiest pin to safely do