Sony BVM 20E1U / BVM-20E1U tube swap and restoration

[pbjr]

@pbjr Yes please, that would really help me out.

Specifically I'm interested in how fat the front faces of the bezel are - I've tried to draw some green lines to show what I mean. The sides, top and bottom. At the moment the sides are 9mm and the top/bottom are 19mm - how does that compare to the real thing?


Overall starting to feel good - think I've found a way to split the model up and make it printable on my printer at home - Then when I've confirmed the sizing is right I might splash the cash as @Nimmers suggested and add to my next PCB order.


Also, if anyone knows anything about painting for 3D printed stuff now would be the time...

Here we are. looks like
top 12.75mm
bottom 13
sides 5.3
If you need feel free to ask. First time I’m using this tool. Lol.

 

[hatmoose]

Here we are. looks like
top 12.75mm
bottom 13
sides 5.3
If you need feel free to ask. First time I’m using this tool. Lol.

Awesome, thankyou. I’m going to struggle to make them that thin, injection moulded is stronger than 3D printed and the walls are already thinner than I would like…
Let me have a fiddle…

 

[hatmoose]

Absolutely no progress whatsoever on the 4:3 mask recently - I need to do a whole bunch of printing and gluing and I've got a bad case of the CBF's (can't be f*cked) so taking some time out on that

The BC board (also called ISR) does fun stuff like generate test patterns, manage a lot of control functions, store the firmware and etc. There are about 50 SMD caps on this board and most of them are big 100/6.3's - I needed some practise with my new Iron so doing a full recap now. Normally there BC board does not give much trouble - but if certain functions are greyed out in the menu it's because of problems here.



I want to change that battery - but I'm scared

 

[hatmoose]

Revision number 28 (I kid you not)



Now to glue it together and confirm I have the dimensions correct, then some final tweaks and learning how to prime/paint PLA

 

[hatmoose]

Just a rough glue-up to confirm dimensions. The finish with supports is so rotten that I might have to print it in different parts, key thing is to get the model right, then I can start on how to actually make it IRL

 

[hatmoose]

They said it could not be done; Actually they said it could be done, but no-one would be silly enough to waste the time and energy required to do it.

I said "Nothing is foolproof for a sufficiently talented fool" and this is the result.


The white lines are where I glued it with cheap epoxy (actually holds really well). And in the top left section I forgot to print with supports (amazed it printed at all) and it needs a MASSIVE amount of post processing for the finish before painting. But other than those minor issues it's better than I really expected.


Model needs a couple of changes so that if fits properly, then I need to work on the retention.
Does anyone know what these things are called? You kind of push them in to lock, then push them in again to unlock.

 

[hatmoose]

In case anyone comes afterwards and is looking for the same thing - these are all over aliexpress called "small door lock switch" or "push lock switch"

Ten for one US dollar, quite a lot more NZ dollars


I need both the male and female elements. Now a short wait of 30 working days...

 

[hatmoose]

Nearly there with the model - it's as close as I can make it to the original taking into account the annoyances of 3D printing.

I still need to trim the shroud down about 1mm all round - at the moment there is some manual rework to sand it down.
I also need those parts from china so I can model the push-to-latch catches at the top
And I need to make sure the clips at the bottom actually clip

So the model is pretty good, but it's impossible to print it - I'm either going to have to cut it up into LOTS of bits, or do a lot of post processing and filling. Because of the way it needs to sit on the bed and the overhang for the convex surfaces, it comes out looking like a dogs breakfast even with supports. Needs to be absolutely smooth.

Started experimenting with post processing today, sanding down the curved surfaces and filling with plastic automotive filler (bog).
80 grit was too corse, I sanded through the outside layers and, the bog couldn't fill all the gaps
100 grit was about right, the bog filled all the gaps pretty well, I might have to sand and re-fill to get it perfect
180 grit I got bored before the job was done

I'll leave to harden overnight, sand it back, and see if it's ready to prime.

 

[JohnRambo'sKnife]

Impressive work with the bezel. What a nightmare to fabricate.

 

[hatmoose]

Recapping the BK board did not go well - Brightness is done by IC701 and his buddy IC704. When they are not doing their thing you get lots of random overloads. Guess who gets lots of random overloads...

C706 and R711 are supposed to be in parallel into IC704.
Unfortunately they forgot C706 (4.7/50) when they laid out the the PCB, so bodged it on afterwards - re-bodging the bodge is where the fun started.

C706 should be in parallel with R711 - but I've destroyed R711 with too much heat, luckily the traces and pads are OK
Negative goes to Pin 4 of IC704 (-5v)
Positive goes to Pin 3 of IC704
R711 is open because I've burned it up - so the fix is to replace R711 - this is easier said than done as you can see from the pictures.



This has a couple of interesting effects
1) Brightness control is inverted (0 = full, 4000 = off)
2) the overload protection sees "too bright" and triggers all the time, sometimes within a few seconds of power on


So 3 weeks for delivery of a tiny resistor the size of a grain of sand, then an hour of work to strip all the other components, replace R711, put all the other components back where they belong, and put C706 back in parallel.

This is a perfect time to finish the bezel, which is nearly done, expect an update in the next few days

 

[hatmoose]

Well, no update on the bezel, but one of my buddies on the Facebook BVM group has posted this color match for the paint, mainly posting here so I don't forget about it later

 

[hatmoose]

Getting close with the bezel

In the end I gave up on the Aliexpress push-catches and modelled my own.
These 3D print just fine - when I print them with PLA they hold on almost too strong- will reprint in more rubber-like TPU


For the Bezel I'm pretty sure that I'm there for the dimensions, have modelled in the posts to mate with the catches. For assembly I've cut 2mm x 5mm channels into each side, can easily print some 2mm x 5mm bars to go into the slots for mechanical strain relief.

 

[hatmoose]

STL's attached if anyone wants to have a mess around - I am 100% not sure if it will actually fit.

It's on the printer now - ask me in 6 x 8 hours

 

[JohnRambo'sKnife]

Amazing dedication. Hats off.