EEVblog 1603 - Sony Amplifier REPAIR

[EEVblog]

Repair of a Sony HCD-SBT20B Bluetooth Stereo. What it's like to nail the repair and then, well come-a-gutsa and have to go down the rabbit hole to fix the fix all whilst battling bad design info.

00:00 -  Sony HCD-SBT20B Bluetooth Stereo with a water ingress problem
01:17 - Water isn't that bad actually, even mud.
02:49 - Comically long screwdriver time
04:09 - Vacuum Fluorescent display for all you VFD fanboys
05:10 - Annoying construction
06:14 - Logic level problem? Doesn't seem to be the PSU.
07:57 - Yuck!
09:58 - PCB Cleaning time
12:11 - Did the cleaning work?
13:28 - Hang on, I think I see something...
14:36 - More corrosion
15:21 - Back to measuring voltages on the VFD
17:15 - Handy use of Auto Hold
18:00 - VFD dispaly under the microscope
19:33 - Cathode measurement
20:13 - Anode connection tracing
22:10 - I wouldn't have designed it like this
23:08 - Sanity check
24:32 - What's in the can?
28:16 - Schematic time. Sony service manuals are something else
33:22 - Don't come-a-gutsa on dual diode pinouts
35:16 - Let's power it up on the bench
37:19 - There's something very strange about this...
40:04 - Oh FFS!
42:03 - Now it'll work...

[Muxr]

That was a fun one Dave! lol 

[SiliconWizard]

Nice Futaba display though.

[EEVblog]

Nice Futaba display though.

Was interesting how it was basically backwards, so you don't see the grid and cathode wires.

[elettrocecco]

Nice that you posted the "How VFD displays work" before!
Thanks

The inductor (L1 min 25:40) seems sealed with silicon to avoid buzzing. I have never seen any as nice as that.
Does any one know who could produce them?

[EEVblog]

The inductor (L1 min 25:40) seems sealed with silicon to avoid buzzing. I have never seen any as nice as that.
Does any one know who could produce them?

Off hand I don't know.

[ksio89]

Great job Dave! Murphy is indeed a tricky bastard lol. Re-checking your steps is yet another stuff that I learnt by watching your repair videos. And kudos to Sony for making such detailed service manuals, they are amazing.

[SiliconWizard]

It's easy to get misled during a "debugging" session, being hardware or software. And often we tend to focus on things that we think must be the most reasonable culprit, and spend a bit too much time on these.
The key is the following:
- Be systematic. Test every little thing that is a possible cause of failure, however silly it seems, one by one. As long as it's factually a possible cause.
- Don't run in circles.

[isometrik]

I guess Murphy showing up this time was payback for all those repair videos that turned out to be easy fixes.

 

[ballsystemlord]

FPC cable! It's gotta be the FPC cable! Come on, check the FPC cable! I've never felt so frustrated by waiting for a you, Dave, to figure it out in my life.

On the plus side, I guessed correctly.
Thanks for the repair vid!

[SiliconWizard]

FPC cable! It's gotta be the FPC cable! Come on, check the FPC cable! I've never felt so frustrated by waiting for a you, Dave, to figure it out in my life.

Did it feel like watching "who wants to be a millionaire" and knowing the answer to the last question?

[ballsystemlord]

FPC cable! It's gotta be the FPC cable! Come on, check the FPC cable! I've never felt so frustrated by waiting for a you, Dave, to figure it out in my life.

Did it feel like watching "who wants to be a millionaire" and knowing the answer to the last question?

Very much so!