Sears SR2000 series, a classic in need of help!

[teryaki]

Hello! My girlfriend and I tried to set up her Commodore 64 today. Tried the living room TV and couldn't get a signal, so... we hooked up the CRT monitor, and the moment that she plugged the RCA video connection into the monitor, with a switched off C64 mind you, the lights dimmed and magic smoke was released.

Still don't know what happened.

Good news is the monitor will still power on, but doesn't take video inputs. I'm trying to get the board out to see where the magic smoke came from (video input is all the way at the front of the board).

I need someone to tell me the proper way to discharge this thing, and how the heck I should go about disassembly. The screen still feels charged just moving my hand near it, and won't clear heatsinks on the board if I try to remove it. While the board has screws that I can't reach because of the screen. Gotta believe someone else has worked on one of these before.

Also, if anyone knows how to add an RGB input to this, that would just make her day. Although honestly the composite looks amazing with this hooked to a 1CHIP SNES.

Gallery here of the disassembly so far, with identifying markings: https://imgur.com/a/1oCuu

EDIT: Googling suggests this is a Toshiba screen with a Sanyo FCC ID?

[piernov]

Re: Sears SR2000 series, a classic in need of help!

Firstly, working on a CRT can be dangerous if you don't know what you're doing so I would advise against it. On this kind of device, always work with one hand in your pocket (so that you can't put both hands in the device and get the electricity flowing through your heart) and never with the device connected to anything (it must not be grounded in particular when you're working on it).
Anyway, I can't help you with this (I only know about LCD displays), but you may check 12voltvids on Youtube which may interest you. He's got some nice videos about CRT repair.

[RJARRRPCGP]

Re: Sears SR2000 series, a classic in need of help!

Sounds like a primary-side failure...

[teryaki]

Re: Sears SR2000 series, a classic in need of help!

Firstly, working on a CRT can be dangerous if you don't know what you're doing so I would advise against it. On this kind of device, always work with one hand in your pocket (so that you can't put both hands in the device and get the electricity flowing through your heart) and never with the device connected to anything (it must not be grounded in particular when you're working on it).
Anyway, I can't help you with this (I only know about LCD displays), but you may check 12voltvids on Youtube which may interest you. He's got some nice videos about CRT repair.

Thanks. Managed to get advice on safely discharging: have to ground the anode on the tube, which is under a suction-cup dealy at the top of the monitor.

[teryaki]

Re: Sears SR2000 series, a classic in need of help!

Sounds like a primary-side failure...

Got it apart and saw the problem soon as I flipped over the board. Surge must have traveled on the composite cable's shielding and gone into the ground trace. Two spots on the board where copper's been blown off that trace as it arced to the chassis and then down the ground wire in the power cable.

Components all look undamaged. Bunch of old Rubycon caps in here look like the day they left the factory +30-odd years of dust.

[RJARRRPCGP]

Re: Sears SR2000 series, a classic in need of help!

Got it apart and saw the problem soon as I flipped over the board. Surge must have traveled on the composite cable's shielding and gone into the ground trace. Two spots on the board where copper's been blown off that trace as it arced to the chassis and then down the ground wire in the power cable.

Components all look undamaged. Bunch of old Rubycon caps in here look like the day they left the factory +30-odd years of dust.

Was the 120 V hot found shorted to the chassis?

[teryaki]

Re: Sears SR2000 series, a classic in need of help!

Was the 120 V hot found shorted to the chassis?

No, no sign of that. I'm pretty sure the Commodore passed the surge along the grounded shielding of the composite video cable. Surge only occurred when that was hooked up, and area of damage being in the video input section of the board seems to confirm that.