TK-880 Power button disabled?!

[WQLU507]

I have a TK-880 that I purchased when a local ambulance service was liquidated. I believe it was used on a local LTR system as an AVL (automated vehicle locator) unit as it has a GPS antennas where the speaker-out should be. For some reason, the power button has been disabled. The radio turns on when it receives power, and off when the power is cut (obviously lol). I couldn't find a setting anywhere in the configuration software for this...is this option an internal DIP switch setting? Hardware mod done by the shop?

 

[ramal121]

If it was used as an AVL unit, I could see where it should always power up. I had an 880 once that would not power up. The flip flop circuit that controls the power on/off was DOA. Customer did not want to pay for a new front control board, so I bypassed the flip flop somehow so it would always power up and hooked power lead to switched ignition power. So yes this is possible, and no there is not a way in software to defeat the power switch.

The 880s will also suffer from dead buttons although the volume up/down is most common. Try this, pull off the top and bottom covers and then pop off the front display cover (4 plastic tabs). The button membrane will also fall out. Wrap a pencil eraser with tin foil and try pressing on the pcb lands that the power button would contact. If this works turning the radio on/off, then you would just need to clean the button and pcb land for a better contact.

 

[WQLU507]

Any chance you remember how you bypassed the flipflop circuit? I spoke with a guy that used to work for the company and he confirmed what I thought, that these radios always turned on when they turned the trucks on.

 

[ramal121]

Not specifically, it was a few years back and I'd have to peruse the schematic to guess.

Tell you what though. The "brains" of the radio live on the front control board and this is where a mod would be. Follow my previous post to get to the front board, then remove the 2 (?) screws from the printed circuit board and pull it away from the chassis. Look on both sides of the board for a wire jumper that has been added by a tech (there should be none from the factory). If there is, you could try and cut it to see if it restores the power button.

If there is a jumper but cutting it does nothing for restoring the power button, then it might be used for something with the AVL in which you may have to resolder it back together to get something else to work properly. Your call.

 

[WQLU507]

FIXED IT! BOOYEAH! Take that Radio One of Atlanta! So...the fix is amazingly high tech and intriquite. Opened the radio, looked around, cussed. Drink 1/2 a smirnoff ice. Cuss some more. Look at service manual. Cuss. Remove useless GPS module. Drink other 1/2 of smirnoff ice. Start taking other stuff apart delving deeper. Getting really technical now. Everyone, tricoders out! Phasers to stun! I took the front panel off, pulled the rubber buttons away. Prepare the deflector dish! Some moron put a small piece of electrical tape of the power button's contact! Removed it, removed leftover adhesive. Powers up and down like it should :-D :-D

 

[ramal121]

You work like I do. Right on!

 

[Luis_R]

FIXED IT! BOOYEAH! Take that Radio One of Atlanta! I took the front panel off, pulled the rubber buttons away. Prepare the deflector dish! Some moron put a small piece of electrical tape of the power button's contact! Removed it, removed leftover adhesive. Powers up and down like it should :-D :-D

That's great!!! Not sure if the Radio One you are talking about is the same as the one here in Florida, but the shop I work for gets stuff from them to fix periodically. The tape over the contact really isn't moronic, it's a cheap way to keep the radio from turning off without having to modify it by bypassing circuitry. You need to remember the radio was being used for tracking, gps. So that was an easy way to keep employees from turning the radio off without removing power. But none the less you got it working and without having to spend $.

 

[code3cowboy]

FIXED IT! BOOYEAH! Take that Radio One of Atlanta! So...the fix is amazingly high tech and intriquite. Opened the radio, looked around, cussed. Drink 1/2 a smirnoff ice. Cuss some more. Look at service manual. Cuss. Remove useless GPS module. Drink other 1/2 of smirnoff ice. Start taking other stuff apart delving deeper. Getting really technical now. Everyone, tricoders out! Phasers to stun! I took the front panel off, pulled the rubber buttons away. Prepare the deflector dish! Some moron put a small piece of electrical tape of the power button's contact! Removed it, removed leftover adhesive. Powers up and down like it should :-D :-D

Heh. Time to upgrade to big boy beer. Glad it was that easy of a fix.