ColecoVision graphic glitches on startup.

[ViciousTengu]

I purchased a ColecoVision recently that worked fine the first time I plugged it in, but then I bumped the power cord and it looked like it shorted out. Now everytime I turn on the console I get the same garbled text each time. I'm afraid that I may have fried some of the 4116 DRAM chips by doing this and was wondering what everyone thinks my next course of action should be? I read on another thread about piggybacking another chip to test for the bad one... I'm comfortable with soldering but I have read some things about the Coleco's board and how fragile it's supposed to be and would like to avoid ruining such an old console.

[cOLeCoHiTMan]

here's a link to Yurkie's list of items in order to check:

http://www.atariage.com/forums/topic/188248-bummer-colecovision-gets-the-screen-garbage-problem/page__p__2378676__hl__switch__fromsearch__1?do=findComment&comment=2378676

 

(there's a pdf link somewhere here too to rebuild a switch)

[ViciousTengu]

Excellent, I will post updates of my progress with photos. I'm ruling out the cart slot.

[ViciousTengu]

Ok, So it looks like the power supply is giving the right voltages. This is a picture of the startup screen without a cartridge plugged in. These glitches are not random the text stays the same each time I turn it on.

 

[+5-11under]

If you move the Nintendo and Atari products away from the TV it will work much better.

 

I would guess it's a DRAM issue, but, and I know it may sound a bit strange... first I'd double-check the power supply, while the console is powered up, and also spray the inside of the power switch with WD40 or contact cleaner (followed later by a proper disassembly/cleaning), just to be sure.

[NIAD]

I'm no technician, but when you said you bumped the power cord maybe you jarred something loose on the connector inside the console such as a solder joint. A number of people have thought that the DRAMs were the problem with their systems only to find out that it was either a faulty power transformer (need to test voltages with the system on), a worn out power connector plug and the biggest one is a worn out On/Off Switch that can be quickly tested/cleaned like 5-11under stated, but needs to be completely disassembled and refurbished to correctly fix.

Edited January 23, 2012 by NIAD

[ViciousTengu]

I have just replaced the switch with a new one and have the same results. Just checked out the DRAM chips and noticed that they bend the pins down when they install them looks pretty tough to upgrade with the 5v RAM upgrade sockets....

[FABombjoy]

The unsightly alternative is to cut the DRAMs out and solder the sockets to the old DRAM legs. It's not pretty but it's completely functional. I have done this in situations where proper desoldering tools were not available.

[ViciousTengu]

Unsoldered all eight DRAM ram chips and installed 2 of 8 sockets. Waiting for parts so i can do the +5v ram modification. Hoping there's no lifted traces or cold solder joints. So far the multimeter is telling me everything is okay...

[ViciousTengu]

Okay, all eight sockets have been soldered but now I'm having a problem with the instructions. It says that there should be no connection to the red or blue wires yet I get continuity on some of the IC socket pins when connecting to the red or blue wires. Removing coils L2 and L3 shoud have taken care of this right?

[ViciousTengu]

IT WORKS!! Updates tonight. Thanks FABombjoy!

[ViciousTengu]

My freshly installed socketed VRAM from console5.com. Just need to get the component video upgrade & my Donkey Kong cart and we'll be playing Coleco like a boss.