How do I Remove the VIC 6560 chip

HermanVIC · Post by **HermanVIC** » Wed May 01, 2013 10:43 am

The VIC chip is enclosed by the metal box. How do you get it out of the socket to swap it out and see it is the problem?

Can anyone recommend an inexpensive, but useful, logic probe? I have a 100mhz frequency counter, if that is helpful.

Thanks
Herman

HermanVIC · Post by **HermanVIC** » Sun May 05, 2013 12:46 pm

The 6560 is a long chip and some room is needed to get it out from the metal enclosure shielding the chips noise it generates. I removed the metal enclosure and swapped out the VIC chip with another. Still have blank screen.

Herman

Mike · Post by **Mike** » Sun May 05, 2013 12:54 pm

You could (have) use(d) IC extraction tools that can grip longer chips from both sides, and wiggle until the chip pops out.

As a rule of thumb, you should test a suspected defective chip in a functioning unit (i.e., VIC-20) - never the other way round. If there's something that killed your VIC in your non-working unit, it might quite as well kill your working VIC chip, and you'd just be off with *two* dead chips!

I somehow lost track over your help requests. Please could you summarize:

- how many VIC-20s you got, working/defective state and motherboard revision of each one (2-prong or DIN);

- what measuring equipment do you own (voltage, multimeter, scope, etc.);

- where you are located (it's also useful to include that information in your profile)?

HermanVIC · Post by **HermanVIC** » Mon May 06, 2013 6:51 am

I have three VICs. One is working through composite video. All use two prong power supply.

I have multimeter and frequency counter (100mhz max)

Pittsburgh PA USA

Mike · Post by **Mike** » Mon May 06, 2013 10:34 am

HermanVIC wrote:One is working through composite video.

O.K. I read about that one in another thread. At first, let's assume the modulator is at fault here, and concentrate on the two defective VIC-20s.

All use two prong power supply. I have multimeter [...]

I suppose the fuse is in order. With voltage measurement set to DC, when the power is switched on, do you get a voltage of about 5 Volts (plus/minus, say, 0.2 V) within a few tenths of seconds? If it's too high, the regulator is fried - switch off immediately before damaging other chips. If it's too low, there might be a short-circuit somewhere (but that would eventually blow the fuse).

Now, with the multimeter set to AC, what ripple do you measure? If it's too high (say, 0.4 V, or more) most probably the big stabilizing capacitor near to the regulator has too much ESR, and you should replace it.

Please take these two short measurements on both non-working VIC-20s and compare them against your working VIC-20, and post the results.

and frequency counter (100mhz max)

We'll come to that later.

HermanVIC · Post by **HermanVIC** » Mon May 06, 2013 1:03 pm

Hi Mike,

AC on the supply is around .4 volts on all three.
Power supply is 5vdc plus just a little on all three.

HermanVIC · Post by **HermanVIC** » Mon May 06, 2013 1:06 pm

Mike BTW
The working VIC is no longer working. I tried to fix it working in normal mode without extension card by replacing two RAM chips along with sockets. I read in another post he removed the sockets and soldered directly in and the VIC is now working. These are wicked little boxes when broken. ha ha

Herman

Mike · Post by **Mike** » Mon May 06, 2013 2:39 pm

HermanVIC wrote:AC on the supply is around .4 volts on all three.

Now that's definitely outside spec.

You should replace both C39 (4700 µF/16 V) and C44 (100 µF/16 V). As with all electrolytic capacitors, take care of their polarization. Then redo both DC and AC checks on the 5 V supply voltage.

HermanVIC · Post by **HermanVIC** » Tue May 07, 2013 11:08 am

VIC20 A
Blank Black screen with minimum configuration. Using a CART is the same. .001 AC across 4700 microfarad and 100 microfarad caps. I don't have enough caps for all three VICs. Will get more later. Using composite video to TV.

VIC20 B
There is a checker board pattern of random characters fill the screen in the std 3583 byte config. A CART will work and display properly. Using composite video to TV.

VIC20 C
Default minimum configuration 3583 bytes works.
CART works also. Using composite video to TV.

HermanVIC · Post by **HermanVIC** » Tue May 07, 2013 7:13 pm

I swapped out VIC20 A's VIC chip, the one in the metal enclosure with the VIC20 B's VIC chip. VIC20 B screen with random characters cleared up and now have a second working VIC20. The screen colors are a bit smeared even in composite mode.

So I need a VIC chip to put into VIC20 A.

Herman