Hello ts1000user
Welcome to the world of the ZX81 and TS1000
And Welcome to our forum
Your English is fine. So please don't worry about that. There are members here from other countries, where their first language is also not English, so even if your word useage is slightly different, we are still likely to understand you.
The Sinclair ZX81 and the Timex TS1000 are very similar. Sinclair made a USA model of the ZX81, which were very much like the TS1000. The main difference are to do with the different TV standards and the need for a RF shield to comply with the regulations in the USA.
As you may know, the USA versions can output a TV signal on one of two diffent TV channels (frequencies), VHF channel 2 or channel 3. The USA uses a 525 line, 60Hz TV system.
In the U.K. the TV system was a 625 line 50Hz standard. UHF TV channel 36 was not used for broadcast television. So most computer manufacturers used this channel. Hence we don't have a channel selection switch. ZX81s exported to Europe (except France) also used UHF channel 36 on a 625 line 50Hz standard. Because the French used a different TV standard, these had different video circuitry.
ts1000user wrote: ↑Sat May 27, 2017 7:48 amCan the socketed chips be easily pulled out just by pull them out with hand? I'm scared of break the chips.
No, not just by hand. There is a "trick" to it. The chips are held very firmly (tight) in their socket. So it takes some force to remove them. If you see or come across a IC (integrated circuit) or chip removal tool - do not buy or try to use such a tool. It will get a chip out of a socket, but it will also bend a lot of the legs (pins) on the chip.
Instead, we gently and gradually ease the chip out of the socket a bit at a time. Use either a normal table knife (a blunt table knife with a rounded end) or a small/medium normal slotted screwdriver. Working alternatively from each end, insert the blade of the knife or screwdriver in the small gap between the plastic case of the chip and the plastic of the socket. Don't push in too far, or you may damage the PCB under the chip (some sockets have large holes in the bottom). With a screwdriver, you only need to go in about 4 to 5mm. Then use the knife or screwdriver up in a lever type action to lift the chip about 1mm up from the socket. Then do the same at the other end. With a screwdriver, you can also twist it slightly to help lift the chip. Keep a finger or thumb resting on top of the middle of the chip, just in case it suddenly comes free unexpectedly. At first, the chip may "seesaw" but keep working from each end, each time raising it a bit further. Eventually the pins at one end will leave the socket, then be careful as you free the other end. When all pins are free, you can lift if off with your hand with no force and no bent pins
Also have a read of the description at this
link. I can't find a good video showing this method:-(
Although the ULA chip is fairly hardy, take basic electro static discharge (ESD) precautions. Don't wear clothes made with man made fibres. Touch an earthed (grounded) metal item such as a cold water tap on a sink unit, or the metal case of an electrical item that is earthed/grounded each time before you handle a chip. If your environment if dry, you may want to use a ESD wrist strap (no need to keep touching an earthed/grounded item then) and
/or a ESD bench work mat. Also try not to touch the pins of the chip - hold it on the plastic case at the ends.
The pins on these chips (called DIL for dual in line) are splayed / sprung out. So it the pins may not line up with the holes in the socket when you go to refit it. Grab a plain sheet of paper and put it on top of a magazine, which in turn goes on top of your bench or worktop. This is to protect your worktop. Hold the chip horizontal between a finger and thumb at each end in using both hands so that one row of pins are near the paper on the worktop and the other row are upon the air furthest from the worktop. Push the pins at the bottom on to the paper and gently rock the chip backwards and forwards so that you bend the pins until they are at a 90 degree angle to the plastic case. Repeat for the other row of pins. You should find that it is now much easier to refit the chip in the socket. But still be very careful and check that all the pins go in the holes in th socket. If one does not go in the hole properly, the pin will bend and there is a very real risk that it may break off when you try to straighten it.
More later...
Mark
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