开云体育

I just received a 7704 and several of the card edge connectors on the main interface board have their left and right (or A and B?) covers falling off. They are not completely disintegrated yet, though

Is it this gadget? https://www.velleman.eu/downloads/0/infosheets/datasheet_edu06-uk.pdf It requires an AC input, 9V to 12V. Is it possible that you have attached a DC source?

Jeff, the assumption of a disconnect inside the CRT is likely true. Varying the mesh voltage has a visisble effect on ghosting indeed, some Volt up or down make a significant difference when the CRT

Do you have an instruction book for it? There is some information on the web. I did not search for a free instruction book but its worth your doing so. ?? Have you much experience using a scope?

Hi I solved the issue. I was not the U2890. I was a broken trace underneath U2965- probably a result of the leaky capacitor and at that time for repair I did not notice the broken trace because it was

Hi I solved the issue. I was not the U2890. I was a broken trace underneath U2965- probably a result of the leaky capacitor and at that time for repair I did not notice the broken trace because it was

----- For horizontal shift Mark's reply is most likely. If it doesn't fix the shift confirm that you see 0V at connector CJ of sheet <10> with Ext Horiz grounded, and Ext Horiz mode selected.

Mike, Which resistor did the lead come out of? As for replacing or new build, I use 1% Xicon 1/2w. I have found that the Chinese sellers on "that auction" site have excellent 1-5W 1% types and are of

A CRT expert I spoke to today said the "can" behind the mesh is more positive than the mesh and attracts and collects the secondary electrons. There is an electrode on the CRT symbol labeled

While you're at it, you should also verify Vcc to the processor, pins 8 and 35, if you haven't already done so. Use a scope when checking power and ground pins to make sure there's nothing weird

That certainly explains why I have not seen the ghost/reflection on my 475s, all of which are later production, but my 485 is from 1980 (based on the date codes on some ICs) which is even later than

After checking through most of the circuit involved with the Ext Horiz function, and finding the signal going through all the way to Q824, and still no trace, I figured out what was wrong. After

This attitude is a good way to get kicked off of the list, in my opinion. It's not respectful dialogue, just saying. Ross

The "ghost" image is caused by secondary emission from the mesh. Some changes were made to later CRT's to reduce the effect. -- Bob Haas

Can you direct me to a web site describing this tutor device? The first place to start is with a description of the signal. The next is to determine your expectations.

And here you are AGAIN. Don't like it, don't read it. How is your last post not spamming the list? LOL

VMA is not a tri-state output, so it should never be floating. And it is quite strange you are seeing a strong input clock signal (5MHz) on VMA. The XTAL input is indeed floating on my 2465 too, but

Rick, My first inclination is that your outside signal source is not working. Can you give us some sort of feeling for what type of signal that this device produces? This is a 100Mhz scope, so I

Mark - jeez, that sounds perilous, huh? Mega high voltage in there?

Actually no, I haven't checked the voltage of the generator, but there is a light that says that it's "on".