Hello, I read all the posts I could find on replacing or rebuilding the high voltage transformer for the 576. So far I have found two options. Chuck Harris (I am not sure if he ever updated his

Hello, I read all the posts I could find on replacing or rebuilding the high voltage transformer for the 576. So far I have found two options. Chuck Harris (I am not sure if he ever updated his

Hello, I read all the posts I could find on replacing or rebuilding the high voltage transformer for the 576. So far I have found two options. Chuck Harris (I am not sure if he ever updated his

It's effectively the same as a coaxial cable where the energy is passed from one capacitor to the next through the inductor. Pure inductance and capacitance doesn't loose energy so the signal is

I should still have a pile of Commodore 4023 IEEE-488 printers in storage. I had a lot of the early Commodore PET systems in storage when I got sick, and lost my rental warehouse. :(

You can build Jim Williams Pulse generator as described in Linear Technologies Application note 47 on page 96. There is a long discussion about the fast pulse generator topic on the

The first "computer" I bought was a Commodore VIC-20, but by the time that came out, my friends and I had top of the line Commodore CBM systems, mostly 8032's, that we built from scrap out of the

Don: Ah, so they were just LC filters, and used the phase shift for delaying? I wonder if such a 3M dropout compensator could be modified to be used with an analog scope? What do you think? Cheers, D.

I was able to calibrate some parts of the DMM : DCV, ACV, HI OHMS, and LO Ohms. I don't have equipment to generate more than 15VAC so I'm stuck there. Does anybody from the group live in Arizona and

What I call lumped (artificial) delay lines are delays made of a number of discrete inductors in series with capacitors to ground (or the complimentary side) rather than a cable using its

The answer is YES, you are confused, you've just typed the same number twice again. But why should you be any different to the rest of us ;) . Main problem is the original version

Many many messages in the group archive that address repair of the power supply. The PS is cycling. Replace all electrolytic caps then see what symptoms remain. Good luck, Dave Sent from my

The 2N3906 transistors will be too slow and have too much input capacitance which may affect the bandwidth and transient response but you may not even notice without a good test

You are a genius! I just happen to have a 2N3906 in my junk box... I now have two rock steady traces! Thank You! I will track down the proper replacement but for now it looks like this will get me

I looked the transistors up earlier. Q1746 and Q1954 have an Ft of 900 MHz, Ccb of 3 pf, and are similar to a 2N4258 or PN4258. Any PNP RF transistor like an MPSH81 should work but you can

Hi Tom, I checked the transistor with a DMM on diode (which I think I read in the tek manual you shouldn't do... oops) and an analogue meter and I cannot get any sign of life at all. I think all the

Recheck the voltages on Q1746. E-B-C . If you really have +15.02 onthe emitter and +8.92 on the base, that transistor has an open B-Ejunction. Tom

My favorite was the Commodore 64, SX64, 128 & 128D computers, and I did a lot of writing with a freeware program called Speedscript.

I checked those transistors as you requested... here is a link to the schematic with my voltages: 465 schematic 2 Q1845 is showing +15.02 at the base not +9.5. I tried swapping Q1845 with Q1045