Search results

A GQ-4x programmer will do everything you need for the PET, these are readily available on ebay and a good price. It is only when you shift to more vintage ROMs with additional power supply requirements like a 2708, that you have to shift to other programmers. A Bytesaver board works well for...

Generally a potentiometer has two outer connections on the far end of the track. The central connection is placed symmetrically between those two, called the "slider" or the "wiper" because it is connected to the the moving (rotating) arm that slides over the resistive track. The test simply...

I have examined the Joysticks in my Kraft unit. Interesting, they appeared to have moved to a sealed type quality potentiometer (see picture , probably a Bournes part) I would guess that the open frame type with the phenolic wafer became intermittent over time. In any case I was surprised to...

Apart from the size of the square holes and the Kraft hole pattern, how did we figure out the exact placement of all the holes on the front panel ?

Basically there are two universal Sinterglass diode replacements that you can use that are easy to get and work in practically every circuit where there is an unknown one requiring replacement, either in SMPS supplies, high or low voltage and in flyback supplies and H output stages in TV sets &...

I can't understand what this means. You will have to be much more specific with the descriptions of what you are observing for me to be able to help you, for example; when you "saw the signal jump from a partial screen to a full screen" what were you actually looking at ? was it the face of...

The local engraving store told me that the smallest cutter they can use is 1.5mm diameter which is about 0.06". Apparently any smaller than that they have a penchant for breaking. A while back they did a project for me, so I could make a replica enclosure for another project, there are pictures...

The exact value of the pots should not be a problem, in that they are strung across the zener regulated +10 and -12V power supply rail and their output voltage merely encodes the angle. Their output feeds into a high input impedance system, so it should make little/no difference what very the...

Yes, those 2x3 inch speakers would work fine. A pcb would be a little more tidy than the Tag strip they used. But it could be done just by adding another tag strip and leaving it mainly original.

Cool, can you attach those as a separate jpg image ?

I have been working the audio and speaker issues in my lab. Essentially there are three problems: 1) the original audio system was a fairly low level affair. 2) If we are building replica units, we need a larger supply of suitable speakers. The occasional 45 Ohm original type might turn up...

That is great. Ir would save 99.9% of the work getting it done, compared to by hand. Doing it with a routing tool though: the diameter of the small one is about 1.5mm (I think, or similar) So, unlike a square punch, it is not possible to get a perfectly rectangular hole corner. This is where...

I was going to suggest those too ! A great product. The stickers you can make from it normally adhere well and are durable.

I'm not sure that it is "TTL". I have only just seen a version of the schematic I can read (Thanks for that link) . It looks to me so far that the audio signal is derived from the output of the DAC and passed via CMOS selectors that are not digital, in the sense that they act like analog...

But, it might pay to consider that if you are on the edge of a spec, there will be some specimens of the same type number IC which will work, and some that will not. The only way you would know would be if the person on 6502.org sent you his chip and you tried it in your setup, whether it was...

Can you post a video of the "wobble" you are seeing on the screen, it might give a clue as to where the problem is originating.

I think what we should do with the audio and speaker issue for the replicas: Since there is a tag strip assembly there, we simply add another identical one beside it. There is room. It will carry the components for the class-B amplifier and we will make it with the period correct transistors. I...

I could email the switch seller and ask him to change that listing to 16 switches and explain that you would be getting them ?

Could you post the scope recording of the video signal that the VDU is receiving at its input, and the schematic of the VDU ? It is usually fairly easy to work out why the screen is blank. Generally, a normal looking video signal at the video output connector, or the input to the VDU, would...

That does seem a lot better, maybe I could buy 8 switches and 8 of the keycaps through you somehow and have them shipped for some more than that, could that work ?