Re: Help with a Tek 7A26
Just some things I'd think about. If the gain is the same for both channels, then either both channels have the same problem, or the problem is after where the switching happens (or may be something in the switching).toggle quoted messageShow quoted text
I'd put a standard signal into one channel, go for one channel only. I'd look for the signal that Tektronix shows as a reference input. Tek ought to show you the voltage readings (DC and AC) for a particular input value.
As an example, say that at a particular point you're supposed to see 10 volts p-p with the gain controls setup a particular way and with a specific input. If you see 6.6 volts p/p, then I'd suspect the gain of the stage immediately before. If there's an overall gain, I'd look at those parts specifically after you see if you can narrow down where the gain goes wonky.
I'd also look to see if the positioning controls have the proper range, although you can get much the same result with DC inputs or AC inputs.
In this case, I'd take one channel, follow it through from the beginning to the switching and then to the end. While I suspect that the gain is bad somewhere after the switching, I'd still run a test to see if it's where it's ok. You can run a divide by test, where you pick halfway through the chain (approximately) and then check the gain. If it's ok, then after that point, if not, then before. Continue to divide by 2 until you get to one, then play one stage at a time.
On 2/6/2020 5:32 PM, k6whp wrote:
Gentlemen (and ladies),