I'll try the emitter resistors, but there are so many cases of U400 failure that I suspect it is going to be that. Which sucks. A lot.

Vertical nonlinearity on Ch1 and Ch2 but not on Ch3 and Ch4 is typical of a fault in U400. The other symptoms are new to me but I am sure someone here will offer some insight. It would be worth

Got it. Resistors and caps are on order, there are some of the black beauty and bumblebee caps in the unit, I ordered replacements for all of them in the power supply. There will be some delays since

RAMS asked me to post this message. RAMS store will be reopening on Thursday, October 21st, 2021. The days and hours will be as they were before, first and third Thursday each month, 2-4pm for the

I have a 2445B that has gone a bit odd recently. Ch2 and to a lesser extent CH1 have developed vertical non-linearity. Put a sine wave through it and it is obvious, a sort ot cross-over distortion

What would be a sufficient speed? Not knowing the thermal characteristics of a running 492, nor the requirements, I chose to use: * a fan with the highest flow I could find in that size * fiddled

I might just run the new fan continously at a reduced speed to keep it quiet . It's not going to run outside in the sun. Better would be to make a tiny board using a LM35 temp sensor and a LM358

The plugin has several faults. It doesn't count by 1's and I think that's due to the LSB being stuck high. RESET causes it to display a 0001 instead of 0000 for, I presume, the same reason. GATE

BTW, does anyone know why a specially-designed IC was needed? I presume it was to meet the frequency specification but I don't know. Thanks, Barry - N4BUQ

Or find the data on the 7D14 upgrade, and get another 7D14, then use the "bad" one for a source of parts.  Now you know what to look for, and I have to go see if I have any..... Harvey

Thanks for that info, Håkan. Looks like I have yet another doorstop. :( I'm going to need more doors... Thanks, Barry - N4BUQ

Update, I ordered a new 2.5k trimmer cap and temporarily soldered it to the top of the remnants of the original trimmer R4275. With a jumper in place of Q4475, I now have horizontal trace. Next need

I used a small DC fan that fitted into the same foam rubber mounts as the original fan, thus minimising vibrations. I created a crude circuit that used a thermistor to sense the temperature, and an

I was reading the 49x notes doc as I have a dying fan. I have found a good 30cfm fan , 24v, but no temperature speed control. How hard would it be to take the existing 3 phase fan output and filter

I don't see how to PM you.  I am at bob91343@.... Bob K6DDX

Hi Group - I have a Tek 577 D1 for sale in the Los Angeles Area......91602 to be more exact. I got this at auction and repaired the +12V/5v power supply section. I was going to make it into a vacuum

In the early 7D14's U329 was a Tek made IC, 155-0046-00. That became obsolete and from B050000 156-0377-00, MC12090P, was used instead on a redesigned circuit board. The new IC was not a direct

Sorry, I was referring to Archive.org. Wasn’t sure if it was ok to post software links here, but here we go: https://archive.org/details/TEK_WSTR31U_V1.2.2 Enjoy =D

Which archive? KO4BB's site?     A link would have been helpful... -- Bruce Lane, ARS KC7GR kyrrin@... "Quando Omni Flunkus Moritati" (Red Green)

I'm in the process of troubleshooting my 7D14. As I received it, it will only count in free-run mode and gate operations do not work. While troubleshooting, I found that U329 doesn't appear to be