Right Dave. There is enough room to scope the regulator board on top while the PSU is hanging out the back of the mainframe. wrote:

Bob, I found that the diodes seem OK when I disconnected one lead and measured both resistance and diode forward and reverse voltage. I found that the short across those two diodes was due to a

I forgot to mention that you don't actually need to build a load board to work on a 7904 power supply. The cables are long enough that you can let the PS module trail out the back of the scope onto

There was nothing uploaded, it was a short and sweet message: I used 4 ohms on both 5V, 20 on both 15V, and 500 on both 50V. It is not critical, you could probably get by with only 2 ohms on

Hi SImone, What you are describing is right way to use the copy program. It doesn't matter which program "ramhigh.dat" or "ramlow.dat" is run first since they copy independently the upper half and

ciao mirco what programmer do you use for nvram? I'm not very experienced with the programming I'm waiting for all the components to arrive then I will try with the method tested by adas which I

Ciao Das Thanks for your help now I get everything I need and I go with the procedure that you have tested, in the next few days I communicate the results. Ciao Mirco

They say in the article that a low resistance indicates a problem in the mainframe which is true if you are looking at something shorting to ground.  But, in your case I would not discount that high

Hello Lukus, See some answers next to your questions... Indeed it's a weird waveform. Did you try to change the sweep speeds (Time/Div), and or the input attenuator (Volts/Div) settings? Does that

Sometimes the cans can be a tight fit on the chassis. This can be aggravated by any dents, dings, grit, or corrosion that can make the Al surfaces gall and bind up. Once you are sure all the fasteners

The calibration data can be dumped via GPIB, at least on the 2445/2465 and 2445A/2465A. It's not been confirmed it can be done on the 2465B, but I suspect it would work on that too. I'm not aware of

Hi Max, I was looking at the cross-connecting pins from the side and not from the bottom, and misinterpreted the connection. I have been working on replacing or rebuilding the fan on my 453, and

You don’t mention the screw on the side, but you do mention two screws being removed after the back cover was off. I think there are only those two ,the side and bottom screws but I’m not at home

All the resistances with the PSU disconnected from the mainframe are way higher than those indicated in the "Servicing the 7904 High-efficiency PS" doc. When I fix the issues that I have found and the

Yes the resistances were very high. According to that doc, the issue should be on the PSU. I'm going to put the PSU back into the mainframe, connect the cables, and make those voltage measurements on

> hi adas thank you very much for your information I think this method of copying is the fastest and most brilliant of all the methods described I bought the material from digikey and I'm waiting

I have removed the cover from many 22xx Teks over the years but this one has me stumped. I've removed the back plastic and the two ( top and bottom ) small screws and the cover is still locked on

There have nothing about minimum load, but in the "Servicing the 7904 High-efficiency PS" have the resistance for all of power rails. You can to calculate the load but, need to make some for all of

Have you checked resistances as suggested in the Service Scope article? And then voltages with the supply outside the scope but still connected? Bob.

Hey Tom, glad you have this under control, and so much for my speculation :). I see from TekWiki that the DSA600 debuted in 1990, while the 500MHz TDS500s were introduced in 1993, and perhaps around