我可以找到很多这个配件

The power supply capacitor (100uF) in my unit has been replaced and the meter lives again! Thanks!! I found the service manual on the Internet, but it doesn't have the waveforms. Do you have a link to a manual that does?

Nice presentation, what camera are you using ?

Can you not run dynamic drive overlay software so the drives show up?

Thanks so much for the videos on the repair of the 432 power meter. Mine had the same symptoms as yours. I was just getting ready to check my power supply voltages just before watching your video. I found my 100 uF capacitor was bad, just as yours was! I have one on order, but I think I have a pretty good handle on it thanks to your video!!

I have one of these meters and when I turn it on, it pegs the meter in the negative direction and the Coarse Zero does not adjust it up any. Ideas anyone?

Thank you very much for this video it's helping me out a bunch

What exactly is the problem?, no commentary no nothing?

Hi, there are still several things not right.. zero can not be "calibrated", there is probably an issue with the amplifier circuit, you need to check the waveforms and the supply voltages acc. to the manual. In my 845AR, I had to replace two electrolytics, which were dried out. The needle should be much more stable in the 10µV range, even in 1µV, my unit shows much less noise (ok, the damping time constant is much higher there). I just checked: in the 10µV range, the needled slowly wanders +/- 2 divisons, or +/-400nV, in the 3µV and 1µV ranges it's as well +/- 2 divisions, i.e. about +/- 50nV Have you checked the neon bulbs, whether they fire in the dark? If these new ones show the dark effect, then the noise is related to misfiring. We had a detailed discussion on eevblog, identifying possible root causes.

Did you see my last 845AB video, just did the battery really and tested the power supply voltage etc, might be of help to check yours.

Don’t take the 155 degrees “rating” at the face value! What it tells is the INTERNAL hot spot temperature. There is a big difference between the internal and measurable - outside -- temperature. Depending on the heat sinking, it can be several tens of degrees.

I have so much now

😊

I have the HP 5350B version of this and the 5343A as well, all great counters.

I could not locate these fluorescent tubes since these contain Hg and are not longer in production. What I did is purchase a 15 inch LED strip and driver for LCD TV repair from Amazon. I used the +12V input pins on the High Voltage board to power the LED Driver. To hold the LED strip in a 3-D printer was used to make a part which held the LEDs in place inside the metal rail. The LED strips can be trimmed to lenght.The result was a brighter LCD screen on my LA.

thanks

good video! I have many of these relics running in several labs that are used for FPGA emulation. These LA frames now cost a fortune and have fewer I/Os to boot!

Leakage probe is just a 135K ohm resistor (1%), with a shorting bypass pushbutton switch. Can be easily built by almost anyone. Two 270K resistors make 135K. Use the carbon film types, to make sure they are good for 200+volt breakdown. Some chip resistors are not rated for high voltages. PassItOn.

Best thumbnail ever.

+/- 1 uV - its normal (in specs)

quite noisy. looking forward to repair of chopper Neons.

🙂👍

Stepbro, your needle is perfectly centred on zero.

My 432a is acting similarly...your lecture has shown me that the power rails are key to making sense of the issue..not a guess.. I will start there and follow your path...Thanks KA3TXR

Might want to check the memory backup batteries in these units. Consist of 2 AA Nicads if I remember. I have two for these units myself. Also have had tag tantalums go s/c.

Hello, I have an HP 8901B modulation analyzer, it works well up to 600 MHz and up there it doesn't work anymore, as if it were the doubler. Have you seen any failure like this. thank you

Resolved ! .... For use the MGS-71018 ,you must inverted the signal from U26...the MGS relay work with inverted polarisation.....73's ....I5UWU Paolo

I've just purchased an RMS volt meter in the same series. (HP400E)

I mean... thnx for the vid... and the work... but, to me.... an IMO... this seems like to most convoluted way to determine the max power of the S.G., over it's range. Well... maybe, I could think of a harder way.

I can't tell from the vid what S.A. tgsoapbox has (is it a 8563E?) ... if so it has a DANL of about -120 dBM ... a huge dymanic range.

🙂👍

Thank you

My graduation work has graphs produced by one of these plotters. The sound brings back memories 😀

Very nice! Right out of high school, I took a summer grunt job before college. The owner of the company brought his new dual-floppy IBM 5150 and HP 7475 plotter in to see if I could make it do something useful. Thus began my career! Eventually, he got me a 7550A. A lot of what those plotters did was driven by software I wrote. I like to think that my work with those machines and other things that followed were a not-insignificant contribution to the company's rapid growth and eventual domination of the industry (from a small father/son operation). I never did make it to college! 7550A (and also 7475) are very near and dear to me. I wish I had room for one now.

Fajne :)

Lovely old tech

got the same beast a few months ago, sadly only have the A4 paper tray, but it's feeding fine. missing the catch tray too so it flings the finished plot across the room :)

You held me. 8902a measurement frequence indicator - - - -. You advice me? Thank you

Hello. I have an 8902A that somehow can't measure frequencies from 70 MHz to 156 MHz. Can you give advice? Thank you

Actually, the connectors on the digital I/O boards are not custom parts. They are standard DIN41612 connectors. In this case the 96 pin ABC variant (rows A, B and C are populated with pins). All sorts of variants exist, like 64 pin AC in the same plastic shroud, but also shorter ones with less pins, as this HP has on its backplane. Really nice and reliable connectors. Often found in (mostly European I suppose) industrial control systems, T&M stuff. And in VMEbus computers. cheers, Wilko

Where is this dumpster ?? I can move in there 😂😂

🙂👍

The thumbscrews on the coax-based cards screw into the switch controller in the same way that the other cards' (the "non-coax" ones, so to speak) wiring harnesses screw into the unit. IOW, all the cards eventually have something that screws into the back of the 3499 (or 3488).

In addition to feedback loop's suggestion, I would also check the ripple on the power rails. The + 12 V rail is a bit suspect. Regards, David

it's the membrane keypad and the only solution is to replace it. been there done that several times. was never successful in repairing that keypad membrane.

disconnect the keypad altogether before you try bridging contacts on the board

I have the HP 5350B, never really noticed what type of fuse it requires but nice to know that not all of the HP gear require fast blow fuses.

@4:00 the TD notation means Time Delay, or slow blow.

Aaaahh.... The 'ol exploding flux pen trick! Who knew tgsoapbox was a comedy channel :) Never seen that happen before but you gotta' admit it was funny. Nice methodical troubleshooting work TG, looking forward to your next one.

Special Louis Rossmann edition flux pen