@@zombunzedb960 Yes unfortunately there is very little information on these specific power supply units. If you need to repair one, its going to require you to get back into the very basics of electronic troubleshooting. Follow the circuits, understand their layout and function, and then locate the fault. This is further complicated by the fact that the whole unit is AC mains powered and unisolated, as SMPS are. It’s imperative that anyone undertaking this type of repair knows the risks and knows how to do the work safely so as to avoid serious personal injury or death.

@@jmacedo7 That is a valid point. Certainly the transistor should be evaluated for repair. In my case I did not replace it because when I made the video I was still very new to working with SMD components. So, to avoid potentially damaging the fluke further I opted for a less invasive repair. I would say to anyone who’s doing repair work like this, that you should always evaluate your abilities and make decisions based on what you need to do and what you can do. There’s a lot of learning to be had anytime you undertake a repair, but realize that sometimes those lessons are expensive! Now, a few years later I have become much more practiced in SMD work. I would not hesitate to undertake such a repair. So yes, replacing the transistor would be a good preventative measure.

@@Rory-jk9us I will post it to this video if I can figure out a way to get a copy from you. I’m not sure if KZbin has a private message system. I’m not keen on posting my email address here and I’m sure you aren’t as well.

@@FreeElectron Well I can post my snail mail address which I am not worried about being available. If you mail me your postal address I can mail you the schematics which consist of four11 by 17 sheets. The PDF I have was created at a fedx store from the paper copy. Rory Boyce 8554 Lafitte Ct. Fair Oaks, CA 95628. The mail address may end up blocked but I can try sending it.

@@FreeElectron Well I tried posting my snail mail address here but that got removed. I do not care if my postal address is available on line but it seems that is against the rules.

Thanks for the comment. My only guess is that they were looking for ways to reduce cost in production. A failed backlight, while inconvenient, doesn’t render the instrument useless. That’s the trade off.

Removing the fundamental allows me to look at the smaller level harmonics without overloading the front end of the spectrum analyzer. The “down ranging”. On the lower ranges (the more sensitive input levels) the high power of the fundamental will overload the front end of the analyzer. Best case it will cause distortion in the analyzer and a false reading. Worst case it can damage the front end. Also, when you’re taking a harmonic distortion reading you’re measuring the power levels of the harmonics, you don’t include the power of the fundamental. When I use the RMS meter to sum the harmonic levels, I don’t want to add the power of the fundamental. Great question and thanks for the comment.

For signals with high harmonic content you could ignore the fundamental if you’re using a spectrum analyzer. If you’re looking at lower harmonic content, say below about 60 db, you really need to remove the fundamental as most spectrum analyzers will not have the dynamic range needed for very accurate readings. My 3585B tops out at around 70-80db before I have to null the fundamental. Big thing though is over driving the front end.

@@FreeElectron Thanks for the reply! I understand, and I can now see how you are showing that in your video.

@@krandall5285 Thanks for the comment. Yeah the time lapse was kind of different, I just happened on a long build session. Most of my projects stretch over months though with work and family. I’ll definitely try to keep it in mind for a future build.

@@krandall5285 Cutting the board is a bad idea. Sometimes I think out loud going through the options. Thanks for the comment.

@@douro20 Thanks for the information. It’s great to be able to admire the build of this equipment. For me part of the enjoyment in using the older HP gear is knowing a bit of what’s actually happening under the hood and how it all goes together.

I'm glad you enjoyed the series. Thanks for the comment.

I’d say the switches are probably the most expensive. Depends on what you can find or have lying around. I sourced them from eBay so it’s really variable on cost. Components are from Mouser or what I had on hand. I think maybe total cost for me was around 50-75 USD.

@@FreeElectron Thanks! That's not bad.

Thanks for the comment! The 334A is a very capable unit. Even though it lacks auto set level, once you get the knack of making a measurement it isn’t so bad. Not being able to read dB and % distortion at the same time is inconvenient sometimes for me.

Thanks for the comment! Check out my latest series on the HP8595E calibration constants if you want to see me put this sweeper into action.

Yes the auto tune is definitely a nice feature. Manual tuning on the 334A is very finicky. Since this video I’ve acquired an HP339A which has a much lower measurement floor and low distortion source. I’m also in the final stages of building my own measurement set via Robert Cordell’s very capable design in Audio Magazine. I’ll be doing a series on this build hopefully soon. Thanks for the comment.

I’m sorry to hear that that. Sometimes it can’t be helped but I do try and use the tripod when I can. Thanks for the comment.

Very interesting video. My HP 8595E doesn't work properly. I can see a problem with PSU. Your documentation would be very helpful for me. Could you help me, please? Mark

Hello. Thanks for the comment. I do intend to make the documents available. I’m in the process of getting them made into a single pdf. Once that’s done I will have them available on the channel.

Thank's a lot, it is very kind to make this document available. Like the hamradio I sent you all my 73's ON1EV@@FreeElectron

The IF test board is very simplistic. All you really need to reproduce it is a PC board with the correct card edge and a couple of 100 ohm (iirc) resistors. Thanks for the comment.

Yeah funny thing about doing instrument cals outside of a certified cal lab, it’s all relative. Thanks for the comment.

good luck with that

Height must be 12mm. or less.