No.117 - HP 3245A Universal Source Repair, Mods & Upgrades - Part 2
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- Опубликовано: 30 сен 2024
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In this 2nd video I replace the faulty VFD, fit a new front panel and carry out some initial stability tests comparing it to my other 3245A.
Part 1 - • No.113 - HP 3245A Univ...
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Run your slightly moist finger over the VFD connections, and if the missing row somewhere lights up you know where the fault is.
That is looking much better.
Hmm are you sure that Scotland will get a sunny day to whiten your button🙂
Hmmmmm....possibly!
@@IanScottJohnston could you try an ultra violet lamp or torch???
@@fredflintstone1I did try my UV torch (for gluing) but for the few minutes I tried it......nothing.
@@IanScottJohnston not sure about your neck of the woods but I'd try pool shops, they sometimes stock 25-30% peroxide in bulk cans.
That's a nice stack of HP goodness!
The unit is looking like brand new :) Really nice work!
Looks mint mate!
Nice to see the upgrades, curious how much did it cost overall for the unit and repairs ?
Broken units used to cost upwards of a few hundred US dollars and single channel ones functional in reasonable condition used to sell for close to $1000 USD but that's pre-pandemic. It's all crazy pricing now, unless you really need it I don't think it's worth that much.
Hi, can you provide the address of the website where you bought the VFD display ?
Ebay.
Nice lookin stack !...cheers.
Cheese!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Squeak !!!!!!!!!!!!!!!!!!!!!!!!! not much progress yet with the lamp!!@@fredflintstone1
@@andymouse Yes I suppose with winter coming on you will hibernate🙂
Lol ! yep but will poke my whiskers out if its not too cold ! I can't find anything to do with the chip (BP0A 106) so I'm going to take the MIC off and try a bit of reverse engineering squeak!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!@@fredflintstone1
RE VFD's it looks like HP has used (in a number of their instruments) an unregulated filament supply related to mains voltage. Even assuming the mains may be low, in many cases the VFD filament is overheated leading to a shorter life than what could have been. It should be possible to add some resistance to lower the filament voltage to hopefully further extend their life?
Quieter opamps in one, quieter reference in the other 🤣 I don't quite understand why not leave one alone and do all mods to the other, to then test the full difference?
Datasheet spec says (at 1V) 8ppm+15uV for ∓1℃ 24 hour, or 40ppm+31uV for ∓5℃ 90 day
31/5 = 6uV/℃, and your difference was that over 2℃, so still inside 50% of spec?
Bought at different times. The ADR1399 one is meant to be a quick fix upgrade for anyone to do marginal as it is. Plus it is aging well the length of time I have had it and its been on 24/7.
The new 3245A is a totally sacrificial unit for experimentation.
@@IanScottJohnston I would actually be really interested to know which mod has the most effect on noise
@@IanScottJohnston I've read that aged LM399AH would have a more stable performance, did you give that a try or compare against that ?
The sped up sound of that solder removing put me in mind of an Atari game I once played. Can't remember the name, but it was a space game (as most of mine were). Seeing the new display next to the others, looks good and bright!
I'm amazed that parts for these machines are still being manufactured. Making the VFDs is hard but at least shared with other models. Making moulds for the buttons though, there must be a lot of them out there to make it worth while.
I'm not a metrology expert but I am aware that local temperature gradients can cause significant problems. Perhaps you could experiment by removing two of the units from your 'lab' leaving everything else in it unchanged, then mix and repeat. Probably not an issue in your case, but might be interesting anyway.
I had gotten a couple of these from a surplus store that closed. One worked but the other was completely dead, so I used the two to make one. I still would like to do the Channel B mod.
Do you still have parts left over......I could use one of the coax cables that run to the front panel BNC's.....?
It's for a custom mod I want to make.
Sorry, just seeing this now.. @@IanScottJohnston.. I will have a look and see if I still have left overs. If I still have the cable, its yours andI still have the 2nd unit. I was gonna record the process I went through. One of the units was in kinda rough condition. I think the Universal Source is a pretty good unit for what it does. I've been focused on getting my 8662 going.
Got new camera? Video quality is nice, which setup is it? Looking forward for the long-term comparison with 1399 unit.
Panasonic HC-X1500E, and a couple of additional workbench lights so now 4off YN300AirII lights total on my gantry (2 either side).
I have always run Panasonic cameras and so went with the X1500E. This particular cam has a small sensor relatively speaking with it's competition.....so it likes a lot of light for best results. I spent quite a bit of time on this. The AF system is good, but the MF focus assist is GREAT!
I'm doing some tempco tests on this new 3245A and already have some benchmarks to work from. Plan now is to analyze and measure around the Vref/DAC etc and see where the releative instability lies. I know it's not the op-amps as I had already changed them. Maybe I'll end up with my own Vref circuit etc etc......who knows.....but it's great fun!
Do you have airconditioning in your lab to keep the temperature constant?
@@pa1wbu Yes, I have an aircon system that can heat, blow or cool. I am also running my own software to control it which allows me to get the hysterisis to around 0.3degC if I need to.....albeit it's usually switched off at night when I am not in a metrology mode!
Awesome. Nice fix it looks brand new.
Nice work
Nice fix
Hi!