EEVblog 1664 - REPAIR with Junk Bin Parts! Keithley 2302

[@EEVblog]

D'oh, I just noticed the actual part number on the small label on top of the chip! So I went down a bit of a rabbit hole searchign for the silkscreen part number instead.

[@pvim]

Dave are you gonna do a teardown on that Siglent SDS824X HD?

[@ChrisJackson-js8rd]

frankly - a pretty accurate simulation of a battery after 7 years in the bunker nice save :)

[@IanScottJohnston]

I repaired my Keithley 2306 which had same VFD fault. Itron sell new replacements, new generation ones and luckily they have an office in the UK. See my part 2 video.

[@EEVblog]

Shame that doesn't show up on searches for the part number. Looks like the CU16025-UW2J fits, 15 in stock. No price though, you have to get a quote.

[@darrenmurphy6251]

youve assumed loss of vacuum (but getter was not white) or cathode poisoning, but theres a negative bias voltage applied to the heater wires (-17v or more) thats usually dc to dc convertor derrived (same circuit as ac filament drive) dried out high esr filter caps here are very common , tip from an ex hifi / vcr repair tech

[@zaprodk]

5:42 The getter is nice and shiny, there is absolutely no problem with the vacuum in that display. My bet is bad electrolytic caps.

[@aleksadjokic4115]

Getter is almost never the problem, cathode poisoning however, is. There is a rejuvenation option, heating the filament to a point it will outgas and restore the oxide layer, but this is based on luck...

[@TheSadButMadLad]

Am I sad for remembering the original video. 7 years ago?! How time flies.

[@oOMonkeyMagicOo]

Dave you should know, Murphy never sleeps!

[@CoolerQ]

The new part number is on a sticker on the original VFD! I was screaming at the screen, Dave :)

[@andymouse]

Yeah very frustrating !

[@EEVblog]

Just notice this myself and posted a pinned comment just before reading this. Was not easy to read with the aging Mk1 eyeball.

[@JoeMuc2008]

I felt relieved when you attempted a junk bin display because practically all LCDs with a parallell interface follow the HD44780 protocol so there is no need to buy anything extra expensive just because it is closer to the original specification. In turn you can use basically just any LCD, thanks to Keithley being nice and not using anything proprietary. Good thing you found out!

[@piratk]

If it had been a polarizer problem, just adding a third in the middle would give you some display. Light is fun that way, your can have multiple levels of 45° rotation.

[@kg790]

Nice light-hack

[@KeritechElectronics]

Might not be as lovely as the original, but it works and that's what counts! Nice fix.

[@TechSB3037]

The VFD is probably fine with a black getter. THere is a sticker in the HV generation section .Perhaps the sticker glue has turned conductive and is messing up the VFD voltages.

[@EEVblog]

Possible, might have a look.

[@AnnaVannieuwenhuyse]

Honestly... For the price and saving you the hassle, the hakko sucker isnt that bad! Your vfd is fine on vacuum. The getter, the black stain in the corner, is still black; an oxygenated one turns white

[@AnnaVannieuwenhuyse]

The serial interface on the original is usually omitted on modern displays because you can use the modern ones in half bus width (4pin) mode. The serial was hardly used, so it went to contrast settings as a backwards compatibility feature. 😄

[@gorak9000]

probably just the electrolytics in the boost converter went high esr - but how you gonna babble about that for 26 minutes??

[@AnnaVannieuwenhuyse]

@@gorak9000 just all the same. Dave is well capable of that. :)

[@dougobrien2840]

Good repair equipment saved.

[@randall39]

Don’t you love it when you find something that you can use out of your extra parts. I repaired a laser level that got the polarity reversed (no protection) and blew the ass out of one of the chips. I was able to bypass some of the features with a simpler board I had in my spare parts boxes. 😊

[@cremvustila]

Lol, Murphy woke up after all... sometimes you just can't win!

[@QsTechService1]

That’s a winner, chicken dinner looks pretty good I like those this I keep a stockpile of them never know when you’re going to need one nice repair

[@DrFiero]

I'd like to see more 'stuff' on resurrecting VFD's in general. I do pretty much all automotive things, many of which use very (!) custom VFD's for things like the HVAC display that just don't have any other options. I've pondered making a complete LCD replacement, but that's way down the road, and I may not live long enough to complete that project.

[@dine9093]

usually you need to provide the current limiting resistor to the backlight of LCDs

[@EEVblog]

It's built onto the board, 100R

[@ronaldknor]

I've managed to revive a very dim VFD by glowing the wires (what are they called?) red hot for at least a minute. Worked a treat after that. Worth a try.

[@darrenmurphy6251]

if you can increase the drive a little itll last longer , theres often a series cold start current limiting resistor , its a cathode piosoning issue, the heater wires are also the cathode , i realised that when i tried to run a vfd with a dc heater supply ! cathode piosoning is bane of my life with my huge 1n18 nixie clock i have to excercise the tubes every year or so with increased drive current

[@EEVblog]

If you are desperate enough

[@MarianKeller]

@@darrenmurphy6251 Yea, bloody cathodes...

[@TrevorsBench]

This isn't a worn out VFD tube from years of use. It's been sitting for 7 years not turned on. Something else is the culprit here

[@electrodacus]

I will not bother with the florescent display. LCD will just last way longer. Maybe get a blue backlight one if that filter in front is designed for blue.

[@EEVblog]

The green is ok, still quite readable.

[@BobCat0]

@@EEVblog The filter might be painted on or is glued on and removable with a solvent or some heat. I would just cut it out and hot glue the LCD in.

[@realshaoran4514]

Murphy just waked up at the precise moment 😆

[@necessaryevil8615]

I knew about VFD's with HHD44780 interface, but I didn't expect to find one in equipment. Very nice to see an universal component being used. Universal components have a better availability, their lower cost ensure a feasible repair.

[@nonsuch]

That's the worst. When you have a piece of gear you haven't used in a long time, pull it out because you need it, and it just broke on the shelf. I swear if you would have left it on since the last time you used it it would be working. Gear really hates to sit around not being used. It's like all the electrons evaporate or something. It happens to me too often.

[@padmanabhaprasannasimha5385]

The electrons all fall out because they're upside down in 'stralia.

[@nonsuch]

@@padmanabhaprasannasimha5385 They fall out in 'Murica as well.

[@flipschwipp6572]

Solder sucking: I totally stopped soulder sucking in plated through boards. Now I use a wide tip (t12-14xx or a thick solid copper wire), fresh solder and melt the whole row and pull out without any effort. No ripped pads anymore. Yesterday I did a IGBT module with close to 50 pins that way. Now i think about developing a slotted copper block as desoldering helper as a product.

[@AnnaVannieuwenhuyse]

I likewise do like using a t12-d52

[@BobCat0]

Use a 1mm bare copper wire across the row, lots of leaded solder, the whole row melts and the part falls out.

[@Mr.Leeroy]

there is a low temp solder for this kind of work, just flood it all over at like 200C on iron tip

[@LutzSchafer]

These cheapo LCDs also come in blue white and black white.$2 delivered. These ones are inverted so the characters are bright. I bet that looks better than VFD perhaps even brighter.

[@CrypticWritings89]

Nice job Dave, if it works, it works! Like you, I hoard old parts and accessories as spare, sooner or later you'll find you might need one.

[@gonzo_the_great1675]

If the vac failed, I would expect the silver spot on the side to go white. Same as used to happen with vacuum valves (tubes). That silver coating on the glass is from the getter. Which plated off when the getter is heated to purge off the last oxygen from the valve after the envelope is evacuated and sealed.

[@JustinAlexanderBell]

4:45 those vacuum pumps require maintenance after a while, there are rebuild kits available. It's like $30 to rebuild the pump.

[@RomanDvoryadkin]

You can rotate polarizing filter inside display to make it negative, than crank backlight to 11, so it will look almost like VFD.

[@chongli297]

My goodness! If that filter had turned out to be a polarizer at exactly the right orientation to black out the LCD then I would have to really tip my cap to bloody Murphy. I'd say he was working overtime at Keithley when he came up with that trick to block replacement of the VFD with an LCD!

[@jp-ny2pd]

Maybe there's resistors you could swap out to increase the current flow through the backlight? Or maybe bodge on some extra LED's for the backlight?

[@EEVblog]

Yes, I think it's a 100R in series from the 5V supply.

[@marcseclecticstuff9497]

Your board is configured for Parallel M68 mode. No need for probing, just look at JP6 &JP7 according to the datasheet.

[@JanJanson84]

You can also get OLED Displays in the HD44780 industry standard. These ones are brighter and might be a better choice.

[@EsotericArctos]

The LCD looks brighter on camera than the old faded VFD did. I would take that as a win. Always nice to have the original, but this makes device usable until you have the time to do a VFD. Also, it was a way to prove the display was the only issue without spending the cash first.

[@PY4SR]

24:47 Please! Align the characters with the borders😂😂😂

[@FireballXL55]

It may have been the on display voltage generator for the VFD.

[@FirstLast-jl6fr]

haha this was so funny. I replaced some going duff CCLs for LED strips in a HP 20510i LCD monitor only to find the HP control circuit used an analog voltage to control the backlight brightness whereas the Chinese LED strip controller needed an PWM signal. I ended up creating a custom interface board using a PIC16F1615 with firmware that converted the analog into PWM so that the original HP screen controls worked in exactly the same way. It had to scale and invert the control signals and handle 0% and 100% levels correctly. A master hack if I say so myself :o)

[@Basement-Science]

not sure, but maybe you could also buy some thin LED filament or otherwise put together some additional LEDs as additional backlight around the LCD to get more brightness out of it.

[@barrybogart5436]

This is a good example of the right kind of video for me, Not a unit I would ever own but nice watching you work. My favorite of all time is the HP 1742B PSU issue you diagnosed over three videos! I have the same CRO.

[@EEVblog]

That HP repair was a real cracker!

[@00Skyfox]

I have junk bins and drawers full of crap I've been salvaging for nearly 40 years now and every time I need some specific part that isn't just a basic cap or resistor, sure enough it's the one thing I _don't_ have. Same for miscellaneous screws.

[@MikeB_UK]

I would have tested that VFD manually as the getter has not gone white so there is no vacuum fail. Granted the heater wires can exhaust their coating (thorium?) that makes the thermionic emission work properly, but unless the unit has had thousands of hours left switched on then I'd expect the actual VFD to work. VFDs look so much nicer than LCD displays. How about a revisit video just on that display board?

[@DavidLightman]

LMFAO🤣🤣🤣🤣🤣"that happens when PCB designer don't talk to the front display guys"😂😂😂😂 so real

[@Rob2]

Frankly I thought from the moment you considered using an LCD "but Dave, there is a dark blue screen in front of it, how is that going to work???". Fortunately it sort of worked out when using backlighting. Maybe you can improve it by installing a different backlight color like blue or white.

[@TrevorsBench]

Two dead caps can cause a lot of chaos and cost

[@richardbrobeck2384]

That mousert part seems to be a good item to get !

[@Chriva]

The getter still looks intact so am wondering if it's actually the VFD or some driver circuitry around it?

[@danmenes3143]

I was shouting "CHECK THE HIGH VOLTAGE" at the screen.

[@Chriva]

@@danmenes3143 You can visibly see the burn-in so the screen was more or less EOL any way. Think he did the right call not to troubleshoot it further but it would still be fun to know what delivered the final blow.

[@danmenes3143]

@@Chriva True enough

[@OzyWizard1973]

I like the LCD display, but I think it would look better with a second LED on the left side.

[@gonzo_the_great1675]

I've found that many of the Hitachi controller VFDs and LCDs are interchangeable, at a data level. (Posted early on in the video, before I knew what the fix would be...)

[@Anachronos1]

You can use Black display with white letters/numbers. I think they are few background color modes too.

[@johnvecchio4186]

Did you check the caps on the display board. I seen VFD display go dim due to caps going out.

[@EEVblog]

Part two coming tomorrow

[@chrisridesbicycles]

Unbelievable. Murphy made you think you had won only to slap you on the back of the head 😂 Just enough to let you know that he let you win.

[@PhillipRhodes]

As far as desoldering goes... I'm sure there are plenty of good options, but FWIW I've been very pleased with my Hakko FR-301 desoldering gun. It's a real bobby dazzler, as some guy I see on the interwebtubes is always saying.

[@EEVblog]

I started a forum thread on it.

[@benespection]

Loved the repair video, but Dave, Dave! I've been watching your videos for far too long and all I can hear is you screaming: thou must check voltages! :) From repairing hi-fi stuff I've found VFD failures are often an issue with what's driving it rather than something in the VFD itself, as others have mentioned. Will you do a quick second channel follow-up on the original VFD board you pulled out?

[@WaynesWorld999]

I wonder if you hot air peel off the decal, you might be able to remove the tinted layer on the back side?

[@zebo-the-fat]

I was screaming at the screen " turn on the backlight!!"

[@leonkernan]

I was screaming "Straighten up the LCD!"

[@EEVblog]

I prefer not to have a backlight if I can avoid it.

[@clynesnowtail1257]

I wonder if the part number change on the newhaven is due to ROHS update. Same layout just with lead free solder and maybe a couple component changes

[@LawpickingLocksmith]

That is a BIG chicken dinner already for breakfast!

[@lasersbee]

18:43 Backlight pins on the LCD Display

[@KeanM]

Not a bad partial win, pity about the filter - but definitely better than no display when the VFD eventually goes out of stock. I may have to see if I have a spare for my K2306. The extra RJ connector on the display controller board would be for the Remote Display/Keypad Option 2306-DISP which uses an RJ45 flat cable and presumably the same PCB with different BOM. I've seen some people with bad VFDs buy the remote display rather than fixing the internal one. Occasionally they show up on eBay, but the VFD may also be suspect.

[@namibia_2025]

Hello, very good. Congratulations.

[@BaconbuttywithCheese]

The unused strain relief on the IDC plug is causing the clearance issue.

[@RobertWardJones]

Free is free! Hoop jumping is free too. And you have two spare displays to boot!

[@EEVblog]

Don't know where I got three of them from, but junk bin for the win!

[@bertblankenstein3738]

Murphy came late to spoil the party. I'd leave it with the lcd display. You know you won't need to replace that lcd panel.

[@A13tech]

I have this battery simulator at home. It works but user experience is terrible. Set up values etc.

[@eliotmansfield]

i think we need you down the beach bbq and cooking some fried chicken for the family 😅

[@NiHaoMike64]

Try swapping out the backlight LED with a much brighter one?

[@theallotmentbubble9073]

Was there not a backlight connection on both sides of the display? are they just alternative connection points or are there backlights on both sides of the display?

[@sam28z]

Designed to keep the voltage settings secret!!

[@doogie812]

Sometimes we do get lucky!

[@richardbrobeck2384]

Let me know what you get for your solder sucker I am also in the market too . I used to have Hakko I thought about buying a new Hakko .

[@gorak9000]

in the 26 minutes of yapping, you probably could've just changed the electrolytics on the old vfd and been up and running already

[@EEVblog]

Part 2 coming tomorrow

[@GlennHamblin]

Ye ol' HD4480 rocks again!

[@paulnero3885]

insted of a vfd an oled version could maybe fit? dunno if it's available in the right formfactor

[@radarmusen]

I would have thought that there would be oled matrix display there could be used.

[@EEVblog]

Possible.

[@flymypg]

Some LCD display modules have a serial command to invert the display, and a jumper pad to bridge in parallel mode. Would that help?

[@Digital-Dan]

Who else would there be than those playing along at home?

[@zaprodk]

18:29 162 is 16 chars*2, so yeah, coincidence that they are the same? No :D

[@youchooby]

in the same market for a sucker and JBC is currently king

[@adamchrzanowski5857]

18:40 mounting holes dont align

[@leonpijpers7327]

I would keep the LCD display in, repair done. May be the VF display is fine, just some step up converter gone bad on the VF pcb. Or the VF wires gone bad. I guess you have to much work making videos and reading comments to measure the voltage or the wire resistance.. thanks for the video, one more piece of equipment saved. (EEVblog 717 and 1601 video for voltages of large VFDs, DC voltages will make left or right brighter(I tested that once) Anthony Francis-Jones video 203 he shows a single digit VF display (lower voltages) Posy: VFD Displays and Dave's Garage & Zak have also great VFD videos

[@EEVblog]

Part 2 tomorrow.

[@leonpijpers7327]

@@EEVblog Thanks.. looking forward to it

[@lucafurna]

Nice fix; you have been lucky. That JHD162D is not so common ...

[@EEVblog]

I don't recall exactly where I got three of them from, two of them were used, one had the sticker on it.

[@lmamakos]

Clearly you just need brighter LEDs for the backlight!

[@IvyMike.]

Keithley, did you store it upside down so all the electrons ran out??

[@thephlophers]

They also have "reversed" 2x16 LCDs, with black background and lit characters. Those might do better here.

[@68pishta68]

I have a TOTL JVC VCR that has a weak VFD, I wonder if I could convert to a LCD that easily? I think it may have a few proprietry symbols on it a dot matrix would not be able to display, would they just be a dot? Ie. a tape symbol and tape speed script. Iv read there is a way to recharge the VFD with some high voltage, ie glow the grid and burn off some nasties to get the brightness back up?

[@the8bitpc_805]

i would say Bob's your Uncle 😀

[@so4706]

great - like it

[@TY1979KA]

is the confidence guy Udo Kier?

[@andymouse]

Sod the VFD, junk bin wins are too awesome to pass up. I think you should leave it !

[@MrDoneboy]

How about a Hakko FR301?

[@sivoltage]

Was that a eurorack power connector on the driver board lol

[@EEVblog]

Is that what it's called, it seemed oddball.

[@dogastus]

Let the vacuum out???

[@andymouse]

Yes ! If you let the vacuum out, then there is loads of room in there for the air to get in !

[@BillyONeal]

I look forward to EEVBlog Dave Jones being sent the same solder/desoldering setup Macro Reps uses Edit: "I asked grok" and it returns totally wrong part. Story of 95%+ of interactions with AI.

[@geovani60624]

just use a stronger white led for the backlight

[@pear7777]

Soddered does evade contactproblems

[@TheDefpom]

Try out with a different colour display, a blue or yellow might work better

[@KeanM]

Yep, I was just thinking that and came back to say there is a model that looks like it would fit and is available in blue - LC1623. Many other 16x2 LCDs have the connector at top left instead of bottom left, or have different overall dimensions. Oh, and another is the Surenoo SLC1602D which is available with yellow-green, blue, or white backlights.

[@EEVblog]

Possibly, but when the junk bin delivers, you "get what you get and you don't get upset".

[@TheDefpom]

@ I have a plastic bin full of different types and colours of displays, for this exact reason, you never know what you’re going to need to fix something.

[@andymouse]

@@EEVblog :)

[@eimparas]

The think i dont like with Dave is the way he overthinks stuf like these . This interface is a clasic "textbook" almost hd44780 interface basicly inner-compatible with every display of this style out there. (there is even some new oled displays with this interface!) OFC usualy you go open the dataseet of the broken part, check the compatiblity with the replacement etc. but this was so obvious i was "screaming " to my display. This time i think he was overthinking it by checking all these parts websites , by going and almost buying this 60$ part ... Dont get me wrong i dont critique his engineering skils, he and he's videos are amazing but im telling that some times he gets carried away... Keep up the good content dave !

[@EEVblog]

The first thing you do is literally type the part number into google, and the first and only hit was octopart which gave me the correct Newhaven display. Out of curiosity I check find chips as well to see if anyone had it cheaper. Then I checked my junk bin and got lucky. How is this "overthinking it"?

[@eimparas]

@ Bit late reply , semester exams got in the way… I really liked how you went over the whole board, identified the LCD, and then approached the repair methodically in your second video. My comment was specifically about the moment after the 4-minute mark, when the VFD PCB became visible. Seeing the 14-pin header immediately signaled to me that this was the classic HD44780-compatible character LCD. My confidence was nearly 100% when I spotted the PCB markings around the 5-minute mark: RS, R/W, E, followed by DB0-DB7. When I mentioned “overthinking,” I didn’t mean the part where you found the datasheet and went through it-that’s standard practice. What I was referring to was the part where you started going through varius part aggregators, spiral out talking bus analysis with a logic analyzer, browsing multiple component aggregator sites, and almost purchasing a $60 replacement. If it were me, after seeing that display, my first instinct would’ve been to go straight to my parts bin (or junk bin), grab a similar LCD, check voltages, solder it in and if it works, move on with my day. Sorry if I sound arrogant, hasty to jump to conclusions, or too quick to assume that this interface is so widely known. That wasn’t my intention (posted the same on the forum, www.eevblog.com/forum/blog/eevblog-1664-repair-with-junk-bin-parts!-keithley-2302/msg5808157/#msg5808157), went back and commented here... to boost this engagement metric , what that algorythm wants...)

[@jasonhill2180]

Murphy!!!

[@floodo1]

The plastic tearing off the “junk” screen was so satisfying, perhaps more than the repair itself (-8