CRT clock kit instructions

[Nicholas Stock]

Did anyone else on the list buy one of those recent CRT clock kits that was listed on eBay?

like this one...

https://www.aliexpress.com/item/4001330655526.html?spm=a2g0s.9042311.0.0.1a084c4d8VxYDr

I have a kit, but they never shipped the instructions, so if anyone has some that would be great.

Thx,

Nick

[Mac Doktor]

On Dec 11, 2020, at 4:42 PM, Nicholas Stock <nick...@gmail.com> wrote:

Did anyone else on the list buy one of those recent CRT clock kits that was listed on eBay?

like this one...

https://www.aliexpress.com/item/4001330655526.html?spm=a2g0s.9042311.0.0.1a084c4d8VxYDr

It says that they're out of stock until the next production run.

I have a kit, but they never shipped the instructions, so if anyone has some that would be great.

No luck contacting the seller? I'd love to have one of these.

Terry Bowman, KA4HJH
"The Mac Doctor”

"Never install version point-zero of anything"

[Nicholas Stock]

The seller was useless. Continued to promise on sending me the instructions, didn't send me the tube and Aliexpress wouldn't step in. Beware.

Sent from my iPhone

On Dec 11, 2020, at 14:06, Mac Doktor <themac...@gmail.com> wrote:



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[Paolo Cravero]

Hi.

I bought&built that kit and have the docs that were sent on request. That means the diagram, adjustment procedure, firmware canvas. Will send them privately later since they are on another computer.

I documented for myself the kit here http://ik1zyw.blogspot.com/2020/10/kit-oscilloscope-clock-8sj31j-review-1.html?m=1 (plus part 2 and 3).

The CPU is STC, a Chinese 8051. The supplied firmware is incomplete and good luck making adjustments to the code. 

I am thinking of building an emulator of the rotary encoder to change the shape of the display and prevent burning the CRT. Other ideas are welcome.

All I needed was a PSU to test CRTs :) but I am open to attempt improvements.

Paolo

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[Nicholas Stock]

Paolo, you're a lifesaver! Thank you so much...

I take it they didn't add a screen shift procedure to mitigate burn in then..... :(

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[peter bunge]

I bought the older kit from al-truism

https://www.ebay.ca/itm/Oscilloscope-Clock-Kit-OSC4-4-original-vector-design-crt-Cathode-ray-tube-Scope/303740553122?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

It worked without problems using a Russian 6LO1i CRT.

You do require some skill to build it.

He is still selling the newer kits. I recommend him from my experience with this product.

Anyone needing help for this one welcome to contact me off line.

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[Nicholas Stock]

I have some of his clock kits, for the price they're OK, but the lack of blanking really ruins the display IMHO. Circle graphics are where it's at, so David's or Grahame's scope clocks are a cut above the rest. David was working on a follow up to his last design? Any update David?

Nick

Sent from my iPhone

On Dec 11, 2020, at 19:39, peter bunge <bung...@gmail.com> wrote:



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[Alex]

It would be interesting to see the schematic for this kit to ascertain if it would make a good starting point for a homebrew design I guess? Use their HV part but do your own micro board?

[Paolo Cravero]

It would be interesting to see the schematic for this kit to ascertain if it would make a good starting point for a homebrew design I guess? Use their HV part but do your own micro board?

The HV part uses a transformer of unknown specifications. All the rest is common design. Also the analog driver setup is inspired from other open hardware scope clocks. I wonder if we have some Chinese speaking members that could contact the seller to investigate the possibilities of further development or more kits. Writing in plain English language had no effect (I got again all the documentation files, no text).

Nick and Alex I sent you the files privately from another email account. 

Paolo

[Grahame]

Alex

Have a look at my designs if you have not seen them. They are all open source and open design. I sell kits from minimal parts up to a full kit. I sell fractional kits, so for example, I am working with someone who wants to interface a RaspPi so he is only interested in my deflection amplifier and HT PSU boards. If you want to develop your own HT PSU then I sell the custom wound flyback transformer by itself as well... I don't sell and disappear ... I remain to  resolve any problems.

http://www.sgitheach.org.uk/crt.html

Grahame

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[John Snow]

I've tried to get that one from Aliexpress previously, but they later refunded me saying they weren't getting any more stock.

[lokn...@gmail.com]

Have you looked at these kits?

https://oscilloscopeclocknixiecrt.com/Kit.htm

Sent from my iPhone

On Dec 16, 2020, at 00:17, John Snow <jrope...@gmail.com> wrote:

I've tried to get that one from Aliexpress previously, but they later refunded me saying they weren't getting any more stock.

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[John Snow]

There's another 4 of the 8SJ31J kits listed at https://www.ebay.co.uk/itm/265139148431 , I've ordered one on the offchance they have them in stock, also the seller has feedback for selling them previously.

Bit of a premium tho, and only avalible with tube.

[gregebert]

Thanks for the tip; I just bought one. I'll post an update + video after I get it and build it.

[Gelu Burla]

What is the life expectance for this tube?

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[Paul Andrews]

They actually seem very cheap to me...

[John Snow]

The kit was previously 'avalible' from aliexpress for £56.44, but it was from a seller that held no stock - got refunded as unable to ship.

That was minus the tube though, the current ebay link includes the 8SJ31J but lacks a power supply (12V 5A centre+)

Unsure on lifespan of tube.

[John Snow]

Huh, ebay auction says 12V 5A, a previous aliexpress page gives much lower values for amperage:

https://www.aliexpress.com/item/4001142939399.html

I'm assuming it's the same design from the pictures

[John Snow]

I'm trying to figure out how it's put together before I start soldering.

As Paolo mentioned the only mystery part is the transformer T-SC-1 on the parts list - it looks like a custom order. I don't know how to characterise it without destructively pulling it apart, and unfortunately they don't sell them separately.

There's another four without the tube now listed: https://www.ebay.co.uk/itm/265151344483

The kit is listed as configured for 8SJ31J by default, and the documentation linked further up lists the wiring for 3SJ1J/5SJ38J/7SJ32J. No idea if the power requirements differ and requires resistors changing on the circuitboard(s), or if they are plug-and-pray drop-in replacements once you've changed the pinout.

The auction page says it can be used with 3LO1I/7SJ33J/8SJ31D/8SJ40/8SJ42J/8SJ40D/9SJ105Y14/12SJ102J/13SJ38J/13SJ38D.

Unfortunately without knowing the transformer operating characteristics I'd be hesitant to plug in anything else.

I'll probably try to replace the fuses with polyfuses in the future, socketing them for now, and taking measurements while unpopulated for easier case design later.

[John Snow]

Found a conflict between the documentation (both before and after google auto-translation). The conflict is between Anodes A1,A2,A3 in the sellers documentation.

The seller's documentation lists:

A2 (Focusing Anode) - pin 5

A1,A3 (first and third anodes) - pin 9

I've found a separate pinout for the 8SJ31J tube that lists:

Focusing Anode,A2 - pin 9

A1 - pin 5

 The second pinout is from http://www.spectrum-scientifics.com/v/vspfiles/pdf/Properties_of_Electrons_Apparatus.pdf

It looks like the tube in the spectrum-scientifics is the thin-pin version of the 8SJ31J, and the kit uses the thick-pin version of the 8SJ31J, but I'd like a second opinion.

I know they have different power requirements - the thick-pin (old) is around 10W, and the thin-pin (new) is around 7W (I'm assuming which are old and new based on the design of the base socket). The rest of the pinout agrees, is this another difference between the old and new designs of tubes?

Tl;DR I'm not clear on the anodes of the 8SJ31J, which pin is the focusing anode, and why the other two of the three anodes are joined together.

[gregebert]

Most likely, the error is in the text description in the instruction manual. From the datasheet, pin 9 is the multi-anode connection, and pin 5 is the single anode. I am more likely to follow the connections to specific pin numbers in the instructions, rather than the text-description. Pin 9 is the higher-voltage (1500V) anode, and it should not be difficult to verify that in the schematic.

As far as the power is concerned, I cant figure out where 7-10 watts is going. The filament is 6.3V / 150mA so that's less than 1 watt. The electron-beam current is probably less than 100uA, so that is also less than 1 watt. For comparison, a NIMO tube uses 30uA. Even if the anode current was a whopping 1mA, that would still be only 1.5 watts. So that leaves the grid and focus anode as the only other source of power dissipation; maybe some clues will be in the schematic.

My kit arrived in the US earlier this week, so I hope it will get delivered to me next week. I will be placing a 250mA fuse in series with the filament for added protection. I'll post an update after I've either finished it, or ran into a problem.

[John Snow]

When you get your kit can I check the socket wiring with you? Mine doesn't match the wiring for the 8SJ31J in the seller's datasheet, but is pre-soldered & heatshunk and already on the tube. I'm worried they made an off-by-one error wiring it up.

[John Snow]

Ahh, my mistake - the filiment pins 14 and 1 are next to each other - the other diagram above showed a gap between 14 and 1. The pin numbers are nicely moulded in the base if you remove the socket.

The tube has pins 6 and 13 absent from the tube, and the wired-up socket doesn't use pins 4 or 12 either.

I'd taken the gap (pins 12 and 13) as the gap on the diagram above.

Interestingly I have pin 4 present on the socket but not wired up - someone must have changed their mind assembling it.

[Pruttel]

Since this is a CRT topic, I thought I'd ask it here: I got a rectangular Sylvania CRT at a HAM flea market quite some time ago, but I cannot find any info on it. I wanted to attach a photo of the tube + label, but the google website won't let me? The type is SC3015P1B, serial 2391113. Googling that type gets me nowhere, except supplier-partslists. It might be military supply?

It looks to be like the 3BGP* tube, like in this document: https://ia800407.us.archive.org/26/items/bitsavers_sylvaniadaataSheets_13046152/Sylvania_CRT_Data_Sheets.pdf

The pins are actually already connected to wires some 20cm long, and the pins are completely sealed in white caulking-like rubber.

Anybody have some info on this tube?

Iwan

[Pruttel]

Replying to myself: since I couldn't attach, I've put two photos online: https://possob.xs4all.nl/sylvania/

Any help is appreciated!

Iwan

[John Snow]

Assembled all of it & somehow managed to misplace the rotary control board.

They've made a few near-substitutions in the parts list, notably the XYZ board part #46 - 1 piece 510K is now a 1M resistor, this was the last one I soldered, presuming uprated intentionally.

There's a few more with non-standard banding, but multimeter confirmed values.

Also the Control board has downrated the capacitance of #6 from 330pF to 300pF and of parts #9 - now 10V instead of 16V rating, presumably availability.

The fuses are 1A and 2A fast-acting fuses, annoyingly must be desoldered after they've blown, unsure of the voltage tolerance.

Hoping the control board turns up, otherwise I have a paperweight I can't tune.

[gregebert]

My kit arrived today WITHOUT instructions. Damn!   If anyone has an electronic copy, please let me know. I'm contacting the seller. Nothing I could find on their website. But at least I dont have to worry about the CRT connections because they prewired it for me.

[John Snow]

Forwarded the documentation on, rotary control board turned up, I'm on to calibration

[John Snow]

Tried it with a 12V 3A and 12V 4A power supply, can't get either 8SJ31J tube I have to light up from turning R21 Intensity.

Both power board orange bulb and control's red led light up though,

I've ordered a 12V 5A power supply hoping that'll sort it.

[Paolo Cravero]

Hello.

Is the filament glowing visibly after one minute of power on?

Is the filament fuse still good? Can you confirm current flows there?

If all above check positive, in dark room do you see the green shade of the beam out of the screen?

My kit draws less than 2A, I am quite sure. 650 mA go to the filament (1A before conversion?!), the rest for HV. Is there any component getting hot? I reversed a voltage regulator...

Paolo

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[John Snow]

Hi Paolo,

no filament glow after one minute powered on,

both fuses continuity checked, they've not blown

I'm getting 60V across the indicator bulb.

Which voltage regulator did you reverse?

[gregebert]

60V on the indicator bulb (NL1) indicates the transformer is being driven, but you cant tell if the HV is high enough; can you measure VCC_300 to see if it's in the ballpark ?

Can you scope-out pins 1 & 2 of the transformer to see what kind of waveform is present for the filament supply ? 

I'm going to start building mine tonight now that I have enough info (thanks John !).

[Paolo Cravero]

John,

pictures of my build are here: https://ik1zyw.blogspot.com/2020/10/kit-oscilloscope-clock-8sj31j-review-3.html

The code on the HV board is the same. I think I reversed a 79Lxx, but the smell of it burning was too obvious and I cannot tell what the effect was on the CRT.

I do get intermittent failure probably caused by a cold joint at a ground point that was not designed with thermal relief and it took me a while to solder.

Paolo

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[John Snow]

I've been checking over solderjoints, hoping to find a Q or U with a solderbridge, no luck.

Ah, I hadn't made the connection - I found your build guide before, it's what made me decide to order one. It's been useful for making A or B comparions for anything standing out.

I've also been checking over the circuitboard hoping to find a Q or U inverted, but they're all following the soldermask guides.

There's no breakout for and ground VCC_300 to easily probe?

[gregebert]

UPDATE 1: I built the power supply/driver board and completed some basic testing. I installed all components EXCEPT the transistors for the diff-amp that drives the CRT. The standby current at 12V is zero. The HV supply can be enabled by grounding the POWER_ON signal; that causes the inverter to run and the current is 170mA. The neon bulb is on and it's supply is 306V; the +5 and -5 supplies also work. The filament supply voltage on my scope is about 500kHz, somewhat sinusoidal, and about 17V pk-pk, which is about 6.3 Vrms for a pure sinusoid. The HV is beyond the range of my DMM so I had to put a 10meg resistor in-series to double the range (inaccurately, because it's a 10% resistor) and measure around 1270 VDC.

Next step is to build the other board. Stay tuned.

[John Snow]

Paying full attention - what model DMM do you have if you can't directly connect it? I have an 87V I'm happy to connect as it's rated for 1KV.

[gregebert]

I have an Aneng UT61e; cheap but quite good. One of my scopes has a pair of 100x probes that lets me look at a few kV, but I was too lazy to bring it up today. If I run into problems I'll post some screenshots.

After installing the diff-amp transistors and Q1, current-drain increased to 360mA.

I suggest you bench-test your power-supply board by itself first; disconnect all cables, and jumper J5-4 and J5-5 together to enable the HV supply. Make sure all generated voltages are correct, especially the 300V supply (should be around 305V per the instructions).

[Bill Stanley]

Toss another kit on the barbie....

My kit arrived today so I will be building it over the weekend. Watching the comments closely.

  -Bill-

[Bill Stanley]

OK, that was quick. Opened the box, all parts appeared to be in good shape, but no documentation of any kind. If I could prevail on the other builders for a copy of the instructions/schematics, it would speed up my build.

Thanks;

  -Bill-

[Ian Vine]

Any chance the documentation could be shared to all? 

Thanks Ian

On 22 May 2021, at 04:14, Bill Stanley <billsta...@gmail.com> wrote:



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[gregebert]

For copyright reasons I wont post them; the seller emailed them to me within 24 hours so if you dont have them in your kit, be sure to contact them so they know about the problem.

[Paolo Cravero]

Hello.

My boards take about 10W input, that is ~800mA at 13V. Without a CRT connected the current drops to ~470mA.

A word of caution to current builders. Q6, Q9, Q12 and Q15 (all MPSA44) on the PSU board get pretty hot. I measure 60°C on the top of their plastic case! Even without a CRT connected. Please do check yours if they heat up like mine! Possible solutions besides a small heatsink?!

Paolo

[gregebert]

UPDATE 2: Both boards are complete, everything connected together. I was unable to get a visible trace on the CRT. Voltages seem correct, but for some reason the fuse protecting the filament blew out. Filament did not blow as confirmed by continuity. I need to investigate further, and will need to get some slow-blo fuses before I power-up again. The fuses that came in the kit were unmarked, so I have no idea what it was, or it's characteristics. Only info is what is printed in the docs. The CRT datasheet says 150mA at 6.3 Vrms (same as DC).

I will be measuring filament I-V characteristics tomorrow, then decide what fuse is best. Powering-up the CRT without a fuse (eg, shorting it out or using a larger value) is NOT going to happen. I might have to wait to power-on again  after I get some replacements thru DigiKey.

[John Snow]

I had to get the fuses under a microscope to differentiate them before soldering, unsure if this is a manufacturer's brand, or just a symbol to say they're fast-blow fuse, or just a fuse.

My fuses still show continuity, so that's not my problem (yet)

[David Forbes]

I haven't been following this thread closely, but I finally looked through it this morning. 

It looks like this is a copy of my SC200 design from 2008. At least the components look the same in the pictures.

Please send me an email at david at cathodecorner dot com, and I can help you sort it out .

On Fri, Dec 11, 2020, 2:42 PM Nicholas Stock <nick...@gmail.com> wrote:

Did anyone else on the list buy one of those recent CRT clock kits that was listed on eBay?

like this one...

https://www.aliexpress.com/item/4001330655526.html?spm=a2g0s.9042311.0.0.1a084c4d8VxYDr

I have a kit, but they never shipped the instructions, so if anyone has some that would be great.

Thx,

Nick

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[Paolo Cravero]

Hello.

On Sat, May 22, 2021 at 9:22 AM 'Ian Vine' via neonixie-l <neoni...@googlegroups.com> wrote:

Any chance the documentation could be shared to all? 

Thanks Ian

Aliexpress proposed me the kit today even if it is sold out. At the bottom of the description (https://bit.ly/3yNgelV) was the link to the documentation: http://www.mediafire.com/file/4j8cwf8ty3ixn5n/file

HTH,

Paolo

[gregebert]

UPDATE 3: After measuring filament characteristics, it appears I have an older version of the tube that operates at a much higher current (600mA) versus the datasheet I found online (150mA). This explains why a fast-blow 1amp fuse would blow. Data shown below. As you can see, the resistance varies substantially as the current increases; at power-on, the surge current will be around 2 amps, so goodbye fast-blow fuse.....

I ordered an inline fuse holder and several slow-blow fuse values and will replace the fuse on the PCB with a wire jumper. I wont be able to work on it over the long weekend, so maybe next week I will have it running.

[gregebert]

UPDATE 4: Success!  After changing to a 1-amp slo-blo fuse for the filament, the display came up. It takes a few minutes to get the adjustments so that you can read the display in all modes. Start with all adjustments at midpoint, and go from there.

As Paolo pointed out, some of the driver transistors get warm; I measured 62 C. Also, the CRT I have runs at a higher filament current (600mA), and it gets up to 54C at the neck. Everything else, including the transformer and heat sink are much cooler, around 35C.   I'm going to let it run overnight; hopefully it wont go wacko and overheat, etc.

After I get the mounting hardware 3D-printed, I will be able to adjust the display better. The current drain from the 12V supply is 830mA, which is close to the published value (850mA). Be aware the start-up current is higher; I will try to get a plot from my scope later this week.

[gregebert]

UPDATE 5: Startup current

From the photo below, you can see the effect of the filament heating-up. There's an initial delay as the CPU boots-up, then enables the HV. The spiky behavior is probably due to the current-limiting feedback in the HV supply. After the tube stabilizes around 2.7sec, the current-draw is smooth. Ignore the voltage reading at the corner. The stable consumption is 830mA, and it peaks around twice that.