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I'm Right Up To Date With My New Workshop Equipment!


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That's 'up to date' if we are still in the 1980s, as I've bought myself a used Crypton 335 Motorscope. And it works! Mostly, that is. The monitor lights up and displays the expected traces when connected to the engine, and the built in timing stroboscope works well with the built in advance checker. However, the digital display stays resolutely at 0.06 whatever I do, and the enormous multimeter shows readings that I can't work out.

 

I've calibrated it according to the manual, but I haven't got inside it yet, and I fear that it will be just a plate of wiring sphagetti as I have no wiring diagram. Anyone else have this toy or a diagram? Or can suggest how to fix the digital voltmeter and multimeter?

 

And I need experience in using it. One test, of the coil windings, is supposed to show all the traces superimposed, . The traces are not identical, which, the manual says might indicate 2nd winding breakdown. A check of the coil finds the primary is at 3.2 Ohms and the secondary at 8.9kOhms. Is the primary too high?

 

Then, by pressing the appropriate buttons it isolates one plug at a time, to identify HT wire faults, and plug status.

(This getting exciting! Houston, I want a Go-NoGo for launch! Go, Flight!) And they vary, more than this inexpert operator would expect for new leads and plugs.

 

Anyway, I'm lucky to have the garage space to hold this automotove dinosaur, and it's great fun to use!

 

John

PS pics show it not connected up. If anyone wants, I'll take images of the screen in use.

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  • 7 years later...

I got this out to play with in lockdown - and the screen has gone!    The meter works, the vacuum tubes that show numbers light up, but no screen!     

Additional symptom, the sign across the top that says "Crypton 335" should light up, by a fluorescent lamp behind, and it doesn't.   I've used my multimeter to confirm 240V at the lamp, so maybe that's just a dud tube or starter.

Inside the case - there are two covers behind, either side of the support column - I can see that there is one big circuit board, with seven subsiduary boards upright on the mother board.  The mains cable goes in under that. and I cannot see if there is a bank of fuses that might supply the Screen circuits.      The mother board is supported on runners like a roller cab drawer, so could be slid out for maintenance,  but to get it out the whole cabinet would need to be detached from the column!    

Without more information, I'm scared of fiddling with a TV system, as I know those use High Voltages.    Anyone know of where I might get a wiring diagram or similar?   It's back in the corner for now, but we have at least three more weeks and probably twelve of lockdown, so any ideas, please?

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John,

 With the equipment unplugged.

Take a heavy duty flat head screwdriver and wrap some 2.5mm2 bared cable around shaft of screwdriver.

Connect other end to chassis/ground of equipment.

Use blade of screwdriver to go under HT rubber cap on side of CRT. Make contact with metal contact inside.

There might be a spark if CRT is still charged up.

HT now discharged.

Over 30 years since worked on a CRT.

Cheers,

Iain.

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In 'another place'  Martin of Distributor Doctor was recommeneded, as he usd to work for TI, on Crypton kit!

And he comes up trumps!

There is a large cap-headed bolt at the back of the support column, goes right into the cabinet.   I thought it held the cabinet on the column, and that the cabinet must come off the column to slide ot the motherboard tray.   Martin tells me that it's the opposite way around!   Undo the bolt, AND THE WHOLE DISPLAY SLIDES FORWARD!

Top bloke!    OK, back to the mancave!

John

 

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Thank you, fellow primate!

Your advice just reinforces my caution!     This 'bared cable' is to make good contact with the screwdriver, so that it will earth and discharge the TV tube?      If the kit is left unplugged and not 'On' for, say, 24 hours, can it be safe to go into it then?  Or how long might be 'safe'?

 

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John,

It will probably be 100% dead after a few days!

I hate getting zapped and 20KV DC is not pleasant. You can't measure it as its high enough to pop most multimeters.

I just ground it to be safe.

I have only every seen and heard a crack after I have killed the power to a TV & then shorted it. Still better be safe than sorry.

Could still be a few hundred volts across any capacitors that are on the mains side whos bleed resistors are open circuit. A test with a mulitmeter across any capacitors that have a marked voltage rating of over 100V would confirm if energy dissipated.

I would not work alone on anything that's had mains on it until I know its dead.

Probably a dried out capacitor at fault.

Cheers,

Iain.

 

Edited by spitfire6
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under the rights conditions a crt can maintain a lethal charge for up to a week. If you discharge it as described you should then wait a few minutes and discharge it a second time before it is safe, and do all this while keeping one hand in your pocket. Long ago I worked in TV design (Rediffusion).

 

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Martin Jay at DD was spot on! Undo the big bolt,it pushes the front panel out so that you can grasp the edges, and pull it out on the drawer slide mechanism.   It's very well made!

On Martin suggestion, I took out all the sub-boards and cleaned their contacts with an  eraser rubber, but  on reassembly the screen still doesn't light up.    I went nowhere nearer the CRT than I absolutely had to and I'm here to say it was safe(ish).    Only  boards Nos. 8 & 9 are, I think, to do with the CRT, in that they had connections off them that went in its direction.

John

PS, thank you, mossmonaco!   I like the "one hand in your pocket" idea.    A friend runs a small garage and was telling me about a seminar he had been to for those wishing to service electric cars, which run on 400V or higher.    That was one of the first things they were told - one handed work!

Edited by JohnD
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  • 3 weeks later...

Reviving this thread, becasue I have problems with the Crypton, and need advice.

I posted in the "Can't Fix That" thread, and it got confusing, so I'm bringing it over here.    This the post I started with in that thread:

It's not what you know, it's who you know - or can find on t'Net!

I have a Crypton Diagnostic Centre, an enormous yellow cabinet that will link to my engine and aid in timing and working out any faults, complete with strobe and gas analyser.  It's State of The Art, 1970!

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But when I turned it on recently, the Oscilloscope screen is blank.     That's a big b0334r.       So, lacking any electronic nause, I looked for anyone who could advise me.   Crypton is still in business, but either can't help in lockdown or won't - no answer.    Several local TV repair men said, interesting, but not me, mate.  Try so and so, who also demurred.     Then I found "UK Vintage Radio", a message board, whose members had plenty of knowledge, theoretical and practical, on this geneartion of eletrconic kit, but none on the Crypton in particular.     BUt with their guidance, I was able to get inside it, without electrocuting myself.     That High Tension  lead to the TV tube gets earthed everytime I go in, sometimes with a meaty CRACK and flash.

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With the help of the guys on UK Vintage Radio, I've checked that the High Tension Circuit is producing high tension volts - probably unnecessary given the crack and flash! - and established that the TV tube is getting current to its heating coils - I can see them glowing!     I inspected all seven of the boards that plug into the motherboard, and established that Numbers 8 & 9 (there are only seven sockets on the motherboard, all full) are the ones that control the TV tube, as they have direct connections to it - see above.    Further inspectinn found a nasty looking burn on Board 8, see below:

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It's too burnt to read the colour code on that resistor, and anyway. just replacing it doesn't answer, Why?      UKVR guys guess - they can do no better - that another component may have gone bad. maybe the transistor next to it.   The resistor is "R1" and the transistor, "TR1".     The maze of tracks on the back of the printed circuit board is - amazing!

 

Then cruising the 'Net, I found that Fairford Motor Club in the South West had held a "Crypton Day" some years back, published an article in its newsletter and put that online!     An email to the Chairman, and I'm in touch with their member who has a collection of these things!!   AND circuit digrams!!!   He's glad to help, so maybe my Crypton will be up and running soon!   I'll keep you informed!

JOhn

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The space for each component is labelled on the PCB, so the burnt one is "R1".  It has got so hot that all the painted colour codes have burnt off!  

Rather than try to work out the circuit from the board, which is like unravelling spaghetti, I'm hoping that the diagram from my contact in Fairford will help.    He has alreday told me that the burnt resistor was 22 Ohms, but both he and the Vintage Radio guys say that it will have burnt because another component has gone rogue.   But none are so obviously, or slightly, burnt to give me a clue.     When the diagram is available, I'll hope that expert advice will allow an eductaed guess at which parts need replacement.

There must have been specific protocols to check the boards, as each one has several little posts, mared "TP" whihc I am told stands for "Touch point".  The techniocioan would use them to input a signal that could be analysed  at a different point, showing where a fault was.   But I fear that signal will have needed something that generated a sine wave or something.     And anyway, I think I will need to find someone who is competent to unsolder and resolder new components - they may have such a test device.

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usually called test point and used to monitor a signal at a particular part of the cct. Very useful for setting up and diagnosis when things go wrong. 
Can you trace the track on the other side of the PCB from the burnt resistor  to see where it goes? Is the PCB track ok and not burnt, if it is it can be repaired quite easily.

Mike

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No sign of 'burning' of any of the tracks.   I don't know what they should look like, and some appear "crinkled", and they are of course very convoluted, in three diemensions!.   Here's a closeup of the back of B8 with the position of R1 marked.     You can see that some trackes are smooth, while others appear 'crinkled', including one to R1 (right contact and above it),

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But there are many others, all over the board.  Are these 'burnt' tracks?

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Now, extraordinary developments!  My contact, Nigel, of the  Fairford MC, has sent me pages of information about Board8, that describe it as "the timebase and horizontal amplifier"!  He includes a wiring diagram!

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As I hope you can see Resistor R1 is top left.    Nigel also sends me eight other pages, two of 'Fault Finding' notes, and five describing the board, it's function and operation!  But alas!  I am incompetent to interpret them, I just don't know enough electronics to understand.     If youi, Sam, or anyone else wishes, I'll either post them here, or send them to you which might be easier to read.   If you would like to see the pages, please PM me your email address, as I can't send documents by PM.

In the words of Churchill, appropriate today, VE day,  "This is not the end. It is not even the beginning of the end. but it is, perhaps, the end of the beginning!"

Thnaks for your continuing help!

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As I said, Iain, PMs won't support enclosed files.

If you would send me your email address by PM, I will send you all the papers if that is your wish!

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Hi John,

it is entirely possible that the Resistor R1 has simply been cooking over the years and finally popped for no other reason than being fed up.

Perhaps it was a little under rated power wise (t save money - just like a TRiumph)

 

Roger

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