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Old 16th Oct 2017, 4:49 am   #1
SkippedTheEULA
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Default Just found an Advance J1 signal generator - how do I check it out?

Just found an Advance J1 signal generator in the gutter. I'd love to get it working just for a laugh. I collect modern synthesizers and have done pot and part replacements on them but never touched valves. I have the schematics but not opened it yet. And definitley not turned it on yet. Can someone please point me in the direction of advice on restoring old valve gear. I am guessing I need to check the caps are all OK and isolate the power supply to check it if OK first.

What should I do?
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Old 16th Oct 2017, 8:34 am   #2
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Default Re: Just found an Advance J1 signal generator - how do I check it out?

You'll find the manual for the J1 in this thread:-

http://vintage-radio.net/forum/showthread.php?t=60414
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Old 17th Oct 2017, 10:57 pm   #3
SkippedTheEULA
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Default Re: Just found an Advance J1 signal generator - how do I check it out?

Yes thanks, I have two different manuals for the J1.
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Old 18th Oct 2017, 6:42 am   #4
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Default Re: Just found an Advance J1 signal generator - how do I check it out?

They're pretty simple but decent sig gen's. Here's how I'd go about it.

1) Take back off and give it a good visual check, IE no leaking caps burnt out resistors, if ok.
2) Power up, without V4 in, check you have somewhere around 200v AC on both V4 anode's.
3) If ok , V4 back in and power up on lamp limiter/variac starting at 60v AC whilst monitoring/measuring HT at C16/17 and also checking if C16/17 are getting hot. Slowly up/increase AC over an hour say till you get to 240v. If bulb in LL stays V bright or C16/17 get V hot turn off and check C16/17 for ESR/leakage/capacitance. If kaput replace. However I've two advance valve sig gens and havn't had to replace an electrolytic yet.
4) Once you have 250/260v HT check for sine OP. If no OP, check schematic/read manual and check voltages.

Obviously whilst mucking about with valve gear watch what your doing as there is 250v DC inside this that can hurt or even kill if you have a dicky heart. Keep left hand in pocket, on top of head or picking your nose, probe with right hand or even better for a begginner clip red lead onto wotuwantomeasure and then switch on. One further warning C16/17 and other caps could hold a charge after switch off and bite you.

Other than that these Advance sig gen's usually work after all the above and whilst not that accurate are pretty decent sig gen's.

Hope that helps, Andy.
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Old 18th Oct 2017, 8:24 am   #5
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Default Re: Just found an Advance J1 signal generator - how do I check it out?

Hello SkippedTheEULA,
Quote:
check valve voltages
-dont forget please, schematics values are measured with 20KOhms/Volt (analog) Voltmeter and DMMs have nowadays usually 10Mohms, 50x higher input resistance/load, so your measuring will have higher voltage values too -as you have in documents- and be care with high voltages!...
Regards, Karl
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Old 19th Oct 2017, 6:16 am   #6
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Default Re: Just found an Advance J1 signal generator - how do I check it out?

Good point Karl, missed that.

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Old 21st Oct 2017, 1:31 am   #7
SkippedTheEULA
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Default Re: Just found an Advance J1 signal generator - how do I check it out?

Quote:
Originally Posted by Diabolical Artificer View Post
They're pretty simple but decent sig gen's. Here's how I'd go about it.
This is all great advice Andy, thanks. Exactly what I was hoping someone experienced (and not electrocuted) could help me with.

Also hoping its rather inaccurate, apart from a bit of history I am interested in using it for BBC radiophonic workshop type sound design. Even though solid state and digital can do it far better.

Quote:
Originally Posted by karesz* View Post
dont forget please, schematics values are measured with 20KOhms/Volt (analog) Voltmeter and DMMs have nowadays usually 10Mohms, 50x higher input resistance/load, so your measuring will have higher voltage values too -as you have in documents- and be care with high voltages!...
Those old meters really affected the circuits back then! And don't worry, I'm quite terrified to check the J1 out. Very healthy fear.
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Old 23rd Oct 2017, 8:58 am   #8
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Default Re: Just found an Advance J1 signal generator - how do I check it out?

You'll be fine, no need to be terrified, every one of us on this forum has probably had a shock or three, (comes with the job/hobby) and lived to tell the tale. We have to warn you though, of the danger.

Your sig gen will be fine for tones, but very limited and boring. You need a few filters, VCA's and VFO's and not to mention a sequencer. Having said that I'm sure I read that Delia Derbyshire hated synth's and only used reel to reel tape recorders to alter sound samples. Apparantly the original Dr Who theme was done without a single synth. Check out this chap - https://www.youtube.com/watch?v=cudr9Y9lEMI&t=1300s if you like vintage analogue synth's and music synthesis.

Apologies for going off topic for a spell.

A.
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