New scope

Sylvia Else wrote: =============

** I have four scopes all l over that age. Two are Aussie made BWDs and the third a NLS mini-scope made in the USA. The oldest I built myself 50 yeara ago. All are working fine. ** Giant step backwards for any low cost model.

The transistor you need can be bought from WES Components in Summer Hill. Failures are due to time and self heating effects.

I have had to replace half a dozen to get an 80s Taiwanese scope going again. Damn poor design.

...... Phil

Yes, the problem is not sourcing another one, it's a question whether doing so would be a waste of money and/or effort if it's going to fail again before long. It's not even as if it's had that much use since I last repaired it.

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** Then do so.

** Wot - $3 and half an hour? ** Dunno wot POS you bought - big secret ?

My BWDs ( models 821 & 824 ) have had zero repair in 20 years. The mini-scope none in 30.

If an analog scope is all you need and are used to - don't change.

...... Phil

Hardly a secret, I posted the circuit diagram of the X final amplifier previously. It's a Hameg HM203-5.

On closer examination, it looks as if it wasn't the transistor I replaced that's failed, but the corresponding one on the other half of the output (half drives left of centre, half drives right of centre). Which makes a kind of sense. So I'll try repairing it after all.

Also, the circuit diagram specifies BF472, but the transistor itself is a BF470, which is a somewhat lower voltage variant. Perhaps the accountants got involved in the design, and I'm paying the price.

Sylvia.

On a sunny day (Sat, 21 Aug 2021 14:06:35 +1000) it happened Sylvia Else wrote in :

Ha! I Have a Trio CS1562A 10 MHz dual channel analog scope, and is all I ever needed at home. Fix your analog scope if you can!

There are cheap digital ones, USB PC is not practical. All depends on what you do. What counts most is understanding of what you do,

Well I designed and build scope-pic:

Not as good as my analog, but was fun to build, never use it though :-) Most RF (radio) stuff can be done with an rtl-sdr USB stick and software spectrum analyzer (is what I do).

tons of software exists online and free for that.

But if I needed a new scope I would go for a stand-alone, not a PC based one. Isolation for a start.

There are cheap Rigols some you could even modify in software to get more bandwidth IIRC Do not remember a model number right now, oh,

So if I needed a scope I would go for that perhaps ;-) Just for fun.

Does not J. Larkin have one?

Sylvia Else wrote: =================

** Very good scopes.

Even have full Mumetal shielding on the tube - unlike Asian scopes.

** Good. ** BF472 from WES = about $1.25

Maybe buy a few, if they are used elsewhere.

..... Phil

I just wish it were easier to repair. At first sight, it appears quite modular, with plugs and sockets. Then one notices the multiple wires soldered directly to boards. The power transformer has wires soldered directly to more than one board. I even have to wonder how they managed to assemble it, unless they used special right-angle soldering irons.

Sylvia.

The Analog Discovery 2 is very good. I have one I uses with an old Asus notebook PC running Linux, it makes a very portable and capable package.

Though in the office, the four channel Rigol is more convenient.

--
Cheers 
Clive

+1 what Jan said. Plus digital scopes can tell lies; analogue ones don't. And reparability is a major boon, which is where vintage test gear scores highly.

--

"By 2030, you will own nothing and be happy about it."

- Klaus Schwab, World Economic Forum CEO.

Sylvia Else wrote: =================

** Typical German manufacture. They once made elaborate bomb fuses in WW2 that would trigger the explosives if anyone tried to defuse them.

Pure bastardry.

..... Phil

I like a scope with a screen and knobs. The Rigols are great. We haven't had trouble with one yet, out of a dozen at least.

Sharp color traces, infinite storage, cursors, time and voltage precision, signal averaging, all are wonderful compared to an old analog scope. And you can lift one with one hand.

--

Father Brown's figure remained quite dark and still;  
but in that instant he had lost his head. His head was 
always most valuable when he had lost it.

So far, none of our digital scopes have needed repair. Analog scopes break a lot.

--

Father Brown's figure remained quite dark and still;  
but in that instant he had lost his head. His head was 
always most valuable when he had lost it.

On a sunny day (Sat, 21 Aug 2021 08:21:26 -0700) it happened snipped-for-privacy@highlandsniptechnology.com wrote in :

Not sure that goes, my Trio is from 1979 or so and only needed fixing after I accidently sparked to a channel from a TV booster tube. Was on all day for TV repair in my shop, is on here now every now and then:

I destroyed the graticule (soldering station dropped on it) and made a new one myself from plexiglass.

Maybe, but they're all still young so it's not a fair comparison against say a Tek or a Philips or even a Hameg, many of which are still going strong 40+ years on. I can't see anything made in China lasting a fraction of that.

Any analogue scope made after about 1970 you should be able to lift with one hand! (and you can't have "infinite storage" either). --

"By 2030, you will own nothing and be happy about it."

- Klaus Schwab, World Economic Forum CEO.

Most of our old analog scopes died. I have a collection of big old Teks, few of which still work. Telequipments, Kikusuis, Philips, HPs weren't very reliable compared to modern digitals. There isn't actually much inside a 50 MHz scope now.

Failure rate on Rigols so far has been zero. I did see one at another site (Lily Drone, rip) with a smashed screen.

That quote is absurd. People like to own stuff. I bet that Schwab guy owns a lot of things in 2030.

2030 is only 9 years off.

--

Father Brown's figure remained quite dark and still;  
but in that instant he had lost his head. His head was 
always most valuable when he had lost it.

Further examination shows that it's actually the corresponding transistor in the other half of the X-drive circuit. Which makes a warped kind of sense, so I will try replacing it.

Sylvia.

It takes a scope to fix a scope.

--

Father Brown's figure remained quite dark and still;  
but in that instant he had lost his head. His head was 
always most valuable when he had lost it.

Sometimes, perhaps. But in this case, the symptom is that half the x-axis doesn't get used, with a bright dot in the middle instead. And I already knew that failure of a transistor in the final x-axis amplifier could cause this.

Sylvia.

snipped-for-privacy@highlandsniptechnology.com wrote: ===================================

** LOL !! JL always thinks in such dumb cliches.

One of my nice analog scopes developed a sudden fault about 30 years ago - no trace. Having a schem and being already familiar with it's insides, I checked a few voltages with a DMM. Soon found the Y amp outputs were way out of balance.

Checked every BJT for junctions and C-E shorts - no luck. Just for fun, I next tested every 1/3 watt MF resistor. Low probability there. However, one 22kohm ( with about 50VDC normally across ) it tested open.

When replaced, my normal program resumed.

..... Phil