Test Equipment Anonymous (TEA) group therapy thread

[Specmaster]

Ah the badlands. Outside the M25 is risky business. Should build a wall around it 

1000% this, it will keep all of you Londoners locked in and out of our hair, we're getting too much of your London style of crime these days 

[Specmaster]

Beware the Rindsmilchübersättigungsübelkeit! I drank coffee with cow extract until I could not have gotten down another cup. Since then, 90% black and I'm fine.

This is now my favourite German compound word. Suffer badly from it to the point I drink soya milk.

Well, according to my Mum, Soya is no good for you and can actually be dangerous to humans, are you human or what 

[bd139]

Beware the Rindsmilchübersättigungsübelkeit! I drank coffee with cow extract until I could not have gotten down another cup. Since then, 90% black and I'm fine.

This is now my favourite German compound word. Suffer badly from it to the point I drink soya milk.

Well, according to my Mum, Soya is no good for you and can actually be dangerous to humans, are you human or what 

Everything has an LD50 

[mnementh]

BLEEEEARRRRGHHH!!! Black coffee is for bitter people with dried up little souls. Like Sid. 

You rang. Sitting here drinking the stuff 

Engineers and IT folk exist on the stuff mostly.

Edit: med knows how to coffee like an engineer 

Apparently I am a heathen and the equal of an audiophool when it comes to coffee.  Folger's medium roast made in a Bunn coffee maker and served with almond/coconut milk and Truvia-----iced.

(Drops to the ground immediately and army crawls out to avoid incoming from nmem's SBC-soggy boot cannon)

We'll cut you a little slack, old friend. Medical grounds trumps coffee grounds.  

mnem

*prepares for the inevitable and
well-deserved volley of inbound SOBs*

[bd139]

Ah the badlands. Outside the M25 is risky business. Should build a wall around it 

1000% this, it will keep all of you Londoners locked in and out of our hair, we're getting too much of your London style of crime these days 

Hey we like our extra holes here.

Actually saying that, where I’m moving to is in the background in this Guardian article 

https://www.theguardian.com/uk-news/2019/mar/23/isleworth-stabbing-teenager-killed-in-west-london

[Specmaster]

Beware the Rindsmilchübersättigungsübelkeit! I drank coffee with cow extract until I could not have gotten down another cup. Since then, 90% black and I'm fine.

This is now my favourite German compound word. Suffer badly from it to the point I drink soya milk.

Well, according to my Mum, Soya is no good for you and can actually be dangerous to humans, are you human or what 

Everything has an LD50 

True, but Soya is one thing I won't touch following Mums warning, right or wrong, I heeded her warning.

[Specmaster]

Ah the badlands. Outside the M25 is risky business. Should build a wall around it 

1000% this, it will keep all of you Londoners locked in and out of our hair, we're getting too much of your London style of crime these days 

Hey we like our extra holes here.

Actually saying that, where I’m moving to is in the background in this Guardian article 

https://www.theguardian.com/uk-news/2019/mar/23/isleworth-stabbing-teenager-killed-in-west-london

Yeah, thats what I'm talking about, we have had a massive increase in that type of crime of late, last week we had a teenager stabbed just 2 streets away, air ambulance was in attendance and a complete road sealed off with police tape for almost 24 hours and a huge Police presence, about 6 or 7 cars, including a under cover car, which blew its cover because of the flashing blue lights in the windows and sidelights.

[bd139]

Well stranger things has finished now. There’s nothing else to do apart from stab each other.

Anyway on topic, I spent the last 2 hours filling up LTspice with bits of Farnell TM6 and comparing to measurements. It appears unfortunately that the chopper is likely to be faulty. It dumps a hell of a lot of current into the two LEDs and I think they have got dim and it’s not shuffling enough electrons through. Going to attempt to work out a way of proving this one way or another…. TBC…

Edit: also due to the stupid high impedance I need to make a bob pease FET probe…

[mansaxel]

Would just like to add that apart from all that, I get to choose WHEN I want to listen to content. Life is too complicated in 2022 to conform to a media company's schedule. I do not own a TV license as of Friday this week either. That is gone and dead too.

On TE, just found the Farnell power supply I bought under a bed. Forgot to pack that 

I agree fully. This is a very strong trend. Media companies are struggling to adapt. We're very aware of it.

No, they are doing everything thing they can except adapt;

Again: I'm talking about Europe, specifically Sweden, and you're an ocean away. Here, our directors of Various Things note that the viewer count on online is higher than via broadcast, and take action.  So, there.

[mnementh]

That doesn't mean that the legislation they infect the rest of the world with won't affect you... it'll just take a wee bit longer.   

mnem
no further comment.

[factory]

This afternoon I've been sorting out two of the problems with the Systron Donner 6016 counter, which I got at a local radio sale earlier this year.







First was easy, one display choob was stuck showing two & a decimal point (not used in this position at all), I borrowed it's neighbour last week to confirm the decoder/driver IC was fine, the bad choob has internal shorts. Yesterday I had located a board with some spares, fitted one of these and that cured it.

Second was the broken off reset switch, I had already found a similar style button cap some time ago, from a very dead Farnell sig gen.
Next was disassembly of the sides, front panel, BNC & control, to get to the switches, the lower switch bank & BNC input board had to moved out of the way, to access the top switch bar.



Top side required removal of the display counter board & BCD output board, to get to the rear of the mainboard for soldering.



With the front panel trim removed I noticed a hidden switch, this is the auto switch in the 6057 counter, in the 6016 it is cut off flush where the button would attach. I did try this switch with the counter partially reassembled and it does nothing, must be other bits missing on the plug-in boards.



Now I had the switch removed I had to search my spares for a replacement, I found some Toko-Schadow ones from a Sanyo music centre (that we recycled after we failed to sell complete, this was left with the house when we moved in), the pins were too long, but they are easy to take apart & swap bits over with the broken switch, must be good quality as neither had any tarnished contacts.







Here is the repaired switch installed, still need to file the button down.



With the counter mostly reassembled I wanted to check the some transformer connections, the diagrams for the 6016 show a 6.3Vac winding (this is used in the 6057), I found 7Vac-ish on the display board and checking around the rectifier board, quickly found the other voltages, that are used by the mini-CRT in the 6057, so yes these counters appear to have the exact same transformer fitted.

Bonus picture of the 200MHz input board.



David

[mnementh]

Well stranger things has finished now. There’s nothing else to do apart from stab each other.

Anyway on topic, I spent the last 2 hours filling up LTspice with bits of Farnell TM6 and comparing to measurements. It appears unfortunately that the chopper is likely to be faulty. It dumps a hell of a lot of current into the two LEDs and I think they have got dim and it’s not shuffling enough electrons through. Going to attempt to work out a way of proving this one way or another…. TBC…

Edit: also due to the stupid high impedance I need to make a bob pease FET probe…

https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg3623200/?topicseen#msg3623200

Here you go buddy... or maybe you should just get the 60dBm FET probe and call it a day.

mnem
 

[Saskia]

Re public broadcast companies: they extort about 10% of my husband's pension per month even though we do not own a TV and do not watch their programs.
Their programs are made out of propaganda - when I was still working as a journalist I received a letter from our union presidents that it was our duty to make politics and do single sided news to push a political agenda. Then they told us whom to vote for. Which is when I quit.
As far as I am concerned, our broadcast companies can go to where the sun does not shine, and we currently have this huge scandal where they uncovered a huge corruption scandal within one of those state owned public broadcast thingies costing taxpayers half a million per month.

Back to topic:
Korad 3005D PSU, obtained for 25 quid new, tested working. Crosschecked with Fluke 79III which I obtained from our forum friend Neomys Sapiens.

[mnementh]

Ah the badlands. Outside the M25 is risky business. Should build a wall around it 

1000% this, it will keep all of you Londoners locked in and out of our hair, we're getting too much of your London style of crime these days 

Hey we like our extra holes here.

Actually saying that, where I’m moving to is in the background in this Guardian article 

https://www.theguardian.com/uk-news/2019/mar/23/isleworth-stabbing-teenager-killed-in-west-london

Here you go buddy. Just be ready for the zombie apocalypse that comes along with it... 

mnem
an actual dwagon-cave is looking better and better all the time...

[Saskia]

guess why I want an old missile silo (with the Peacekeeper installed) plus all the perimeter defenses ...

TE: Uni-T 116C SMD tester for about 20€. Not much money killed, however it might come handy for quick debugging on dead mainboards.
Such as the Z170 pro that was fished out of the dump. What's good about it: it came with a cooler, initial visual inspection points towards Alpenfoen Ben Nevis which is about 20 quid.
and which passes visual inspection. There should also be a celeron on board which I still need to test. I don't remember if I have an intel 100 chipset board left, though.

[med6753]

2235 update.

The cabinet has been painted. While I'm waiting for the parts to arrive I decided to put the scope back together.

So exterior cleaning is complete.

[Saskia]

looks nice, Med.

another quick update: plastics protectors for the STTNG pinball are on their way.
Replacement "gun" housing (the ball shooter thingie on STTNG and T2 pinballs) has been located thanks to someone in the pinball forum. Plus, the other, normally unobtainium parts to complete this thing, have been located down under and are also on their way. Let's hope they get here soon.

in other news, I caught a bloody lung bug. I don't think it's our fav bug as I don't have fever. Just a bloody headache.

[Saskia]

ah yes, lest I forget: there was a discussion of tapedecks and HX Pro a while back on discord. Anyone on this side of the big pond in need of some ? I have a stack of Yamaha tapedecks, all tested working (except for the counter on the KX260) that would be available to forum friends at very reasonable sums (i.e.€30 - 60 depending on model).
Drop me a note if interested.

[bd139]

It's amazing how far you can get with a service manual and a computer and the test gear stuffed in a box somewhere. Full Farnell TM6 RF voltmeter front end simulation with chopper. Interesting idea. So there are two reasonably matched diodes. These are used to generate a DC voltage proportional to the positive and negative peaks of the RF signal. These are then chopped to give an amplitude which is proportional to the signal peak to peak voltage which is independent of the offset of the next two uA709 based amplifier stages and somewhat unrelated to how much mismatch there is in the diodes. The offset of these opamps can be a good 1-5mV which at 1mV signal levels would render a straight DC amplifier useless. But offset is relative consistent with loading which is consistent here due to a JFET buffer stage added in front of the next opamp.



So for the verification phase for this part of the circuit I will stall the chopper by popping the LEDs out of the block and sticking tape over the hole and inject a 500KHz signal at 1V p-p into the front end and measure the differential signal post rectification with the 34401A. The negative and positive rectified voltages should be the same or at least really close. I will then "unstall" the chopper oscillator and use a DIY FET probe to measure the peak to peak amplitude of the signal at the 100M resistor. This should be at least approximately the same as the sum of the negative and positive rectified voltages.

If that works it's time to reverse engineer the next circuit in the chain.

Now I will write this in notes and ignore it for a couple of weeks. Bah humbug.

Edit: wonder if I should do another thread for this one...

[Wolfgang]

Well stranger things has finished now. There’s nothing else to do apart from stab each other.

Anyway on topic, I spent the last 2 hours filling up LTspice with bits of Farnell TM6 and comparing to measurements. It appears unfortunately that the chopper is likely to be faulty. It dumps a hell of a lot of current into the two LEDs and I think they have got dim and it’s not shuffling enough electrons through. Going to attempt to work out a way of proving this one way or another…. TBC…

Edit: also due to the stupid high impedance I need to make a bob pease FET probe…

Probably capacitance is a problem too. Pease probes can be made really good, I used mine to check the voltages within high performance crystal oscillators without detuning or loading them. Properly built they can have < 1pF and several MOhms.

[bd139]

Well stranger things has finished now. There’s nothing else to do apart from stab each other.

Anyway on topic, I spent the last 2 hours filling up LTspice with bits of Farnell TM6 and comparing to measurements. It appears unfortunately that the chopper is likely to be faulty. It dumps a hell of a lot of current into the two LEDs and I think they have got dim and it’s not shuffling enough electrons through. Going to attempt to work out a way of proving this one way or another…. TBC…

Edit: also due to the stupid high impedance I need to make a bob pease FET probe…

Probably capacitance is a problem too. Pease probes can be made really good, I used mine to check the voltages within high performance crystal oscillators without detuning or loading them. Properly built they can have < 1pF and several MOhms.

Indeed. I built one a few years back. Design reference here:



I have an absolute bucket load of 2N3823's VHF JFETs floating around waiting to be used so good timing

[mansaxel]

It's amazing how far you can get with a service manual and a computer and the test gear stuffed in a box somewhere. Full Farnell TM6 RF voltmeter front end simulation with chopper. Interesting idea.

The chopper style amp is a quite clever thing.  Much like the lathe being able to turn (heh) out parts with better precision than it has in itself, some circuits really are about making the sum greater than the parts, sometimes, like in the chopper, by taking what at first glance is far from the straightest path to target.

[Specmaster]

Well stranger things has finished now. There’s nothing else to do apart from stab each other.

Anyway on topic, I spent the last 2 hours filling up LTspice with bits of Farnell TM6 and comparing to measurements. It appears unfortunately that the chopper is likely to be faulty. It dumps a hell of a lot of current into the two LEDs and I think they have got dim and it’s not shuffling enough electrons through. Going to attempt to work out a way of proving this one way or another…. TBC…

Edit: also due to the stupid high impedance I need to make a bob pease FET probe…

I need to reacquaint myself with LT-Spice, I did start it a while ago and gave up because I found it had a steep learning curve and couldn't be arsed at the time, to much going on, but maybe the time is coming that I could get started again.

[Specmaster]

2235 update.

The cabinet has been painted. While I'm waiting for the parts to arrive I decided to put the scope back together.

So exterior cleaning is complete.

Wow, that looks like a new one now, well done.

[Cerebus]

Beware the Rindsmilchübersättigungsübelkeit! I drank coffee with cow extract until I could not have gotten down another cup. Since then, 90% black and I'm fine.

This is now my favourite German compound word. Suffer badly from it to the point I drink soya milk.

Well, according to my Mum, Soya is no good for you and can actually be dangerous to humans, are you human or what 

How quickly some people forget:

Ook ook it is then