Test Equipment Anonymous (TEA) group therapy thread

[med6753]

Yep, true. I guess I'll go with a single 100uf. As long as the circuit regulates and the ripple is under 10mV p-p call it good. 

[bd139]

Just make sure it’s a 105oC as it’s going inside a cooker 

[Saskia]

@Ice-Tea
do you by chance have an agilent / keysight N6700 series mainframe ?

Thx

[med6753]

Just make sure it’s a 105oC as it’s going inside a cooker 

I always try to use 105C if available and yes, this little guy is definitely a cooker.  Packed real tight and no fan. 

[Brumby]

Nah ... it has multiple fans....

All of us lot living vicariously.   

[madao]

yes  310(A) is hottest Tek for ever 

I have two  310 (one is non A, early model with selenium rectifier, it works, but bumblebee capacitor is already replaced.)

Bumblebee in pictures is not orginal, replicas.

[tautech]

Bumblebee in pictures is not orginal, replicas.

Them caps ? You must be shitting me ! Really ? 

[capt bullshot]

In the meantime I had some success with the K238:

Still somewhat short on time, I checked the spare analog board that Ice-Tea supplied. It's output was stuck at +/- 2V or +/-  15V (depending on range and polarity setting). Some systematic bug hunting lead to a stuck output on this LT1057 OpAmp. Since I don't have the exact replacement readily available, I tried a jelly bean TL072. This was a partial success, the 1.5V range worked then, but was about 10% off. More hunting found an open circuit within the feedback path. Fixing this (with that ugly bodge wire you might notice) made all ranges work again. Yes, the TL072 isn't soldered, I just stuffed it into the PCB with slightly bent pins to make it easier to replace with the correct one, for now it's just a bodge for testing.

[capt bullshot]

And in case you haven't seen that yet (there's some K23x teardown / repair threads in this forum), some high impedance (10G resistor, teflon standoffs and COTO relays) goodness:

[madao]

Bumblebee in pictures is not orginal, replicas.

Them caps ? You must be shitting me ! Really ? 

Yes, it is  replicas..  i must looking  pictures of "birth" of replicas....found :-)

Last pic show orginal bumblebee..

[Fungus]

As I see it my choices for replacement could be 3/33uf, 2/47uf, or 1/100uf. Given that modern capacitors tend have very low ESR I could probably get away with 1/100uf but I think best compromise would be 2/47uf. What does the group think? A single 100uf or two 47uf?

3x33uF

(obviously  )

[McBryce]

Today arrival one of these ACV and ACA Digital LCD build-in meters.
I've bought this one in the bay:

Product type: D69-2049



Before hooking it up to the mains voltage I did some checking first.
Opening was easy, just some plastic snap-in tongues.
I've found some solder debris and one bent snap-in tongue:



This is the top view of the pcbs. I took them apart to check the spacing in the mains section but I missed it to take some pictures.     However, the clearings are looking reasonable to me, the lines to the full bridge rectifier are on the opposite sides of the pcb. All other clearings are reasonable. The LC Display is connected via zebra stripes to the PCB and LEDs were used as a light source together with a diffusor.
I have also applied some ferrules to the cables of the current sensing transformer.



I hokked it up then to my variac and around 180VAC it is starting working. Compared to my BM235 it is a bit off, but this can be eventually calibrated out. On the left 225VAC, zoom to the display which is nice and crisp and on the right 258VAC.



I'm not hundred percent convinced about it but honestly I'd expected worse. As you can see, on the front on the right side there is a little switch. I've shortened the leads of this switch, because right on the other pcb/side there were the leads of the green connector (incoming mains). The space between them are now good 7mm throgh air, before it was more likely 3-4mm.

I'm thinking about purchaising another two of them so I can measure then in my new lab the incoming 3-phase mains voltages and currents.

I have a very similar device that's been connected to my Labs main power cable for about two years without an issue. I checked it before connecting it, but the general quality was good enough, didn't need to upgrade or reflow any parts. The one I have also displays the power factor: https://www.ebay.de/itm/AC-20A-100V-LCD-Digital-Volt-Voltage-Watt-Current-Power-Meter-Ammeter-Voltme-MW/203093560267

McBryce.

[GreyWoolfe]

Skill with firearms isn't going to be the reason the young lady is in the clip. Yes, the pun was deliberate. No, I don't care if you don't like puns.

People who like puns never care how much suffering they are inflicting on others. For this they should be punnished.

Everyone knows that the beauty of a pun is in the OY of the beholder.

[med6753]

Bumblebee in pictures is not orginal, replicas.

Them caps ? You must be shitting me ! Really ? 

Yes, it is  replicas..  i must looking  pictures of "birth" of replicas....found :-)

Last pic show orginal bumblebee..

Replica bumblebees? I guess that's to give audiophools "warm fuzzies"

[mnementh]

RANDOM MODE:

Just stumbled across this at Homeowner Hell while shopping moulding for a bathroom project:
https://www.homedepot.ca/product/alexandria-moulding-metal-flat-bar-mira-lustre-1-8-inch-x-1-inch-x-8-ft-/1000675915

8 feet of 1/8" x 1" clear anodized aluminum bar stock for ~US$12. Simply fabulous...   

mnem
 

What is it that makes you remark on it? Aluminium Warehouse here (not the cheapest nor the best metals supplier) has 2.5m lengths of the same for £8.36 (ex VAT, about $14 CAD, $10.80 USD), £10.03 (inc VAT, $17.10 CAD, $12.96 USD). So it's a fair price, but not an especially good one.

Or is it just that it is shiny? 

Cheap AND shiny AND readily available (Home Despot is like Tim Horton's up here; one on every other block) AND thick enough to tap a hole into but thin enough to bend in a bench vise AND just the right size for 1000 uses from brackets to spacers to impromptu heat sinks...

But mostly the cheap and readily available part. 

mnem
Everything is raw material.

[mnementh]

The link is not working, I'm getting Access Denied error report on my PC.

Hmmm... link still works here (and when I link in from the Jersey side VPN); no idea why it doesn't over there. I thought Ontario province was one of the colonies the motherland still actually liked...? 

mnem
 

[mnementh]

Skill with firearms isn't going to be the reason the young lady is in the clip. Yes, the pun was deliberate. No, I don't care if you don't like puns.

The sad part is... the guys that video is made for aren't even looking at her nicely balanced assets... 

mnem
 

[med6753]

Skill with firearms isn't going to be the reason the young lady is in the clip. Yes, the pun was deliberate. No, I don't care if you don't like puns.

The sad part is... the guys that video is made for aren't even looking at her nicely balanced assets... 

mnem
 

I just went back and looked at the GIF. I didn't realize she was firing a gun. 

[mnementh]

That's because you are a "normal" red-blooded 'merkin boy.

mnem
Well... to certain standards of "normal"...

[ch_scr]

Skill with firearms isn't going to be the reason the young lady is in the clip. Yes, the pun was deliberate. No, I don't care if you don't like puns.

The sad part is... the guys that video is made for aren't even looking at her nicely balanced assets... 

mnem
 

I just went back and looked at the GIF. I didn't realize she was firing a gun. 

How has NOBODY said by now she looks a bit like a certain video game archaeologist?

[mnementh]

Nope. She's entirely too angry-looking. Lara's always happiest when emptying clips hand-over-fist. 

mnem
 

[mnementh]

The interesting bit is while that's true you can replace nearly all of them with boring old silicon ones with a bit of bias adjustment.

In principle, you can do the same with valves and MOSFETs... 

mnem
Just HOW DEEP down that rabbit-hole are you willing to go...?

[mnementh]

I was looking over the circuit for the Type 310A and I noticed something unusual in the -150V reference circuit. C601 consists of three individual dual 15uf cans in parallel for a total effective capacitance of 90uf. This was probably done to achieve very low ESR. As I see it my choices for replacement could be 3/33uf, 2/47uf, or 1/100uf. Given that modern capacitors tend have very low ESR I could probably get away with 1/100uf but I think best compromise would be 2/47uf. What does the group think? A single 100uf or two 47uf?

I'd say 2 47s... as you surmised, lower ESR but as importantly larger mass and surface area to dissipate heat from smoothing all that ripple.

EDIT: Remember that low-ESR is important, but thin leads also affect performance with brute-force filtering. Radial caps are intended to be soldered to a PCB with lead lengths of 1-2mm; thin leads make very little difference over that short a length. Wiring to standoffs makes lead length long enough that lead diameter matters; paralleling two caps makes that much less of a concern.

mnem
Smooth Ripple... hmmm... 

[Cerebus]

RANDOM MODE:

Just stumbled across this at Homeowner Hell while shopping moulding for a bathroom project:
https://www.homedepot.ca/product/alexandria-moulding-metal-flat-bar-mira-lustre-1-8-inch-x-1-inch-x-8-ft-/1000675915

8 feet of 1/8" x 1" clear anodized aluminum bar stock for ~US$12. Simply fabulous...   

mnem
 

What is it that makes you remark on it? Aluminium Warehouse here (not the cheapest nor the best metals supplier) has 2.5m lengths of the same for £8.36 (ex VAT, about $14 CAD, $10.80 USD), £10.03 (inc VAT, $17.10 CAD, $12.96 USD). So it's a fair price, but not an especially good one.

Or is it just that it is shiny? 

Cheap AND shiny AND readily available (Home Despot is like Tim Horton's up here; one on every other block) AND thick enough to tap a hole into but thin enough to bend in a bench vise AND just the right size for 1000 uses from brackets to spacers to impromptu heat sinks...

But mostly the cheap and readily available part. 

mnem
Everything is raw material.

Fair enough, just couldn't see why you'd got excited so easily. Now, if they'd dye transferred My Little Ponies into the wet unsealed anodising I'd have quite understood. 

I bought a 1m piece of similar anodised stock from B&Q, the UK equivalent of the Homeless Despot, for a ridiculously inflated price when I needed to make some brackets to tie the box room shelving back to the wall (If BD139 has a 'cupboard of doom' I have a 'box room of doom'). Criteria was similar, must be hand/vice bendable. I was a bit unthinking in grabbing it and of course with bending the anodisation cracked horribly. Not enough to be a mechanical problem, it's sat there for 15 years performing quite adequately, but I know it's sitting there hiding behind all the crap taunting me that I should have known better than to use anodised for something I was going to put a bunch of small radius 90º bends in.

(Annoyingly my spelling checker believes that anodised is a word, also anodized, but not anodisation or anodization.)

[mnementh]

Yeah... there's better solutions for some things for sure. But having it handy is important.

Where I lived in the Finger Lakes there was a metal shop nearby that did a lot of custom heliarc-welded aluminum ductwork (plenums, buffalo boots, heat-exchanger housings and condensate trays, etc); I'd go in there every few months and buy a trunkload of their off-cuts by the pound. They'd let me run bigger cuts through the shear for free; I'd usually come away with several dozen 4-ft strips of 030-032" med-hard sheet in 1/2", 3/4" and 1" widths just because it was so convenient for a million random things.

mnem