What is on your workbench right now?

[Wombat]

Darn Tantalums.
Had to replace a whole bunch of them (most of them out of precaution) in a railway safety system.
Some of them started leaking current. Could be within a few days or months.
In this case 47uF/16V.
Replaced them all with Kemet.
View attachment 81949

Now I see why you are Solderdude.

 

[solderdude]

I've inhaled more solder fumes than fresh air on some days...
As a matter of speech...

 

[Soundstage]

iPad : distortion of -0.5dBFS 1kHz sine, 16bit, TPD dithered, 3.5mm jack analog output. Volume slider about 80%.

View attachment 78884

Is this as actually better than the famous Apple Dongle?
I am currently plugging the Dongle on my IPad...

 

[Wombat]

I see you are using your new fine tip temperature controlled soldering iron...


I have a story. A short one:

My father bought a soldering iron to solder some DIN speaker terminals in around 1974. He'd never soldered before but being a doctor, he figured it couldn't be too difficult- anyone should be able to do it. I remember looking at this brand new thing and being so jealous as I'd begged for a soldering iron for a while (I was about 7yo at the time). I wasn't allowed to go near it or touch it. It was "dangerous" apparently...

What frustrated me was, he tried to use it once and gave up, put it in its box with all the attachments up in the cupboard. It was teasing me.

He asked what I wanted for my birthday and I said the soldering iron. I guess he figured that was an easy gift- he had it already, so I got it. The rest is history but here is the soldering iron (scroll down):
























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Never used the "cutting" tip, maybe melted a bit of plastic with the "smoothing" tip, but went through quite a few soldering tips. I taught myself to solder with that iron. Even fine PCB work on boards I made from scratch (my mum hated ferric chloride stains). Lost count of how often the pistol grip got so hot it would burn my palm. Several years later saved up enough to get a proper fine tip iron and the temp controlled ones came later.

It is still the goto iron for big cap terminals, star earth points or soldering metal shields- nothing else has the grunt of that thing.

You guys are so pampered:

P.S. My workbench gathers dust, nowadays.

 

[KR500]

A Pass B1 Buffer that wants to be a radio antenna .

I finally got around to fixing this issue and am moving to put the B1 in a better case. Instead of having some larger caps on a daughter board I just soldered some Kemet caps directly to the Pass PCB. Then replaced the twisted pair solid copper I/O cable with shielded Mogami. Completely silent and works very well now

 

[restorer-john]

You guys are so pampered:


View attachment 81975





P.S. My workbench gathers dust, nowadays.

"You better be solderin' them leakin' water pipes agin Jethro! Don' let me catch you makin' them damn stereo thangs or you'll git anutha beat'n' "

 

[Doodski]

While discussing accuracy in meters in @watchnerd 's thread, I was testing various meters against my Time 1044 Voltage and Current calibrator. It has been a faithful device albeit seemingly a little hard on batteries of late. I put it down to poor batteries as a new 9V got rid of the "batt" symbol and all was well.

Or was it? Usually the testing is a quick confirmation, the 1044 is turned off and it's put away, often for many months. It's a physical hard switch and about six months ago, I replaced the 9V clip wire as it was getting a bit loose and I figured it was developing a resistance, enough to trigger the low batt event. Then I figured the 2.5mm external power switch could be the culprit as it had never been used so I poked the internal switch leaf NC contact, put a new battery in and the problem went away. Or did it?

Yesterday, I put a new battery in (again), lined up a few meters to test, and within a minute, the low batt indicator was on and it started giving erroneous readings. OK, there's a problem. So, I put a meter in series to monitor the current and one across the cell to watch the terminal voltage, turned it on and watched. All looked normal, around 40.00mA. I looked away and when I looked back, the "batt" indicator was on and the current consumption was 0.400A. Wait a minute, that's 400mA! And terminal voltage was below 8.2V. I repeated this several times to confirm. It was killing the batteries after a short delay.

It was time sensitive. I figured that extra 360mA at 9V (~3W) is going to produce some heat from something fast. Defintely don't power it from the bench supply unless I want smoke- the 9V battery was essentially its own current limiter. But it was somehow resetting and the unit worked perfectly after a minute's rest. There was a tiny smell I know when I sniffed the battery compartment. Tantalum caps. Bastards. I know you're in there!

View attachment 81939
So in I went. Off came the colletted brass/plastic knob (lovely little thing), the nut and I hoped the unit would come apart without having to peel off the front panel (that would wreck it). And what did I see? 4 tantalums, 20 years old, nice Wimas and a heap of 25 turn trimmers (8) and quality construction. A separate A/D board for the meter etc.

View attachment 81940

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In circuit testing of the tantalums showed ESR was normal, actually good, but I wasn't convinced. Fired it up without the display A/D board and the consumption went up to 400mA after about a minute. I waited for a bit and then felt the caps. Yes! The rail decoupling 10uF 35V tantalum feeding the LM10CLN was hot- really hot. (rail is 24V). So, replaced the little bastard with a lowish ESR Nichicon Fine Gold (so audiophile huh) and all is well again. Consumption is 16-24mA when not sourcing current, a far cry from the 400mA before. The other three 2.2uF 35V tantalums were fine (only seeing 3-5V) and in parts of the circuit where I might screw up the calibration, so I left them alone.

View attachment 81943
Some members wanted to see the internals of this little thing so here's a few more pics.

View attachment 81944
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Here's the little troublemaker- he's cost me about 6x 9V Alkaline batteries.

View attachment 81946

And my tester thinks it's a double diode with two different voltage drops...

Please email the company and ask what a recalibration will cost after your repair. I'm sooo curious.

 

[pma]

Is this as actually better than the famous Apple Dongle?
I am currently plugging the Dongle on my IPad...

Unfortunately I do not know the Apple Dongle. I am playing music from iPad either through analog jack or through lightning-USB cable (connected to iConnectivityAudio4+) and in both cases I have been pleasantly surprised by the good sound quality.

 

[Soundstage]

Unfortunately I do not know the Apple Dongle. I am playing music from iPad either through analog jack or through lightning-USB cable (connected to iConnectivityAudio4+) and in both cases I have been pleasantly surprised by the good sound quality.

I was referring to the review here:
https://www.audiosciencereview.com/...pple-vs-google-usb-c-headphone-adapters.5541/

It shows a SINAD of 99dB. How reliable is your measurement?
Thanks.

 

[pma]

I was referring to the review here:
https://www.audiosciencereview.com/...pple-vs-google-usb-c-headphone-adapters.5541/

It shows a SINAD of 99dB. How reliable is your measurement?
Thanks.

In the plot shown, THD is reliable. Noise is not optimized, so THD+N (reciprocal of the SINAD) is not reliable. It will be lower than shown, in fact.

 

[Soundstage]

In the plot shown, THD is reliable. Noise is not optimized, so THD+N (reciprocal of the SINAD) is not reliable. It will be lower than shown, in fact.

So under the SINAD metric the Ipad makes the perfect DAC, doesn’it?

 

[Rick Sykora]

Not much to mention on my bench, except I did bother to wire up a test fixture so I could do impedance measures for the DIY speaker builds...

Am ramping up as I get ready to test active speakers designs (not production speakers), so I need something more to test amplifier performance. Recently picked up some high wattage resistors and have some massive heat sinks for them. Was researching digital scopes and came across a review comment that stated a dedicated SA is a lot more sensitive (also stating that would need to spend about $1500). This is about 3 times what I was planning to spend and so started to look into it. After finding a couple of decent choices, started to wonder if I made the same spend, could I get a scope with "good enough" SA capability for audio. The weekend hit and had relatives visiting, so am now back in the hunt.

Any thoughts/suggestions? Really need something soon but want to get it right!

 

[GeorgeWalk]

 

[MarsianC#]

AKG K180.

Cable is already replaced (curly one from 990 Pro) and foam replaced. Sounds like sh!t! Needs tuning with more/less/other foam...

 

[Rick Sykora]

Was wrapped up in new equipment purchase in previous post, forgot to include this...

This is my first DIY amp. It is in my office and is headed to my workbench as the fan runs too often. Another DIYer that was building his own amps, suggested these Class D amps from Sure Electronics are almost as good as his design. Am not so sure...

 

[restorer-john]

Please email the company and ask what a recalibration will cost after your repair. I'm sooo curious.

I'd have to send it all the way from Australia to the UK and back, plus the cal/cert cost. Or use RS Components service at vast cost (it was done three times by them back in the day) It just isn't worth it, I'm not certifying sensors in jet engines like @March Audio was.

 

[Doodski]

I'd have to send it all the way from Australia to the UK and back, plus the cal/cert cost. Or use RS Components service at vast cost (it was done three times by them back in the day) It just isn't worth it, I'm not certifying sensors in jet engines like @March Audio was.

Okidoki. Why do you suppose they chose tantalum caps in the first place? Space/size? Accuracy? I'm familiar with tantalum caps but not really up to speed why in this application they would choose those.

 

[NTK]

Not much to mention on my bench, except I did bother to wire up a test fixture so I could do impedance measures for the DIY speaker builds...

Am ramping up as I get ready to test active speakers designs (not production speakers), so I need something more to test amplifier performance. Recently picked up some high wattage resistors and have some massive heat sinks for them. Was researching digital scopes and came across a review comment that stated a dedicated SA is a lot more sensitive (also stating that would need to spend about $1500). This is about 3 times what I was planning to spend and so started to look into it. After finding a couple of decent choices, started to wonder if I made the same spend, could I get a scope with "good enough" SA capability for audio. The weekend hit and had relatives visiting, so am now back in the hunt.

Any thoughts/suggestions? Really need something soon but want to get it right!

What measurements are you running?
Requirements:

• Voltage/current range
• Frequency bandwidth
• Resolution/accuracy
• Test signal generator? If required, what specs
• Anything else?

 

[restorer-john]

Why do you suppose they chose tantalum caps in the first place? Space/size?

20 years ago when this was made (it's still in production), it was likely low leakage, low ESR, high capacity in a small package, reliability etc.

But, as time has shown us, bead type tantalums are arguably one of the least long term reliable capacitor types, the get pinholes in the epoxy and explode or release lots of magic smoke. They can behave as everything from a resistor, to a zener diode when they go funky and modern electros are just as compact and in my opinion, more reliable.

Anything made in the 90s with bead tanatalums is a time bomb if it isn't already in landfill by now. I hate the little bastards.

 

[Rick Sykora]

What measurements are you running?
Requirements:

• Voltage/current range
• Frequency bandwidth
• Resolution/accuracy
• Test signal generator? If required, what specs
• Anything else?

Mainly looking to do functional and qualification testing and high level troubleshooting. As the amps are modular, will not be doing component level diagnosis or repair. Figure if I can run a decent power vs. distortion test, will cover a lot of territory. Currently just generating signals out of REW and Audigy sound card.