Test Equipment Anonymous (TEA) group therapy thread

[mnementh]

So is its name Huey, Dewey or Louie?

mnem
Off. Slightly.

[bd139]

Love that film

[med6753]

I received the frequency reference from nixiefreqq. Thanks pal! 

Here it is connected to the 7904 with the 7260 in tow. I tried connecting the reference to the reference input on the back of the 7260 and nothing happen. I made sure the switch was flipped to "external". I also tried it on the input on the back of the 1912A and again nothing.  What am I doing wrong? In both cases the switch was set to "external".  Me confused. 

I am a dope. I'm not thinking. Connecting the reference to the back of the counter just gives you a more accurate time base in which to measure other frequencies.   

[med6753]

So is its name Huey, Dewey or Louie?

mnem
Off. Slightly.

Like a lot of things today this has gone right over my head. 

[bd139]

https://en.wikipedia.org/wiki/Silent_Running

[med6753]

Never saw that movie. No wonder I didn't get it. 

[Neomys Sapiens]

Thanks for bringing these, Spec... lots of awesome shots there. I've been meaning to share this; I've kept these in the back of my desk since my dad (USAF Retired/COBOL programmer) gave them to me as a teenager. we occasionally play a few hands when he visits, but for the most part just a keepsake. If you're wondering, the date on the box is Oct 1979.

mnem
*back to the daily grind*

I have the equivalent one for armoured and other combat vehicles (GTA17-2-13). Beside it missing the box, everything is there. It has a nice typo: on the T54/55 card, user states are given as 'USSR and Warsaw Pack'.

[med6753]

So after several hours here's how the counters stack up against the PCOXO:

Fluke 7260A       10000.04kHz

Fluke 1912A       10000.05kHz

VC2000              9.99998MHz

2465DMS           9.999975MHz

Not too bad overall. The 2465DMS follows the VC2000 which makes sense. When I first got that scope years ago it was failing boot up for the counter being out of calibration. All I had at the time was the Chinese VC2000 so I had to use it along with the Heath IG-4244 to calibrate it. But now I can get a better cal now that I have this reference. Hello time nuttery. 

Oh...forgot about the Fluke 1900A. I'll have to get that guy warmed up. 

[bd139]

Hello time nuttery. 

Told you ... 


Ok I am 100% sold on the Hameg component tester / curve tracer now.

My current project ground to a halt miserably for another debugging session. Suspected 2n2219 failure. So stuff it on the chinese "transistor tester". Yeah looks fine. Still won't oscillate. Hmm. Stuff the Hameg across the B-E junction. Oh that's not right - should be a diode but apparently has turned into a resistor when reverse biased!



This is quickly becoming a very useful purchase.

[med6753]

I wasted most of my day too. Decided to swap out the vertical pre-amp board in that troublesome 465B to see if it would clear up the frequency roll off issues.

Good news is that the replacement board works. Bad news is still has the same symptoms. So I figure it's due to the failing caps in the PSU.
The capacitors are on order and should be here by Saturday. 

[Mr. Scram]

Royer converter win. This is why I need more Fluke 87s 

Think another 3 should do it. 

This little bugger runs ~ 85% efficient, no cooling required and delivers dual 15V rails at 20mA from 5V in. I've designed a feedback loop to give it precise voltage control but not added it yet. Too hot for more soldering today 

I thought you sold the 87V?

[bd139]

Nah didn't in the end. Needed it.

Have given up selling stuff. Had some serious asshattery. Plus I tend to end up needing it 

Edit: to note I have 5 DMMs at the moment plus two on power supplies and I ran out during this project ... figured not a good move to shift stuff.

Also got another 87 on the watch list.

Edit 2: I've actually sat down and though that I've long felt pressured into keeping things "trim" due to my bench being in the main living area in the house. This lead to me clearing out stuff which I inevitably end up needing. I'm not exactly broke so I don't need the cash income from it, but the pressure has been there from SWMBO mostly. Now that it is not dared to be spoken of and my kids are too busy staring at netflix to give a crap, the pressure is gone so fuck it I'm not selling anything!

[Mr. Scram]

I'm done buying TE for a while, just picked up a 2020 Ford Explorer ST (because you need 400HP and 415 lb-ft AWD SUV to haul your bicycle around).  Well, at least until my next paycheck 

A 2020 model? Does it happen to be a Delorean in disguise?

[bitseeker]

I'm done buying TE for a while, just picked up a 2020 Ford Explorer ST (because you need 400HP and 415 lb-ft AWD SUV to haul your bicycle around).  Well, at least until my next paycheck 

Congrats on the new wheels! It just occurred to me that the Explorer looks like a Range Rover. Although they used to own Land Rover (2000-2008), it's interesting that it looks like a 2012+ model.

[mnementh]

   I'm done buying TE for a while, just picked up a 2020 Ford Explorer ST (because you need 400HP and 415 lb-ft AWD SUV to haul your bicycle around).  Well, at least until my next paycheck 

A 2020 model? Does it happen to be a Delorean in disguise?

Naaahhh... this is the US of A; the land of "Instant Gratification" where patience is a myth and the hype train never even slows down, you just have to jump off/on and pray for the best. 

The next model year is "released" earlier and earlier every iteration; before I die, I fully expect to see next year's models being released for Christmas the year before. 

mnem
"Does that come with temporal lobe massagers for when my brain wants to explode...?"

[bd139]

Discovery... ?

[tggzzz]

I wasted most of my day too. Decided to swap out the vertical pre-amp board in that troublesome 465B to see if it would clear up the frequency roll off issues.

Good news is that the replacement board works. Bad news is still has the same symptoms. So I figure it's due to the failing caps in the PSU.
The capacitors are on order and should be here by Saturday.

Why would PSU caps reduce the high frequency performance?

Firstly I would check the contacts of the 20MHz switch, and nearby components.

If both channels are affected, I would start at the CRT Y plates and work towards the input,  one stage at a time, looking for lack of rolloff.

If only one channel is affected, I'd start at the attenuator output and work towards the CRT, looking for rolloff. It might be in the attenuator; jiggle the little buggers.

[tggzzz]

Hello time nuttery. 

Tee hee Sometimes people are so predictable.

[tggzzz]

Nah didn't in the end. Needed it.

Have given up selling stuff. Had some serious asshattery. Plus I tend to end up needing it 

Edit: to note I have 5 DMMs at the moment plus two on power supplies and I ran out during this project ... figured not a good move to shift stuff.

Also got another 87 on the watch list.

Edit 2: I've actually sat down and though that I've long felt pressured into keeping things "trim" due to my bench being in the main living area in the house. This lead to me clearing out stuff which I inevitably end up needing. I'm not exactly broke so I don't need the cash income from it, but the pressure has been there from SWMBO mostly. Now that it is not dared to be spoken of and my kids are too busy staring at netflix to give a crap, the pressure is gone so fuck it I'm not selling anything!

Tee hee Sometimes people are so predictable.

[med6753]

I wasted most of my day too. Decided to swap out the vertical pre-amp board in that troublesome 465B to see if it would clear up the frequency roll off issues.

Good news is that the replacement board works. Bad news is still has the same symptoms. So I figure it's due to the failing caps in the PSU.
The capacitors are on order and should be here by Saturday.

Why would PSU caps reduce the high frequency performance?

Firstly I would check the contacts of the 20MHz switch, and nearby components.

If both channels are affected, I would start at the CRT Y plates and work towards the input,  one stage at a time, looking for lack of rolloff.

If only one channel is affected, I'd start at the attenuator output and work towards the CRT, looking for rolloff. It might be in the attenuator; jiggle the little buggers.

It's both channels. The 20MHz switch goes along with the pre-amp board so that's not the issue. Yes, it could be something in the final Vertical amp but I'm going to wait until I get rid of all the 120Hz ripple that intermittently becomes visible on both traces. One thing at a time. First rule: Clean power then go after what's left. 

[BU508A]

[Ok I am 100% sold on the Hameg component tester / curve tracer now.

My current project ground to a halt miserably for another debugging session. Suspected 2n2219 failure. So stuff it on the chinese "transistor tester". Yeah looks fine. Still won't oscillate. Hmm. Stuff the Hameg across the B-E junction. Oh that's not right - should be a diode but apparently has turned into a resistor when reverse biased!

[snip]

This is quickly becoming a very useful purchase.

Told you .... you know   

[tggzzz]

I wasted most of my day too. Decided to swap out the vertical pre-amp board in that troublesome 465B to see if it would clear up the frequency roll off issues.

Good news is that the replacement board works. Bad news is still has the same symptoms. So I figure it's due to the failing caps in the PSU.
The capacitors are on order and should be here by Saturday.

Why would PSU caps reduce the high frequency performance?

Firstly I would check the contacts of the 20MHz switch, and nearby components.

If both channels are affected, I would start at the CRT Y plates and work towards the input,  one stage at a time, looking for lack of rolloff.

If only one channel is affected, I'd start at the attenuator output and work towards the CRT, looking for rolloff. It might be in the attenuator; jiggle the little buggers.

It's both channels. The 20MHz switch goes along with the pre-amp board so that's not the issue. Yes, it could be something in the final Vertical amp but I'm going to wait until I get rid of all the 120Hz ripple that intermittently becomes visible on both traces. One thing at a time. First rule: Clean power then go after what's left.

Clean power is always beneficial, but it won't cure all ills, natch.

If both channels and changing the big y amp board didn't have any effect, then it may well be on the small vert amp CRT driver.  Remember to check both sides of the differential chain; in a 485 I found a resistor inside an IC was too high - but I was able to solder in an external resistor

[bitseeker]

The HP 432A with 478A thermistor mount arrived. Yay! But, I can't zero it. Boo!

As shown in the pics, the physical zero is good with nothing connected (far left).

When powered on with nothing attached, still zero (second from left).

When set to any range and with the thermistor attached, it drops to below zero (third from left).

When set to COARSE ZERO, it's still below zero and no position on the coarse zero adjustment pot moves the needle (last photo).

I've also tried it on a 431C and 431B and can't zero them either. The zero knob has no effect. Neither does the null pot. However, since this is the first time I have a thermistor mount to test with, I don't know if it's the mount or all the meters (or both).

When powering on any of the meters with the mount attached and the range knob set to COARSE ZERO (or NULL on the 431) the meter deflects past max range and then drops below zero.

I checked out Tony G's video on his 432A for comparison with how a working meter and mount should behave.

[0culus]

Nice! That brings up a question...on my 432A (which also came with a thermistor!) the physical zero screw seems to have either fallen out or gotten jammed inside. I can still zero it by sticking a flat screwdriver in there, but I'm wondering if it can be fixed by tearing into it and removing the meter movement?

[bd139]

These are all of the problems that scares me away from buying those power meters and heads

Annoying really because they're damn good