Test Equipment Anonymous (TEA) group therapy thread

[txNgineer]

Just a little word of caution on the 86601 low frequency plug in. Maybe I have bad luck or something but I have bought 2 supposedly "working" plug-ins (different vendors) and both have problems that let them put out a wierd frequency and level but they definitely were not "working". If you don't have a riser card to move them out of the unit while testing/troubleshooting - they are a bear to try to repair. YMMV, just a little warning.

[mansaxel]

In the competition(?) messiest desk, I introduce mine. It is full of meters. And projects.

[BU508A]

Don't let see med6753 this picture!
He'll probably suffer of a heart-attack!   

[bd139]

That's a proper bench 

[med6753]

Meh. 

[Specmaster]

And it even has a decent analogue Avo meter on it, well done sir I salute you 

[bd139]

Ok PCBs completed and ordered snail mail 12-16 days. Fingers crossed   

[mansaxel]

And it even has a decent analogue Avo meter on it, well done sir I salute you 

There are representatives for several more traditions in electromechanical analog. USA via the Weston AC meter far left and Germany by the H&B Elavi 3. I'd like to get my grubby hands on a Simpson 260, something Philips, and a french Metrix, to round things out.

Then of course, your usual 465, a british valve volt meter, movement upside down, (it's like driving on the wrong side of the road), a 428b, and top row from left a 500 Series distortion set, the 432A power meter, a 5221A counter (my first with Nixies), a 427A (hi, BD!), TF 830 counter and 3438 DMM. (my only GPIB instrument). Uni-T dual voltage supply (voltmeters not precise, but stable and dependable), the FeelTech we all hate-love, and another counter, a tiny Philips, made in Sweden, smashed up in Poland.

Hidden on top of the 465 lies the DE-5000, and the crank Megger is packed away in its case just right of the 428b.

Soldering equipment is a Chinesium desolderer, which is a wonder machine. No doubt there are much better machines on the market, but this so, so much better than the braid or the syringe style sucker.  To add more solder onto PCB's I've got an Ersa. I'm happy with it.

Missing is the Fluke 10 in my tool bag, a Taylor 1950s miniature meter, a british 1920s vintage DC volt meter that serves as indicator for the 24V battery bank I've got for my Clansman radios.

Edit: Also missing is my Solartron Nixie DVM. I've not been able to power it, since I lack the (im)proper Bulgin plug. It's in my Mouser cart. To get it on the shelving, I'll have to do some rearranging. It's 3HE and full depth. Proper anchor material.

I did not win another 8060A today, I was overbid, but tomorrow a second Avometer, a Model 7, arrives.

[factory]

A strange Motorola frequency meter with dual plug-ins (made by Systron Donner) on eBay if anyone is interested, from the same seller that had the Beckman counter I bought.
It looks to have some display problems, the seller will probably take a lower offer.
eBay auction: #254753158721



David

[tonyalbus]

PowerFix KH3322 , Mastech VA19.. Edison 5-1

Bought it for 9,- incl shipping... fixed it.... and its fully working...the thing just messures everything..

[mnementh]

   In the competition(?) messiest desk, I introduce mine. It is full of meters. And projects.

pffft. Amateur. That bench is a paragon of order and tidiness... 

mnem
You can do better... err, worse...! 

[bd139]

Quick check out, clean up and cal of the LT30/2.



Have lightly brushed off the transformers and wiped them with some very light silicon oil to stop them rusting any further. Then cleaned the guts out, replaced one of the cable tie bases that had decomposed and calibrated it and it's bang on. There was what I thought was burn marks on the series resistor for the voltage reference (green at bottom left) but it turned out to just be baked on gack that had come through the vents and cleaned off.

Going to be honest, these are very nice supplies. I like it more than the HPs so far. No 50Hz buzz. Metering is bang on. Allows you to monitor voltage on the meters with the output off. Roughly same footprint as a 6236B but higher but will kick out 60V @ 2A or 30V @ 4A or 2x30V @ 2A. No funny American parts and no mains voltages all over the place trying to kill you

[tautech]

Quick check out, clean up and cal of the LT30/2.



Have lightly brushed off the transformers and wiped them with some very light silicon oil to stop them rusting any further. Then cleaned the guts out, replaced one of the cable tie bases that had decomposed and calibrated it and it's bang on. There was what I thought was burn marks on the series resistor for the voltage reference (green at bottom left) but it turned out to just be baked on gack that had come through the vents and cleaned off.

Going to be honest, these are very nice supplies. I like it more than the HPs so far. No 50Hz buzz. Metering is bang on. Allows you to monitor voltage on the meters with the output off. Roughly same footprint as a 6236B but higher but will kick out 60V @ 2A or 30V @ 4A or 2x30V @ 2A. No funny American parts and no mains voltages all over the place trying to kill you

Are the bridge rectifiers hanging on the transformer lugs ? 
And them little round bridges that give trouble on the PCB in the foreground ? 

[LootMaster]

Here is the fab.

[tonyalbus]

Quick check out, clean up and cal of the LT30/2.



Have lightly brushed off the transformers and wiped them with some very light silicon oil to stop them rusting any further. Then cleaned the guts out, replaced one of the cable tie bases that had decomposed and calibrated it and it's bang on. There was what I thought was burn marks on the series resistor for the voltage reference (green at bottom left) but it turned out to just be baked on gack that had come through the vents and cleaned off.

Going to be honest, these are very nice supplies. I like it more than the HPs so far. No 50Hz buzz. Metering is bang on. Allows you to monitor voltage on the meters with the output off. Roughly same footprint as a 6236B but higher but will kick out 60V @ 2A or 30V @ 4A or 2x30V @ 2A. No funny American parts and no mains voltages all over the place trying to kill you

It does look a lot better from the front... but all that wirering looks a bit messy, i like that better with the older ET30/2

https://youtu.be/J7_efVmkjYs

but yours...on al other points is much more modern... nice catch! 

[LootMaster]

Here is to be to be peaceful and orderly. Without bad smell due to my old crappy smoke extractor. Now its a covid proof fart extractor?

#1 rule to limit test gear damage: Limit coffee movement, hold coffee in stainless steel screwable mug. Always.

[Robert763]

   In the competition(?) messiest desk, I introduce mine. It is full of meters. And projects.

pffft. Amateur. That bench is a paragon of order and tidiness... 

mnem
You can do better... err, worse...! 

How about mine, taken just now nothing, touched or posed.
deplorable state. I think the clear bit on the right  because something fell off

[tonyalbus]

3rd time today i see that same desoldering iron.... both your pictures, and my desk :-)

[mnementh]

Juicy.

mnem
 

For those who care; while I built unit number 4 this morning, I decided to snap a few MFT of pics along the way. Due to gross pixel displacement (2 posts, 30-something pictures), I put it up in its own thread in the Projects, etc... subforum as a courtesy to fellow TEA members who might be a bit tired of seeing this adventure every day for the last week or two. 

Article is here: https://www.eevblog.com/forum/projects/dell-aa23300-server-psu-mod-conversion-to-14v-1v45a-fixed-bench-supply/msg3286178/#msg3286178

Cheers!

mnem

[tautech]

How about mine, taken just now nothing, touched or posed.
deplorable state. I think the clear bit on the right  because something fell off

much like my deplorable mess.

[FransW]

... but all that wiring looks a bit messy...

...on al other points is much more modern...

Sure about messy & modern??

[Specmaster]

OK, back on the PL310, I think I may have found something, seeing as we are playing about on the detection circuit with such low voltages, and given that all parts appeared to check out OK when removed from the circuit around the IC7, OP AMP, I decided to revisit the supply rails again and discovered that while the +5V and the +7.5V was spot on, the -5V was actually -5.3V.

Now within that detection / control section, the IC requires +7.5V and -5V, so could this slight variation on -5V side be the culprit of my failure to get this power supply to hold its voltage on anything above a couple of mA load?

It is derived from a 5.1V Zener and measuring the output directly at the Zener it reads -5.3V. I'm not 100% sure about this, having had very little to do with Zener before. I thought that I'd replace the Zener and see but I'm puzzled by the part number as I'm drawing a complete blank on the part number given in the parts list, normally diodes have a number such as 1N4002 etc, but the parts list states ZEN 5V1 W4. Looking at RS website shows 5.1V Zeners with numbers like BZX79-C5V1 which has a rating of 500mW?

Does the Zener in the parts list denote 4watts? or 400mW, its is a very small glass type and I doubt that it is capable of dissipating 4W

Does anyone think that is the problem, given that it has had a full recap, replaced IC7 (LM324), replaced TIP120 transistor and also 7805 5V regulator and the 2N3055 pass transistor which was fried?

[Cerebus]

OK, back on the PL310, I think I may have found something, seeing as we are playing about on the detection circuit with such low voltages, and given that all parts appeared to check out OK when removed from the circuit around the IC7, OP AMP, I decided to revisit the supply rails again and discovered that while the +5V and the +7.5V was spot on, the -5V was actually -5.3V.

Now within that detection / control section, the IC requires +7.5V and -5V, so could this slight variation on -5V side be the culprit of my failure to get this power supply to hold its voltage on anything above a couple of mA load?

It is derived from a 5.1V Zener and measuring the output directly at the Zener it reads -5.3V. I'm not 100% sure about this, having had very little to do with Zener before. I thought that I'd replace the Zener and see but I'm puzzled by the part number as I'm drawing a complete blank on the part number given in the parts list, normally diodes have a number such as 1N4002 etc, but the parts list states ZEN 5V1 W4. Looking at RS website shows 5.1V Zeners with numbers like BZX79-C5V1 which has a rating of 500mW?

Does the Zener in the parts list denote 4watts? or 400mW, its is a very small glass type and I doubt that it is capable of dissipating 4W

Does anyone think that is the problem, given that it has had a full recap, replaced IC7 (LM324), replaced TIP120 transistor and also 7805 5V regulator and the 2N3055 pass transistor which was fried?

I read that "ZEN 5V1 W4" as a 400 mW part, same as with the current sense resistor it looks like they're using the "unit as decimal point" convention. Depending on the exact part and the current through it, 5.3V isn't an unreasonable figure and would be in spec. Zeners are usual quite loose spec parts 5% typical, unless you pay big bucks for top spec parts - even than you tend to buy high stability for your money, not a precise voltage. The specified voltage tolerance is at one current only, move away from that (and there can be good reasons epople do) and you get a different voltage.

I presume you're talking about D11. Looking at the circuit around there it looks very like they're after a pretty nominal 5V, not a precise one. Without knowing the transformer rating it's hard to figure out any more. What's the measured voltage at PJ6 3, 5, and 4 - e.g. 3 to 5, and 5 to 4 (the transformer windings entry to the board)?

[BU508A]

If you have some 1N4148 laying around, I'd suggest to put 7 or 8 of them in series and replace the Zener with them. The advantage is: if you want to test some voltage changing, you can shorten one of them and check, how your power supply behaves.

As for the Zener: if the Zener is rated for 0.5W then it is very likely, that it will have a case similar to a 1N4148. Next step is usually 1.3W and those have a bigger case and thicker leads, because the heat will be dissipated by the leads.

Hope this helps.

[Specmaster]

@Cerebus, the input voltage is the same on both 3-5 and 4-5, 11.1Vac.

I did wonder about the accuracy of that required voltage because on other circuits where the voltage was critical I have seen the use of negative regulators, like the 7805 on the positive rail.