Test Equipment Anonymous (TEA) group therapy thread

[Brumby]

The real question is "Who is EEVBlog's token sane person?"

Mrs EEVblog.

[Zoli]

And so, tested common PSU tubes in the Type 535A and no issues. I was especially concerned with the 5080 Series Regulator tube and it's OK. I also have a tested spare. The unique tubes in the Type 547 PSU have been swapped out with supposedly tested ones from EBay. I verified again all static resistance checks to ground and all are in spec as per the manual. I pulled the Type 1A1 plug-in to lighten the load on the PSU in this initial test. Gave the beans. The cathode resistors to V677 got hot enough to melt the solder on the strip. So.....still have same issue.
...

My conclusion is something is drawing to much current on initial power. Finding it will be a real chore. The +100V forms the basis of the Vcc for almost all the transistors scattered throughout the instrument. But I think I found a common point where I can pull the entire load at once. Right at C709C but keep R677 in circuit which is a high wattage resistor to allow the +100V to properly regulate when the plug-in is removed. So, going to isolate at that point and after replacing the cathode resistors see if the +100V comes up. If it does I'll definitely be on a long hunt to find the culprit. If it doesn't come up it may actually be an easier fix. I refuse to give up.

...

I think I found your problem...
/ducks away from the incoming boots

[Vince]

Long, long time ago I've had a red 27XL - that's all whats left; PM if you want it.

Thanks for the offer !  I will have to decline though... shipping anything from Canada to France is not going to be economical. Luckily I found it in PDF form online in excellent quality.  Also found a calibration procedure (single page), 3 trimmers one for Voltage, another for Capacitance and another for Inductance. Sadly only sets the bare minimum, the scaling factor. That then answers my question: no, it's not possible to zero out the parasitic 30pF of capacitance that the meter displays when no test leads are inserted. So, will have to deduce the 30pF in my head every time I read a low value cap. No big deal...

And, also found a freaking schematic for it, yeah !   
All crammed into one single page, boy it's hard to read, but it's all there if I need it 
Indeed it's all a bunch of op-amps and logic gates.

[Robert763]

<SNIP>
...

My conclusion is something is drawing to much current on initial power. Finding it will be a real chore. The +100V forms the basis of the Vcc for almost all the transistors scattered throughout the instrument. But I think I found a common point where I can pull the entire load at once. Right at C709C but keep R677 in circuit which is a high wattage resistor to allow the +100V to properly regulate when the plug-in is removed. So, going to isolate at that point and after replacing the cathode resistors see if the +100V comes up. If it does I'll definitely be on a long hunt to find the culprit. If it doesn't come up it may actually be an easier fix. I refuse to give up.

...

I think your issue is a shorted capacitor (or posisibly semiconductor) in the base circuit of transistor. This will read high resistance power off. But when you get above a certain voltage the transistor saturates and overloads the supply.
 

[Robert763]

My Super 50 arrived late yesterday. I was in the middle or installing Windows on the T10 so only had a quick look.
The cut out reset easilly. The dial under the "AC" knob is loose and turning with the knob. There is something going on with the parallax mirror. It's either moved or a bit is broken of the end.
On the plus side it gives a reading in the ballpark on a battery, the meter case is very good (a lot of these have turned a odd pink colour from light exposure). The leads look original if old.
I'll get it open when I clear a spot on the bench.
www.ebay.co.uk/itm/Vintage-retro-electrical-test-meter-Selectest-Super-50-/154485650790?

[med6753]

And so, tested common PSU tubes in the Type 535A and no issues. I was especially concerned with the 5080 Series Regulator tube and it's OK. I also have a tested spare. The unique tubes in the Type 547 PSU have been swapped out with supposedly tested ones from EBay. I verified again all static resistance checks to ground and all are in spec as per the manual. I pulled the Type 1A1 plug-in to lighten the load on the PSU in this initial test. Gave the beans. The cathode resistors to V677 got hot enough to melt the solder on the strip. So.....still have same issue.
...

My conclusion is something is drawing to much current on initial power. Finding it will be a real chore. The +100V forms the basis of the Vcc for almost all the transistors scattered throughout the instrument. But I think I found a common point where I can pull the entire load at once. Right at C709C but keep R677 in circuit which is a high wattage resistor to allow the +100V to properly regulate when the plug-in is removed. So, going to isolate at that point and after replacing the cathode resistors see if the +100V comes up. If it does I'll definitely be on a long hunt to find the culprit. If it doesn't come up it may actually be an easier fix. I refuse to give up.

...

I think I found your problem...
/ducks away from the incoming boots

I got nothing against transistors as long as they play nice.   

[med6753]

<SNIP>
...

My conclusion is something is drawing to much current on initial power. Finding it will be a real chore. The +100V forms the basis of the Vcc for almost all the transistors scattered throughout the instrument. But I think I found a common point where I can pull the entire load at once. Right at C709C but keep R677 in circuit which is a high wattage resistor to allow the +100V to properly regulate when the plug-in is removed. So, going to isolate at that point and after replacing the cathode resistors see if the +100V comes up. If it does I'll definitely be on a long hunt to find the culprit. If it doesn't come up it may actually be an easier fix. I refuse to give up.

...

I think your issue is a shorted capacitor (or posisibly semiconductor) in the base circuit of transistor. This will read high resistance power off. But when you get above a certain voltage the transistor saturates and overloads the supply.

Yep, one possible scenario. This fail is making me wish I had a +50 volt PS. My selection of DC supplies is pitiful. One 0-15VDC/2A and one 0-15VDC/10A. Those were scratch built by me years ago. And a hp 6215A. Even if combined in series I don't think that will be enough to tickle any power on short.     

[GreyWoolfe]

The real question is "Who is EEVBlog's token sane person?"

Mrs EEVblog.

Sure about that?  She did marry Dave after all.  Mrs. GreyWoolfe loves to keep reminding me how 'special' I am.  I keep reminding her that she was the one who married me.

[Specmaster]

My Super 50 arrived late yesterday. I was in the middle or installing Windows on the C10 so oly had a quick look.
The cut out reset easilly. The dial under the "AC" knob is loose and turning with the knob. There is something going on with the parallax mirror. It's either moved or a bit is broken of the end.
On the plus side it gives a reading in the ballpark on a battery, the meter case is very good (a lot of these have turned a odd pink colour from light exposure). The leads look original if old.
I'll get it open when I clear a spot on the bench.
www.ebay.co.uk/itm/Vintage-retro-electrical-test-meter-Selectest-Super-50-/154485650790?

I like that a lot, good catch, makes a change from Avo's and if IRRC there were roundabout the same kind of money back in the day.

[Specmaster]

Ok as promised, here are the photos of the calculator, it is one of the few that provides direct access to some engineering terms, T,G,M,u,m,k,f,p & n etc. The holy grail of course would be the Casio fx-61 with its dedicated electrical functions, but they are serious money.

As is always the case with these dual power calculators, the internal battery was toast, reading just .6v instead of 3v, so a quick clean of the contacts and a new battery it was back up and running in no time. Now to try and locate a decent copy of the owners manual for it, I have found some, but they all suffer from terrible scan quality that make of the instructions difficult to make out.

Edit: Oh and yes it has that equals key 

[Brumby]

The real question is "Who is EEVBlog's token sane person?"

Mrs EEVblog.

Sure about that?  She did marry Dave after all.  Mrs. GreyWoolfe loves to keep reminding me how 'special' I am.  I keep reminding her that she was the one who married me.

That perspective did occur to me.... 

.... but if I remember correctly, when Dave moved out of the garage, she made it clear the lab would never be allowed back.  I call that a sane action.

[Specmaster]

I spotted this Avo meter on Gumtree, and it was the unusual colour that caught my eye and then the price being asked was just £10, complete with authentic Avo leads with the extra push on wire grabbers, they alone are worth more than the asking price. Enter discussions with the seller, a very nice man who agreed to send it to me at cost by DHL, paid via PayPal none of this bank transfer malarkey this time, and it is already on its way to me and the seller sent me photographic proof of the dispatching last night.

I'm not an expert on Avo's at all, although I already own 3 working ones and another model 8 MkV that needs some spare parts, hence this acquisition. I'm not aware of Avo ever releasing one in a yellow colour, all the ones I've seen have been black. So is this yellow one an official colour they did for certain customers, or has someone at some point in its life painted it like that?

More details and photos once it arrives, and I get it laid naked on the bench

[BU508A]

My selection of DC supplies is pitiful.

No HP, Xantrex, Sorensen, TDK Lambda or other reputable brand:

https://www.ebay.com/itm/273807882321




https://www.ebay.com/itm/283609203786

[beanflying]

Why opt for quality when you could have a powerful inner core  My 120V 3A supply will be here Monday so there will be pictures and some testing.

[Cerebus]

I'm not aware of Avo ever releasing one in a yellow colour, all the ones I've seen have been black. So is this yellow one an official colour they did for certain customers, or has someone at some point in its life painted it like that?

It looks like factory paint, it's too neat for the kind of customer modification done because someone in health and safety says "All XYZ equipment must be painted safety yellow". Safety yellow as a mandatory colour for certain classes of equipment is common in some industries, so it wouldn't be unlikely that it was a standard or special order factory option.

[vk6zgo]

I'm not aware of Avo ever releasing one in a yellow colour, all the ones I've seen have been black. So is this yellow one an official colour they did for certain customers, or has someone at some point in its life painted it like that?

It looks like factory paint, it's too neat for the kind of customer modification done because someone in health and safety says "All XYZ equipment must be painted safety yellow". Safety yellow as a mandatory colour for certain classes of equipment is common in some industries, so it wouldn't be unlikely that it was a standard or special order factory option.

I have a vague memory of seeing just such a colour scheme on an AVO.

[Specmaster]

I'm not aware of Avo ever releasing one in a yellow colour, all the ones I've seen have been black. So is this yellow one an official colour they did for certain customers, or has someone at some point in its life painted it like that?

It looks like factory paint, it's too neat for the kind of customer modification done because someone in health and safety says "All XYZ equipment must be painted safety yellow". Safety yellow as a mandatory colour for certain classes of equipment is common in some industries, so it wouldn't be unlikely that it was a standard or special order factory option.

That was my thinking as well, if so then it adds to the value I think as I have never seen a yellow one and if it cleans up nicely I think I'll keep it in that case rather than the spare black one I have. Hopefully when it arrives there will be other clues, maybe even a sticker that gives details as to where it came from?

[McBryce]

Why opt for quality when you could have a powerful inner core  My 120V 3A supply will be here Monday so there will be pictures and some testing.

Is the picture above an example of its failure mode?

McBryce.

[mnementh]

"Ponder likes to think of himself as the University's token sane person."

mnem
So... pretty much the sa :clap:as any University then...

The real question is "Who is EEVBlog's token sane person?"

That would be "little moi".

Ahhhh-Haaaahhhh! I'm so proud of you... you actually managed to say that with a straight face... 

mnem

[mnementh]

The real question is "Who is EEVBlog's token sane person?"

Mrs EEVblog.

Sure about that?  She did marry Dave after all.  Mrs. GreyWoolfe loves to keep reminding me how 'special' I am.  I keep reminding her that she was the one who married me.

DANGER WILL ROBINSON, DANGER!!!

Do not approach the topic of sanity and marriage; it is a black hole and the event horizon is radioactive! ABORT! ABORT! ABORT!!!

mnem
I know my wife is insane for marrying me; but as I am the beneficiary of said madness, I do NOT bring it to her attention lest she finally come to her senses...

[Robert763]

I'm not aware of Avo ever releasing one in a yellow colour, all the ones I've seen have been black. So is this yellow one an official colour they did for certain customers, or has someone at some point in its life painted it like that?

It looks like factory paint, it's too neat for the kind of customer modification done because someone in health and safety says "All XYZ equipment must be painted safety yellow". Safety yellow as a mandatory colour for certain classes of equipment is common in some industries, so it wouldn't be unlikely that it was a standard or special order factory option.

That was my thinking as, if so then it adds to the value I think as I have never seen a yellow one and if it cleans up nicely I think I'll keep it in that case rather than the spare black one I have. Hopefully when it arrives there will be other clues, maybe even a sticker that gives details as to where it came from?

Looks hand painted to me. A bit patchy for a factory job.

[med6753]

After poking around in the bowels of this Type 547 for several hours I am totally convinced that the only alternative I have to tracking down the +100V issue is to purchase an external supply capable of 100VDC. There are just too many branches of the +100V bus scattered around in the scope and I'll risk damaging the internal +100V supply with "try this, and try that".

Got this one from Amazon. States it can source up to 120VDC/3A and can be current limited. Should have it by Wednesday. Yep, cheap Chinese and probably dodgy construction but it should be good enough for what I need.

[mnementh]

"That's good... you've taken your first step into a larger world. One full of cheap Chinese electronic gadgets for a pittance all over your bench, delivered in no time via Amazon Prime..."

mnem
 

[Bud]

I'm not an expert on Avo's at all, although I already own 3 working ones and another model 8 MkV that needs some spare parts, hence this acquisition. I'm not aware of Avo ever releasing one in a yellow colour, all the ones I've seen have been black. So is this yellow one an official colour they did for certain customers, or has someone at some point in its life painted it like that?

More details and photos once it arrives, and I get it laid naked on the bench

The painting job is so dodgy it can be seen right away it was someone used a spray can and masking tape. If i bought it i would immediately gave it a fresh black spray.

[mnementh]

I'm not aware of Avo ever releasing one in a yellow colour, all the ones I've seen have been black. So is this yellow one an official colour they did for certain customers, or has someone at some point in its life painted it like that?

It looks like factory paint, it's too neat for the kind of customer modification done because someone in health and safety says "All XYZ equipment must be painted safety yellow". Safety yellow as a mandatory colour for certain classes of equipment is common in some industries, so it wouldn't be unlikely that it was a standard or special order factory option.

That was my thinking as, if so then it adds to the value I think as I have never seen a yellow one and if it cleans up nicely I think I'll keep it in that case rather than the spare black one I have. Hopefully when it arrives there will be other clues, maybe even a sticker that gives details as to where it came from?

Looks hand painted to me. A bit patchy for a factory job.

Yeah, that was my reaction at first as well.. but I decided to give Spec the benefit of the doubt, at least until he's able to post pics taken with a proper camera. I think it's even odds that appearance may also be a byproduct of decades of grubby fingers and a lick and a prayer wipedown (maybe with alcohol) for posting on the Bay of Fleazz...

mnem