Test Equipment Anonymous (TEA) group therapy thread

[0culus]

TEA day, as seen on discord earlier. Very nice shape Tek Type 184. There's one problem. The seller listed as tested and working, but the fuse and fuse holder are missing! Looking back, they were missing in the listing pics too, so I messaged them. They said they'll look for it on Tuesday.  And I don't have a .6A slowblow on hand either, so I can't even scrounge a fuze cap to test it out. 

Scored one recently, most output spotted on except those below 50ns. Carried out adjustment all fixed except the 2ns  The 2ns output never make a stable waveform except when my adjustment tool (esd safe plastic) touch the C70 

I changed the input voltage to 220V as I am living in 220v area, the 10MHz oven started giving out smell and blow the fuse (0.3A) after around 1 hr  Disconnect the heater as temporary fix.

Any chance to help me to measure the resistance between pin 1 to 5, 2 to 5, 1 to 2 on the 10 Mhz crystal after removing it from socket ?

Sure, if I get to needing to take it apart...I'm not even quite sure where the crystal oven is! First things first is to either get the seller to cough up the missing parts or give me a partial refund.

[syau]

TEA day, as seen on discord earlier. Very nice shape Tek Type 184. There's one problem. The seller listed as tested and working, but the fuse and fuse holder are missing! Looking back, they were missing in the listing pics too, so I messaged them. They said they'll look for it on Tuesday.  And I don't have a .6A slowblow on hand either, so I can't even scrounge a fuze cap to test it out. 

Scored one recently, most output spotted on except those below 50ns. Carried out adjustment all fixed except the 2ns  The 2ns output never make a stable waveform except when my adjustment tool (esd safe plastic) touch the C70 

I changed the input voltage to 220V as I am living in 220v area, the 10MHz oven started giving out smell and blow the fuse (0.3A) after around 1 hr  Disconnect the heater as temporary fix.

Any chance to help me to measure the resistance between pin 1 to 5, 2 to 5, 1 to 2 on the 10 Mhz crystal after removing it from socket ?

Sure, if I get to needing to take it apart...I'm not even quite sure where the crystal oven is! First things first is to either get the seller to cough up the missing parts or give me a partial refund.

It is the green can (as circulated) , mind is orange.

[Neomys Sapiens]

TEA day, as seen on discord earlier. Very nice shape Tek Type 184. There's one problem. The seller listed as tested and working, but the fuse and fuse holder are missing! Looking back, they were missing in the listing pics too, so I messaged them. They said they'll look for it on Tuesday.  And I don't have a .6A slowblow on hand either, so I can't even scrounge a fuze cap to test it out. 

Scored one recently, most output spotted on except those below 50ns. Carried out adjustment all fixed except the 2ns  The 2ns output never make a stable waveform except when my adjustment tool (esd safe plastic) touch the C70 

I changed the input voltage to 220V as I am living in 220v area, the 10MHz oven started giving out smell and blow the fuse (0.3A) after around 1 hr  Disconnect the heater as temporary fix.

Any chance to help me to measure the resistance between pin 1 to 5, 2 to 5, 1 to 2 on the 10 Mhz crystal after removing it from socket ?

Sure, if I get to needing to take it apart...I'm not even quite sure where the crystal oven is! First things first is to either get the seller to cough up the missing parts or give me a partial refund.

It is the green can (as circulated) (Attachment Link) , mind is orange.

Yes, 'Bulova' can be taken as a good indicator for that. 

[med6753]

TEA day, as seen on discord earlier. Very nice shape Tek Type 184. There's one problem. The seller listed as tested and working, but the fuse and fuse holder are missing! Looking back, they were missing in the listing pics too, so I messaged them. They said they'll look for it on Tuesday.  And I don't have a .6A slowblow on hand either, so I can't even scrounge a fuze cap to test it out. 

Scored one recently, most output spotted on except those below 50ns. Carried out adjustment all fixed except the 2ns  The 2ns output never make a stable waveform except when my adjustment tool (esd safe plastic) touch the C70 

I changed the input voltage to 220V as I am living in 220v area, the 10MHz oven started giving out smell and blow the fuse (0.3A) after around 1 hr  Disconnect the heater as temporary fix.

Any chance to help me to measure the resistance between pin 1 to 5, 2 to 5, 1 to 2 on the 10 Mhz crystal after removing it from socket ?

Sure, if I get to needing to take it apart...I'm not even quite sure where the crystal oven is! First things first is to either get the seller to cough up the missing parts or give me a partial refund.

It is the green can (as circulated) (Attachment Link) , mind is orange.

And just to the left is a roll of silver bearing solder to use on the ceramic strips. And those 3 capacitor cans? Outta here. 

[0culus]

Ah, ok. I'm blind. I just thought it was another cap. 

I put it away for now, but I can take the measurements you want tomorrow. 

[tggzzz]

TEA day, as seen on discord earlier. Very nice shape Tek Type 184. There's one problem. The seller listed as tested and working, but the fuse and fuse holder are missing! Looking back, they were missing in the listing pics too, so I messaged them. They said they'll look for it on Tuesday.  And I don't have a .6A slowblow on hand either, so I can't even scrounge a fuze cap to test it out. 

There will be a reason they have been removed. Personally I wouldn't bet that it will work when they are replaced. How much do you trust the seller?

[nfmax]

Well, eBay has ceased to be shit - for me at least.

Just scored an Agilent E3610A for £82 + a very reasonable £6.71 postage. Cushty. For those, like me, who don't keep an encyclopaedic list of model numbers in their heads that's a 2U 1/2 rack DC bench PSU 0-8V@3A or 0-15V@2A. Fanless, naturally, like the rest of my slowly growing stack of HP/Agilent/Harrison 1/2 rack PSUs. Due Weds/Thurs all the way from sunny Southend-on-Sea. I beat some other cheapskate by one bid increment over the minimum bid - if that was one of the resident fellow cheapskates, my apologies.

In other news, I found my de-burring tool and a little packet of mixed precision/fast op amps that I'd been trying to find for weeks. Bloody cat had batted them out of the tray they were in, and down the back of the bedroom bookcase when she'd been climbing up to the forbidden heights of War-Drobe. Normally she limits her electronics 'help' to ESD testing.

Ah, you grabbed that supply! There were no bidders the first time round. I was tempted, as I have a hole the exact size and shape on top of my E3630A, but I really don't need another low voltage supply. Ideally, I'd like the E3612A, the 60V/120V model, but the 230V versions are rare. These supplies are single mains voltage only

[bd139]

Didn’t even see that supply. I am sucking at eBay recently.

[nfmax]

I've been paying more attention to eBay recently while convalescing. I picked up a nice Agilent E3616A (60W, 35V, with OVP) to replace an old Farnell 30V, 1A supply that killed three prototypes. Transient over voltage, to >45V for a few tens of nanoseconds, when switching the output on and off. How they managed to generate that short a pulse using a circuit built round 741's and 2N3055's is a mystery to me. For various good and sufficient reasons my prototypes are limited to no more than about 2.5 uF on the 30V rail...

[tggzzz]

.. to replace an old Farnell 30V, 1A supply that killed three prototypes. Transient over voltage, to >45V for a few tens of nanoseconds, when switching the output on and off. How they managed to generate that short a pulse using a circuit built round 741's and 2N3055's is a mystery to me.

Inductance + dI => ringing? What was the PSU's max output?

But I'm surprised that short a transient wasn't removed by whatever is across the UUT's rails.

[syau]

Ah, ok. I'm blind. I just thought it was another cap. 

I put it away for now, but I can take the measurements you want tomorrow. 

Thanks. 

Someone post the internal of the oven control crystal https://www.vintage-radio.net/forum/showthread.php?t=65988 which made me withdraw the idea of opening it up.

[Specmaster]

And all this complaining about those lovely redheads...
In Germany, there is an old proven saying of cicil engineers: 'Umso rostiger das Dach, umso feuchter der Keller!'
(The more rusty the roof, the more moist is the basement!)
Who knows, if not them?

While that may very well be true, you also want to know for sure that the basement is yours and yours alone 

[nfmax]

.. to replace an old Farnell 30V, 1A supply that killed three prototypes. Transient over voltage, to >45V for a few tens of nanoseconds, when switching the output on and off. How they managed to generate that short a pulse using a circuit built round 741's and 2N3055's is a mystery to me.

Inductance + dI => ringing? What was the PSU's max output?

But I'm surprised that short a transient wasn't removed by whatever is across the UUT's rails.

The circuits, when undamaged, we're drawing about 20mA at 30V. The absolute maximum for the chip was 33V or so, can't remember exactly. The spikes only arose when the DC switch contacts bounced, and the feedback loop was momentarily broken as the sense was O/C while the output was not. I think it was a really bad move switching the sense terminal as well as the output, not a good design.

I suppose the decoupling on the prototype reduced the amplitude, but increased the length, of the over voltage transient. The effect on the chip wasn't a hard fail, the circuit just behaved weirdly (wrong voltages, low gains) but you expect that to some extent with a prototype. The transient didn't happen every time, and it was only when the third prototype worked correctly at first, then didn't after being power cycled, that I started to suspect the supply.

[bd139]

A few of the mastech designs do that. Best stick a fat clamp zener across the output. In the case of the mastech it looks like there is a massive lag in the feedback loop so if you load it lightly from the start, it carries on servo’ing the output past the set point. Yes that crap.

I actually had great fun finding all the bugs in my old HY1503D. I occasionally search for broken ones to play with.

[bd139]

And all this complaining about those lovely redheads...
In Germany, there is an old proven saying of cicil engineers: 'Umso rostiger das Dach, umso feuchter der Keller!'
(The more rusty the roof, the more moist is the basement!)
Who knows, if not them?

While that may very well be true, you also want to know for sure that the basement is yours and yours alone 

Bloody mutant basement probably has teeth. Different colour next time

[med6753]

OK, first world people problems and the dragon can go piss up a rope.

Dear Amazon, how can my coffee order arrive today when it hasn't even been fulfilled and shipped yet? 

[med6753]

If you check out my repair/resto 561B thread in the Repair section...

I'm having better luck obtaining obsolete Tek parts on this forum than anywhere else. The unobtanium Tek spec TO-3 regulator transistor and last night another member contacted me and offered up replacement peaking coils for the ones broken on the 3A6 plug-in. He's pulling them off a junker 3A1 and sending them early this week.     

[Specmaster]

Yeah, shows really what a bloody great bunch of people use the forum generally. OK you get the odd so and so but by and large we are all similar minded people and share the same great passion.

[nfmax]

A few of the mastech designs do that. Best stick a fat clamp zener across the output. In the case of the mastech it looks like there is a massive lag in the feedback loop so if you load it lightly from the start, it carries on servo’ing the output past the set point. Yes that crap.

I actually had great fun finding all the bugs in my old HY1503D. I occasionally search for broken ones to play with.

You will note the E3616A replacement has adjustable OVP! Also no DC output switch, which makes sense. I sometimes think the startup and transient performance of a bench supply should be listed first in the specification. HPAK (with one recent lamentable exception!) are exemplary in this respect.

[bd139]

Well almost. The E36xx had some performance issues in that space to start with and there were mods to fix them.

[nfmax]

Well almost. The E36xx had some performance issues in that space to start with and there were mods to fix them.

You mean the current production models E36xxx, I think? They released a B model that fixed it - that's the exception I was thinking of.

[bd139]

No the E36xx. The E3630A had some serious problems with it when it dropped. Don't know if it spanned other models. There was a return and fix thing that went on for about a year when they came out. They were good oscillators!

[nfmax]

No the E36xx. The E3630A had some serious problems with it when it dropped. Don't know if it spanned other models. There was a return and fix thing that went on for about a year when they came out. They were good oscillators!

I didn't know that! Mine's Agilent branded, so well after they first came out. Nice little supplies, only really lacking adjustable current limiting, and ammeter resolution. But when they came out, you were usually pulling 10-15mA per OPAMP off the +/-15V rails, so it didn't matter that much.

[bd139]

Agilent ones are good. My only complaint with those supplies is the buttons fall to bits and the calibration is dangerous as hell as for some reason they always put the trim pots right next to the mains switch.

[xrunner]

The Heathkit IG-18 repair is completed.

I designed an adapter bushing in Fusion 360 to mate the new pot into the mounting plate. It had to be 9.4 mm o.d. by 7.0 mm i.d., and 1 mm thick. I had to cut off most of the new pot's shaft so the slot in it would accept the U-link. with the new bushing and other nuts and washers for spacing it fit perfectly. I replaced the 150 ohm resistor just because it was easy and finished wiring it up.

I also added a heat sink to Q10 on the PS. The original heat sink was not present and it gets hot. I cleaned each contact ring on all the wafer switches. I cleaned the top and bottom cabinet panels and dumped all the knobbies into the ultrasonic cleaner. Looking and working good, ready to give back to the "customer". I need to explain how the INT / EXT 600 ohm load switch affects the output level because I know from speaking to him he doesn't understand it, but it probably won't matter to him in the end.

May your next Heathkit acquisition be free of gorillas.