Test Equipment Anonymous (TEA) group therapy thread

[med6753]

I am dropping in on this huge topic to give a shout out and big thank you to med6753 for publishing his idea and circuit to stabilize the Fluke 8000A. 

I recently picked this a 8000A locally for cheap (hope this qualifies for this thread) and it was relatively unstable with the 5volt filter cap swollen and the +15 supply low.  I followed med6753s advice and swapped out the caps and installed voltage regulators and built the 5 volt supply.   Its stable and reads 4.99 vs. my DMMCheck which is 5.0000. A couple of pics are at the bottom I hope.

So its working now and is reliable enough for what it is.

There is tons of great info here and I appreciate you all sharing you knowledge and experience.

Thanks again
Dave

You're most welcome.  And don't be a stranger. We always welcome new victims.  And we like "cheap" too. 

[Saskia]

ok, my pocket calculator with an enter key has arrived.

49G w/ manual for 25 Brussels Pesos.

[med6753]

ok, my pocket calculator with an enter key has arrived.

49G w/ manual for 25 Brussels Pesos.

Are you firing the first round of another calculator wars?

You naughty girl. 

[bd139]

Ok the glued connector didn’t work. Turns out the glue doesn’t stick to the plastic that the plug side is made of.

Thus the whole connector assembly was ripped out, a hole drilled next to the fuse holder and a cable gland installed (a decent one not those little rubber ones). Power supply refurb worked 

[Saskia]

 

ok, my pocket calculator with an enter key has arrived.

49G w/ manual for 25 Brussels Pesos.

Are you firing the first round of another calculator wars?

You naughty girl. 

The mere thought has not even begun to speculate on the merest possibility of crossing my mind. 

[Robert763]

So the 492BP is not perfect.
It now does not always power up at the first attempt. The main tuning knob is stuck in marker mode. The Tune / Marker pushbutton seems to work with the LED toggling but the knob stays in marker mode and the * on the screen does not move. A couple of other push buttons don't work properly either. I've not opened it up but looking at the circuits all the troublesome buttons are on multiplex strobe Y9. Most of the others are on another dual 1 of 4 decoder IC. The decoder for Y9 is the same IC type, 74LS156. It does however have one input tied directly to the +5 V rail. I suspect a noisy +5 V supply, probably casued by faulty capacitors. I'll have a look at the 5 V supply on the probe power connector but it looks like a partial re-cap is called for. I beed to do a major bench clean-up to get this beast on it.

[tggzzz]

So the 492BP is not perfect.
It now does not always power up at the first attempt. The main tuning knob is stuck in marker mode. The Tune / Marker pushbutton seems to work with the LED toggling but the knob stays in marker mode and the * on the screen does not move. A couple of other push buttons don't work properly either. I've not opened it up but looking at the circuits all the troublesome buttons are on multiplex strobe Y9. Most of the others are on another dual 1 of 4 decoder IC. The decoder for Y9 is the same IC type, 74LS156. It does however have one input tied directly to the +5 V rail. I suspect a noisy +5 V supply, probably casued by faulty capacitors. I'll have a look at the 5 V supply on the probe power connector but it looks like a partial re-cap is called for. I beed to do a major bench clean-up to get this beast on it.

Based on my experience with a 492ap, take many many photos while slowly and thoughtfully removing the A30 end "cap" assembly containing the PSU. Lots of thought should go into how to avoid bending pins on multicore connectors on the end of cables (166 going to A30W560), and how to reach the blasted things when reassembling.

Here's the A30 assembly from the ArtekMedia service manual, which should cause you to cease worrying how to spend your next £10



Scopes? Pah; they're mechanically trivial!

[tggzzz]

ok, my pocket calculator with an enter key has arrived.

49G w/ manual for 25 Brussels Pesos.

Are you firing the first round of another calculator wars?

You naughty girl. 

She's sensible enough to only start a skirmish that she knows she will win 

[Robert763]

So the 492BP is not perfect.
It now does not always power up at the first attempt. The main tuning knob is stuck in marker mode. The Tune / Marker pushbutton seems to work with the LED toggling but the knob stays in marker mode and the * on the screen does not move. A couple of other push buttons don't work properly either. I've not opened it up but looking at the circuits all the troublesome buttons are on multiplex strobe Y9. Most of the others are on another dual 1 of 4 decoder IC. The decoder for Y9 is the same IC type, 74LS156. It does however have one input tied directly to the +5 V rail. I suspect a noisy +5 V supply, probably casued by faulty capacitors. I'll have a look at the 5 V supply on the probe power connector but it looks like a partial re-cap is called for. I beed to do a major bench clean-up to get this beast on it.

Based on my experience with a 492ap, take many many photos while slowly and thoughtfully removing the A30 end "cap" assembly containing the PSU. Lots of thought should go into how to avoid bending pins on multicore connectors on the end of cables (166 going to A30W560), and how to reach the blasted things when reassembling.

Here's the A30 assembly from the ArtekMedia service manual, which should cause you to cease worrying how to spend your next £10

<SNIP>

Scopes? Pah; they're mechanically trivial!

Indeed. There are specific instructions in the service manual on how to remove the PSU module. I'm working from the 494A/AP manual (from Didier KO4BB's site) as the 492BP is basicaally a 494AP without the (troublesome) 10Hz RBW filter and associated improved OCXO.

[Kosmic]

So the 492BP is not perfect.
It now does not always power up at the first attempt. The main tuning knob is stuck in marker mode. The Tune / Marker pushbutton seems to work with the LED toggling but the knob stays in marker mode and the * on the screen does not move. A couple of other push buttons don't work properly either. I've not opened it up but looking at the circuits all the troublesome buttons are on multiplex strobe Y9. Most of the others are on another dual 1 of 4 decoder IC. The decoder for Y9 is the same IC type, 74LS156. It does however have one input tied directly to the +5 V rail. I suspect a noisy +5 V supply, probably casued by faulty capacitors. I'll have a look at the 5 V supply on the probe power connector but it looks like a partial re-cap is called for. I beed to do a major bench clean-up to get this beast on it.

If you open the power supply check for Rifa caps. I have a 2794 and 2792 on the bench for repair and they both have Rifa all over the place. The PSU of the 492 should be similar.

Also check the line filter, I had to change 2 small Rifa on that small board located at the back of the PSU.



(The green caps are the new one.)

[mnementh]

So the 492BP is not perfect.
It now does not always power up at the first attempt. The main tuning knob is stuck in marker mode. The Tune / Marker pushbutton seems to work with the LED toggling but the knob stays in marker mode and the * on the screen does not move. A couple of other push buttons don't work properly either. I've not opened it up but looking at the circuits all the troublesome buttons are on multiplex strobe Y9. Most of the others are on another dual 1 of 4 decoder IC. The decoder for Y9 is the same IC type, 74LS156. It does however have one input tied directly to the +5 V rail. I suspect a noisy +5 V supply, probably casued by faulty capacitors. I'll have a look at the 5 V supply on the probe power connector but it looks like a partial re-cap is called for. I beed to do a major bench clean-up to get this beast on it.

Based on my experience with a 492ap, take many many photos while slowly and thoughtfully removing the A30 end "cap" assembly containing the PSU. Lots of thought should go into how to avoid bending pins on multicore connectors on the end of cables (166 going to A30W560), and how to reach the blasted things when reassembling. Here's the A30 assembly from the ArtekMedia service manual, which should cause you to cease worrying how to spend your next £10

   Scopes? Pah; they're mechanically trivial!

I've never once regretted the money spent at Artek. I've  bought a dozen manuals since my first experience with them; a premium copy of the SM for my Tek 2230 (instead of just bumbling through with the free preview) and I was able to get the schematics for the PSU & HV section printed up in poster size on the large-format Laser Printer at Kinko's. Lines 0.30mm wide at that scale; still crisp and clear and unbroken. 

mnem

[Specmaster]

Bah, missed discord again  , spent the time driving around the supermarkets in a failed attempt to purchase some Mother's Day cards and presents, all cards and flowers etc completely sold out 

Shows how little imagination these accountants have in controlling the stocks they buy and hold. During this pandemic, they have had pretty much a monopoly on things like cards etc as the card shops are not allowed to open. Wouldn't you have thought that they would have ordered larger stocks knowing that they had the market cornered? 

I've bought my wife an Avo Minor for Mothers Day (which does not occur until May 30th here, it's one of those things that exist in most of the world but is on different days in different countries, and this one is not differing through calendar reform in the 18 century..)

The logic behind this is I suspect that you end up with it because she has no use for an AVO meter? 

[FransW]

Today  (Saturday) arrival:

The long awaited letter from overseas!  Thanks med for sending me this nice PCB adapter. 

Geez....took long enough for it to get to you but I'm glad it finally arrived. 

Med, question, OSH Park?

[bd139]

Urf just spent an hour working out how to update the firmware on my NanoVNA-H. Finally got it 

[med6753]

Today  (Saturday) arrival:

The long awaited letter from overseas!  Thanks med for sending me this nice PCB adapter. 

Geez....took long enough for it to get to you but I'm glad it finally arrived. 

Med, question, OSH Park?

Yes, Kosmic sent me in their direction.

[med6753]

So the 492BP is not perfect.
It now does not always power up at the first attempt. The main tuning knob is stuck in marker mode. The Tune / Marker pushbutton seems to work with the LED toggling but the knob stays in marker mode and the * on the screen does not move. A couple of other push buttons don't work properly either. I've not opened it up but looking at the circuits all the troublesome buttons are on multiplex strobe Y9. Most of the others are on another dual 1 of 4 decoder IC. The decoder for Y9 is the same IC type, 74LS156. It does however have one input tied directly to the +5 V rail. I suspect a noisy +5 V supply, probably casued by faulty capacitors. I'll have a look at the 5 V supply on the probe power connector but it looks like a partial re-cap is called for. I beed to do a major bench clean-up to get this beast on it.

Based on my experience with a 492ap, take many many photos while slowly and thoughtfully removing the A30 end "cap" assembly containing the PSU. Lots of thought should go into how to avoid bending pins on multicore connectors on the end of cables (166 going to A30W560), and how to reach the blasted things when reassembling. Here's the A30 assembly from the ArtekMedia service manual, which should cause you to cease worrying how to spend your next £10

   Scopes? Pah; they're mechanically trivial!

I've never once regretted the money spent at Artek. I've  bought a dozen manuals since my first experience with them; a premium copy of the SM for my Tek 2230 (instead of just bumbling through with the free preview) and I was able to get the schematics for the PSU & HV section printed up in poster size on the large-format Laser Printer at Kinko's. Lines 0.30mm wide at that scale; still crisp and clear and unbroken. 

mnem

And the manuals are tabbed and indexed so you can navigate them easily. 

[mnementh]

         

Here you go bd.... I think I may have found a keyboard we can't beat to death. 

This ReDragon K556 has been on my RADAR for a while; I like the compact footprint, minimalist design and and was interested in the promise of an aluminum chassis. Did they ever deliver on that! Bottom frame is aluminum extrusion; top is  1.55mm brushed-finish black anodized plate. Even the end-caps are aluminum. 

I'd been thinking aboot this one or the white-backlit Durgod K310 for a while; when I got lucky and Windoze activated with the Key off the side of the boi's old PC, I decided it was okay to actually shop a new KB for me and kick my old one down to him. The clincher was yesterday morning when the K556 showed up in my Wish List with a $20 off Prime Member discount; that made it ~US$66 delivered.

According to reviews, switches are Outemu browns; they are nice & quiet with a medium detent at approx 2mm/50% deflection. The metal chassis makes the dull thunk as the keys bottom out quite satisfying to these brutish old dwagon paws.

As you can see, they included an assortment of other keys for you to experiment with. In this application, I think I'll stick with the original switches; maybe shop a set of Romer-Gs or even genuine Cherry browns if they don't hold up.

The only thing I see that bothers me even a little is the fact they used SMD RGB LEDs on the mainboard instead of the usual 3mm LED inside the keycap; as brightness and clarity are more than adequate, I only mind this in principle, and will choose to see it as one less probable point of failure.

mnem
*clicky-clicky-clickety-clickety*

I did actually take a look at those here when I was shopping around. They’re £40 a pop which isn’t bad. The only thing that put me off is I know what cherry reds feel like and I didn’t want any variation. If I bugger this K320 I’ll head in that direction as the pricing is better 

Any idea what processor it has on it. I’ve looked at the K320 and if you brick it, it’s a standard STM32 part. Assume it’s probably same or similar.

I haven't actually taken it apart past the endcap and a couple switches; it appears you have to take ALL the switches out to get the top cover off. I will admit it has a VERY satisfying clunk when you plop it on the desktop. 





I haven't even looked at the software for it... this review goes over it in great detail; it offers three 103-key macro profiles and per-key lighting granularity. Also, it appears all changes are stored in NVRAM on the keyboard; reviewer states all setting are retained if plugged into another PC without the software. 

Considering that, I'd guess you're absolutely right; STM32-based.

I have confirmed that my color choice setting is retained by plugging into my wife's laptop; the only thing I see different is it appears that instead of a set of blue switches to upgrade the usual FPS Gamer keys, it now ships with a "candy box" assortment for people to try which switches they like best.

If I have problems with any switches, I'll tear it down and post some pics of the guts. I can tell you that I already spend a lot less time correcting my horrible typing with this KB; especially the really annoying  '  vs  ;  transposition issue I always seem to have with any membrane KB.

Right now, the only things I wish it had is slightly more elevation at the rear flip-out feet and the good ol' L-shaped oversized carriage return.

mnem
 

[mnementh]

Is this better?     

Much more proper. We used to get wrapped over the knuckles (yes physically not verbally) for undressed screws in School so why should you escape here 

But what is the torque setting? One or more may be over or under tightened. Unless you adjusting the washer thickness or using bellville washers (which is possible with Telequipment).
I once knew a model engineer who would put hand made chamfered and hardened washers under critical faasteners and then adjusted the thickness so the flats lined up. Having a surface grinder makes this a lot easier.

For some fucked-up reason... your tale reminds me of this scene from Dogma... 

mnem
 

[Saskia]

ok, the questionable PSU (Corsair RM1000) has been running for 6 hours now without problems.
Current load: Mainboard/i5 6500/8GB/SSD Graphics: 1660TI, 2070, 3060ti, 3080, 3090
I don't dare hooking up the 3070 as I suspect the graphics boards will eat about 850W alone ...

[mnementh]

Ok bodge time. D755 connector is toast so I’m repurposing it as a boot.      I’m sure it’ll violate many safety things but less than the current situation.

Looks good to me. 

mnem

[mnementh]

ok, the questionable PSU (Corsair RM1000) has been running for 6 hours now without problems.
Current load: Mainboard/i5 6500/8GB/SSD Graphics: 1660TI, 2070, 3060ti, 3080, 3090
I don't dare hooking up the 3070 as I suspect the graphics boards will eat about 850W alone ...

   

Ummm... are you aware that typical setup for a 2x4 GPU mining rig is to parallel one or more DPS-1200FB server PSUs just to feed the GPUs along with the ATX PSU on the MB...?

Typical setup I've seen is one DPS-1200FB feeding 2-4 GPUs in the RX-580 family; with RTX30x0, probably be lucky to feed 2 per DPS-1200FB, depending on the load.

Search string for the PSU is something like: DPS-1200FB-01 A HSTNS-PD19 570451-001 579229-001 490594-001 438203-001 498152-001 for DL380G7 580 585G7 G8

You can also buy them modded and ready to go with a breakout board made for Crypto-mining, if you don't feel like soldering oodles of PCI-e power pigtails. Search string is Breakout Board DPS-1200FB ; this should return both modded PSUs and a variety of the breakout boards.

Good hunting!

mnem
 

[Specmaster]

         

Here you go bd.... I think I may have found a keyboard we can't beat to death. 

This ReDragon K556 has been on my RADAR for a while; I like the compact footprint, minimalist design and and was interested in the promise of an aluminum chassis. Did they ever deliver on that! Bottom frame is aluminum extrusion; top is  1.55mm brushed-finish black anodized plate. Even the end-caps are aluminum. 

I'd been thinking aboot this one or the white-backlit Durgod K310 for a while; when I got lucky and Windoze activated with the Key off the side of the boi's old PC, I decided it was okay to actually shop a new KB for me and kick my old one down to him. The clincher was yesterday morning when the K556 showed up in my Wish List with a $20 off Prime Member discount; that made it ~US$66 delivered.

According to reviews, switches are Outemu browns; they are nice & quiet with a medium detent at approx 2mm/50% deflection. The metal chassis makes the dull thunk as the keys bottom out quite satisfying to these brutish old dwagon paws.

As you can see, they included an assortment of other keys for you to experiment with. In this application, I think I'll stick with the original switches; maybe shop a set of Romer-Gs or even genuine Cherry browns if they don't hold up.

The only thing I see that bothers me even a little is the fact they used SMD RGB LEDs on the mainboard instead of the usual 3mm LED inside the keycap; as brightness and clarity are more than adequate, I only mind this in principle, and will choose to see it as one less probable point of failure.

mnem
*clicky-clicky-clickety-clickety*

I did actually take a look at those here when I was shopping around. They’re £40 a pop which isn’t bad. The only thing that put me off is I know what cherry reds feel like and I didn’t want any variation. If I bugger this K320 I’ll head in that direction as the pricing is better 

Any idea what processor it has on it. I’ve looked at the K320 and if you brick it, it’s a standard STM32 part. Assume it’s probably same or similar.

Where did you get that valuation from, Amazon are asking £72.89, and I don't see it coming up in any other searches as being available apart from Amazon in the UK

[mansaxel]

and the good ol' L-shaped oversized carriage return.

I depend on that, no such keyboard for me. Fortunately, I've got loads of Model M.

[Saskia]

@mnem yes, I know.

but my setup is working, too.
and this PSU is holding up quite well.

[BU508A]

We should offer him a senior membership in the TEA forum: