Test Equipment Anonymous (TEA) group therapy thread

[Specmaster]

Some more philips love / fanboyism. They put all the damn caps on the same sheet as the power supply on the schematic 

Also a mayor advantage is a linear power supply as well, easier to work on.

[bd139]

That's actually both types of power supply in one. The right half is a linear that generates ~28V at 1.5 amps and the left half is a Royer-ish switching converter. This has the advantage that it runs on both 28V DC (military etc) and mains. The switching converter is much easier to unbugger compared to other topologies like flybacks and is a lot less noisy electrically speaking as well. It's similar to the one I built the other day albeit more complicated and more refined than mine

[beanflying]

grr.

Got all my cabling sleeved up and tidied literally just as the new processor arrived.

New CPU installed; no boot. "Memory Error" beep code. Memory is BALLISTIX/MICRON, checked part # on MB QVL before I bought. Cleared CMOS... removed cooler, checked CPU; installed flush & tight & good coverage. Still same.  Stripped down to MB, RAM, & Processor... still no boot.    Gonna step back, go play with my son and get the eff away from this monster for a little bit. Will probably come back after the wee beasties are in bed and go through all the obvious troubleshooting step by step. I know it's something STUPID.

mnem
"You know it's bad when you annoy yourself..."  

This is why I tend to buy ex corporate workstations and laptops now. I find it too worrisome integrating a PC now. I used to build everything myself up until about 2005 but I had a bad experience which cost me £400 in the end as the retailer refused to honor their warranty and the machine was never stable enough for my requirements. I sold it and bought an HP desktop and never looked back.

Before this one the last one I built was an XP based Athalon 2400 from memory at the time it was harder to sort out bits and drivers by far. Since then I have made do with re tasked ones apart from my Asus Laptop. Overall mine was dead easy apart from the BIOS upgrade and it was always going to be a bit of a risk buying in week one of a release.

Nothing wrong with second hand ex work stations but depending on the use needed and buying someone else's potentially cooked gaming rig didn't make sense as locally they sell for 80-90% of parts pricing.

[tggzzz]

Some more philips love / fanboyism. They put all the damn caps on the same sheet as the power supply on the schematic 

For any caps on the rails exactly as good schematics should be. 

Not always.

For sensitive and/or fast analogue circuits it is standard practice and good practice to put them near the other relevant components. They are, after all, just as much part of the circuit's function as the resistors and semiconductors.

[Ice-Tea]

I agree. Decoupling caps (local ceramic and the like) should be close to the target component.

[tautech]

Some more philips love / fanboyism. They put all the damn caps on the same sheet as the power supply on the schematic 

For any caps on the rails exactly as good schematics should be. 

Not always.

For sensitive and/or fast analogue circuits it is standard practice and good practice to put them near the other relevant components.

Your cap numbering scheme can fix that. 
Decouplers numbered the same # as the IC it's alongside...IC1 C1, IC2 C2............

With modern CAD programs we generally hide the VDD/VCC and GND for IC's so leaving a decoupler hanging in the air somewhere just throws DRC errors so it's simplest to place them all on a relevant strip of the rail and to one side of the schematic then define the correct Nets and let the program sort it out.

Far far tidier than running IC supply rails all over schematics. 
It's all fixed by the CAD program in the PCB layout.

[bd139]

Not always.

For sensitive and/or fast analogue circuits it is standard practice and good practice to put them near the other relevant components. They are, after all, just as much part of the circuit's function as the resistors and semiconductors.

This is only supply decoupling which is fair enough though as the objective is to separate the functional part of the circuit from the notion of an ideal voltage source that supplies that bit. The signal chain is the money shot for me at least. You can derive the decoupled analogue sections pretty easily though:



From a technician's perspective it's a hell of a lot easier than flicking back and forth in the service manual and signal tracing everything then as well and analysis sections can be throw in LTspice and traced out with minimal effort.

Tek have some quite horrible decoupling tangles in some of their schematics. They actually stopped doing this on the 2000 series and later I noticed. Perhaps they read a Philips service manual 

[bd139]

And TEA strikes again. I now own a Fluke 8050A 

[tautech]

Tek have some quite horrible decoupling tangles in some of their schematics.

I think everyone did until they woke up and realised schematics don't have to represent PCB layouts.
Still, the component labeling scheme needs to make sense too if a PCB vs schematic is to make any sense at all !

Bit or an art to get right/nice but very satisfying when you do.

[bd139]

Yeah it is indeed an art. I find so many horrid schematics TBH it appears that it's an art that is mostly lost.

This is my favourite turd at the moment:



I had to redraw that to work it out 

[horo]

Some more philips love / fanboyism. They put all the damn caps on the same sheet as the power supply on the schematic 

You should also look at X2 C101. Due to the dual power option (mains or 24V DC) the power switch doesn't switch off the mains but only the secondary voltage. The primary side is powered permanently and after years this X2 will give up I found some reports of burnt Philips scopes recently, e.g. in this thread: 
https://www.eevblog.com/forum/repair/philips-pm3055-osciloscope-repair


Martin

[med6753]

And TEA strikes again. I now own a Fluke 8050A 

My Bench A standard. 

(Bench B is the Siglent)

[bd139]

You should also look at X2 C101. Due to the dual power option (mains or 24V DC) the power switch doesn't switch off the mains but only the secondary voltage. The primary side is powered permanently and after years this X2 will give up I found some reports of burnt Philips scopes recently, e.g. in this thread: 
https://www.eevblog.com/forum/repair/philips-pm3055-osciloscope-repair

Thanks for the heads up but yes aware of that one. This is my third PM3217 and the second one exploded on me  ... RIFA of course:



Incidentally my PM3310 exploded on me as well but that was an inline schaffner that started hissing like a snake and was powered down very bloody quickly 

And TEA strikes again. I now own a Fluke 8050A 

My Bench A standard. 

(Bench B is the Siglent)

I approve 

I really like the dB againt ref impedance function on the 8050A. Very neat thing that is.

[tggzzz]

Some more philips love / fanboyism. They put all the damn caps on the same sheet as the power supply on the schematic 

For any caps on the rails exactly as good schematics should be. 

Not always.

For sensitive and/or fast analogue circuits it is standard practice and good practice to put them near the other relevant components.

Your cap numbering scheme can fix that. 
Decouplers numbered the same # as the IC it's alongside...IC1 C1, IC2 C2............

For sensitive and/or fast analogue circuits, no, it can't:

• single IC, multiple decouplers, often in parallel
• single IC, multiple PSU rails
• that's only one of many conventions. Why should a reader have to work out what convention you have chosen to use?
• you should make it easy for the many readers, not a single creator

With modern CAD programs we generally hide the VDD/VCC and GND for IC's so leaving a decoupler hanging in the air somewhere just throws DRC errors so it's simplest to place them all on a relevant strip of the rail and to one side of the schematic then define the correct Nets and let the program sort it out.

Leaving them hanging is a strawman argument.

I want someone looking at the schematic to understand all aspects of its operation. I don't care about a program sorting it out; that will happen anyway!

Far far tidier than running IC supply rails all over schematics. 
It's all fixed by the CAD program in the PCB layout.

Running IC supply rails all over the schematic is a strawman argument. Nobody has suggested that either for digital or analogue/RF circuits.

CAD programs fix nothing, at best they ensure consistency.

[tggzzz]

Not always.

For sensitive and/or fast analogue circuits it is standard practice and good practice to put them near the other relevant components. They are, after all, just as much part of the circuit's function as the resistors and semiconductors.

This is only supply decoupling which is fair enough though as the objective is to separate the functional part of the circuit from the notion of an ideal voltage source that supplies that bit. The signal chain is the money shot for me at least. You can derive the decoupled analogue sections pretty easily though:



From a technician's perspective it's a hell of a lot easier than flicking back and forth in the service manual and signal tracing everything then as well and analysis sections can be throw in LTspice and traced out with minimal effort.

Tek have some quite horrible decoupling tangles in some of their schematics. They actually stopped doing this on the 2000 series and later I noticed. Perhaps they read a Philips service manual 

I agree on all counts, which is unusual for me

I even noted one of Tek's "tricks" w.r.t. C911 in the 485

I'll reiterate the point I made in my reply to tautech: it is A Good Thing to make it easy to read.

[bd139]

Yep readability is everything.

On that subject, straight from the 485 SMM:



If you run out of space, bend that compensation network around a corner! 

Edit: also screw going through that many compensation trimmers at each stage!

[tggzzz]

On that subject, straight from the 485 SMM:
...
If you run out of space, bend that compensation network around a corner! 

Edit: also screw going through that many compensation trimmers at each stage!

A man's gotta do what a man's gotta do.

That bending reminds me of other contemporary technology... Back in the days of red/blue rubylith pcb layout technology, I had a technician that, once he had put a track down, he would never move it. I had some sympathy!

[bd139]

I can understand that on rubylith. Major screw ups mean start again. However no excuse not to pencil the design out first. I usually do that even today before I hit kicad. I've caught a lot of weird problems with kicad libraries that way!

[med6753]

Out in the garage today woodworking. It is TEA related. Making more room. Pix when I have it done and installed. Most likely Saturday.

In other news. About 25 years ago rabies spread like wildfire among the raccoon population. Well it appears it has hit them again...hard. Multiple police calls of alleged rabid raccoons and the cops are shooting them. Which is a good idea. Raccoons are nocturnal. If you see one out during the day wandering aimlessly you can be 99% certain it's rabid. And if I see one I won't hesitate for one second to plug it with my .22 rifle.     

[mnementh]

Currently doing ANYTHING BUT fucking around with that new PC; even if it means BBQ for breakfast.

mnem
Fuck. That. Noize.

[Mr. Scram]

Out in the garage today woodworking. It is TEA related. Making more room. Pix when I have it done and installed. Most likely Saturday.

In other news. About 25 years ago rabies spread like wildfire among the raccoon population. Well it appears it has hit them again...hard. Multiple police calls of alleged rabid raccoons and the cops are shooting them. Which is a good idea. Raccoons are nocturnal. If you see one out during the day wandering aimlessly you can be 99% certain it's rabid. And if I see one I won't hesitate for one second to plug it with my .22 rifle.     

The same applies to other wildlife. If it's unusually friendly or approachable you may be a Disney princess, but it's more likely rabies.

[med6753]

I'm taking a risk here. What do you Brits think of new guy Boris? Keep it to a dull roar. 

Every time I hear the name I think of this. 

[tggzzz]

I'm taking a risk here. What do you Brits think of new guy Boris? Keep it to a dull roar. 

Don't go there. Seriously. Don't go there.

Do, however, read the headlines at https://newsthump.com/ but don't bring any of that back here.

[med6753]

I'm taking a risk here. What do you Brits think of new guy Boris? Keep it to a dull roar. 

Don't go there. Seriously. Don't go there.

Do, however, read the headlines at https://newsthump.com/ but don't bring any of that back here.

Oh boy...I guess I hit a REAL SENSITIVE spot. Nevermind. Forget I asked. I know the answer. 

[tggzzz]

I'm taking a risk here. What do you Brits think of new guy Boris? Keep it to a dull roar. 

Don't go there. Seriously. Don't go there.

Do, however, read the headlines at https://newsthump.com/ but don't bring any of that back here.

Oh boy...I guess I hit a REAL SENSITIVE spot. Nevermind. Forget I asked. I know the answer. 

Politics is always a very sensitive issue, and rightly banned on this forum.