Oscilloscope (DSO) and bench PSU choice for repair/analysis...

For discussion of triage and repairs to SGIs as well as general hardware questions
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mapesdhs
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Oscilloscope (DSO) and bench PSU choice for repair/analysis...

Post by mapesdhs » Tue Jul 31, 2018 12:54 pm

Hello all! :)

I've begun the process of tooling up to start doing CLB repairs of SGI parts. Much to learn, will probably take at least a year to get decent at it. Two items I've yet to order though are a bench PSU and a Digital Storage Oscilloscope, something I want to do this week. Before ordering, I thought I'd ask here for opinions about what might be sensible now that I've boiled things down to a couple of choices each. Hard to guage beforehand what would be optimal, but even so, may aswell brainstorm a bit.

For the PSU, I'm dithering between these two models:

https://www.amazon.co.uk/Linear-Bench-S ... 00GJVAEZU/
https://www.amazon.co.uk/gp/product/B00PS5HAPA/

Given the kind of voltages and currents one might find whizzing around on SGI boards, I figure the former unit probably makes more sense, but would welcome comments. One person in a review did say they found the single-turn pots made it hard to refine the desired voltage/current accuracy at the 0.1% level (final digit in the display) but I doubt that matters for SGI boards, though if anyone reckons it does then there is a model which has multi-turn pots for more precise voltage/current selection (just costs more):

https://www.amazon.co.uk/Linear-Bench-P ... 00BCPTG66/

As for the DSO, I'm torn atm between these two (first has 100MHz bandwidth, the 2nd has 200MHz):

https://www.amazon.co.uk/dp/B00I5EWF1U/
https://www.amazon.co.uk/dp/B01M15LZ5Q/

The latter has a wider bandwidth range, but costs a fair bit more. Main thing I was thinking was that supporting up to 200MHz might be handy for being able to check stuff related to VPro boards, given the DACs such boards use. I'm no expert in this stuff atm though, so apologies if my base assumptions are wide of the mark. Still, I don't mind spending the extra if it's going to be worth it.

Comments/suggestions welcome!

For reference, the DMM I've bought is a BK Precision 393, hot air station is a Quick 861DW, microscope is an Amtech SE400-Z (with an LED ring light), ultrasonic cleaner is a Skymen 30litre (6.7 gallon) 600W, plus all sorts of other stuff, eg. Kester solder, Remington 34/44 AWG magnet wire, Kapton tapes, etc. Only exception is a fume extractor, those are way too expensive to buy new, so I'm making my own, ditto a custom monitor mount for a 24" IPS for viewing live device readings from the 393 and DSO, checking stuff online, etc. (just a simple P55 PC for that)

It's all a heck of an outlay, but if I can repair just one DCD for O2 I have, that alone will cover almost the entire cost of the equipment. After that, I have a whole pile of potential repair targets for 4D, Challenge/Onyx, O2, Fuel, etc.

Oh, one other item I wanted to get was a camera for the microscope, so I can have a live view on the monitor, perhaps record stuff for upload to YT, etc. Was pondering this model:

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 2890980271

Anyone have any experience with this kind of camera?

Ian.

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GRudolf94
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Re: Oscilloscope (DSO) and bench PSU choice for repair/analysis...

Post by GRudolf94 » Tue Jul 31, 2018 6:46 pm

Your DMM, rework station and whatnot should be alright for a beginner. I take it you have watched Louis Rossmann's videos?

I would replace the magnet wire for Kynar wire instead, though, and as for the bigger bench equipment:
An oscilloscope should be a lifetime investment. Give preference to buying something better just once. Older Tektronix and HP/Agilent equipment may be bigger and whatnot, but I would prefer that over a new Hantek scope. Rigol seems like an alright choice for cheaper, newer stuff.

Those PSUs you listed, I'd actually choose neither. Better have a look at the EEVblog forums and see what do they have to recommend there.

Cheers

P.S: consider acquiring a small logic analyzer, such as a Saleae clone
:Indigo2: R10k@195MHz/64MB RAM/XZ/ATX PSU conversion in the works/acting up
:Indy: R4600@133MHz/128MB RAM/XL-24/Gruesomely plasti-welded together
:Octane: R10k@225MHz/1536MB RAM/SSI

SGI Ultra64...erm, Nintendo64 console :D

and lotsa non-SGI stuff

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mapesdhs
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Re: Oscilloscope (DSO) and bench PSU choice for repair/analysis...

Post by mapesdhs » Tue Jul 31, 2018 7:49 pm

GRudolf94 wrote:
Tue Jul 31, 2018 6:46 pm
Your DMM, rework station and whatnot should be alright for a beginner. I take it you have watched Louis Rossmann's videos?
Hehe, his vids have been the staple of my telly viewing since about March. :D YT has largely given up trying to recommend me anything else. I did buy a few items from his site btw, eg. the flux, probes, etc.

Note I wouldn't say I'm a complete beginner, been doing general electronics/solder stuff for a long time (though 30 years ago my passion was more for lasers, high voltage experiments, building guitar effects units, etc.), but not at this level before, and it'll be my first time using an oscilloscope. Ah what fun to jump in at the deep end. :) Tbh I wish I'd started this years ago, but never mind, hindsight is always perfect.

GRudolf94 wrote:
Tue Jul 31, 2018 6:46 pm
I would replace the magnet wire for Kynar wire instead, though, ...
Bit late now, already bought the wire, though if the wire I bought is not good, tell that to Louis, it was on his recommended list. ;)

GRudolf94 wrote:
Tue Jul 31, 2018 6:46 pm
An oscilloscope should be a lifetime investment. ...
At this stage though I don't really know what I'll need, so I reckon it makes more sense to just buy something reasonable now and think about something top-end later when I know a lot more about what I'm doing and what actually matters to do the work, assuming I do end up deciding I need something better. I know there are better models, but that doesn't necesssarily mean they're better for working with SGI parts. And of course older gear does mean no warranty, which at this cost level is something I'd rather avoid. I did look at Rigol, but was put off for various reasons, partly price (it was quite a lot more than the models I cited above).

However, as you say I will if I have a chance peruse EEVblog to see what's there about this.

GRudolf94 wrote:
Tue Jul 31, 2018 6:46 pm
Those PSUs you listed, I'd actually choose neither. Better have a look at the EEVblog forums and see what do they have to recommend there.
Ok, I'll have a look. I wanted to before but didn't have the time, though I'll check his YT channel first, don't really have the time to wade through endless forum posts. :D Still, it's not as if I'm opting for one of the units that's way down into the 50 to 70 UKP range which seem to be popular atm.

And as with the 'scope, I can always buy something better later if it turns out that makes sense, and I can still make use of the existing unit.

GRudolf94 wrote:
Tue Jul 31, 2018 6:46 pm
P.S: consider acquiring a small logic analyzer, such as a Saleae clone
Yikes, another item on the list, hehe. Hmm, maybe later, I think it's best to get up and running at least to a basic extent, especially since most of the initial repairs I want to tackle mainly involve reflow, missing SMCs, PSU issues, that sort of thing. Part of it though involves creating new info about these boards, eg. diode mode testing responses for parts that are working ok, so one can compare to parts that are faulty (hence the microscope and being able to record stuff). Sooo much to do. Like I say, I'm sure it'll be at least a year before I'm up to any kind of speed, but gotta start somewhere. I'm going to start with PSUs, bit easier to get to grips with, and to get used to the new specs I bought for short/medium range vision. First target for diode mode baseline measurements will be a DCD for O2 (I have a working board and a faulty board). Inb time, who knows, maybe I can help create new boardview files for SGI parts (I bought FlexBV to help out Paul Daniels; he's going to help me get his live measurement sw working with the BK 393).

Thanks for the reply!!

Ian.

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Re: Oscilloscope (DSO) and bench PSU choice for repair/analysis...

Post by GRudolf94 » Wed Aug 01, 2018 2:02 am

On the phone here so I'm just gonna get lazy with the reply and not quote anything:

as for anything you might need help with, shoot me a PM. I'm in no sense of the word any kind of engineer, but I'm a fairly decent tinkerer (or at least I consider myself so), to the point I can design and build my own hardware (PCB layout and all)

As for SGI boardviews, we'd need the schematics and whatnot for those, and, unless we were to manually disassemble, measure, probe and even delaminate board layers to reverse engineer all that, we're lost. It's the equivalent of trying to make an yellow pages phone book just by looking at an overhead view of a city map
:Indigo2: R10k@195MHz/64MB RAM/XZ/ATX PSU conversion in the works/acting up
:Indy: R4600@133MHz/128MB RAM/XL-24/Gruesomely plasti-welded together
:Octane: R10k@225MHz/1536MB RAM/SSI

SGI Ultra64...erm, Nintendo64 console :D

and lotsa non-SGI stuff

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jan-jaap
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Re: Oscilloscope (DSO) and bench PSU choice for repair/analysis...

Post by jan-jaap » Wed Aug 01, 2018 3:48 am

Keep in mind that large parts of switch mode PSUs are *not* isolated from mains. If you want to do measurements there, you need an isolated probe or you will destroy the scope, the test subject and possibly kill yourself in the process.

High bandwidth isolated probes can easily cost more than a decent scope, I'm afraid.

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mapesdhs
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Re: Oscilloscope (DSO) and bench PSU choice for repair/analysis...

Post by mapesdhs » Wed Aug 01, 2018 6:43 am

GRudolf94 wrote:
Wed Aug 01, 2018 2:02 am
as for anything you might need help with, shoot me a PM. ...
Thanks!! I'll bare that in mind. 8)

GRudolf94 wrote:
Wed Aug 01, 2018 2:02 am
As for SGI boardviews, we'd need the schematics and whatnot for those, and, unless we were to manually disassemble, measure, probe and even delaminate board layers to reverse engineer all that, we're lost. It's the equivalent of trying to make an yellow pages phone book just by looking at an overhead view of a city map
Very true; I don't expect to be able to create complete diagrams, that'll never happen, but something is better than nothing, and even the basics of a board would be useful for diagnosing faults. One can do a heck of a lot with a PCB to resolve problems even without schematics, as numerous vids by Louis and iPadRehab show.

jan-jaap wrote:
Wed Aug 01, 2018 3:48 am
Keep in mind that large parts of switch mode PSUs are *not* isolated from mains. If you want to do measurements there, you need an isolated probe or you will destroy the scope, the test subject and possibly kill yourself in the process.
Indeed; like I said, much to learn. :D I've bought a number of books on PSU theory, construction and operation, so I won't be going in blind, but sure, at least at first any scope will be faaar away from such tech.

The most lucrative units to fix are of course those for Fuel and IRIS Indigo; I have a lot of them.

Ian.

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Re: Oscilloscope (DSO) and bench PSU choice for repair/analysis...

Post by GRudolf94 » Wed Aug 01, 2018 9:26 am

jan-jaap wrote:
Wed Aug 01, 2018 3:48 am
High bandwidth isolated probes can easily cost more than a decent scope, I'm afraid.
about 200 quid if buying from China, as much as a decent scope if from a reputable manufacturer
:Indigo2: R10k@195MHz/64MB RAM/XZ/ATX PSU conversion in the works/acting up
:Indy: R4600@133MHz/128MB RAM/XL-24/Gruesomely plasti-welded together
:Octane: R10k@225MHz/1536MB RAM/SSI

SGI Ultra64...erm, Nintendo64 console :D

and lotsa non-SGI stuff

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mapesdhs
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Re: Oscilloscope (DSO) and bench PSU choice for repair/analysis...

Post by mapesdhs » Wed Aug 01, 2018 10:10 am

OK, after some eevblog digging, how about one of these?

https://www.amazon.co.uk/Siglent-SDS110 ... 0771N1ZF9/
https://www.siglent.eu/sds1204x-e.html

The 1104 can apparently be hacked to 200MHz, but I'm not so keen on doing something like that. The 1204 is a bit of a price bump, but as you say, a purchase for life.

Amazon doesn't have the 1204, so a suitable UK source would be (it would cost about 42 more to order from siglent.eu, so this is better):

https://labtronix.co.uk/drupal/shop/osc ... sds1204x-e

I found an overview video and a more detailed review:

https://www.youtube.com/watch?v=qCqQzdj2aGU
https://www.youtube.com/watch?v=Cwbwq-AKbPc

Thoughts? The 1204 costs a lot more than the Hantek I was looking at, but then it ticks many more boxes, eg. twice the channels, better bw, deeper memory, etc.

Ian.

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Re: Oscilloscope (DSO) and bench PSU choice for repair/analysis...

Post by GRudolf94 » Wed Aug 01, 2018 1:29 pm

mapesdhs wrote:
Wed Aug 01, 2018 10:10 am
The 1104 can apparently be hacked to 200MHz, but I'm not so keen on doing something like that. The 1204 is a bit of a price bump, but as you say, a purchase for life.
The hardware probably is about the same, with just a firmware change. But then there goes your warranty on a pricey bit of a kit.
mapesdhs wrote:
Wed Aug 01, 2018 10:10 am
Thoughts? The 1204 costs a lot more than the Hantek I was looking at, but then it ticks many more boxes, eg. twice the channels, better bw, deeper memory, etc.
Looks like one hell of a nice buy. Definitely go for it, if you feel like it.
:Indigo2: R10k@195MHz/64MB RAM/XZ/ATX PSU conversion in the works/acting up
:Indy: R4600@133MHz/128MB RAM/XL-24/Gruesomely plasti-welded together
:Octane: R10k@225MHz/1536MB RAM/SSI

SGI Ultra64...erm, Nintendo64 console :D

and lotsa non-SGI stuff

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mapesdhs
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Re: Oscilloscope (DSO) and bench PSU choice for repair/analysis...

Post by mapesdhs » Wed Aug 01, 2018 2:32 pm

I'm certainly erring towards the 1204 atm. WIll decide tomorrow.

Re the PSU, I couldn't really find anything useful on eevblog. After some more digging, I'm now considering this:

http://cpc.farnell.com/tenma/72-2540/po ... dp/IN07294

I like the programmability from a PC, and If I found I needed more than 5A I could just buy a 2nd 72-2540 and rig them in parallel (with diodes to prevent them affecting each other), which is another way of having dual supplies at different settings should that be necessary.

There is a 10A version which I would prefer, but I'm not sure if it has the same coms ports and is supplied with the same sw CD (will call CPC tomorrow):

http://cpc.farnell.com/tenma/72-2930/po ... dp/IN07642

Ditto a 60V 5A with similar sparse details (not sure if a broader voltage range would be wiser):

http://cpc.farnell.com/tenma/72-2940/po ... dp/IN07644

Ian.

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