Test Equipment Anonymous (TEA) group therapy thread

[bd139]

Let me get digging. See what I can find...

@AVGresponding: nice tear down  .  Might want to examine the electrolytic capacitors near the smaller heat sinks carefully. Some of the HP supplies cook them quite badly.

[factory]

HP 6633B teardown pics:

Taking its clothes off:


snip...

Here we can see a factory bodge. Annoyingly the service manual doesn't cover the digital (interface) board, so no idea what the IC is, but it looks like afterthought pull-up/down resistors:


snip...

This resistor looks like its been pushed quite hard, might have to look at replacing it:


Looking at the schematic its purpose seems to be as part of a voltage divider for the pre-regulated DC rails, I'll have to look deeper when I have more time and less of a hangover...

snip...

I'll do a review post at some point, after that suicide cap has been replaced and I have a free long weekend.

I'm quite used to seeing parts soldered to IC's like that and even 3D assemblies of components due to the design errors, shame I can't add pictures as it's work related & photography is prohibited. 

Those large blue resistors were common in certain items at work too, maybe it needed spacing off the board to keep the heat away from the joints. It probably measures fine, we used to resolder them & only replaced them if the coating was flaking off.

David

[bd139]

Let me get digging. See what I can find...

@AVGresponding: nice tear down  .  Might want to examine the electrolytic capacitors near the smaller heat sinks carefully. Some of the HP supplies cook them quite badly.

Ok I only have the older hitachi one was well annoyingly.

Yours uses a uPC13789C which has the hsync stuff inside the IC rather than outside it. Datasheet here https://www.silicon-ark.co.uk/datasheets/UPC1379C%20datasheet%20-%20NEC.pdf

Looks not too horrible to debug so agree with your assertions about the components around it being likely. Let us know how you get on. I'm so absolutely bored at the moment I'd love to have something like that on the bench to debug 

[bd139]

I'm quite used to seeing parts soldered to IC's like that and even 3D assemblies of components due to the design errors, shame I can't add pictures as it's work related & photography is prohibited. 

Yeah I was employed one summer for two weeks to solder a solitary resistor across two pins across the bottom of a PCB on an alarm circuit 300 times over. Wanted to kill myself by the end of that. Someone forgot a pull up 

[Specmaster]

@AVGresponding What is the date of your service manual for the HP 6633B that you have, there seems to be 3 editions but none of them annoyingly cover board A2 which is the interface board with factory bodge on it.

I have in my collection of manuals here 2 versions of manual, 2000 printed by Agilent and 2014 printed by Keysight if they are any good to you, let me know.

[wolfy007]

The HP 54615B from CDL arrived yesterday with no damage and no obvious signs of futzing, complete with horizontal rolling fault on the picture bulb. 


CAL switch wasn't in unprotected position on arrival, it's hard to tell from the listing picture or maybe they read here.


Some pictures of the insides which were cleaner than expected, mainboard with ST NVRAM module & Computer Products PSU module, I can only see one RIFA stinkbomb to replace. 


CRT monitor module is a Hitachi, but the picture bulb is Toshiba. 


I've replaced most of the larger capacitors on the CRT board, but as Shango006 often states it hasn't magically cured the fault yet. The horizontal hold control does work but it's impossible to get a stable display, currently looking at parts around the uPC1379C IC.


David

Check for a small electrolytic on pin 13

I've pulled the 1uF 50V in the horizontal hold circuit, it tests OK as does another nearby, I've fitted a couple of new ones, but had run out of time last night to try it, also wanted to check the other passive components in that circuit before refitting the board.

That’s looking hopeful. Do you have schematics for the monitor assembly? If not I think I’ve got them somewhere.

No I haven't, I did search but could only find the diagram for an earlier Hitachi monitor board. This is the one fitted to the 54615B.


David

 I have repaired a couple of HP 546XXX with this CRT board (in fact a 54602B same CRT boards just last week), both cases was bad electros. For both repairs I replaced all of the 1uf 50v and a 47uf 16v, one also had a bad 220uf 16v on the other a bad 330uf 16v. After verifying it operated correctly (and waiting for more ordered caps) I replaced them all just to be safe. This recent once had such bad caps it was pulling down the power supply and had the scope in a perpetual startup cycle with front end relays clicking away but the screen didnt even come up till the bad caps were replaced including a couple that might even be considered not to bad.

PS: Photo shows the board during testing, the black coloured electros are bad, the red dot ones I wanted to pull out to verify if ok.

[Kosmic]

There's cheap and there's too cheap. If the Ferengi feels it's a worthwhile investment I'm not going to argue.

I generally agree with this. however, I would NOT buy anything from that MPJA sale I wasn't already interested in anyways, so the "free" resistor pack would be truly free, and I'd get to see what shows up. When they get there I'd test 'em quick, and if I found any that didn't please me, out they'd go. Not like it's any scale off my arse one way or t'other. I can't count the number of name-brand resistors I've bought over the decades off eBay for the $4-6 they value these kits at. 

Bottom line is we're making assumptions based on a grainy pic in a sale flyer and the Ferengi's hard-wired "sour grapes" attitude.  Meanwhile, the whole world runs on those shitty Chinese resistors, for the most part. 

Cheers,

mnem
It's a fucking resistor, man.

Sooo, 1.5 year later. I also bought some Chinese Hair legged resistors. I was a bit skeptical of the first one I got so I ordered a second batch from a different source.

The first was one of those super duper special combo pack on ebay. No name and normally really cheap.



The second I ordered from what it look like a branded component seller (IC Touch)



I needed some resistors for a voltage divider where low tempco is important so I decided to test them with some other resistor I had lying around.

The Setup:
The goal was to have a linear approximation of tempco between room temperature and around 60 deg C. So I used my 34401a multimeter to measure the resistance at room temperature and in a bath of mineral oil at around 55-60 Deg C. The HP 974a equipped with a thermistor was used to measure the temperature of air and mineral oil.

[Kosmic]

The Results:


No name 1% metal film resistor from Ebay:
Leg diameter: 0.34mm
Value: 240k
Measured Tolerance: -0.06%
Measured Tempco: -459ppm/DegC


IC Touch 1% metal film resistor:
Leg diameter: 0.38mm
Value: 130k
Measured Tolerance: 0.53%
Measured Tempco: 137.5ppm/DegC


Stackpole 24k 1% 50ppm/DegC:
Leg diameter: 0.42mm
Value: 24k
Measured Tolerance: 0.68%
Measured Tempco: 4.5ppm/DegC


Unknown 1% Metal Film:
Leg diameter: 0.49mm
Value: 82.5k
Measured Tolerance: 0.004%
Measured Tempco: 9.3ppm/DegC


Unknown 5% Carbon Film:
Leg diameter: 0.38mm
Value: 120k
Measured Tolerance: 0.86%
Measured Tempco: -671.6ppm/DegC


Unknown 0.1% (Metal Film?)
Leg diameter: 0.61mm
Value: 200k
Measured Tolerance: 0.02%
Measured Tempco: 11.9ppm/DegC


Old resistor, not sure of the type:
Leg diameter: 0.8mm
Value: 220k
Measured Tolerance: 0.33%
Measured Tempco: -28.7ppm/DegC


Dale 1% (metal film ?):
Leg diameter: 0.63mm
Value: 500k
Measured Tolerance: -0.2%
Measured Tempco: 5.33ppm/DegC


Wirewound resistor:
Leg diameter: 0.63mm
Value: 100k
Measured Tolerance: 0.1%
Measured Tempco: 28.76ppm/DegC

Conclusion:

You get what you pay for I guess. The cheaper you pay, the thinner are the legs and the higher tempco is. It's important to note though that even the cheapest no name ebay metal film resistors are as good as carbon film resistors.

[bd139]

That China metal film is worse than their carbon films. That took some skill 

[Cerebus]

They moved the 3D Printing topics to a corner "Off Topic Hobbies" 
Off Topic 3D Printing? Electronics is the core of those machines....

https://www.eevblog.com/forum/supporters-lounge/off-topic-hobbies/new/#new

 I do not understand.

Well, I could quite successfully argue that electronics was the core of many devices nowadays, would that make them automatically 'on topic'? I think not. Would the fact that one of those Peleton^TM style static exercise cycles would be impossible to make without a shitload of electronics make static cycling 'on topic'? Making one would be*, but just using it? No.

The same applies to 3D printers, CNC mills and lathes and so on. One can see how all those have a peripheral rôle in electronics construction, but not as core electronics.

* I have done. Magnets and Hall effect sensors on the rear wheel and cranks, 5 kHz PLL receiver for a heart rate monitor, add Arduino, add serial connection to an old Mac notebook for a display, done.

[Kosmic]

That China metal film is worse than their carbon films. That took some skill 

They might also be cheap carbon film painted in blue 

[sb42]

You get what you pay for I guess. The cheaper you pay, the thinner are the legs and the higher tempco is. It's important to note though that even the cheapest no name ebay metal film resistors are as good as carbon film resistors.

Interesting, thanks for sharing that. Though I now feel compelled to ask about the sample size for each group (and what the intra-group variance was), as well as the variance in a set of measurements for the same resistor.
My OCD would probably demand about 30 samples for each type of resistor so I'd never get as far as you did with this experiment.

[nfmax]

My OCD would probably demand about 30 samples for each type of resistor so I'd never get as far as you did with this experiment.

Of course! That's why you need a 6 1/2 digit multichannel data logger, and a calibrated precision PRT thermometer, and a thermostatically controlled stirred water bath...

 

[Cubdriver]

That China metal film is worse than their carbon films. That took some skill 

They might also be cheap carbon film painted in blue 

Based on the observed temperature coefficient that would be my guess.

-Pat

[Kosmic]

You get what you pay for I guess. The cheaper you pay, the thinner are the legs and the higher tempco is. It's important to note though that even the cheapest no name ebay metal film resistors are as good as carbon film resistors.

Interesting, thanks for sharing that. Though I now feel compelled to ask about the sample size for each group (and what the intra-group variance was), as well as the variance in a set of measurements for the same resistor.
My OCD would probably demand about 30 samples for each type of resistor so I'd never get as far as you did with this experiment.

Yeah this is really just to give you an idea. I tested tempco only on 1 sample of each groups. Legs diameter though, I measured something like 4 resistors in each groups and it was pretty consistent.

[Kosmic]

My OCD would probably demand about 30 samples for each type of resistor so I'd never get as far as you did with this experiment.

Of course! That's why you need a 6 1/2 digit multichannel data logger, and a calibrated precision PRT thermometer, and a thermostatically controlled stirred water bath...

 

Haha I thought about acquiring a stirred bath while doing the measurement 

[McBryce]

https://www.ebay.de/itm/Philips-Digital-Multimeter-PM-2421-Pr%C3%BCfger%C3%A4t-mit-Nixie-R%C3%B6hren-Me%C3%9Fger%C3%A4t-defekt/303866737710

I don't need more Nixies, I don't need more Nixies... Ooo, it does nA.... I DON'T NEED MORE NIXIES!!!

Can I get some support here?

McBryce.

[AVGresponding]

Legs diameter though, I measured something like 4 resistors in each groups and it was pretty consistent.

So you're a leg man, eh?   

[nfmax]

My OCD would probably demand about 30 samples for each type of resistor so I'd never get as far as you did with this experiment.

Of course! That's why you need a 6 1/2 digit multichannel data logger, and a calibrated precision PRT thermometer, and a thermostatically controlled stirred water bath...

 

Haha I thought about acquiring a stirred bath while doing the measurement 

That's your problem, right there: thinking! https://www.eevblog.com/forum/chat/what-did-you-buy-today-post-your-latest-purchase!/msg3202972/?topicseen#msg3202972

[Cubdriver]

https://www.ebay.de/itm/Philips-Digital-Multimeter-PM-2421-Pr%C3%BCfger%C3%A4t-mit-Nixie-R%C3%B6hren-Me%C3%9Fger%C3%A4t-defekt/303866737710

I don't need more Nixies, I don't need more Nixies... Ooo, it does nA.... I DON'T NEED MORE NIXIES!!!

Can I get some support here?

McBryce.

Fixed it for you.     You're welcome.   

-Pat

[factory]

Finally one that isn't silly priced and has make offer, buy it to save me from asking about shipping. 

David

[Hydron]

Haha I thought about acquiring a stirred bath while doing the measurement 

Just chuck a small DC fan in there and run it at whatever minimum voltage it will spin at, will take care of the stirring, at least while the oil temperature isn't high enough to cook it. I have actually done this in water at ~80C or so, the fan amazingly survived, though I tossed it after that abuse.

[Kosmic]

Haha I thought about acquiring a stirred bath while doing the measurement 

Just chuck a small DC fan in there and run it at whatever minimum voltage it will spin at, will take care of the stirring, at least while the oil temperature isn't high enough to cook it. I have actually done this in water at ~80C or so, the fan amazingly survived, though I tossed it after that abuse.

This is actually a good idea. Thanks!

[mnementh]

They moved the 3D Printing topics to a corner "Off Topic Hobbies" 
Off Topic 3D Printing? Electronics is the core of those machines....

https://www.eevblog.com/forum/supporters-lounge/off-topic-hobbies/new/#new

 I do not understand.

Well, I could quite successfully argue that electronics was the core of many devices nowadays, would that make them automatically 'on topic'? I think not. Would the fact that one of those Peleton^TM style static exercise cycles would be impossible to make without a shitload of electronics make static cycling 'on topic'? Making one would be*, but just using it? No.

The same applies to 3D printers, CNC mills and lathes and so on. One can see how all those have a peripheral rôle in electronics construction, but not as core electronics.

* I have done. Magnets and Hall effect sensors on the rear wheel and cranks, 5 kHz PLL receiver for a heart rate monitor, add Arduino, add serial connection to an old Mac notebook for a display, done.

My guess would be much more likely just Simon being a butthead. He had a tantrum in the 3DP thread a couple weeks ago and everybody told him off; then he peeved that it was an unimportant thread and should die off anyways. Why not just help it along a little by making sure it doesn't show up on the main page, where every new post just taunts him...?

Or maybe it was unwittingly instigated by one of the 3DP thread regulars, who shall remain nameless to protect the guilty. 

mnem
*punt*

[McBryce]

Finally one that isn't silly priced and has make offer, buy it to save me from asking about shipping. 

David

Low-ball automatically rejected. Time to ponder a while....

McBryce.