Test Equipment Anonymous (TEA) group therapy thread

[mnementh]

Huh...? Now why didn't eevBlog popup the usual "a post has been made...  " message...? 

mnem
meh.

For the purpose of making you look daft   

It worked!

mnem
fuck you very much...

[mnementh]

I'm intrigued as to what lies under that rather elegant heatsink, since the power output semis seem to be mounted to the bottom rear of the chassis.

IIRC, those "shaved fins" are carved from a piece of Al angle extrusion, the bottom leg of which you can see underneath.

They're supposed to be much more efficient for size; seems to me a lot of that efficiency is lost in the angle transition. 

mnem
 

[med6753]

It turns out the antenna was wired traditionally with twin lead, but then someone extended the twin lead cable inside the house with some random 3 wire jobby.
After looking at the condition of the twin lead outside, it looks like someone is going to run some new coax.
Oh hello my lovely carol rg-6 wire, how long have you been waiting for attention? 

I can't believe someone still has an outdoor antenna fed with 300 ohm twinlead. That shit must be brittle as hell. 

[ch_scr]

@med6753
This https://www.vintageshifi.com/repertoire-pdf/pdf/telecharge.php?pdf=Sansui-A-909-Service-Manual.pdf
looks fairly similar. Uses the same voltage preamp and what I can make out of the internal photo looks like a similar heatsink?
Edit: Power board seems right "F-3728"
Edit2: Front Panel checks out as well

[Specmaster]

@med6753
I have come up with the same result as ch_scr but also I have discovered that the A990 is a localized version of the A9090, so you might be able to find a manual for that, and it is thought that the only differences is the power supply, the A990 being the USA and the A9090 is the European version?

Edit. It would seem that the Sansui numbering system jumps around all over the shop from year to year or decade to decade or something or other because sometimes the "A" range refers to amplifiers and other times to receivers when generally "AU" would appear to be receivers, but I'm drawing a complete blank on the A9090 front as far as a amplifier is concerned.

Oh shit, I just realised that it's Saturday and so that means that once again I've missed Discord. I'm all over the place with what day it is this holiday and I can't even blame the booze either, apart from a glass of the bubbly on Christmas day, I've not had a drop.   

[med6753]

@med6753
This https://www.vintageshifi.com/repertoire-pdf/pdf/telecharge.php?pdf=Sansui-A-909-Service-Manual.pdf
looks fairly similar. Uses the same voltage preamp and what I can make out of the internal photo looks like a similar heatsink?
Edit: Power board seems right "F-3728"
Edit2: Front Panel checks out as well

Thanks!  It looks identical and although some pages are missing it gives me enough.....and especially how to adjust the bias.   

[Specmaster]

People who are of the opinion that Covid is like the Flu needs to see this, it is much worse than any flu could be and the authorities on this film, in Italy made the UK government aware of it very early on and yet, we seem to have ignored them 

It is criminal really the way that we buried our heads in the sand of this virus and still continue to do. Gagging the experts, the NHS and despite the NHS pleading that they do something to shut up those that continue to claim that it is all a hoax etc. This week they have been holding demonstrations outside of hospitals where people are dieing the virus and still the authorities do nothing about shutting these morons down, the same goes for the 5G brigade as well, what will it take before these people are dealt with, they are causing others to suffer immensely. Is now the way of the world, where people are happy to see others suffer?

[URI]

I wasn't on discord tonight because I missed the time chasing a malfunction on one of my HP 3456A-DMMs:
On one of them I happened to notice that the 10V range wasn't working right: to about 2,5V it's readings are ok but above that it starts being progressively to low with 10V reading as noisy ~8,5V.   

Checked the service manual, went to service group C and found out that if that happens most likely the 1000V range is broken the same way.
Hmmm. How would I check the 1000V Range? The highest single voltage has one of my supplies delivering 80V.   

Started to check ebay for suited supplies (Keithley, Fluke, HP, PD,...) and found no bargains.

Then I remembered my Isolation Tester with test voltages of 100V, 250V, 500V and tada: 1000V!
Pulled the Isolation Tester from the repair stack and then had to face why it was there: battery and supply dead. 
Checked the supply, found a deaf Elko and a shorted diode, replaced both and was back in business. 

Checked the input impedance of my 3456As, all at 10MOhms.   
Two measuring the test voltage as 1022V, the defective one measures noisy ~850V. Bingo!

I'll have to check inside next but will do some sleeping before that. Tired.   

[URI]

@Saskia & @Specmaster:

My understanding of Gibraltar now being part of the Schengen treaty is that Gibraltarians can cross the Gibraltarian/Spanish border without checks like the Spanish, it's an open border. But the Spanish Government puts up the checks at Gibraltar airport because it's now an EU outer border. Gibraltar can't do these checks because it's not a European state (it's not a state at all). That's part of the latest Spanish/British bilateral treaty.
That's what I understood from the newspapers.

[mnementh]

I stopped in the Discord for a minute, but my wife had a Taco Bell attack and I was elected to go running. The things we do for domestic tranquility...



Things like this...   

mnem
 

[med6753]

I stopped in the Discord for a minute, but my wife had a Taco Bell attack and I was elected to go running. The things we do for domestic tranquility...



mnem
 

Doesn't she have a driver's license? Can she go places without getting lost? Can she use the drive thru window or do they speak French only? 

Oops...that's right, Toronto is in Ontario. My bad. 

[25 CPS]

I stopped in the Discord for a minute, but my wife had a Taco Bell attack and I was elected to go running. The things we do for domestic tranquility...



mnem
 

Doesn't she have a driver's license? Can she go places without getting lost? Can she use the drive thru window or do they speak French only? 

Oops...that's right, Toronto is in Ontario. My bad. 

And Toronto had (still has?) a bylaw banning the construction of new drive-thrus so they're not that common in the city.

[0culus]

Well, I had another big TEA weekend. Same source as the 575s came from. Picked up a nice 7904 that has all options but known power supply issues and phosphor burns. However, I also got an R7903 which is similarly optioned (both have the high writing rate crt with 0.5cm divisions) so that tube could be a donor. Needless to say I am probably going to go all medieval on recapping this one since it has known problems in the power supply area. Other grabs include a 5103N dual beam scope with plugins, a rackmount 5441 (which may be a parts source), and a 7313 storage scope. All of these I'm going to evaluate for repair and stuff in time.

I *also* got my 428B clip on milliammeter...appears to be in excellent working order. Pics later on as I'm exhausted. 

[Neomys Sapiens]

I stopped in the Discord for a minute, but my wife had a Taco Bell attack and I was elected to go running. The things we do for domestic tranquility...



Things like this...   

mnem
 

Does that mean that we have to repeat the comments we gave to that power supply again here? Really, that sort of language doesn't come easy to us!

[med6753]

Well, I had another big TEA weekend. Same source as the 575s came from. Picked up a nice 7904 that has all options but known power supply issues and phosphor burns. However, I also got an R7903 which is similarly optioned (both have the high writing rate crt with 0.5cm divisions) so that tube could be a donor. Needless to say I am probably going to go all medieval on recapping this one since it has known problems in the power supply area. Other grabs include a 5103N dual beam scope with plugins, a rackmount 5441 (which may be a parts source), and a 7313 storage scope. All of these I'm going to evaluate for repair and stuff in time.

I *also* got my 428B clip on milliammeter...appears to be in excellent working order. Pics later on as I'm exhausted. 

Now old I freely admit. But medieval? 

[0culus]

Well, I had another big TEA weekend. Same source as the 575s came from. Picked up a nice 7904 that has all options but known power supply issues and phosphor burns. However, I also got an R7903 which is similarly optioned (both have the high writing rate crt with 0.5cm divisions) so that tube could be a donor. Needless to say I am probably going to go all medieval on recapping this one since it has known problems in the power supply area. Other grabs include a 5103N dual beam scope with plugins, a rackmount 5441 (which may be a parts source), and a 7313 storage scope. All of these I'm going to evaluate for repair and stuff in time.

I *also* got my 428B clip on milliammeter...appears to be in excellent working order. Pics later on as I'm exhausted. 

Now old I freely admit. But medieval? 

 

Ok, ok, this was supposed to be a Pulp Fiction reference, but I'll go with it. 

[mnementh]

I stopped in the Discord for a minute, but my wife had a Taco Bell attack and I was elected to go running. The things we do for domestic tranquility...

Things like this...      
mnem
 

Does that mean that we have to repeat the comments we gave to that power supply again here? Really, that sort of language doesn't come easy to us!

Doesn't she have a driver's license? Can she go places without getting lost? Can she use the drive thru window or do they speak French only? 

Oops...that's right, Toronto is in Ontario. My bad. 

Lets put it another way... My wife asked me nicely.   

Also, she's a right proper Cajun Queen (when she wants to be  ). French is not a barrier for her.

mnem
Happy wife=happy life.

[cyclin_al]

The best bit of advice I have for management is that when dealing with software developers, look for the quiet, slightly worried looking chap/chapesse in the meeting and afterwards take them for a beer and listen to them.

huh!  That resonates, but in a different perspective here (not only because it is something other than software).  The last couple of months of 2020 have been very frustrating at work.
That comment made me realize what it is.  Essentially, I have been tapping on the shoulder of management, and trying to tell hint to them to listen to the quiet chapesse in the other corner.
That management used to pay attention to what I had to say and now for some reason are no longer listening.
Meanwhile, the chapesse is holding back leaks in a firehose with her fingers, while management is heading down a slippery slope and about to ask me to open up the water main....
She will be the one drowning because of the path taken by management, and most likely she will be the one crapped on afterwards for it.

Any insights or resources on how to best handle this sort of thing?

[cyclin_al]

I'm in total agreement with everything stated here concerning the buffoons, blowhards, know-it-all's, and egomaniacs. They are everywhere and a can of bullshit spray and a shovel is almost a mandatory carry.

Tony goes to the trouble of producing and publishing video's of his TE activities. Who else in our group of addicts does that?

Don't all answer at once. 

Exactly, no one else. Now I have no problem pointing out to him if something is factually incorrect. But IMHO the callousness in which it was done earlier is unjustified.

I think what sets Tony apart is his attitude.  He is sharing his understanding of things, which creates opportunities for discussion so that he (and I as well) can learn from it.  He is obviously open to feedback and improving from it.

However rough the knocks are and how difficult the path is, keep going Tony.  I admire your approach, Tony!

[Brumby]

Essentially, I have been tapping on the shoulder of management, and trying to tell hint to them to listen to the quiet chapesse in the other corner.
That management used to pay attention to what I had to say and now for some reason are no longer listening.
Meanwhile, the chapesse is holding back leaks in a firehose with her fingers, while management is heading down a slippery slope and about to ask me to open up the water main....
She will be the one drowning because of the path taken by management, and most likely she will be the one crapped on afterwards for it.

Any insights or resources on how to best handle this sort of thing?

The first thing I would do is put together all the information you have and write it down.  Make sure it is dated.  Go over it and ensure you have made a note of all the relevant points, implications, resource impacts, personnel issues and anything else that you've winced about.  Include a timeline of events - ones that have already occurred and those that will follow.  This should reflect anything relevant from project issues, responses, information reported to management and directives issued.  Set out what you can remember now, but don't get lost in filling in every detail if you can't remember this second.  You can always come back to it later and add stuff you've remembered.  Add all types of info - positive, negative and neutral (this will make it more objective - and be seen as such, rather than written off as a witch-hunt).

Start doing this now.

The second step is working out what to do with this information.  This is the tricky bit - and I will offer one idea. (Since I have no appreciation of the actual situation, it could be completely inappropriate - but it is just to get the ball rolling...)

My thought is to put together a risk analysis assessment - detailing what could go wrong and how bad it could be.  How you phrase things - and who you would distribute such a document to are questions only you could dare answer - and I full appreciate that the distribution list could be rather short.  I could also suggest an "Executive summary" that might be distributed to a higher level audience so that they are made aware of a potential problem.

Whether or not any of this can be done "safely" is another point - and I fully appreciate the distinct possibility that any attempt to "sound the alarm" could result in dire repercussions to your employment.  Only you will have an idea of that risk.

An alternate approach might be to let the "problem management" know you are keeping notes of what you are seeing and would really hate to have to present them at a project post mortem (including why they weren't addressed before things blew up).  ** (Upon re-reading this, I realise how dangerous this would likely be.)

Looking back at the above, I don't know how to proceed - but I would certainly be taking notes.  If such information would have value at some point, it's better to have it on hand - rather than go scrabbling around trying to throw it together.

As for actually speaking out.......
Damned if you do.
Damned if you don't.

Good luck.

Edit: Typo

[Robert763]

This is why I wasn't on Discord. Just got back from picking this up.

Sansui "Classique" A-990 Amplifier. Local Craig's List. Was only $50 USD which is why I jumped on it. And it works. Full demo by the seller. I'm going to make some changes to my audio system.

Peek inside. Dusty but otherwise looks untouched by Gorillas. The 6800uF capacitor on the right is bulging on the top. So a re-cap will be scheduled.

That looks like just the insulating disk is popped up, not a bulging capacitor. I'd leave it alone. A modern capacitor won't last as long as the original.

[nfmax]

I bought myself a Christmas present bundle of goodies from Farnell & RS, which included two of these:

https://uk.farnell.com/desco/229625/adj-wrist-strap-metal-10mm-stud/dp/2484082

An expanding metal watchstrap-style static control band. A revelation! 
So easy to slip on & off when I need to get something from the other side of the lab, or move to the other bench. The old strap & clip bands were getting to be a bloody pain - particularly since I have quite suddenly developed osteoarthritis in both hands 

[Robert763]

I'm intrigued as to what lies under that rather elegant heatsink, since the power output semis seem to be mounted to the bottom rear of the chassis.

IIRC, those "shaved fins" are carved from a piece of Al angle extrusion, the bottom leg of which you can see underneath.

Heat "flow" is not affected by right angles or other bends as long as the cross sectional area is maintained. In practice the edge to edge thermal resistance for a typical bit of extruded angle will be less than a flat piece of the same nominal thickness and width equal to the two sides of the angle. This is because there is more material in the extrusion to fill out the corner.


They're supposed to be much more efficient for size; seems to me a lot of that efficiency is lost in the angle transition. 

mnem
 

[Robert763]

I bought myself a Christmas present bundle of goodies from Farnell & RS, which included two of these:

https://uk.farnell.com/desco/229625/adj-wrist-strap-metal-10mm-stud/dp/2484082

An expanding metal watchstrap-style static control band. A revelation! 
So easy to slip on & off when I need to get something from the other side of the lab, or move to the other bench. The old strap & clip bands were getting to be a bloody pain - particularly since I have quite suddenly developed osteoarthritis in both hands 

They are even better if you replace the snap with a couple of small button magnets. Then if you forget to take it off when leaving the bench it just disconnects. If you have a steel bench frame it lets you "park" the end of the lead easily.

[nfmax]

I bought myself a Christmas present bundle of goodies from Farnell & RS, which included two of these:

https://uk.farnell.com/desco/229625/adj-wrist-strap-metal-10mm-stud/dp/2484082

An expanding metal watchstrap-style static control band. A revelation! 
So easy to slip on & off when I need to get something from the other side of the lab, or move to the other bench. The old strap & clip bands were getting to be a bloody pain - particularly since I have quite suddenly developed osteoarthritis in both hands 

They are even better if you replace the snap with a couple of small button magnets. Then if you forget to take it off when leaving the bench it just disconnects. If you have a steel bench frame it lets you "park" the end of the lead easily.

Like a Magsafe power supply connector? It's not a bad idea. I've taken a similar approach before, using the button connector. The problem for me is that I forget to reconnect it when I return to the bench - I feel the band on my wrist so I think I'm OK, but it's not connected to anything (q.v. "cordless wrist strap")