4 minutes ago, kevin gilmore said:

the ones I used had the bottoms of the pins covered and were black

Can you please link them  parts

no idea at this point what the part numbers are, nothing on the bags.

I have plenty of 400VDC-rated black terminal blocks that I ordered from Mouser. Here is a part number for one of them: 651-5452258.

They may not be the same one that Kevin mentioned. I'll check to see if they have their bottom covered when I get home.

 

2 hours ago, Whitigir said:

It takes some bones to get used to, I guess I should start buying some chain mails and motorcycle helmet

a pair of glasses and some patience, might be a better choice ...in rgrds to the terminal block, screw'ing too hard will never give you that kind of enjoyment (although @swt61 might object)

Too hard? Impossible! 

17 hours ago, sorenb said:

a pair of glasses and some patience, might be a better choice ...in rgrds to the terminal block, screw'ing too hard will never give you that kind of enjoyment (although @swt61 might object)

Then using these connectors on the front side is just a disaster waiting to happen  . 

1 hour ago, Whitigir said:

Then using these connectors on the front side is just a disaster waiting to happen  . 

too much solder and heat might be the root cause

4 minutes ago, sorenb said:

too much solder and heat might be the root cause

It certainly seems like almost everyone uses these connectors, and there must be dozens of amps built with them by regulars and lurkers here by now. This is only the second report of this failure mode. Not good, certainly, and it would be nice to find a better alternative. I wanted to switch to Molex or something similar, but couldn't find parts with sufficiently high voltage ratings.

You might take a look at something like the TE Dynamics line, which appear to be rated @600V. You would need 5.08mm pitch to fit the board(s)?


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Interesting. Using a 5-position connector as a starting point, I ran a Mouser search for a TE Dynamics connector (link) which found a 600V wire housing and receptacle pair. The datasheet for the receptacle says it's 34.32mm wide, but a comparable Phoenix (datasheet) is about 10mm smaller. I don't think the TE unit fits on most of Kevin's boards.

(I also haven't looked to see how much an appropriate crimping tool costs. Prices on those things are usually eye-watering.)

3 hours ago, sorenb said:

too much solder and heat might be the root cause

There is no such thing as too much... Oh... I read that as soldier...

 

Sometimes you can use normal crimpers/needle nose pliers plus soldering on them, but yes, agreed on the $300+ prices one can see on specialty crimp tools.


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I think you can buy wires pre-crimped in various lengths for some connectors, forgot the part number... maybe someone else remembers

And if you use some Kapton tape between the hole and connector?

20 minutes ago, mypasswordis said:

I think you can buy wires pre-crimped in various lengths for some connectors, forgot the part number... maybe someone else remembers

https://www.pololu.com/category/71/wires-with-pre-crimped-terminals

http://www.mouser.com/new/molex/molex-pre-crimped-leads/

https://www.digikey.com/products/en/cable-assemblies/jumper-wires-pre-crimped-leads/453

On 8/28/2016 at 7:23 AM, spritzer said:

As I said, this is a solder mask issue. 

Spritzer was correct, and this is really a solder mask issues.  When trying to open up the mask to fix the burned trace, I noticed that it was fairly thin and very easy to remove.  Then I did put in layers of acrylic for isolations.  After replacing many active parts and zener, she lights up just fine.  Will do the balance/offset adjustment later

This Carbon was running fine for months before starting to act up, and finally blew

5 hours ago, sorenb said:

too much solder and heat might be the root cause

^this, given some of the generous amounts of solder used in other areas shown in the pics. The excess solder sits on the trace and the mask eventually breaks down...

On 8/22/2017 at 0:51 PM, mwl168 said:

I have plenty of 400VDC-rated black terminal blocks that I ordered from Mouser. Here is a part number for one of them: 651-5452258.

They may not be the same one that Kevin mentioned. I'll check to see if they have their bottom covered when I get home.

 

I checked my parts bin. The black Phoenix 651-54522548 has open bottom. 

interestingly, my green, Phoenix 651-1935174, which is rated at 400VDC, has the covered bottom. Maybe this should be the "official" Stax Mafia endorsed terminal block for B+ and B-?

Edited August 24, 20178 yr by mwl168

The datasheet for Phoenix part 1935174 says the following:

Rated voltage (III/3)	250 V
Rated voltage (III/2)	400 V
Rated voltage (II/2)	630 V

What does that mean, and how do you know it's not just good for 250V? (The Mouser page for the product says 250V, but I don't trust it.)

1 hour ago, gepardcv said:

The datasheet for Phoenix part 1935174 says the following:

Rated voltage (III/3)	250 V
Rated voltage (III/2)	400 V
Rated voltage (II/2)	630 V

What does that mean, and how do you know it's not just good for 250V? (The Mouser page for the product says 250V, but I don't trust it.)

Interesting. Looks like Mouser downgraded its rating since I ordered them some time ago.

The Phoenix datasheet states "nominal current 17.5A, Norm. voltage 400V". Although this is not the first time I see manufacture datasheets for the same part contradict each other. 

Horse before cart. So do we need to ups pitch size to accommodate components that are within correct operating voltages...?

6 hours ago, mwl168 said:

I checked my parts bin. The black Phoenix 651-54522548 has open bottom. 

interestingly, my green, Phoenix 651-1935174, which is rated at 400VDC, has the covered bottom. Maybe this should be the "official" Stax Mafia endorsed terminal block for B+ and B-?

 

Yes this look ways better for High voltage applications , but somehow they are rated 250V

Edited August 24, 20178 yr by Whitigir

It's no so much contradictions as the manufacturer specifying thresholds the component is tested to meet under various standards for operation.

http://www.ni.com/white-paper/2827/en/

Assuming you're powering your amp from a wall outlet in your house rather than straight from the distribution lines :), I think the 630V rating applies.

 

23 hours ago, sorenb said:

too much solder and heat might be the root cause

This amp was working for months before it would act up and finally it did arced through, soldering is one of many possibilities.  However, I say it would be safer to give it more clearances, isolations, or another type of connector, or mount it in the back for more preventative. 

23 hours ago, gepardcv said:

It certainly seems like almost everyone uses these connectors, and there must be dozens of amps built with them by regulars and lurkers here by now. This is only the second report of this failure mode. Not good, certainly, and it would be nice to find a better alternative. I wanted to switch to Molex or something similar, but couldn't find parts with sufficiently high voltage ratings.

Yes, many amps are built with this connectors, and when put in at the back sides, it would be safe as there are no traces to potentially cross through the bare metals.  

 

  She is banging again !!  offset and balances are fine, both boards is sitting equally 250mV balances and 13V offset for Opto Servo.

Edited August 24, 20178 yr by Whitigir