Repair question re: threshold 400a

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#161
AR2 said:
Man, you have a wrong part.

Here is the pdf explaining what do you have.

It is electrically conductive material used instead of "GREASE"[/B] and NOT instead of "PAD"

Since you are new here, if you didn't know - you had best of the best that this forum has to offer helping you with your problem.

Please follow literally what they say. It is very easy to make mistake when ordering from DIGI Key or Mauser. It is overwhelming amount of variables and choices, as you have experienced after 7 hours of ordering. Follow the direction and than once you gain some experience than do experiments and mods. [/B]
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Thanks.. Like I said I'm calling digikey, if anything I ordered about 1100 too many! lol.

Steve, did ya see how good I did with that last post? 🙂 My lip has a hole in it 🙂


Is this a floating ground on this board? Is that why this pad can't be conductive? I think my error is that I assumed the base was grounded on the t03?
 
#162
Okay; spoke to a technician.. he thought the part I ordered would work as well.. however I pushed him to get me a mica replacement per advice here.. so he substituted it with BER139-ND.. I hope this is right!


Thanks for everyones help!

EDIT: and it is per unit.. not sure why they are so expensive but I am too tired to change it.. and I had to up the order to 24!
 
#166
Okay now they are telling me 4662K-ND

Transistors..

1 13 MJ15003GOS-ND TRANS PWR NPN 20A 140V TO3 0 3.29000 $42.77
2 13 MJ15004GOS-ND TRANS PWR PNP 20A 140V TO3

We verified 2 lead and the spacing and t03. I cant believe how difficult this is! LOL..

EDIT: thanks netlist!

EDIT:
Technical/Catalog Information 4662K-ND
Standard Package 100
Category Hardware / Accessories
Family Insulators
Vendor Keystone Electronics
For Use With/Related Products Transistors TO-3 Case
Material 0.003" Thick Mica
Lead Free Status Lead Free
RoHS Status RoHS Compliant
Other Names 4662K
4662K-NDR
 
#168
Netlist said:
Those are perfect. Go and order them.
You will need grease with them.

/Hugo
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I did.. qty 30.. and grease was on the order already..

Makes sense too:
roddyama said:
Those are a grease replacement. If you look real close at the Q-Pad description at the top of the Bergquist/Digikey page, it says "(Elecrically Conducting Material)". You need an insulator. I would suggest the Keystones seen below on the same page.
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LOL... FWIW my error was I did not know T03 came in different lead packages.. duh.. but then again the tech should have asked!

Sorry guys.. but this is good for new guys to see how difficult this can be! 🙂
 
#171
Okay... on a not so stessful note..

This post got deleted yesterday... I assume a restore was required here.. 🙂

So; I cleaned up my front plate.. used paper towel; water, alcohol, paint reducer and a black sharpe.. and here is where I am..

Before;
An externally hosted image should be here but it was not working when we last tested it.


And after...

An externally hosted image should be here but it was not working when we last tested it.


An externally hosted image should be here but it was not working when we last tested it.


I am thinking it looks good enough to use as is.. plus I get to keep part of the logo.. If Mr. Pass agrees to sign it; I thought I'd have him print in "class A" or whatever he wants underneath the threshold logo...

EDIT: (reanodizing would wipe out the logo if I went that route).
thoughts?
 
#174
anatech said:
Hi Joe,
You're on the right track now. See, many good people on this forum to assist you!

Time to clean up the PCB's and get them ready for your new parts.

-Chris
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I cleaned up the sinks and all.. I plan to fire up the repaired side all by itself before I tear down the other side.. I just want to be sure I have everything working..

Parts already shipped.. and I paid for 3 day UPS.. so will be here for the weekend 🙂

I hope Mr. Pass sees my post soon so I can send in the front plate for a signature. 🙂 Although I guess that can wait until its all fixed.. 🙂

Yup.. lots of great people.. thanks to all who have helped thus far.. the big pay off is within my sights! 🙂
 
#175
anatech said:
Hi Joe,
You're on the right track now. See, many good people on this forum to assist you!

Time to clean up the PCB's and get them ready for your new parts.

-Chris
Click to expand...


Chris,your heart is big as mountain....... 😉
but-this thread is really pathetic ,few pages ago.
sad; you are mod here,and I'm sure that you have at least equal honest attitude to your customers ;
but- customer (or not) with attitude as OP................!?

that's self esteem issue,at least for me.

anyway, all my respect for you.
 
#177
Hi Guys!

Wow, have I missed a lot!!!!

Looks like we have it all in this thread, amp repair, soap opera drama, psychology, ordering 101, and good will to boot!!! LOL!!! 🙂

Thanks to all for jumping and keeping Joe on track! This thing is going to get fixed come hell or high water...

Joe - looks like you're on the right track. Just keep plugging away...

Faceplate came out good. Agreed that you don't need to redo it.

Glad you ordered all new output transistors.

And yes, you bit your lip well!!!! LOL!

Chris - great catch on the incorrect insulators!!! 😉 Talk about a flame thrower if we had missed those.... :hot:

Great job everyone and thanks again for jumping in!
 
#178
Joe,

Just for background, the reason you need to insulate the output devices is because the heatsinks are attached to the chassis and as a result are grounded.

The cases of the TO3 output devices are the collectors for the transistors and are tied to the main power supply caps. Now imagine the sparks if instead of using insulating pads you used the conducting ones by mistake and they passed all of the power supply current to ground... LOL! :hot:

Just because they use the case as one of the transistor leads doesn't necessary mean that they should be grounded. Actually, 99% of the time they are not...

The greaseless pads are nice. Just be sure to not superman them when you tighten them. As Chris mentioned, there's no need - just snug them up uniformly and you'll be good.

Please make sure everything is absolutely clean prior to reassembly. Also make sure the holes in the heatsinks don't have any raised edges that could cut through the insulators as the silicone/fiberglass are softer than the mica. Just double check to make sure everything is smooth and they'll work perfectly.

Figured that I'd send a bit of the "why" behind how critical those insulators are.
 
#179
Apogee said:
Joe,

Just for background, the reason you need to insulate the output devices is because the heatsinks are attached to the chassis and as a result are grounded.

The cases of the TO3 output devices are the collectors for the transistors and are tied to the main power supply caps. Now imagine the sparks if instead of using insulating pads you used the conducting ones by mistake and they passed all of the power supply current to ground... LOL! :hot:

Just because they use the case as one of the transistor leads doesn't necessary mean that they should be grounded. Actually, 99% of the time they are not...

The greaseless pads are nice. Just be sure to not superman them when you tighten them. As Chris mentioned, there's no need - just snug them up uniformly and you'll be good.

Please make sure everything is absolutely clean prior to reassembly. Also make sure the holes in the heatsinks don't have any raised edges that could cut through the insulators as the silicone/fiberglass are softer than the mica. Just double check to make sure everything is smooth and they'll work perfectly.

Figured that I'd send a bit of the "why" behind how critical those insulators are.
Click to expand...


Thanks Steve.. yeah I have not been sent to "Texas" yet..

Umm.. yeah I thought the stupid collector was grounded.. which I realize is just really ignorant but thats where I made my error.. and the insulators are Mica that I bought.. I think/hope.. Sinks are sily smooth, no issues there..

thanks for the nod on the front panel.. I think I will try and write Nelson Pass directly and see if I can send it to him.. its in the box with a paint pen already 😉

I knew ordering parts was gonna be a bitch for me.. and I bet I got some others wrong.. but I will measure them all compared to the good side before I install. They should all be here in thursday! yippeee!!!!

I gotta remember to make note of the bias pot reading as well.. that was a great suggestion by Jon.. in case I bump it or something .. (might be too late!) ...

Yeah lotsa drama and I hope its over. I just want to get this done and then move on to my other amp.. want to upgrade and tweek it as well.. only the large caps (the two big boys) were replaced.. and the bias I think is way off.. its not getting hot enough.. and according to Jon it will sound way sweeter with the biad hot..


Okay... I'll let you know when things start happening again.. 🙂

J
 
#180
Hi Joe,
and according to Jon it will sound way sweeter with the biad hot..
Click to expand...
Nope. It's better with the bias set to manufacturer's specs. Make no mistake.

want to upgrade and tweek it as well..
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Warning! Warning! Will Robinson!

Be careful where you tread. It's hard to keep a balance with what matters and the flake factor (someone will be mad at this line! 😉 ).
There are some component replacements that matter. Keep in mind that it's the component type and construction over brand names that matters. "Your milage may vary". In my view, power cords ain't gonna help you out at all, unless your wallet is just too darn heavy!

-Chris
 
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