Parts Database

[J!m]

But the Teflon is not very flexible.

I agree it is about as good as "wire" gets, and that's why it's used in aircraft. Insulation will not chafe on itself in bundles, because it's so slippery. They should have used that in BMW E36 trunk wiring harnesses, to avoid all those fires...

 

[George S.]

F... those P-traps (sic). They belong in a sewer. The common failure mode is a broken lead due to the mounting stress. The result is all of the outputs turn full on and go to war with each other. 12 blown drivers/outputs per channel on 700's.

Don, it this still working out for you and do you recommend it for original back walls?
"""I've used MJF31's in that application before and much prefer it over the 2N3403/P-strap. The TO220 pin spacing is 0.1" which is also the same spacing for three wire computer fan connectors. Cut the cables off of a couple cheap fan motors and push the connector on the transistor leads. It's a very snug fit and requires no soldering on the transistor leads."""

 

[WOPL Sniffer]

Hey Dennis, what kind of wire is that stuff you carry? I was under the impression it was Teflon

 

[MusicSteve]

What do you use "Silicon" for?????? Why on earth would you put silicon on the board???
HUH????

BNTECHGO 22 Gauge Silicone Wire Kit 7 Color Each 50 ft Flexible 22 AWG Stranded Tinned Copper Wire

https://www.amazon.com/BNTECHGO-Silicone-Flexible-Stranded-Tinned/dp/B08FMF3NBL/ref=sr_1_4?crid=Q2JC35O18MKM&keywords=BNTECHGO+22+Gauge+Silicone+Wire+Kit+7&qid=1662750138&s=hi&sprefix=bntechgo+22+gauge+silicone+wire+kit+7,tools,122&sr=1-4

 

[Skratch]

Don, it this still working out for you and do you recommend it for original back walls?
"""I've used MJF31's in that application before and much prefer it over the 2N3403/P-strap. The TO220 pin spacing is 0.1" which is also the same spacing for three wire computer fan connectors. Cut the cables off of a couple cheap fan motors and push the connector on the transistor leads. It's a very snug fit and requires no soldering on the transistor leads."""

I have also used MJF31 for bias transistors and they work very well and are very rugged

 

[Gepetto]

I have also used MJF31 for bias transistors and they work very well and are very rugged

The beta of that device is very low. The bias application relies on a very high beta device to make it very sensitive to temperature change.

 

[George S.]

Joe, question I've been wanting to ask. On a WOAD build, should the 3 bias wires be twisted like PL did them? I do remember you saying to keep them short because they carry high frequencies.

 

[MusicSteve]

I have some NTE192A and stock 2N3403 , 2N5088, BD139 so the 2N5088 is the best for less noise and longer wires w the Original backplane?

Yes the 2N5088 is used for its low noise figure and its high gain

Thanks Joe
back to this
https://www.ebay.com/itm/185093744057

 

[George S.]

The beta of that device is very low. The bias application relies on a very high beta device to make it very sensitive to temperature change.

Have you run across a better device in a similar package for the guys using point to point backwalls?

 

[WOPL Sniffer]

BNTECHGO 22 Gauge Silicone Wire Kit 7 Color Each 50 ft Flexible 22 AWG Stranded Tinned Copper Wire

https://www.amazon.com/BNTECHGO-Silicone-Flexible-Stranded-Tinned/dp/B08FMF3NBL/ref=sr_1_4?crid=Q2JC35O18MKM&keywords=BNTECHGO+22+Gauge+Silicone+Wire+Kit+7&qid=1662750138&s=hi&sprefix=bntechgo+22+gauge+silicone+wire+kit+7,tools,122&sr=1-4

Here is a snippet from a guy's review of that wire: The sheath is so soft that you can use a thumbnail and fingertip to strip it.

That wire is bullshit. If it strips with your fingernail, I don't want it in my amps.

 

[MusicSteve]

Here is a snippet from a guy's review of that wire: The sheath is so soft that you can use a thumbnail and fingertip to strip it.

That wire is bullshit. If it strips with your fingernail, I don't want it in my amps.

Never had that happened, its thicker than I want it to be

 

[WOPL Sniffer]

Never had that happened, its thicker than I want it to be

Have you tried the wire Dennis sells??? You'll dump the puffy easy strip wire.

 

[MusicSteve]

Have you tried the wire Dennis sells??? You'll dump the puffy easy strip wire.

No, How flexible is it?

 

[Gepetto]

I have some NTE192A and stock 2N3403 , 2N5088, BD139 so the 2N5088 is the best for less noise and longer wires w the Original backplane?

Thanks Joe

The NTE192 (not A) is a suitable replacement for the 2N5088 and comes already packaged with the P-strap applied. The newer revisions of the Backplane boards, both PL400 and PL700 support the NTE192 option. But there are some differences in the application, so I have not officially launched that option yet. My most recent build is with the NTE192.

 

[WOPL Sniffer]

No, How flexible is it?

I've wired over 100 WOPLS with it.

 

[Gepetto]

As mentioned earlier, the teflon works great when you dump the quasi comp and move to full comp with backplanes. No stress on the transistor wires.

 

[MusicSteve]

The NTE192 (not A) is a suitable replacement for the 2N5088 and comes already packaged with the P-strap applied. The newer revisions of the Backplane boards, both PL400 and PL700 support the NTE192 option. But there are some differences in the application, so I have not officially launched that option yet. My most recent build is with the NTE192. View attachment 68642

Will they support both? I think you said the 2N5088 was a little better?

 

[Gepetto]

Will they support both? I think you said the 2N5088 was a little better?

Yes, you can see that in the silkscreen print in the photo shared. The close in holes are marked NTE192 and the outer holes are marked 5088

Either works. The 2N5088 application is what you are used to. The NTE192 application is flipped over as shown in the picture with a 3/8" standoff v. the 1/4" standoff for the 2N5088

 

[wattsabundant]

We can debate what is the preferred device for the bias circuit. Regardless which device is used, I believe the important thing is verification that the circuit works.

When I work on an amp, I check the bias and then run the amp at about 2/3 of it's rating at 8 ohms which gets it hot fast. I shoot all of the output transistor cases with an infrared gun to make sure the screws are properly torqued. I run it until case temperatures are in the 90C (that's right 90C) range and then check the bias to make sure it's not running away. I check it again when the amp cools down. I then do the short circuit test called out in the P/L manuals.

Of course not everybody has the means to do all of the recommended testing and they are still successful in rebuilding a reliable amp. With shipping costs what they are, I think it is important to do everything possible to make sure the amp doesn't come back.

 

[MusicSteve]

We can debate what is the preferred device for the bias circuit. Regardless which device is used, I believe the important thing is verification that the circuit works.

When I work on an amp, I check the bias and then run the amp at about 2/3 of it's rating at 8 ohms which gets it hot fast. I shoot all of the output transistor cases with an infrared gun to make sure the screws are properly torqued. I run it until case temperatures are in the 90C (that's right 90C) range and then check the bias to make sure it's not running away. I check it again when the amp cools down. I then do the short circuit test called out in the P/L manuals.

Of course not everybody has the means to do all of the recommended testing and they are still successful in rebuilding a reliable amp. With shipping costs what they are, I think it is important to do everything possible to make sure the amp doesn't come back.

Thanks
So w this test, (I have never done this)
So what is the typical voltage range starting at warm temp .350 vdc and at your max (I don't know if I'm that brave to go that far @176 degrees) And what happened if the Bias runs away and is it Temp related? I had more failed Bias transistors than anything else in the Original PL II and if I recall I also replaced also Q103.