NAD/Project SVT Blueline

[greengoblin]

Not everything was well thought through, it was good enough and done to a budget.

It would have been better, in terms of noise, to have two bundles coming from the preamp chassis.

It is good to run the shielded cable outside but strapped to the bundle of other wires. This keeps the preamp signal wire more away from twisted pairs carrying AC.

Currently the shielded cable is outside of the bundle and I kept it that way. I see that Mouser lists the parts as obsolete, but Newark has most of them. I see you list the 1545prt which is a 2 pin connector which I dont have anywhere on mine. May have been removed by someone previously. Was this an additional connector for the fan by chance?

Since your amp was originally setup to run 6146s, Rev C is probably the right schematic, especially if node H has already already been built into the amp, which I believe you mentioned earlier. Here's the power amp side...I haven't seen the Rev C preamp schematic, but it should be fairly easy to deduce the circuit connections.

The Rev B preamp doesn't quite match up with the Rev C power amp. The pilot light is connected to pin 3 in the Rev B preamp. There may be other differences as well.

Well the more I think about the amp and set-up and the age of the amp, I think I am going back to 6146's to keep it stock/factory. Just did a brief glance at the Molex connector on the power amp side and I see a few missing pins, so more than likely I will have to re-do those as well.

Looking at the Magnavox premap schem, it is a different wiring config at the plug than the Linden, NJ schem. Will have to compare them both... Really havent looked at the power amp side mouch except to take pics so I havent figured out f it has Node H, but someone did try to configure it for 6550's.

 

[Wasnex]

Currently the shielded cable is outside of the bundle and I kept it that way. I see that Mouser lists the parts as obsolete, but Newark has most of them. I see you list the 1545prt which is a 2 pin connector which I dont have anywhere on mine. May have been removed by someone previously. Was this an additional connector for the fan by chance?




Well the more I think about the amp and set-up and the age of the amp, I think I am going back to 6146's to keep it stock/factory. Just did a brief glance at the Molex connector on the power amp side and I see a few missing pins, so more than likely I will have to re-do those as well.

Looking at the Magnavox premap schem, it is a different wiring config at the plug than the Linden, NJ schem. Will have to compare them both... Really havent looked at the power amp side mouch except to take pics so I havent figured out f it has Node H, but someone did try to configure it for 6550's.

FYI it's normal for some of the pins to be missing. No need to add pins when there is no connection.

My apologies for misspeaking. You didn't say Node H had been installed, but it is clearly there in the gut shot you provided. I circled it in the attached image.

 

[greengoblin]

FYI it's normal for some of the pins to be missing. No need to add pins when there is no connection.

My apologies for misspeaking. You didn't say Node H had been installed, but it is clearly there in the gut shot you provided. I circled it in the attached image.

View attachment 3256198

Oh yeah, but just want to make sure all pins line up at the power section and preamp correctly. The preamp is missing pin 3 and the power amp has two pins missing. I will go over them and make sure they all are positioned as they should and the missing pins line up.

No apologies needed. I think I am kind-of inadvertently avoiding the power section for now as it looks as though it may be a mess, but I am up for the challenge!

 

[beans-on-toast]

Currently the shielded cable is outside of the bundle and I kept it that way. I see that Mouser lists the parts as obsolete, but Newark has most of them. I see you list the 1545prt which is a 2 pin connector which I dont have anywhere on mine. May have been removed by someone previously. Was this an additional connector for the fan by chance?

Yes, a two pin male and female connector is inserted inline between the twelve pin molex and the fan wires and hangs in the air.

When you remove the back panel to get at the tubes, having the fan wired in is a pain. The connector allows you to remove the back grille without the risk of breaking a wire or having to remove the fan.

 

[Wasnex]

Oh yeah, but just want to make sure all pins line up at the power section and preamp correctly. The preamp is missing pin 3 and the power amp has two pins missing. I will go over them and make sure they all are positioned as they should and the missing pins line up.

No apologies needed. I think I am kind-of inadvertently avoiding the power section for now as it looks as though it may be a mess, but I am up for the challenge!

I doubt the power amp will give you much trouble. Rewire the tube sockets, reinstall plates contactors, and check components like you did with the preamp.

I don't know which capacitors you bought. I redid my 69 with the 6550 capacitor scheme. A benefit was this allowed me to run R52 between the terminals of a twist lock cap instead of having to install a terminal strip on the circuit card. It probably makes no functional difference but it looks a lot neater.

 

[Wasnex]

Yes, a two pin male and female connector is inserted inline between the twelve pin molex and the fan wires and hangs in the air.

When you remove the back panel to get at the tubes, having the fan wired in is a pain. The connector allows you to remove the back grille without the risk of breaking a wire or having to remove the fan.

It may not be necessary to add the 2 pin Molex quick connect.

My Orion fan has the 2 pin molex connector and also a plug like this that goes straight into the fan housing.

The Orion pigtail P/N is C45-12.

 

[beans-on-toast]

It may not be necessary to add the 2 pin Molex quick connect.

My Orion fan has the 2 pin molex connector and also a plug like this that goes straight into the fan housing.

View attachment 3256256
The Orion pigtail P/N is C45-12.

Other fans such as the Ebm-Papst that I’ve used in SVT’s have that as well. I find that it’s easier to still use the molex quick disconnect. Most SVT’s have the two pin Molex so it keeps it looking the same.

One some fans the connectors on the fan don’t stand up well when they are pulled and plugged too many times.

Some people cheap out and don’t buy the cord and solder the wires directly to the fan’s terminals. I prefer not to see that.

 

[Wasnex]

Other fans such as the Ebm-Papst that I’ve used in SVT’s have that as well. I find that it’s easier to still use the molex quick disconnect. Most SVT’s have the two pin Molex so it keeps it looking the same.

One some fans the connectors on the fan don’t stand up well when they are pulled and plugged too many times.

Some people cheap out and don’t buy the cord and solder the wires directly to the fan’s terminals. I prefer not to see that.

I don't believe the fan in my 69 is an Orion fan, but it uses the same plug. I researched and bought what I thought was a lower velocity/quieter Orion fan. Never bothered installing the pigtail as the existing plug is exactly the same. Unfortunately the Orion was not really noticeably quieter, so I pulled it out and put the old fan back in. I later noticed Mouser lists the noise as 27dBA on the product specifications, but the Orion datasheet lists 37dB. That might be were I got pulled off track.

I prefer to use the 2 pin Molex quick connect for exactly the reason describe you describe. Plus it can be really hard getting the plug out of the fan.

Here is the Orion Fan I ordered: OA125AP-11-2 TB (120x120x25mm, 60CFM, 37dB)
I believe this is the quietest Orion option in the same case size: OA125AP-11-3 TB (120x120x25mm, 53CFM, 33dB)
Here's the P/N for the guard if you want/need it: G109-15AB
The previously mentioned pigtail: C45-12.

 

[beans-on-toast]

The original fan was made by Rotron.

 

[greengoblin]

I purchased a new fan from Fliptops, it has a plug similar to the orions. Have a new wire/connector pigtail as well. Will see how much wire play I have before installing the molex connector, but I ordered one just in case. Newark still has most of the Molex parts instock including the male/female molex pins, the 1360 blocks and the 1545 blocks. Ordered extras of each as most was on the cheap side and hopefully this will not be the only vintage SVT I redo.

 

[greengoblin]

I blieve I am over thinking this and probably at a point where I should take a break and eat. The Polarity switch referencing off the Rev C preamp with (2) .047 600v caps. Looking at the back of the switch there are three prongs, two at the "bottom" and one on top right. With the switch "off" (toggle towards the mounting groove), the bottom two pins are connected. With the switch "On", (looking at the back) the bottom left and the top prongs are connected. So am I correct in thinking the caps should go to the bottom left pin, while the bottom right goes to Black #9 and top goes to Tan #6? This would switch the caps from black to tan.

 

[Wasnex]

I blieve I am over thinking this and probably at a point where I should take a break and eat. The Polarity switch referencing off the Rev C preamp with (2) .047 600v caps. Looking at the back of the switch there are three prongs, two at the "bottom" and one on top right. With the switch "off" (toggle towards the mounting groove), the bottom two pins are connected. With the switch "On", (looking at the back) the bottom left and the top prongs are connected. So am I correct in thinking the caps should go to the bottom left pin, while the bottom right goes to Black #9 and top goes to Tan #6? This would switch the caps from black to tan.

From your description it sounds like you have it figured out.

In one position the switch should connect the caps to pin #6, and in the other position the switch should connect the caps to pin #9.

Here's an image from Fliptops.

 

[beans-on-toast]

Many people do away with the polarity cap when a three prong power cable is installed. It is still usefull to keep the circuit as it can reduce power line noise. Ampeg has a polarity switch in the current SVT-VR.

If you keep the circuit, the capacitors should be a special Type Y safety capacitor, not a typical film cap.

The wiring varies depending on the revision. Here is one. It doesn’t matter how you do it in terms of molex pins, just as long as the circuits are connected properly.

 

[greengoblin]

From your description it sounds like you have it figured out.

In one position the switch should connect the caps to pin #6, and in the other position the switch should connect the caps to pin #9.

Here's an image from Fliptops.

View attachment 3261023

Many people do away with the polarity cap when a three prong power cable is installed. It is still usefull to keep the circuit as it can reduce power line noise. Ampeg has a polarity switch in the current SVT-VR.

If you keep the circuit, the capacitors should be a special Type Y safety capacitor, not a typical film cap.

The wiring varies depending on the revision. Here is one. It doesn’t matter how you do it in terms of molex pins, just as long as the circuits are connected properly.

View attachment 3261035

You guys are really awesome and I appreciate all of your help! When I was looking at my schematics, something didn't seem right in my head thinking about the hook-up and started second guessing myself so I knew it was time to take a break. lol Thank you for the reassurance. And yes, that is the switch that I have for the polarity.

And Beans, thank you for the illustration! Have you thought about publishing that notebook?

 

[greengoblin]

Havent made any progress with the holidays and a recent trip. But I did receive my Molex items and figured I would post with possible helpful info. Mouser didnt have any of the Molex items and listed them as obsolete. Newark showed everything in stock except the 1360PRT and 1545PRT. Ordered pins separately and the female side of the block just in case I need it. They didnt list the male side of the block (or I didnt look hard enough) so I also ordered the 1360PRT and 1545PRT (2 pin connector). The 1360PRT is the complete unit that includes the make and female connectors as well as the 12 pins. Same with the 1545PRT, it is the full assembly with pins. The 1360PRT and 1545PRT drop shipped from Molex so there are a few extra days for shipping.

Im going to use the original connectors with new pins, but I have new connectors now just in case and plenty of pins. lol

 

[Wasnex]

Havent made any progress with the holidays and a recent trip. But I did receive my Molex items and figured I would post with possible helpful info. Mouser didnt have any of the Molex items and listed them as obsolete. Newark showed everything in stock except the 1360PRT and 1545PRT. Ordered pins separately and the female side of the block just in case I need it. They didnt list the male side of the block (or I didnt look hard enough) so I also ordered the 1360PRT and 1545PRT (2 pin connector). The 1360PRT is the complete unit that includes the make and female connectors as well as the 12 pins. Same with the 1545PRT, it is the full assembly with pins. The 1360PRT and 1545PRT drop shipped from Molex so there are a few extra days for shipping.

Im going to use the original connectors with new pins, but I have new connectors now just in case and plenty of pins. lol

Current numbers have superseded the old part numbers. I had copied a post from another community that listed modern parts, but deleted it because there appears to be some errors in the post. I'll provide a link below.

I started correcting the P/Ns and cross-referencing with the old P/Ns listed in @beans-on-toast 's scan and found Molex datasheets with references to the obsolete P/Ns. Pretty sure Mouser had stock of the modern P/Ns, but it got more confusing and labor intensive than I wanted to deal with, so ultimately I gave up and deleted the post.

This is the link to the modern P/N for the 1360R2 connector @beans-on-toast provided:
Link Removed
Here is the mating part.
Link Removed

The link in the other web community suggested the following is the correct P/N (traces to obsolete P/N 1360R)
Link Removed

The 1360R and 1360R2 use the same mating connector and pins. The P/Ns for various pins are available on the links above. There is also PDF and 3D drawings of the plugs. If I read the PDF correctly. 1360R2 is the correct model because it has locking ramps to hold the plug in place in the chassis, which are missing on the 1360R.


The post I copied and then deleted is post #3 in this thread. Use with caution.
[Invalid or Expired Link Removed]

 

[Wasnex]

@greengoblin Did you give up on the Blueline?

 

[greengoblin]

@greengoblin Did you give up on the Blueline?

No, just too many other things going on. Once I finished the Kiss SVT I've been trying to get a couple other things done. Buttoned up a couple old BK tube testers. I do have the preamp finished and ready to go.

 

[greengoblin]

So my SVT-II no pro is done as well as my SVT 2 Pro Kiss project. Back to the SVT even though I have a couple other projects as well....

Came across a cut on the board where R4 meets R47, negative feedback if I am not mistaken..??.. Common cut or a mod someone was trying?

Have it stripped down to almost a bare power chassis at the moment to see if I can remove all of the dirt, cobwebs and corrosion. What have you guys been using to clean up the corrosion? Used a scotchbrite pad and some Deoxit at first, but it is not doing much. May pull out some metal polish for the non lettered areas.

 

[Wasnex]

So my SVT-II no pro is done as well as my SVT 2 Pro Kiss project. Back to the SVT even though I have a couple other projects as well....

Came across a cut on the board where R4 meets R47, negative feedback if I am not mistaken..??.. Common cut or a mod someone was trying?

Have it stripped down to almost a bare power chassis at the moment to see if I can remove all of the dirt, cobwebs and corrosion. What have you guys been using to clean up the corrosion? Used a scotchbrite pad and some Deoxit at first, but it is not doing much. May pull out some metal polish for the non lettered areas.

Perhaps your dyslexia is acting up: Schematic shows R46 is 47R I am not aware of any mod that involves cutting the feedback loop. I would think this would be a big no, no with this amp.