5E9 Tweed Tremolux Build Thread: Pics on Page 11

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Racing
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Re: 5E9 Tweed Tremolux Build Thread: It's Alive!

Post by Racing » Mon Sep 18, 2017 10:35 pm

Been giving that redplate condition of yours some thought.

A while back i had a couple of DLR RI in the door that did this too,albeit being according to schematic. IOW it is likely that the issue was the tubes in themselves,not the amp and running condition it presents per se.

A real easy manner in which to conclude this would be a SMALL modification in my opinion. Point here being that..."cut to the chase" kind of attitude,in short fast results.
What you do is order a pair of 10V zener diodes of 5 watts a pop.

Pin 4 is g2 right. Install one such zener per socket with the ring AWAY from the socket (iow ring TOWARDS voltage feed) and do so between pin 1 and 4. (As pin 6 was occupied by a gridstopper).

A mere 10V voltage drop won´t amount to anything sound wise really. What it WILL do though,see above,is guarantee that g2 will never surpass plate as far as potential and this might very well be your issue seing the direct lack of screen grid resistors.
If you want you can install a 100 Ohm/2w resistor in series with said zeners,the resistors then AFTER the zeners. Ie;the resistors are what´s to be soldered to pin 4. What these resistors will do is act as EMI/RFI protection. In short calm g2 down when needed and so called for.

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Re: 5E9 Tweed Tremolux Build Thread: It's Alive!

Post by wproffitt » Tue Sep 19, 2017 5:51 am

Racing,
Thanks for your help with this!

As for the redplating:
I've ordered the diodes, but have a couple of questions for you while I'm waiting for them to arrive:
1) the only place I can see where I've deviated from the 5e9 layout is where I wired 1k resistors in between pins 5 and 6 of the 6v6s, like you would on a 5e3. Is there any reason why this would be problematic?
2) the color code on the wires for my OT did NOT correspond to anything drawn on Leo Fender's layout for this amp, so I took an educated guess when wiring things up. I took the red wire from the "left" side of the OT up to the standby switch, the brown wire to pin 3 of the leftmost 6v6 and the blue wire to pin 3 of the 6v6 to the right. Does anything about this sound problematic? For reference, here is the layout for the 5e9:

Image

As for the trem wiring:
Yes, the orange wire coming off of the "speed" pot in the picture above does meet up under the board at the turret holding the .02 MFD 600v capacitor. The "depth" pot is wired up as shown in the wiring layout shown above. Is it possible that I have a bad pot or is there a more obvious wiring issue?

Thanks for your time!

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Re: 5E9 Tweed Tremolux Build Thread: It's Alive!

Post by sookwinder » Tue Sep 19, 2017 6:16 am

Scott I do not understand this sentence
I took the red wire from the "left" side of the OT up to the standby switch
where is the stand by switch ... are you meaning the AC on/off switch?
As far as I can read the layout, one wire goes to pin 3 of one 6V6 another goes to the other 6V6 pin 3 and the third wire goes to the rectifier valve/first filter cap

Image
relaxing alternative to doing actual work ...

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Re: 5E9 Tweed Tremolux Build Thread: It's Alive!

Post by sookwinder » Tue Sep 19, 2017 6:18 am

when you bought the OT was there instructions listing what coloured wire was what ? or were the wires fitted with sticky labels saying what they were ?
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Re: 5E9 Tweed Tremolux Build Thread: It's Alive!

Post by wproffitt » Tue Sep 19, 2017 6:44 am

David,
The second I clicked "submit", I realized that I had left out something important. I substituted a standby switch where the "ground" switch would be. Sorry for the lack of clarity here. As for what I meant by left side of the OT, I meant that, if you are looking at the amp from the back, you would see that three wires come into the chassis on the left and two come in on the hole to the right. This is reflected in the "wiring diagram" given on the Mojotone website in the link below.

http://www.mojotone.com/amp-parts/Trans ... ransformer

No, there were not instructions or labels for the wires saying where they were supposed to go. This is what I get for not working from a kit, right? :D

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Re: 5E9 Tweed Tremolux Build Thread: It's Alive!

Post by sookwinder » Tue Sep 19, 2017 6:59 am

you don't need a kit ... you just need the correct info.

Just checked the wiring diagram on the mojo site and the brown and blue wires each go to a 6V6 and the red wire goes to the rectifier (or in your case the standby switch) / first filter cap
relaxing alternative to doing actual work ...

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Re: 5E9 Tweed Tremolux Build Thread: It's Alive!

Post by wproffitt » Tue Sep 19, 2017 7:05 am

David,
thanks for looking that over for me. So, if I've wired it up with the brown going to pin 3 of one 6v6 and blue going to pin 3 of the other, I should be good, right? Sorry again for not mentioning the standby.

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Re: 5E9 Tweed Tremolux Build Thread: It's Alive!

Post by Racing » Tue Sep 19, 2017 12:47 pm

Yes.
Then you should be ok. None the less measure.

Amp off and drained of voltage. Measure DC resistence between red and blue...and in turn red and brown. Should show similar numbers. If you measure between brown and blue in turn (on the sockets) and get approx double that value in Ohms...then we´re sure.

Standby switches in turn.
Don´t with tube rectifiers. We can get into why but over the long run standby switches and tube rectifiers don´t mix well. Just loop the thing and be done with it already.

No. Wiring a gridstopper between pin 6 and 5 shouldn´t amount to anything. In fact if you pull a 6V6 and look pin 6 should even be missing on the actual tube.

Wire the zeners up per my description. Measure voltage at pin 4 for each tube BEFORE..then measure after. After there should be 10VDC less for each pin 4. These mere 10 volts are to secure that the bias backs off a tad and in turn...to make sure that g2 voltage can never surpass plate. Thus securing both their jobs.

As the screen grids of 6V6 and 6L6 both draws relatively little current you could just as well up them zeners to 47V/5w at will. That´d change the behavior of the amp tho.

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Re: 5E9 Tweed Tremolux Build Thread: It's Alive!

Post by Racing » Mon Oct 02, 2017 5:43 pm

Did you ever get around to post a schematic for us?
Would come in real handy.

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Re: 5E9 Tweed Tremolux Build Thread: It's Alive!

Post by wproffitt » Tue Oct 03, 2017 8:07 am

Racing,
Thanks for checking in! David posted the 5E9a schematic a few posts up from here. Since I last wrote, I've done a couple of things with the amp.
1) Before I put in the Zener diodes, I thought I'd do screen resistors (470 ohms, 3 watts) as a safety feature. I ran them from pin 6 on my 6v6 to pin 4. I'm also now bringing my power in at pin 6 and have pins 6 of each 6v6 jumpered.
2) My next step is to put in beefier grid stoppers (2.2, 2 watts). Alas, I ordered to two sets of 470 ohm resistors, so I'm waiting my 2.2k ones to arrive before I see whether or not beefier grid stoppers will take care of my red plating. One measurement that I need to retake is the voltage now coming in at pin 6.

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Re: 5E9 Tweed Tremolux Build Thread: It's Alive!

Post by Racing » Wed Oct 04, 2017 3:51 pm

You need to read up a bit as far as gridstoppers,and how the work and what they perform,as entry on powertubes.

The practical perceived difference vs let´s say 1k or 1,5k is nil-from an audiable POW.

IOW? For gridstoppers basically anything goes. Just toss that in there that you´ve got around.

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Re: 5E9 Tweed Tremolux Build Thread: It's Alive!

Post by wproffitt » Thu Oct 05, 2017 3:17 pm

Thanks, Racing,
Does this apply to the wattage of the grid stopped as well? What I had in before were 1/2 watters. The ones I've ordered are 2 watters. What do you think?

Best,
Scott

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Re: 5E9 Tweed Tremolux Build Thread: It's Alive!

Post by Racing » Fri Oct 06, 2017 12:59 am

As for gridstoppers,the currents involved are so small that resistor wattage...anything basically goes.

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Re: 5E9 Tweed Tremolux Build Thread: It's Alive!

Post by wproffitt » Fri Oct 06, 2017 6:58 am

Gotcha!

As for the Grid Stoppers:

I'll be able get something in there Monday night. Real life has had a way of getting in between me and my amp build!

I had a thought on the Trem issue:

-On the 5E9, the Trem/PI is V2. Perhaps I just have bad tube in this slot? If so, that'd be great (because it's simple) but that tube wasn't cheap! Perhaps a tube swap is all this needs. I'll check into it when a get a free moment and report back to the group.

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Re: 5E9 Tweed Tremolux Build Thread: It's Alive!

Post by wproffitt » Fri Oct 06, 2017 10:11 am

Progress alert!
I pulled the nice tube I had in V2 and inserted a newer Tung Sol. I then fired up the ampnin a dark room and watched the tubes glow. No red plating. However, when I engaged the foot switch, there was a "hum" sound and V5 began to redplate. When I clicked the foot switch off, the red plating stopped.
However, when I turned there lights on, I noticed that the tube in V2 didn't look so good. There was an ashiness to the color. It must have broken when I inserted it, because it was certainly cracked when I removed it.
Whatever the reason for the above, I now know that the Redplating on v5 is for sure tied to my trem/PI tube. I guess I should check the wiring on V2? Is there a chance that the socket itself is problematic?

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