Traynor YGM-3 (early) - Selmer cab

[Reeltarded]

Snow globe lost it's Santa.

[Structo]

Cool!

I have never seen a tube burn a hole through the envelope.

Instead of redplating it must have white plated.

[Barks]

I'll have to take a photo of one of the power tubes from my Late 60's Pioneer SX-34Bs Hifi amp/receiver.

Same thing happened a couple years back - after 45 years of service...another project another day!

[Barks]

ECL82 from the Pioneer SX-34Bs:
[IMG575]http://i650.photobucket.com/albums/uu222/katbarks/2%20Tokai%20Guitars/Pioneer%20Pioneer%20SX-34Bs/IMG_20150623_164945857_HDR.jpg[/img]
Blurry Gubbins:
[IMG575]http://i650.photobucket.com/albums/uu222/katbarks/2%20Tokai%20Guitars/Pioneer%20Pioneer%20SX-34Bs/IMG_20150623_164956407_HDR.jpg[/img]
Front:
[IMG575]http://i650.photobucket.com/albums/uu222/katbarks/2%20Tokai%20Guitars/Pioneer%20Pioneer%20SX-34Bs/IMG_20150623_164910075.jpg[/img]

This will be another project. Most likely cause?

[Barks]

ok, still waiting for the transformer to arrive. :/

Thought this may be a good opportunity to ask for advice on what I should consider as I remove the old one and connect up.
Prep, measurments as I go etc?
I was looking at the light bulb limiter unit for new builds etc, and was wondering if this is a good idea -if I understand it! - when adding something like a new transformer to an older cicuit?

thanks

Barks

[rp]

Trust me do it, it keeps the smoke in. When doing modifications to the power section or with a new build a DBL can save expensive parts. You might also want to install a line fuse in the B+, but with a ss rectifier you'll need a slow-blow and I'm not too sure how much protection that really is on the DC side. When I boot for the first time I de-rate the mains fuse by like half too.

If you are only going to use the DBL once you don't need anything fancy. I built the one that Martin made a sticky of, I made the nice one as a motivation to make me use it. Previously I had an extension cord with a socket wire-nutted in one side but never used it, the nice one had that, " oh, boy, I get to use my clever new diy gadget" thing going for it.

Anyway when that bulb lights up bright you'll be very glad you built one. Still got incandescents on hand??

BTW the Hammonds have a center-tap on the 5V - Don't connect that!!!

[martin manning]

Barks, I'm pretty sure this is your plan. See if it makes sense to you.

[Barks]

Thanks so much Martin - I've been studying the diagram and the photo and it is really helpful!

Can I just clarify that the right hand switch in the picture (with the yellow and red circle) is the standby switch and the one to the left is the relocated power switch.

Also the amp has both a 1amp fuse and a slow blow 1/4 amp HT fuse installed (previously a ground switch)

[IMG768]http://i650.photobucket.com/albums/uu222/katbarks/Traynor%20-%20Selmer/IMG_20150508_132858655.jpg[/img]

I'll take a picture of this inside for clarity soon when I get a chance.

thanks again - I'm pretty excited by all this!

[Barks]

Here are the fuses.
The one on the right is the 1A that is in series with the brown mains and power switch.
The left is the HT 1/4A fuse. Grounded to the chassis and connected to the standby switch.

[IMG575]http://i650.photobucket.com/albums/uu222/katbarks/Traynor%20-%20Selmer/IMG_20150701_194232783.jpg[/img]

[rp]

Here's a suggestion for the primary taps, you can just tape them off but if you think the amp might ever travel around the globe a terminal strip and jumpers makes rewiring pretty clean. Don't follow the pict, mine's for 240V.

Without reading the back posts, you could create a new bias circuit if yours is fed off the secondary rather than the 50V just because you have the tap, otherwise just tape off the 50V. Whatever you chose you should check the bias -V without the power tubes in first to see if the voltage is in a safe range or high enough to keep the tubes from red plating. Then you can tweak the bias with them in place. Don't count on what you had before being good as you are going to have a fairly different Pv w/ new PT. I'm not sure what range is for 400v on EL84s. Maybe the -V is on the schematic. You can play with this:

http://www.tedweber.com/webervst/tubes1/calcbias.htm

[martin manning]

Yes, understood. By now you can tell the circles in the marked-up photo correspond to the transformer wire colors. The standby switch lifts the red/yellow HT center tap from ground, and in your case the HT fuse is also in that ground path.

I would remove the wire connecting the side terminal on the HT fuse holder to the power tube cathode ground, and replace it with a wire going to the reservoir capacitor ground terminal, which is shown by the black circle in the marked-up photo. That wire has very high current pulses traveling through it, and it is best to keep that off of the chassis to minimize 100Hz noise.

I'm guessing the bias voltage will be reasonable since it is presently working with 450V on the anodes. I would also leave the bias supply as is, rather than using the new PT's bias tap, since the standby switch is in the CT.

[Barks]

Ok, transformer has arrived.

Martin - just for my clarity (sorry for the newbie question) - soldering the Brown and Black wires together of the primary effectively joins two 120V sides to make the 240V?

Busy week so this'll have to wait a few more days!

thanks

Barkley

[martin manning]

...soldering the Brown and Black wires together of the primary effectively joins two 120V sides to make the 240V?

Exactly. In North America they would be connected in parallel.

In the meantime, see if you can round up some small nylon zip-ties to bundle the unused leads. Do you have solder and and desoldering braid?

[Barks]

Thanks!

In the meantime, see if you can round up some small nylon zip-ties to bundle the unused leads. Do you have solder and and desoldering braid?

Yes I have everything else bar the desolder braid - though have desoldering pump.
I run an analogue studio so soldering leads and simple desk maintenance are my area of expertise (and the odd iPad screen repair)

This is my first foray in high voltage - especially power supplies.

[martin manning]

Ah, good. Pump vs. braid may be personal preference. I have both but usually go for the braid.