Odd 5AR4 rectiver (proberly blown) on TSEII Checkout

[lykkedk]

My TSEII build [and some hickups along the way]

Hi all.

Finally i recieved my transformers (torids), and everything good for checkout.

The first thing i did was to power the board up with no tubes, checking the B+ / B- and 6.3 / 5.2 v at PCB as instructed.

After that i installed the Sovtek 5AR4 rectifier, and B+ came up within seconds to ~427vdc, B- is ~-267vdc and stable.

When i had looked at this for some minutes i installed the two 5842's and adjusted them to ~175vdc also as instructed. -I had it run for a few minutes, and when i should power it off, the B+ suddently was missing?

I waited until everything was cold, and plugged all 3 tubes out, and inserted the 5AR4 again, and after coffebreak, i turned it on again, and B+ was comming fine up again.
This was the last time i saw B+, now i cannot make the 5AR4/B+ voltage anymore.

I have checked all connections and solderings, and found no strange thing's

Looking at the schematic, i see that it's simple, that rectifier needs 5v on T1-YEL-1/2 and the HV on T1-RED-3/1 on pins 2,8 4,6, and when meassuring directly into to socket this is as expected.

My guess is that my (new) Sovtek 5AR4 did blow, or was nearly defective when i got it, but maybe there is something i am missing? i donno.

Any suggestions, something to investigate, something to meassure ?

Thanks very much in advance.

Jesper.

 

[lykkedk]

Just a quick reply to my own thread...

I forgot to tell, that the Sovtek 5AR4 doesen't glow and get hot anymore also; that's also why i belive it's defect.

Jesper.

 

[mike567]

Check for 5 volts on the filament winding.

check your solder joints on the rectifier socket.
check for continuity in pins of your tube. no continuity is bad filament or bad solder joint in tube pin. pins 2 and 8 are the main area of interest.

 

[lykkedk]

Check for 5 volts on the filament winding.

check your solder joints on the rectifier socket.
check for continuity in pins of your tube. no continuity is bad filament or bad solder joint in tube pin. pins 2 and 8 are the main area of interest.

Cool, thank's man!

I have ~5,2 with no tubes installed, and when the 5AR4 was working there was between 5.0 and 5.1 v there.

Between 2 & 8 i have jumpy ohm's... I can even make the connection dissapear when eg. turning the tube around/shake it a bit

Between 6 & 8 & 4 there is no connection no matter what. (also tried with my diode tester buildin my DMM)

One more thing... George aka' Tubelab wrote somewhere this ::

One can always add a CL-140 in series with the HV CT wire on the power transformer to blunt the spike in the HV winding itself. I have both on my SSE amps, but they run at much higher power and voltage than the TSE. The Inrush Current Limiters help protect some of today's less than stellar rectifier tubes.

I think i have some CL-140 laying around somewhere, would it be wise to do that, before plugging a new not yet here rectifier-tube ??

Thanks & Rgds; Jesper..

 

[Tubelab_com]

Between 2 & 8 i have jumpy ohm's... I can even make the connection dissapear

This sounds like a poorly soldered connection inside the tube's pins. Try reheating the tip of pins 2 and 8 on the tube itself and perhaps feeding a bit of solder to the tip while it is heated with a solder iron. A bit of filing may be needed before inserting it in the socket. I have found a few tubes that can be fixed this way if that's where the fault lies.

 

[lykkedk]

Soo...

I will try to heat the pins tomorrow, and see if i can do something about it?
There should be 0.1 or next to nothing in ohm's between 2&8 on cold tube right?, and steady.

Exciting it is for sure...

Well regarding this ::

One can always add a CL-140 in series with the HV CT wire on the power transformer to blunt the spike in the HV winding itself. I have both on my SSE amps, but they run at much higher power and voltage than the TSE. The Inrush Current Limiters help protect some of today's less than stellar rectifier tubes.

Bad idea or way to go?

Anyway i also read about soldering two diodes on rectifier socket for protection if rectifier will fail and short, preventing AC getting into the cap's on board...

Rgds; and thanks for answering...

Jesper.

 

[lykkedk]

UPDATE.

I tried to heat the tip's at leg 2&8, and i actually could see the resistance change a bit.
I also filled in some solder, and after that the resistance was not so jumpy anymore (~1.5 - 3 ohm)

I cannot make the connection dissapear anymore, but unfortunately it still does not work.
-- But this was a good shot George...

Let's see what happend, i will get a new TAD-GZ34/5AR4-STR within next day's.

Jesper.

 

[lykkedk]

Update part II

Video, just for the fun of it : YouTube

So i recieved my TAD rectifier today, and guess what? still nogood

So i'am not really proud of myself, beeing paid by my job as technician crane repairman (electrical problems/fault-clearance mostly) and not finding this "error" before i used time&money buying a new rectifier... Well the he.. with it, i found the error and i now am the proud owner of a warehouse of tube-rectifiers

The RED wire on the first picture was connected through the insulation giving bad bad connection.

B- ~240
B+ ~350
Bias for now 65mA + 65mA very stable after ~30min. or so.

Music is playing nicely. The "test" speakers is feed through RPI+cheapDAC+50Kohm pot into the TSEII,

Rgds; and thanks for helping me along!

Jesper.

 

[lykkedk]

Things come along

Hi here.

Just wanna post a few pic's of the chassis build.

Along the way i tried to remove the little noise/hum i had on my test setup here, and the best cure is to just connect the shield(gnd) of one of the input jacks to the bottomplate of the chassis... Really nice, almost 100% clean sound now... one of them next day's i will bring the thing downstairs connecting it to my mainstereo.

Jesper.

btw.:: Sovtek rectifier gives ~5vdc more on my B+ than the TAD.