Orange 86 Build Thread - no PCBs for sale

[imo]

Hello,
I finally got around to putting a channel together. I don't have the relay power supply so i bypassed all of the relay/pad/di boards, went from the input transformer directly into the grid of the EF86. I used a 12Bh7 for V2. I put in the jumper for the 12BH7, ran the heater wiring from the 2 pads near the heater input to the 2 pads by the EF86. I ran the heater wiring as per page 13 of the wiring diagram, linking the V2 ground to pin 9 and linking V1 pin4 to pin2. I correctly wired the Edcor pt with the centertap closest to the chassis ground, and then the 2 secondary windings to the proper input to the board. Ran the chassis ground to my star ground point. Had the primary of the PT connected properly..Everything seems right. no tubes in.output trannie hooked up and give it a go
Connect to a variac and slowly ramp up the voltages. The edcor was humming pretty loud and as i got it about half way up i popped a fuse, tried replacing it, same thing. Something is either wrong with the PT or with the board. I am a little flummoxed as i am not using the various other boards, wondering if there is something i'm not thinking about..I have a good ground, the HV windings are right. I am getting around 50r from each secondary winding to the centertap, so that seems right. I have tried disconnecting the heater as i wanted to make sure there wasn't something there. Same thing..
Are there any obvious 'duh' things that are slipping by me? there are no obvious shorts on the board, no solder bridges, etc.
Wondering if i got a funky pt from edcor?
Mercy
Ian

 

[guavatone]

The Custom Edcor XPWR097-120/240 has 10V for DC Heaters.  You will need a 275-0-275 V with 6.3V for heaters.  The Allied XFMR or Ecor XPWR106  would do better(see below).    I prefer edcor since they are 120V primary giving the heaters closer range of voltage.

Also, the High Voltage CT should go to the PCB as the diagram says.  I'll look into the rest of your wiring soon.  what amp fuse do you have?


540V CT transformer
http://www.alliedelec.com/search/searchresults.aspx?N=0&Ntk=Primary&Ntt=540vCT

Edcor Options:
XPWR009
XPWR038
XPWR106 **** cheapest

 

[imo]

Charlie,
I actually have the Edcor XPWR106. I am convinced that the transformer must be funky. I have 2 of your boards. I tried using the second board with nothing connected but the starground and the ht windings(centertap to ground). I left the heaters unhooked to just try the HT. Same result, i actually kept the variac low as i didn't want to blow another fuse, but i could hear the Edcor vibrating more than it should. It was also getting warm, and possibly a wisp of smoke.

AC is getting to the board and getting rectified. I am able to see DC at the plates of the tubes, so it seems the power supply is functioning, at least to some point.

Something is sucking a lot of current out..Either it is the transformer or something in the power supply section. It is enough to blow a 2A fuse, even with it hooked up as above and the variac at about 50v AC.

In reference to your last post, the AC centertap is, and was, going to the PCB as well
again, there are no obvious shorts to ground. The heater wiring was a little confusing and i thought possibly tying the V1 heater(ground side) to pin 2 was causing something weird, but i am seeing the same problem with all of the heater circuitry unhooked
Ian

 

[phatmateo]

why don't you test the transformer out when it isn't hooked up to the orange86 to see if it is working?  I like funky, but not that type of funky

 

[guavatone]

I agree.  Please test the secondaries of XFMR with full AC on primary.

Also, The secondary HT CT should go to CT on the board.  Then the board's ground goes to your AC Mains ground tap by your AC inlet.
It is bad practice to have the CT which is carying HT to both places.  Maybe I am misunderstanding, but I am not sure if It is clear.

Test the Edcor first.  They are built really well and should be ruled out first.  

Then, test to make sure you didn't short out the TIP transistor in the HT Power.  They can blow easily with the wrong wiring.

 

[imo]

I will definitely test the transformer when I get back,out of circuit.
To be clear on the power hookup, the centertap and 2 ht windings are going only to the board. The chassis ground pad to the right is going to a ground lug that also grounds the iec. This is the way it has been wired since the start, which is why I have been a bit baffled. It seems like a pretty simple circuit, without a lot to get in the way
when I tried the second board, the ONLY 2 connections to the board were the ac in and then the chassis ground. The heater wires weren't even wired to v1. That's what made me suspect the transformer
will check and report later today
thanks
Ian

 

[imo]

Ok, the good news is that the power transformer is working out of circuit..the bad news is, well the pt is working out of circuit.

-I went through and checked every diode for direction and condition(all good) tested the power transistor(tested good in circuit with diode tester)
checked every resistor, both with dmm and against color charts(in circuit but most power and plate resistors still read right)
checked all caps for orientation
Everything reads as it should.
no solder bridges on either side

again, here is how i had it hooked up:
1. 3 header connector going to power inlet (pin closest to chassis ground is ground, other 2 are HT)
2. heater wires from PT not connected(though i did have them connected initially)
3. wire run underneath board from '6.3v' and 'LT 0v' V2 to V1 '6.3v' and 'LT 0v'
4. jumper for V2 to make heater voltage 12.6(12Bh7a)--as per AC wiring diagram
5. jumper  connecting pn9 V2 to 0v--as per AC wiring diagram
6. jumper connecting "squish" points
7. originally had jumper connecting V1 pin2 to shield, but tried taking this off.
8. originally had input tran hot connected to 100r grid of V1, and cold to ground(both jumpered to use the input zobel but took it out
9. Wire from chassis ground to ground lug where IEC ground is also connected(only ground connection from board)

The PT is wired correctly, and is the Edcor with the 6.3v heater winding 550ct HT.
I checked again on the Tip50 pinout, just to make sure, and it is correct

just to try to save as many back and forths as possible, all of the solder joints are solid and clean, the board is clean of flux
the zeners are the right types. all the board grounds seem solid..all caps are rated for the voltage and more

-i did not have the gain switch hooked up for the last few tests
-no tubes were in the sockets except for one time just to check

something is sourcing a lot of current. I ran out of 'proper' fuses and tried putting in a bigger fuse thinking maybe i had miscalculated fuse values. The next size was 3.15A. I current draw dimmed my work lighton the same circuit before i shut it down. blew on of those fuses while doing it

Also, i have a second board(again without the heater wiring connected on this) and all the same components(checked again for correct values and orientation) this board has the exact same problems as well..

help me obi wan..

something is sourcing a LOT of current, even hooked up like this.

 

[guavatone]

You are using only 2 diodes to rectify, correct?
They are to the left of the HT connectors.

Can you take a picture of your Board?

 

[imo]

I did had the full 4 diodes, which makes complete sense with the problem. I should have caught that, but i was using the schematic as reference, and didn't open the BOM until reading your post,so thankyou, problem solved.
You don't have any reference voltages do you? It looks like around 290 or so coming into circuit. I have been using a Red47 schematic for reference, but would be curious to see your readings on your units
Thanks
Ian

 

[guavatone]

285-300.  I was shooting for 290-295 after the diode that does to V2's anode.

The important thing is to have 10-30 Volts more at that spot than feeding the Reg transistor and Zeners.


Sorry for the confusion.  The project is a little more difficult since there are open ended options.

Hopefully the rest of your project goes smoother.  What's the rating on your LT edcor?
You are going to need 2 AMPS at least not counting lamp it adds to 1.8A IIRC

 

[imo]

its 4a on the heater circuit. are you using a 2.5amp fuse with the lamp?
I have signal, though a pretty hefty ground buzz..
Right now i have it in a proto box, with one ground point by the IEC, with IEC ground and chassis ground(from the board)
i have a second groundpoint that has the 2 XLR grounds as well as the white and black wires from the cinemag input tran
I'm assuming i should tie the 2 ground wires(ground and chassis ground) together as there is no other ground point for them.

the power is pretty clean, by the time it gets to the reg there is almost no ac at all, so i am assuming the groundbuzz is either some funky grounding thing or something with the heater circuit. with that in mind i had a couple of questions.
1. in your build did our heater winding have a center tap and if not did you put 100rs to make a ground?
2. on the EF86 woudn't it be better to tie pin 7-2 to ground, as opposed to the low side of the heater, which as wired with AC heaters is floating from circuit ground?
3. how are you grounding your unit? I am not using the relays, di's, or other pcbs right now, until i figure out a 48v, 24v solution.

 

[imo]

well, i did both things at once, 100r's to ground on either side of the heater windings, and also detached the jumper from pin 2/7 of V1 from the heater low and attaching it to the ground point nearest. That seemed to work.
I would put that in the notes. With a DC heater there will be a ground point there, but with AC heaters it is floating.
Any docs on adjusting the gain trim pot, or is it just to taste?
Ian

 

[guavatone]

YEs the EF86 should have pins 2 and 7 to ground and not AC.  There may be a mistake in the document.
So Jumper shield to the ground plan point on the board below(looking from the input/output section on bottom)

V2 diagram should be right.  one side of 6.3VAC to pins 4 and 5 and other side to pin 9.  You may want to keep the jumper to pin 9 away from PCB.

The trim is pretty insignificant.

I actually haven't built a 2 channel one of these with 12BH7 tubes. but 2 channels should draw 1.6 AMPS.  600max2 for 12BH7 and 200mAx2 for EF86, ad a half amp for margin of error.  Add 500mA for lamp (probably less but that's a good estimate.  So 3 should be fine.

I generally don't like LT center taps and use 1/2W 100R to Star Ground.  Not to PCB ground.  Like in fender amps by the big old jewel lamp.

Is your box metal?  proto box makes me think ABS.

I hope you are not cursing me out every time something isn't working.
We are in somewhat experimental mode with the 12BH7.  When u get it working put a 10K for R13  and 1K pot in parallel to experiment with Rk.  You will see extra PADs bu R13 for this.

 

[imo]

Charlie,
Not at all. Though it is nice having good preamps and such, my goal is to continually learn more as i go along.
Right now i have the 100r's to the pcb as i don't have a light or any convenient place to put them. I will do it Fender style when i get all the parts together.
Everything is working. I think i need to tweak it a bit..
What is your plate voltage on the EF86? RIght now i have about 70 volts. Is that where it should be? I have a little more than 200 going into the plate resistor. That puts the current around 1.3mA, which is in line with the Redd schematic i have.
When i go through the gain settings however i have a really distorted signal at the lowest setting. As it gets louder things clean up a bit, but the gain quickly gets to be too much.
The fine gain pot would probably be a lot more important with the 3 switch original version. This one has much more control with the resistor ladder. It doesn't seem to do anything really.
I will try the 10k with the 1k pot. see what happens

 

[imo]

the 10k/1k is nice on the 12Bh7, but i'm still getting a pretty serious crunch at the bottom of the gain switch. It sounds like a tube screamer. would the 100r in series-grid before the ef86 help tame that or do i need to look elsewhere?
it seems like something is wacky in the gain switch area. there isn't much difference in actual db level through the play of the switch, more it sounds like it cleans up, gains more lowend and highs and has a sllight gain boost
  Looking at the 12bh7 curves, the most linear area i can get to is around -7.5 on the grid, 170 or so on the plate..brings the current down from the 18.5mA  to around 12 or 13mA

 

[guavatone]

The fine gain pot would probably be a lot more important with the 3 switch original version. This one has much more control with the resistor ladder. It doesn't seem to do anything really.

I am not sure what u mean here.  Do have a grid to ground resistor (R2) on V1?

I would double check the gain/feedback switch.  Do have the compensation caps in?  c-FB1 and C FB-2

70 Volts is a bit low, theoretically, since I don't have that value on hand.  What is V before R14 feeds V2? This should be 305-330V.
What is your HT V before after R21?  This should be 285-300V.
Then R15 and R6 should drop about 200V from that last test point.

You could take the feedback/gain switch out and put in a 20K resistor and keep C-FB1 and R-FB-1 in there.

 

[imo]

-yes i do have a ground resistor, i was talking about R3, the optional series 100r resistor going into the grid of V1

-i do have both comp caps 6.8n for FB1 and 10n and 22n for FB2

-HT feeding R14(plate resistor of V2) should be the full regulated voltage. Mine is around 295

- voltage into R21-341 after-328 then the regulator/zener pulls it to around 295

-R15 drops the Ht to 210, then the 100k plate(R5) is dropping it to around 70

r4(cathode r for V1) is dropping about 1.7v..puts plate current around 1.7mA

 

[guavatone]

Did you try swapping tubes?  Are there tubes you didn't have in the sockets when you had faulty Power issues?

 

[imo]

yeah, the tubes are fine. i tried new ones in either socket.
again, the only prob is when the gain switch is at its lowest setting. how does your preamp perform there?
what about voltages? do these, especially v1, conform with you build?

 

[imo]

I tried the other channel, and it sounds great, so i'm gonna go through the feedback section and find out what is measuring differently.
Getting close. curious to figure out what is going on with the first channel
Ian