Hello all.
I'm putting together a bench test of my SSE. I'm starting by connecting up the Hammond 274BX power transformer, but I have a question before I proceed.
The green wires, red wires, red and yellow wire, and yellow wires are all very straightforward, and I have the connected to the appropriate spots on the PCB. However, I'm not entirely sure about the remaining wires.
Here are the remaining unconnected wires:
White
Gray
Black
Yellow+Black
Green+Yellow
I'm not clear on which of these should be connected to power. Which one is live, and which is neutral? The top of the transformer says "WHT - GRY: 115V 60Hz"
Does that mean white is live and gray is neutral?
The label also says "WHT - BLK: 125V TAP".... I'm not sure what that means. I'm in the US which means 115V is the correct option, yes?
I'm putting together a bench test of my SSE. I'm starting by connecting up the Hammond 274BX power transformer, but I have a question before I proceed.
The green wires, red wires, red and yellow wire, and yellow wires are all very straightforward, and I have the connected to the appropriate spots on the PCB. However, I'm not entirely sure about the remaining wires.
Here are the remaining unconnected wires:
White
Gray
Black
Yellow+Black
Green+Yellow
I'm not clear on which of these should be connected to power. Which one is live, and which is neutral? The top of the transformer says "WHT - GRY: 115V 60Hz"
Does that mean white is live and gray is neutral?
The label also says "WHT - BLK: 125V TAP".... I'm not sure what that means. I'm in the US which means 115V is the correct option, yes?
Connect only one of the gray or black leads at a time, and insulate the other lead.
white is neutral = 0VAC
gray is 115VAC
black is 125VAC
yellow/black is filament #1 center tap (yellow wires, 5VAC)
yellow/green is filament #2 center tap (green wires, 6.3VAC)
yellow/red is HV center tap (red wires, 750VAC)
These colors are reasonably standard, and have been commonly used for years.
https://www.hammfg.com/electronics/transformers/classic/200.pdf
white is neutral = 0VAC
gray is 115VAC
black is 125VAC
yellow/black is filament #1 center tap (yellow wires, 5VAC)
yellow/green is filament #2 center tap (green wires, 6.3VAC)
yellow/red is HV center tap (red wires, 750VAC)
These colors are reasonably standard, and have been commonly used for years.
https://www.hammfg.com/electronics/transformers/classic/200.pdf
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Awesome, thanks!
And here's another question for you, about OPT wiring.
My OPT has input wires labeled UL, +U and A. I know where the UL wire goes if it's used, but I'm not sure where the A and +U wires belong. There's three connectors on the OPT input on the board. 1, 2 and 3. UL goes to 2 if used, but which wires go to 1 and 3?
Edit: the transformers in question are Toroidy TTG-EL34SE
And here's another question for you, about OPT wiring.
My OPT has input wires labeled UL, +U and A. I know where the UL wire goes if it's used, but I'm not sure where the A and +U wires belong. There's three connectors on the OPT input on the board. 1, 2 and 3. UL goes to 2 if used, but which wires go to 1 and 3?
Edit: the transformers in question are Toroidy TTG-EL34SE
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https://www.tme.com/Document/b49426edcf5a71fd9f30c16e58824cdf/ENG_EL34_SE.pdf
green +U is positive terminal of the HV power supply (+U sometimes means +V for voltage)
yellow UL is ultralinear tap
blue A is anode of the output tube (A means anode)
black is 0R
red is 4R
white is 8R
green +U is positive terminal of the HV power supply (+U sometimes means +V for voltage)
yellow UL is ultralinear tap
blue A is anode of the output tube (A means anode)
black is 0R
red is 4R
white is 8R
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OK, so we've identified U, UL and A. Which one goes to which connector on the PCB? That's not clear from George's wiring diagrams.
If I've got this right... A (anode) goes to O1, UL goes to O2, and U goes to O3. Is that right?
If I've got this right... A (anode) goes to O1, UL goes to O2, and U goes to O3. Is that right?
Found this on a website recommended by someone (I don't remember who.)
(Transformer and Wire Color Standards for Tube amps)
From the ARRL handbook:
BLA - grounds, grounded elements, returns
BRO - heaters/filaments, off ground
RED - power supply B+
ORA - screen grids (and base 2 of transistors)
YEL - cathodes (and transistor emitters)
GRN - control grids, diode plates (and base 1 of transistors)
BLU - plates (and transistor collectors)
VIO - power supply, minus leads
GRA - AC power line leads
WHI - bias supply, B or C minus, AGC
Is there a standard scheme for power transformer wire colors?
From Orr's Radio Handbook:
Primary leads -------------- black
(if tapped)
Common ----------------- black
Tap -------------------- black/yellow
End -------------------- black/red
High voltage secondary ----- red
Center tap ------------- red/yellow
Rectifier filament winding - yellow
Center tap ------------- yellow/blue
Filament winding No. 1 ----- green
Center tap ------------- green/yellow
Filament winding No. 2 ----- brown
Center tap ------------- brown/yellow
Filament winding No. 3 ----- slate
Center tap ------------- slate/yellow
I have seen primaries with other color schemes; if it includes black it should be a primary lead of some sort. I've seen transformers with only one filament winding that was brown. I've seen high voltage secondaries with red/white centers. And on old transformers, the colors may have faded to the point brown looks black or green looks black or brown, and so forth. I'm not aware of any standard for filament winding numbering, so if there is more than one, verify the voltages. The rectifier winding will normally be 5 volts, but again, verify it. If you have an old tranny with odd or indistinguishable colors on the leads, verify them. In fact, it's a good idea to verify any PT before using, just to be safe. Miswirings are, AFAIK, rare, but do occur, as do shorts.
Is there a standard scheme for output transformer wire colors?
Derived from the ARRL Radio Amateur's Handbook:
Single-ended transformers:
Plate lead (pri.) -------------- blue (or brown)
B+ (power supply) lead --------- red
speaker (typ. +) (sec.) -------- green (or yellow)
speaker return (sec.) ---------- black
Push-pull transformers:
Plate lead (pri.) -------------- blue (start)
B+ (power supply) lead --------- red (center tap)
Plate lead (pri.) -------------- brown (finish)
speaker (typ. +) (sec.) -------- green (or yellow)
speaker return (sec.) ---------- black
Ordinarily the black side should also be grounded, if the speaker is grounded. Replacement transformers are not always identical, so if you get squeals or other odd sounds when hooking up a new output transformer, try reversing the output leads. "Start" and "finish" are arbitrary terms with respect to this configuration.
Is there a standard scheme for interstage coupling (such as phase inverter) transformer wire colors?
From the ARRL Radio Amateur's Handbook:
Plate finish lead (pri.) ------- blue
B+ (power supply) lead --------- red (whether center tap or not)
Plate start lead (pri.) -------- brown
Grid finish (sec.) ------------- green
speaker return (sec.) ---------- black (whether center tap or not)
Grid start (sec.) -------------- yellow
(Transformer and Wire Color Standards for Tube amps)
From the ARRL handbook:
BLA - grounds, grounded elements, returns
BRO - heaters/filaments, off ground
RED - power supply B+
ORA - screen grids (and base 2 of transistors)
YEL - cathodes (and transistor emitters)
GRN - control grids, diode plates (and base 1 of transistors)
BLU - plates (and transistor collectors)
VIO - power supply, minus leads
GRA - AC power line leads
WHI - bias supply, B or C minus, AGC
Is there a standard scheme for power transformer wire colors?
From Orr's Radio Handbook:
Primary leads -------------- black
(if tapped)
Common ----------------- black
Tap -------------------- black/yellow
End -------------------- black/red
High voltage secondary ----- red
Center tap ------------- red/yellow
Rectifier filament winding - yellow
Center tap ------------- yellow/blue
Filament winding No. 1 ----- green
Center tap ------------- green/yellow
Filament winding No. 2 ----- brown
Center tap ------------- brown/yellow
Filament winding No. 3 ----- slate
Center tap ------------- slate/yellow
I have seen primaries with other color schemes; if it includes black it should be a primary lead of some sort. I've seen transformers with only one filament winding that was brown. I've seen high voltage secondaries with red/white centers. And on old transformers, the colors may have faded to the point brown looks black or green looks black or brown, and so forth. I'm not aware of any standard for filament winding numbering, so if there is more than one, verify the voltages. The rectifier winding will normally be 5 volts, but again, verify it. If you have an old tranny with odd or indistinguishable colors on the leads, verify them. In fact, it's a good idea to verify any PT before using, just to be safe. Miswirings are, AFAIK, rare, but do occur, as do shorts.
Is there a standard scheme for output transformer wire colors?
Derived from the ARRL Radio Amateur's Handbook:
Single-ended transformers:
Plate lead (pri.) -------------- blue (or brown)
B+ (power supply) lead --------- red
speaker (typ. +) (sec.) -------- green (or yellow)
speaker return (sec.) ---------- black
Push-pull transformers:
Plate lead (pri.) -------------- blue (start)
B+ (power supply) lead --------- red (center tap)
Plate lead (pri.) -------------- brown (finish)
speaker (typ. +) (sec.) -------- green (or yellow)
speaker return (sec.) ---------- black
Ordinarily the black side should also be grounded, if the speaker is grounded. Replacement transformers are not always identical, so if you get squeals or other odd sounds when hooking up a new output transformer, try reversing the output leads. "Start" and "finish" are arbitrary terms with respect to this configuration.
Is there a standard scheme for interstage coupling (such as phase inverter) transformer wire colors?
From the ARRL Radio Amateur's Handbook:
Plate finish lead (pri.) ------- blue
B+ (power supply) lead --------- red (whether center tap or not)
Plate start lead (pri.) -------- brown
Grid finish (sec.) ------------- green
speaker return (sec.) ---------- black (whether center tap or not)
Grid start (sec.) -------------- yellow