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Hi all,
I'm underway with my plexi build and about to wire in the AC power and PT primaries.
Looking to confirm the right config before I start snipping and soldering. The AU/NZ standard is 230VAC and I'm getting 233-235 out of the wall.

Firstly, the 240V wiring diagram on page 43 of the builder’s guide doesn’t seem to exactly match the schematic.
I’ve marked up a snip of the diagram with some scribblings of what I think should be correct. Appreciate confirmation or have I just misinterpreted the drawing.


Secondly, for the 230V config on the PT, wanting to double check my understanding of the diagram in the appendix (page 100)


Wiring plan:

1. IEC Active to power switch lug 1
2. Power switch lug 2 to Black/Red (120V) PT wire
3. Power switch lug 2 to 120V neon lamp lug 1
4. 120V neon lamp lug 2 to free terminal strip lug (let's call it lug 1)
5. Terminal strip lug 1 to joined Black (0V) and White/Red (120V) PT wires
6. IEC Neutral to free terminal strip lug (lug 2)
7. Terminal strip lug 2 to White/Black (110V) PT wire
8. The White (0V) Black/White (110V) PT wires are unused and insulated/bundled

When I first looked at the PT taps, I had it in my mind that for step 5 above, I should connect the Black (0V) and Black/White (110V) wires together, and that the White (0V) wire should connect to IEC neutral. Would that be electrically identical to the above, or are the gaps in my knowledge of transformers showing?

Thanks in advance,
Dougal

The layout is misleading. There are extra wires shown that should not be there. Your plan is good.
Suggest you carefully test your wiring in advance.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Wired up as above, 1A fuse installed, and tested.
Lamp comes on, a noticeable hum for about 2 seconds, then the fuse blows.

For the second attempt, I used a Variac starting at 120VAC.
At 120 the lamp is lit and getting some expected voltage readings:

• ~490VAC between each leg of the HT tap and chassis ground
• ~3VAC between each leg of the green filament tap to chassis ground
• ~6VAC across the rectifier filament tap
• ~118VAC across the two terminals of the neon lamp

Turning slowly up to 230VAC, the humming starts somewhere close to 200VAC and the fuse blows again.

Here are pictures of my power hookup according to the plan in my original post:

1. IEC Active to power switch lug 1
2. Power switch lug 2 to Black/Red (120V) PT wire
3. Power switch lug 2 to 120V neon lamp lug 1
4. 120V neon lamp lug 2 to free terminal strip lug (let's call it lug 1)
5. Terminal strip lug 1 to joined Black (0V) and White/Red (120V) PT wires
6. IEC Neutral to free terminal strip lug (lug 2)
7. Terminal strip lug 2 to White/Black (110V) PT wire
8. The White (0V) Black/White (110V) PT wires are unused and insulated/bundled

Wires will be trimmed to length when it all works




Help is welcomed!

Thanks

Sounds like you have wired it for 120 volts.


1. IEC Active to power switch lug 1
OK

2. Power switch lug 2 to Black/Red (120V) PT wire
OK

3. Power switch lug 2 to 120V neon lamp lug 1
OK

4. 120V neon lamp lug 2 to free terminal strip lug (let's call it lug 1)
OK

5. Terminal strip lug 1 to joined Black (0V) and White/Red (120V) PT wires
OK

6. IEC Neutral to free terminal strip lug (lug 2)
OK

7. Terminal strip lug 2 to White/Black (110V) PT wire
No. Do not connect White/Black to anything. With it connected to neutral, that's why it's wired for about 130 volts.

8. The White (0V) Black/White (110V) PT wires are unused and insulated/bundled
No. You can insulate Black/White and White/Black but you need the White wire going to neutral on lug 2 of your terminal strip.

Thank you - my original inclination was to connect the white 0V to IEC neutral but the diagrams in the appendix of the build guide show something different.

I think for 230V wiring, in step 5 above, I should have the black 0V connected to the black/white 110V tap, so we have in series - 120-0-110-0 for 230V across the primary side. Sound about right?

Maybe. Connect black to white/red for now. Then after you get all your tubes in, check the heater voltage. If it's higher than 6.3 vac, connect black to white/black and see if that gets you closer. Pick whatever configuration gets the heater voltage closest to 6.3. The B+ voltage isn't overly critical. Your tubes will last longer if the heater voltage is 6.3 or a bit lower.

Also keep in mind that the line voltage coming in from the wall might vary depending on the time of day. This will affect the transformer's secondary voltages, so check the line voltage to see if it's a good average value.

Thanks Mitch, all working now with the 240V config. Will adjust down if necessary once I get to testing with valves in.

Just finished normally working 230V wiring. Here's my version of routing.

Finish "Wire the Power Supply" section of Builder's Guide Version 3.1. You will have pair of Black and White twisted cables running from Fuse SIDE terminal to Power switch Lug1 (Black) and IEC Connector Neutral 'N' Lug to PT 5 lug terminal strip (White).

230V MAINS WIRING

Follow instructions below and connection diagram (see attachment):

1. Braid White, Black and White/Red PT cables together and run them to PT Terminal strip. This is BRAID1.

2. Braid Black/White, Black/Red and White/Black PT cables together. This is BRAID2, you will use it later.

3. Connect the White PT lead from BRAID1 to No2 terminal strip (strips are counted from Plexi faceplate). This will be the Common or Neutral 'N' tag.

4. Connect the IEC terminal Neutral 'N' to No2 terminal strip.

5. Connect Black and White/Red from BRAID1 to No1 terminal strip.

6. Route BRAID2 to twisted Black and White cables (from Fuse Side and IEC 'N' lugs), unbraid Black/White lead from BRAID2 at place where IEC terminal Neutral 'N' comes of twisted Black and White cables. Twist FUSE SIDE Black cable and Black/White PT lead together and connect them to different lugs of Power Switch (see attached photos).

7. Isolate BRAID2 unused Black/Red and White/Black cables, twist them together and hide inside chassis.

8. Twist any two cables (this can be cut-offs from PT secondaries) and connect each lead to Indicator lamp lugs. Connect these cables to No1 and No2 lugs of PT Terminal Strip.

Finish wiring PT secondaries according to Builder's guide and test the power supply.