1965 Park 45 Transformer identification

[zen.state]

Here are some pics of my Park 45, which I believe to be a 1965.....

where better to try and identify the transformer types....I believe the PT is Radio Spares....

1/. I am trying to identify the output transformer...the colour codes are now visible in the pics...primary = red, black, brown; secondary = yellow, green, blue, white. Is the weird frame a red herring?

also,

2/. is it unusual for the RS mains transformer to NOT have a shroud?



























many thanks

Roy

[zen.state]

The frames on the Mains transformer and Power transformer look very very similar to me....

[Brian Wallace]

Zen,

I'm still thinking it's a late, November, 65 Park with a 103 that has a strange mounting bracket on it for some reason.

Anyone else have any ideas?

[adrian]

Zen,

I'd say probably both non original trannies, but it's hard to tell without seeing the wiring and mounting under the chasis and the selectors.

Adrian

[RS DeLuxe]

Is it me, or does it seem like the PT frame is mounted upside down; that is
it's on top of the tranny rather than underneath?

[Brian Wallace]

Well Zen,

We need shots of the wiring for the PT and OT.

[zen.state]

Thanks People, I will try and get some more shots...

I've had the OT out a few times anyway and the mains and standby switches were changed by Marshall, they added an earth connection, to the chassis, I think...I can't remember how much wiring they altered at that time, back in 95 or so, I will have to look.....

the pilot light was changed by me to one of similar period because the amp had a seventies ( I think) type pilot light in it.....



I'm going back in...see what I can see...

I have some busy days ahead, so it may take a few days....

[zen.state]

I moved the pics so the links do not work so here they are re-upped:






















I think that the wiring around the PT has been messed with as well, certainly the mains and standby switch were replaced, and the pilot light is a replacement I wired in....

the OT has shortened leads as well...which is suspicious....

maybe both transformers are replacements done back in the late 60's and that's probably the case but it's my amateur guess and by no means an expert opinion....

[zen.state]

Some new pics to help identify this weird OT -

Grateful for all help

[zen.state]

AHA....the original lugs on the covers have been CUT OFF











this must help us......

[Brian Wallace]

Looks like a legless 103 to me. Get some DCR reading from the primary and secondary and we'll see what it comes up with.

[zen.state]

Thanks Brian

I had the transformer out yesterday and measured it unconnected...dc resistance

I had:

Primaries,
Bn Bk = 99.2 ohm
Bn Rd = 121.5 ohm

Secondaries,
Wh Y = 16.7 ohm
Wh Gn = 16.3 ohm
Wh Bl = 16.1 ohm




Oh dear, I think I disturbed something on taking out and putting back together and I have a fault now...

I've also extended the leads of the transformer with some old mains lead stripped out, and wired it back into the impedance selector, I had to disconnect a few wires to pull the board up to get underneath, ie the choke wire to the board, a yellow to the PI, and the wire resistor to the el34 etc

without el34s but with the rectifier in I have about 495 volts on the pos of the first smoothing cap both before and after standby is switched on.

with el34s and rectifier in, the pos on the smoothing cap is at about 495 volts on standby but as soon as standby is switched on the volts drop to 460 momentarily, then go back up to 495 and slowly crawl down to 440 volts - takes about ten seconds or so to drop.

with a different pair of output valves same thing happens but it only drops to about 465 volts

Any thoughts on what to check please?



Thanks again

Roy

[Brian Wallace]

Can you measure the secondary taps again using Yellow as the common? Yellow to Green, Yellow to Blue and Yellow to White.

[zen.state]

ahhh, this looks like an odd set of readings...

y - gn = 0.6
y - bl = 0.4
y - wh = 16.9

[Brian Wallace]

The readings from the 103 in my 66 is as follows,

PRIMARY: (Red = Center Tap)
Black to Red = 224.7 ohms
Black to Brown = 100.4 ohms
Red to Brown = 124.2 ohms

SECONDARY:
Yellow = Common = 0 ohms
Green = 8 ohms = .6 ohms
Blue = 16 ohms = .9 ohms
White = 100V = 17.3 ohms