The guy who did the work on this seems to think i’ve blown the output transformer. Sounds expensive to me i suppose it can be replaced.
Not sure if it applies to your amp, it will depend on the design, but I was always told to never switch on a valve amp without speakers connected (or an equivalent load across the output).
Not doing so could potentially fry the output transformer.
1 Like
They can but I think the 1st audios used Hinchley transformers which were very good and you can’t get them anymore 
@murrayjohnson can probably recommend a good replacement.
I think that applies to any (non OTL) valve amp, never switch it on without a load connected.
The damage to mine was caused by a blown valve on 1st try, it was fully connected
1 Like
That would do it if the valve shorted.
Was it David Coe?
Actually I’ve got some Lundahl LL1663 transformers I bought a while ago to upgrade a cheap 2a3 amp I bought.
According to google AI they will fit in the chassis as they are smaller than the Hinchleys but would need new mounting holes drilling.
Looks like Majestic or Sowter can rewind them for you which seems to be the preferred approach according to searches
2 Likes
I’ve been in touch with David Coe and advised that I do still have one SP Wound Components transformer of the type that would’ve gone in an FAA, at least one made after about 1989.
2 Likes
Thanks.
If David does not want it let me know.
1 Like
Just e-mailed Majestic to see how much to rewind it.
Have taken out the dud out put transformer to look for a part number all i can find is a sticker on the bottom with M&G transformers a out of date phone number and written in pen 2.90 anyone know anything.
2/90 implies that the amp was likely assembled in Weymouth rather than Brighton. M&G was Geoff Budden’s company which did become SP Wound Components & was based in Christchurch, Dorset. Is it a 01202 number?
Yes it is. Have just heard back from Majestic seems they have no record of this and they are asking way to much to have a look and maybe strip it down and rewind it. Could buy a new pair for what they are asking, (if i knew what the spec was for them)
Do you know of any suitable replacement’s?
They need to be a PushPull transformer with a primary impedance of 5KOhm - 6.6KOhm and secondaries of 8 & 4 Ohms. That primary spec is fairly common as many amps using 300B, EL34, KT88, 2A3, could use them. Pentode amps often also need screen taps so the transformers you find may have those but you wouldn’t need them in a PushPull triode amp so you’d ísolate the ends of those & tie them out of the way.
With regard to suppliers, it depends on your budget. You might pay £500 for a pair of Hashimoto HW-40-5 or equivalent Tango.
I bet these would be nice but you’d need to make sure they’d actually fit and make a couple of raised platforms to mount them to.
https://www.ebay.co.uk/itm/358448233372
Hammond 1615 & 1620 ought to be ok & more affordable
Sowter UA21 and UO79. Get the tapped 4 & 8 Ohm secondary version.
Of course there are loads on Ali Express
Who knows how good any of those are?
6 Likes
Thanks for that, very helpful.