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woodchips 7th Apr 2021 8:19 pm

Pye 8440 stabilised PSU
Does anyone have any info, circuits, on this Pye power supply please?

It is a monster, 500V at 500mA, was full of valves, now not.

What to do with the carcass? Nice transformer and choke, paper caps, lots of other things to make up its 30+kg weight, I can scarcely lift it now.

beamcurrent 7th Apr 2021 8:28 pm

Re: Pye 8440 stabilised PSU
I sort of half recognize the number, a picture would help


woodchips 8th Apr 2021 8:16 am

Re: Pye 8440 stabilised PSU
2 Attachment(s)

beamcurrent 8th Apr 2021 8:51 am

Re: Pye 8440 stabilised PSU
Alas I don't recognise the picture, it's not from the television side of Pye.

It looks to be VERY heavy but the paper smoothing caps are good. The missing valves are likely to be rectifiers and perhaps 6080s double triodes for the regulator pass valves.

GrimJosef 8th Apr 2021 9:05 am

Re: Pye 8440 stabilised PSU

Originally Posted by woodchips (Post 1361691)
... What to do with the carcass? Nice transformer and choke, paper caps, lots of other things to make up its 30+kg weight ...

I don't think it could be easily modified to do any other, more useful, job. So your options would seem to be

i) break it for parts (perhaps rather a lot of effort for not much reward)

ii) sell it 'as is' as a project for someone (easiest, and might get you a reasonable sum for little effort)

iii) get it working and either keep it or sell it (it would sell for more as a 'worker', but demand is relatively limited so the increased value might not repay your effort, in cash terms at least).

In any event, shipping might be expensive !



Cobaltblue 8th Apr 2021 9:09 am

Re: Pye 8440 stabilised PSU
It's a shame when equipment like this looses its original purpose.

But I guess you cant save everything ...... or can you :thumbsup:

I nicely built High voltage Power supply worth restoring IMHO


Mike T

factory 8th Apr 2021 7:44 pm

Re: Pye 8440 stabilised PSU
There is clearly some interest in high voltage PSU's like this, a similarly bulky twin 500V Solartron supply made over 700 in February, it was complete but not tested, the two supplies had switches for operation in series or parallel or separately. A single version with lower current capability made over 200.

I seem to remember a valveless HP 712B power supply got offered on here some years ago, I hope it got restored.

My Farnell E350 & HP 711A power supplies get used regularly for testing parts of other equipment I'm repairing.


woodchips 9th Apr 2021 11:35 am

Re: Pye 8440 stabilised PSU
Didn't see any mention on the Pye web site.

Was the Solartron PSU for 700 with its original valves? If sso then can see why it is worth that amount, this one used five EL34's as the series pass valves. I have a much smaller Solartron with two EL37's as the series pass valves.

They are so heavy, once in place they can't be moved, even to repair and turn over is a real struggle.

Freya 9th Apr 2021 6:55 pm

Re: Pye 8440 stabilised PSU
1 Attachment(s)
This is my APT 504, bought many years ago from Sean on this forum, also weights in at 37Kg. Only used few times a year, 250mA 500v output from four 807`s

Skywave 9th Apr 2021 10:45 pm

Re: Pye 8440 stabilised PSU
Woodchips: I would make the effort to restore it - although I appreciate that the (probably) extensive effort to do that must bear a sane relationship to the use you are then likely to give it.

By what you've said, it sounds like all it needs are replacement valves - and then - presumably - adjustment & calibration. The big Q. is what valves does it need? In the absence of appropriate technical literature for this PSU, it's time for some detective work. You need get stuck in to the wiring and try to trace out as much circuitry as possible: the object being to discover what valves you can fit in to make it work, even if they are not the original types. I don't know, but I suspect on account of the age of this item we are talking about International Octal based valves for rectifiers and pass valves.

Typical candidates, rectifiers.
5R4, 5U4, 5Z4, GZ32, 33, 34, 37. (All Octal based).
It'll be a question of measuring the H.V. output from the mains transformer: determining just how max. d.c. current the transformer will deliver.

Typical candidates: series pass valves.
12E14, 12E1, 6080, 6L6, KT88. (All Octal based).
Again, it will be a question of max. d.c. voltage input that a given valve can accept and max. d.c. current it can pass.

Typical candidates: stabilizer valves.
0D3, VR150/30 (Octal based),
5651 (English Electric Valve co.), B9A based,
85A2, B7G based.

It's almost certain that some degree of modification of the existing circuitry will be necessary with any on those choices, but if you can trace out a clear block diagram of how the major components inter-connect with each other and determine certain critical values of some components, voltages and currents, you should be in with a fighting chance - but this will certainly not be a 'five-minute job'!

And I wish you the very best of luck!
Al. / Apr. 9th.

trobbins 10th Apr 2021 12:40 am

Re: Pye 8440 stabilised PSU
I'd suggest that the restoration path could take quite some technical nous in order to determine what you have and the capabilities of parts, and then to sort through the options on how to reinstate functions and performance, and even extend some functions and performance using modern day knowhow. If you are technically minded and don't need to consider commercial recompense and have the incentive then any restoration project like this is a great journey to take. If you just want to flip it for a profit then I'd suggest flip it as is without testing or modification, as it may well go to a restorer.

woodchips 10th Apr 2021 9:21 am

Re: Pye 8440 stabilised PSU
The PSU came from Cranfield many years ago, along with two trailer loads of other items they were clearing out. From the look of it I doubt if it has had much use, no dust and grot inside.

Valve line up from a hand written list on the transformer is:

12AX7 x2
EL34 x5
EF91 x2

I have no use for it, other valve transformers I have tried to sell get no response, so not worth the effort of removing.

If anyone wants it then here for the taking, but is currently in the trailer waiting for a load to go to the scrappy, next week probably.

I will repeat that it is heavy, not a single person lift, possibly not a two person lift sideways into a car boot either.

factory 10th Apr 2021 11:24 am

Re: Pye 8440 stabilised PSU
You should really add a post in the offered section, hopefully someone will save it, too much of our vintage test gear is being lost to history.


turretslug 10th Apr 2021 1:18 pm

Re: Pye 8440 stabilised PSU
If this were, say, 350V and 250mA and half the size and weight, I and I daresay others might be interested but, as you rightly say, a bit of a monster. I might have thought that Andy (Diabolical Artificer) would be tempted for one of his fearsome amp projects.... ;D


GrimJosef 10th Apr 2021 5:13 pm

Re: Pye 8440 stabilised PSU
I would like it please, and the car needs a run ! I'll drop you a PM about collection.



woodchips 11th Apr 2021 8:55 am

Re: Pye 8440 stabilised PSU
Looks like GrimJosef had the short straw, so off to him.

GrimJosef 11th Apr 2021 9:48 am

Re: Pye 8440 stabilised PSU
Many thanks !

Now to find five EL34s, 2 EL81s and whatever a DSL16 is (a lamp, perhaps ?) :).



turretslug 11th Apr 2021 10:16 am

Re: Pye 8440 stabilised PSU
I have a hunch (only a hunch) that it could be some sort of thermal time delay device.

Mind your back....


GrimJosef 11th Apr 2021 10:23 am

Re: Pye 8440 stabilised PSU
Thanks Colin. That would make sense.

Fortunately I have an estate car, so there's no boot lip to get over and also plenty of headroom. I'm likely to be shifting one of these this week

(I don't own it, I hasten to add). The amp weighs 45kg. Plus packaging.



Cobaltblue 11th Apr 2021 10:26 am

Re: Pye 8440 stabilised PSU
If DSL is a typo and its DLS turretslug may have it.


Mike T

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