Afternoon all,

I have here an old and heavy PSU unit, apparently made by ITT and is
model MP10B V

It seems to be a standard 723 design - well almost, however before I
wreck my brain & eyes on tracing the pcb out. does any one have any info
on it?

I've spent several hours google-ing for details but none to be found
(either as text or images).

I've put photos of the unit he

http://www.dctower.co.uk/images/MP10B/IMG_4329.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4329.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4329.JPG

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On Mon, 04 Jul 2016 14:20:15 +0000, The Nomad wrote:

Afternoon all,

I have here an old and heavy PSU unit, apparently made by ITT and is
model MP10B V

It seems to be a standard 723 design - well almost, however before I
wreck my brain & eyes on tracing the pcb out. does any one have any info
on it?

I've spent several hours google-ing for details but none to be found
(either as text or images).

I've put photos of the unit he

http://www.dctower.co.uk/images/MP10B/IMG_4329.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4329.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4329.JPG

AGGGH

It was not supposed to post that - Let's try again

http://www.dctower.co.uk/images/MP10B/IMG_4329.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4330.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4331.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4332.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4333.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4334.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4335.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4337.JPG

Many thanks in advance

Regards

Avpx




--
The Auditors avoided death by never going so far as to get a life
(The
Thief of Time)
15:20:01 up 1 day, 17:03, 6 users, load average: 1.03, 1.07, 0.74

On Monday, 4 July 2016 15:22:31 UTC+1, The Nomad wrote:
On Mon, 04 Jul 2016 14:20:15 +0000, The Nomad wrote:

Afternoon all,

I have here an old and heavy PSU unit, apparently made by ITT and is
model MP10B V

It seems to be a standard 723 design - well almost, however before I
wreck my brain & eyes on tracing the pcb out. does any one have any info
on it?

I've spent several hours google-ing for details but none to be found
(either as text or images).

I've put photos of the unit he

http://www.dctower.co.uk/images/MP10B/IMG_4329.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4329.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4329.JPG

AGGGH

It was not supposed to post that - Let's try again

http://www.dctower.co.uk/images/MP10B/IMG_4329.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4330.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4331.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4332.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4333.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4334.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4335.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4337.JPG

Many thanks in advance

Regards

Avpx


I assume it's not working. So you could start replacing the parts, I'd remove the 723 and put a socket in to start with.

The Nomad wrote:
On Mon, 04 Jul 2016 14:20:15 +0000, The Nomad wrote:


Afternoon all,

I have here an old and heavy PSU unit, apparently made by ITT and is
model MP10B V

It seems to be a standard 723 design - well almost, however before I
wreck my brain& eyes on tracing the pcb out. does any one have any info
on it?

I've spent several hours google-ing for details but none to be found
(either as text or images).

I've put photos of the unit he

http://www.dctower.co.uk/images/MP10B/IMG_4329.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4329.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4329.JPG

AGGGH

It was not supposed to post that - Let's try again

http://www.dctower.co.uk/images/MP10B/IMG_4329.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4330.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4331.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4332.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4333.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4334.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4335.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4337.JPG

Many thanks in advance

Regards

Avpx





These units IIRC were made by ITT/STC Harlow around 1966. They have
essentially the same linear analogue circuitry as the Advance PSUs of
the same period. From memory( a bit shaky these days) , the regulators
were 3055? transistors. The circuit was a transformer, bridge rectifier,
large reservoir capacitor, Zener reference diode, buffer amplifier and
series regulator. With load and over current sensing. Can't remember any
more details, but the circuitry was common to a number of manufacturers.

On Mon, 04 Jul 2016 15:55:31 +0100, Capitol wrote:

The Nomad wrote:
On Mon, 04 Jul 2016 14:20:15 +0000, The Nomad wrote:

It was not supposed to post that - Let's try again

http://www.dctower.co.uk/images/MP10B/IMG_4329.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4330.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4331.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4332.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4333.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4334.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4335.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4337.JPG

Many thanks in advance

Regards

Avpx





These units IIRC were made by ITT/STC Harlow around 1966. They have
essentially the same linear analogue circuitry as the Advance PSUs of
the same period. From memory( a bit shaky these days) , the regulators
were 3055? transistors. The circuit was a transformer, bridge rectifier,
large reservoir capacitor, Zener reference diode, buffer amplifier and
series regulator. With load and over current sensing. Can't remember any
more details, but the circuitry was common to a number of manufacturers.

Oh ta! This one has a 723 and associated circuit - so a bit posher than
just a zener :-) (and it's been hacked by someone)

It has given me a few more search terms to try out ...

I may be some time

Avpx



--
'Luck is my middle name,' said Rincewind, indistinctly. 'Mind you,
my first name is Bad.'
(Interesting Times)
16:15:02 up 1 day, 17:58, 6 users, load average: 0.91, 0.61, 0.49

The Nomad wrote:
On Mon, 04 Jul 2016 15:55:31 +0100, Capitol wrote:

The Nomad wrote:
On Mon, 04 Jul 2016 14:20:15 +0000, The Nomad wrote:

It was not supposed to post that - Let's try again

http://www.dctower.co.uk/images/MP10B/IMG_4329.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4330.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4331.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4332.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4333.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4334.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4335.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4337.JPG

Many thanks in advance

Regards

Avpx





These units IIRC were made by ITT/STC Harlow around 1966. They have
essentially the same linear analogue circuitry as the Advance PSUs of
the same period. From memory( a bit shaky these days) , the regulators
were 3055? transistors. The circuit was a transformer, bridge rectifier,
large reservoir capacitor, Zener reference diode, buffer amplifier and
series regulator. With load and over current sensing. Can't remember any
more details, but the circuitry was common to a number of manufacturers.

Oh ta! This one has a 723 and associated circuit - so a bit posher than
just a zener :-) (and it's been hacked by someone)

It has given me a few more search terms to try out ...

I may be some time

Avpx



I would split the problem into two parts.
Firstly all the power transistor effectively forming one dirty great
emitter follower. So put a modest load on the output - a filament light
bulb say and drive the base of the mega emitter follower with a pot
connected to the input DC supply. you should be able to vary the output
voltage with the pot. If any of the pass transistors are short circuit
the lamp will be at max output all the time.
Assuming voltage out changes then somewhere each transistor should have
a small emitter resistor to facilitate current sharing.
Measure the voltages across all these and confirm they are around equal.
if some are different then the relevant transistors are not sharing and
maybe open circuit say.

Part 2, With a current limited bench supply, you should be able to fire
up the control board with reference to a 723 data sheet and close the
loop around that in isolation and prove that will regulate small loads
just using its diver transistors. Obviously you will have to re-do the
solder joints on those pins to get any sense out of it.
Take a logical approach, keep notes on what you are doing and you should
have a good chance of sorting it out. 723 regulators are not rocket
science but there are lots of opportunities to prang it especially with
lots of charged up uFds if you are not careful.

I'm sure there are lots of 723 datasheets/application notes online but
if you are really stuck I could scan one for you.

Watch out if they implemented foldback current limiting. It can lead to
some strange effects ie errors lead to the regulator not starting up etc.

Have fun

On Mon, 04 Jul 2016 17:37:05 +0100, Bob Minchin wrote:

I would split the problem into two parts.
Firstly all the power transistor effectively forming one dirty great
emitter follower. So put a modest load on the output - a filament light
bulb say and drive the base of the mega emitter follower with a pot
connected to the input DC supply. you should be able to vary the output
voltage with the pot. If any of the pass transistors are short circuit
the lamp will be at max output all the time.
Assuming voltage out changes then somewhere each transistor should have
a small emitter resistor to facilitate current sharing.
Measure the voltages across all these and confirm they are around equal.
if some are different then the relevant transistors are not sharing and
maybe open circuit say.

Not trivial to take apart but I have the feeling it 'works'. Must find a
24V light bulb!(lux)

Part 2, With a current limited bench supply, you should be able to fire
up the control board with reference to a 723 data sheet and close the
loop around that in isolation and prove that will regulate small loads
just using its diver transistors. Obviously you will have to re-do the
solder joints on those pins to get any sense out of it.
Take a logical approach, keep notes on what you are doing and you should
have a good chance of sorting it out. 723 regulators are not rocket
science but there are lots of opportunities to prang it especially with
lots of charged up uFds if you are not careful.

As I say I get a nice stable 24V (variable from about 21V - 25V with the
pre-set I've V on the pcb)

I'm sure there are lots of 723 datasheets/application notes online but
if you are really stuck I could scan one for you.

Got one ta! and a couple of circuits as well.

Watch out if they implemented foldback current limiting. It can lead to
some strange effects ie errors lead to the regulator not starting up
etc.

I suspect that may be why it has been 'bodged'

Many thanks

Avpx


(lux) Yes I know 2x12V is series!
--
I WAS AT A PARTY, he added, a shade reproachfully.
- Death is summoned by the Wizards
(Terry Pratchett, The Light Fantastic)
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On Mon, 04 Jul 2016 14:20:15 +0000, The Nomad wrote:

Afternoon all,

I have here an old and heavy PSU unit, apparently made by ITT and is
model MP10B V

It seems to be a standard 723 design - well almost, however before I
wreck my brain & eyes on tracing the pcb out. does any one have any info
on it?

I've spent several hours google-ing for details but none to be found
(either as text or images).

I've put photos of the unit he

http://www.dctower.co.uk/images/MP10B/IMG_4329.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4329.JPG
http://www.dctower.co.uk/images/MP10B/IMG_4329.JPG

Meccano brackets??



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My posts are my copyright and if @diy_forums or Home Owners' Hub
wish to copy them they can pay me £1 a message.
Use the BIG mirror service in the UK: http://www.mirrorservice.org
*lightning surge protection* - a w_tom conductor

On Mon, 04 Jul 2016 18:46:59 +0000, Bob Eager wrote:

http://www.dctower.co.uk/images/MP10B/IMG_4329.JPG

Meccano brackets??

Now you mention it - yes I think you may be right, so ...

Not the original PCB?

or ...

?

Oh well onward

Many thanks

Avpx

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Thunder rolled. ... It rolled a six.
(Guards! Guards!)
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