Seeking diagram.

[Les. Hayward]

Would any kind souls happen to have a circuit diagram for a Motorola
variable PSU Mod. number S-1347D?

Les (MW0SEC).

[RustyHinge]

On 02/04/2023 12:25, Les. Hayward wrote:
> Would any kind souls happen to have a circuit diagram for a Motorola
> variable PSU Mod. number S-1347D?

http://motorola.justanswer.co.uk/ ?

--
Rusty Hinge
To err is human. To really foul things up requires a computer and the BOFH.

[Les. Hayward]

On 04/04/2023 09:51, RustyHinge wrote:
> On 02/04/2023 12:25, Les. Hayward wrote:
>> Would any kind souls happen to have a circuit diagram for a Motorola
>> variable PSU Mod. number S-1347D?
>
> http://motorola.justanswer.co.uk/ ?
>

Thanks. Paid a quid and tried it. Waste of a quid, but worth a shot.

[Paul]

The controller board:

https://i.redd.it/v3655qp6cy881.jpg

See if one of these is on the controller board.

https://datasheetspdf.com/pdf/791050/Motorola/MC1566L/1

"Datasheet Download MC1566L Datasheet"

The puzzle would be, why are there seven trimmers on the controller board ?

There could be two output windings on the transformer. One
winding is for the supervisor voltage (the DC to run the 1566).
Since the controller can series-pass much higher voltages,
a second winding provides the power source for the output.

In the diagram with the back to back diodes, those diodes protect
a back to back pair inside the chip. That's what some of the other
diodes do as well. My only concern with this, is whether any of the
diodes are being operated outside their current flow limits. Apparently
one diode on that controller board, likes to burn. All the diodes
are similar to 1N4007 series diodes, 1 ampere, and the characteristic
is similar to what is inside the chip. The fourth page of the PDF,
has all of the "theoretical" diodes shown (diodes for protection purposes,
diodes for stuff like capacitor discharge paths during a dead short).
In the same way a 7805 has a theoretical diode you can place outside
the device, which runs in parallel with a parasitic substrate diode.

Paul

[Les. Hayward]

Thanks. There is one of those controllers in there and I have studied
the application notes in the hope of seeing a correlation. The circuitry
in the PSU does not seem to follow the examples closely enough.
The item I am trying to repair does have the burnt diode as shown in
your piccie. What confuses me is that the item which looks like a large
yellow ?diode? at the bottom left of the pcb is also fried. It is black
in my example and about the size of a 1N5408 - but is it a big zener?
The owner confessed to me that he was trying to charge a car battery
with the PSU (with no limiting resistor) so anything could have happened...

There are two windings on the transformer as you suggest and I am trying
to trace the circuit out, but it is quite a job to do so! My biggest
problem is trying to establish the value and purpose of that big diode.

Les.

[Paul]

Check and see if the TO-220 style device that burned, was
a transistor with three legs. I have some surplus parts,
that somehow I identified or made a tentative identification.
Things like 2N6109, TIP35, and 2N5296. What is interesting
about them, is the novel mechanical features. On one of them,
the tab (and probably the central pin) seem to be made of
ordinary tin plate metal. The others look more like proper
transistor packages and not quite as cheesy.

[Picture]

https://i.postimg.cc/ZqywxcFP/tabbed-transistors.jpg

Paul

[Les. Hayward]

On 07/04/2023 10:59, Paul wrote:

>
> Check and see if the TO-220 style device that burned, was
> a transistor with three legs. I have some surplus parts,
> that somehow I identified or made a tentative identification.
> Things like 2N6109, TIP35, and 2N5296. What is interesting
> about them, is the novel mechanical features. On one of them,
> the tab (and probably the central pin) seem to be made of
> ordinary tin plate metal. The others look more like proper
> transistor packages and not quite as cheesy.
>
>    [Picture]
>
>    https://i.postimg.cc/ZqywxcFP/tabbed-transistors.jpg
>
>   Paul

No, all of the transistors are fine. What I really need is the spec. for
the diode at the bottom left of your earlier picture. I suspect that as
one of the diodes across part of the IC is knackered, that a replacement
IC will also be required.

[Paul]

I agree, without a Bill Of Materials, this problem is not
going to be easy to solve. This happens every time components
burn on a design.

This means you're going to have to trace the circuit, and
see exactly which diode that happens to be, and what potential
role it has. While it could be a series diode on the high side
of the power transistor (on the heat sink), it would make more
sense for a diode like that, to be bolted to the heatsink. That
diode is only supposed to be used for 200V bench supplies or the like.

I can't tell from here, where that diode sits in the design,
and potentially, what pins on the IC it is across.

A lot of the tiny SMT stuff on designs now, even if the
component is not burned, you can't identify it. I was at
the factory at work, I pointed at some resistor and it
had some bogus "35" or "79" printed on it, so I asked
the tech "how do you know what that is?". And he picks
up a sheet of paper from the bench, and says, "see, I have
this table with them all listed". Of course this did not
answer the question, of the thousands of sheets of paper out
there, how do you know this sheet is the correct one ? With the
BOM for the design, and a schematic, I'm better able to work
out what such a thing is.

Paul

[Les. Hayward]

Having just seen my credit card statement, I note that these pirates
have deducted an unauthorised £35.00 in addition to the £1 for the enquiry.

I strongly advise AGAINST anyone using this "service"!

Les.

[mm0fmf]

Looks like you have paid for one month's worth of Technician answers.
You'd better cancel or you'll get charged £35/month from now on.

"JustAnswer is a monthly membership-based service. Single-question
customers must cancel during their trial period to avoid incurring
monthly membership charges. Membership will continue until cancellation."

[Jeff]

On 15/04/2023 21:36, Les. Hayward wrote:

Beware; looking at their website they will charge you a monthly fee
unless you cancel.

Jeff

[Les. Hayward]

Silly me - replied to sender instead of follow -up. Try again:

You are right - the sneaky thing being that the £35 was charged around
the day after - so you don't get much time to do it. Very sharp
practice. Have informed card company to block any further payments...

[Julian Macassey]

On Sun, 16 Apr 2023 09:28:47 +0100, Jeff <je...@ukra.com> wrote:
> On 15/04/2023 21:36, Les. Hayward wrote:
>> On 05/04/2023 10:02, Les. Hayward wrote:
>>> On 04/04/2023 09:51, RustyHinge wrote:
>>>> On 02/04/2023 12:25, Les. Hayward wrote:
>>>>> Would any kind souls happen to have a circuit diagram for a Motorola
>>>>> variable PSU Mod. number S-1347D?
>>>>
>>>> http://motorola.justanswer.co.uk/ ?
>>>>
>>> Thanks. Paid a quid and tried it. Waste of a quid, but worth a shot.
>>
>>
>> Having just seen my credit card statement, I note that these pirates
>> have deducted an unauthorised £35.00 in addition to the £1 for the enquiry.
>>
>> I strongly advise AGAINST anyone using this "service"!
>

> Beware; looking at their website they will charge you a monthly fee
> unless you cancel.

A sophisticated fraud, but a fraud nonetheless. So why
aren't these people in prison?

It seems that these days fraud isn't a crime but just
another business strategy.

--
The £1.37 billion that the Gates Foundation distributes every
year is a measly 2.5 percent of Gates’s fortune and provides him
with hefty tax deductions. - Susan Rosenthal May 2015

[mm0fmf]

On 16/04/2023 12:48, Les. Hayward wrote:
> Have informed card company to block any further payments...

You should also cancel with the people who you now have a subscription with.

For reference:

https://www.citizensadvice.org.uk/debt-and-money/banking/stopping-a-future-payment-on-your-debit-or-credit-card/

[David Woolley]

On 16/04/2023 10:20, Julian Macassey wrote:
>> Beware; looking at their website they will charge you a monthly fee
>> unless you cancel.
> A sophisticated fraud, but a fraud nonetheless. So why
> aren't these people in prison?

Doesn't seem to be different in principle from the way that you get
tricked into subscribing to Amazon Prime. I've got caught at least
twice, although have always cancelled.

[Roger Hayter]

Yes, the credit card companies don't do the same guarantee to allow you to
cancel as the banks do with direct debit. They argue, with some logic, that it
is not their job to help you break a contract. So if the people charging you
act illegally your only remedy is to either go to court or raise a formal
dispute with the credit card company and present evidence to them. They make
too much money out of people inertia selling subscriptions to make it too easy
to get out of it.

--
Roger Hayter

[jim.gm4dhj]

looked perfectly leglit to me....fully spelt out

[Roger Hayter]

On 19 Apr 2023 at 16:21:27 BST, ""jim.gm4dhj"" <kinvig...@ntlworld.com>
wrote:

Note I carefully didn't give an opinion on that - I just said *if* he thinks
he has been unfairly treated, and the web site won't give him his money back
then he needs to prove his point, unlike the DD system where you can cancel it
no questions asked. Though you still can't get money you've already paid back.
I think it's different in America, which confuses people who've read American
sites.


--
Roger Hayter

[Les. Hayward]

I have no problem with credit cards - they tend to be as helpful as
possible. As to the vendors, I have no doubt that their actions are
legal (just). What I object to is the very sharp practice of withdrawing
the full amount almost immediately the "trial" period starts.

[mm0fmf]

On 20/04/2023 09:25, Les. Hayward wrote:
> What I object to is the very sharp practice of withdrawing the full
> amount almost immediately the "trial" period starts.

My bank used to offer single-use credit cards. i.e. you got a credit
card number and CVV2 and a short expiry date through your online account
page. You could use the card for a single purchase and was ideal for
online use. After it had been used once, no more transactions would be
paid. Sadly they stopped doing them some time back.

[M C]

On 20/04/2023 12:55, mm0fmf wrote:
> My bank used to offer single-use credit cards. i.e. you got a credit
> card number and CVV2 and a short expiry date through your online account
> page.  You could use the card for a single purchase and was ideal for
> online use. After it had been used once, no more transactions would be
> paid. Sadly they stopped doing them some time back.

top up cards even better, you keep the balance at zero most of the time
and top up just the right amount before the purchase.. no surprises
afterwards