On 01/21/2017 12:43 PM, Adrian Graham wrote:
> Hi folks,
>
> Does anyone know what this is? It's obviously a transformer coil(s)
> but image search and googling those markings produces nothing:
>
> http://www.binarydinosaurs.co.uk/la4543.jpg
>
> It's taking and giving +5V but I'm sure it should
On 01/21/2017 02:43 PM, Adrian Graham wrote:
Hi folks,
Does anyone know what this is? It's obviously a transformer coil(s) but
image search and googling those markings produces nothing:
http://www.binarydinosaurs.co.uk/la4543.jpg
It's taking and giving +5V but I'm sure it should also be produc
On 21/01/2017 21:08, "Chuck Guzis" wrote:
> On 01/21/2017 12:43 PM, Adrian Graham wrote:
>> Hi folks,
>>
>> Does anyone know what this is? It's obviously a transformer coil(s)
>> but image search and googling those markings produces nothing:
>>
>> http://www.binarydinosaurs.co.uk/la4543.jpg
>>
On Sat, Jan 21, 2017 at 8:43 PM, Adrian Graham
wrote:
> Hi folks,
>
> Does anyone know what this is? It's obviously a transformer coil(s) but
> image search and googling those markings produces nothing:
>
> http://www.binarydinosaurs.co.uk/la4543.jpg
I think the LA number is the number for the fe
On 21/01/2017 21:59, "Tony Duell" wrote:
> On Sat, Jan 21, 2017 at 8:43 PM, Adrian Graham
> wrote:
>> Hi folks,
>>
>> Does anyone know what this is? It's obviously a transformer coil(s) but
>> image search and googling those markings produces nothing:
>>
>> http://www.binarydinosaurs.co.uk/la4
On Sat, Jan 21, 2017 at 11:33 PM, Adrian Graham
wrote:
> On 21/01/2017 21:59, "Tony Duell" wrote:
>
>> On Sat, Jan 21, 2017 at 8:43 PM, Adrian Graham
>> wrote:
>>> Hi folks,
>>>
>>> Does anyone know what this is? It's obviously a transformer coil(s) but
>>> image search and googling those markin
On 22/01/2017 07:31, "Tony Duell" wrote:
>>> It looks to be part of a switching regulator circuit. Possibly to generate
>>> other voltages from the 5V line. Can you post a picture of more of the PCB
>>> around it.
>>
>> Its second output goes via an IN4148 to the -24V regulator:
>
> What do you
On 22/01/2017 07:31, "Tony Duell" wrote:
>> The -24V regulator can be seen just above the 4 blue caps, The regulator
>> that can be seen under the black wire is a 7812. The LF351N has -12V present
>> at its bias outputs, the opamp to its right has no markings helpfully.
>
> What about that IRF52
> Result! Whilst photographing the board to trace out that circuit (it's
> quicker for me than drawing it) I removed all the big capacitors. While they
> were out of circuit I tested them and discovered that not only was one dead
> in the -12V rail but also the through hole plating for another on t
On 1/21/2017 2:46 PM, Adrian Graham wrote:
On 21/01/2017 21:08, "Chuck Guzis" wrote:
On 01/21/2017 12:43 PM, Adrian Graham wrote:
Hi folks,
Does anyone know what this is? It's obviously a transformer coil(s)
but image search and googling those markings produces nothing:
http://www.binarydin
On 22/01/2017 20:10, "Tony Duell" wrote:
>> That looks like an opamp to me, with bias pins connected to GND?
>
> Does it? It looks like a 555 timer to me at first glance. I would have
> expected another
> capacitor from pins 2/6 to ground though.
>
> 1 Ground
> 2 Trigger (linked to threshold, a
On Mon, Jan 23, 2017 at 6:48 PM, Adrian Graham
wrote:
> On 22/01/2017 20:10, "Tony Duell" wrote:
>
>>> That looks like an opamp to me, with bias pins connected to GND?
>>
>> Does it? It looks like a 555 timer to me at first glance. I would have
>> expected another
>> capacitor from pins 2/6 to gr
On 23/01/2017 19:07, "Tony Duell" wrote:
>> I didn't think of a 555 in that scenario but that makes sense. I've marked
>> it as such for now, cheers!
>
> Is there another capacitor from the 2/6 junction to chassis? Any other
> components
> around? It might be one of the special SMPSU ICs, but it
On Mon, Jan 23, 2017 at 9:23 PM, Adrian Graham
wrote:
> On 23/01/2017 19:07, "Tony Duell" wrote:
>
>>> I didn't think of a 555 in that scenario but that makes sense. I've marked
>>> it as such for now, cheers!
>>
>> Is there another capacitor from the 2/6 junction to chassis? Any other
>> compone
On 23/01/2017 21:38, "Tony Duell" wrote:
> I normally trace connections using my DMM, but of course you have to know
> what will fool it (i.e. low resistance components). I find I have to desolder
> relays, switches, inductors, transformers, low value resistors, etc before
> starting to trace the
On Mon, Jan 23, 2017 at 11:38 PM, Adrian Graham
wrote:
> On 23/01/2017 21:38, "Tony Duell" wrote:
>> Oh... The trace isn't open-circuit, is it? Check it with the
>> multimeter. Given the
>> corrosion damage to the tape drive I could well believe PCB problems of a
>> similar nature.
>
> I've meas
On 24/01/2017 06:06, "Tony Duell" wrote:
>>
>> and it's 0.6ohm max.
>
> Are you telling me that if you put 2 logic analyser inputs on 2 points on the
> same trace (which tests as continuous with an ohmmeter) that said 2 LA
> channels don't show the same thing? If so, the LA needs repairing!
..
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