The Sinclair QL Forum

And now my hands are sticky. Oh, I see. This is the "back-up" SGC, and it looks like it was previously owned by a heavy smoker.

Well, into the acetone bath for you then!

Dave wrote:
Well, into the acetone bath for you then!

Dave last seen floating past the moon

Nope. That was the time the missus didn't spot a pen in the laundry and tumble dried it. Ruined a load of clothes, and the dryer - OR SO SHE THOUGHT! I figured, "oh, this acetone will get that right off!"

There are two parts to this tragedy:

The acetone fumes. Obvious result when I had my head in the tumble dryer.

The dryer was a gas dryer. It had just stopped. The pilot light was still lit.

The fumes didn't stand a chance, and I was apparently not too bothered about the burns I got.

Dave,

Naming the three pins from left to right, as shown in your photo, A, B and C

Results -
Resistance (Ohms)
+ve to -ve
A to B 35M
B to C 1.3K
A to C 34M

-ve to +ve
A to B 243K
B to C 3.2K
A to C 252K

Diode test (Volts)
+ve to -ve
A to B 0.0
B to C 0.23
A to C 0.0

-ve to +ve
A to B 0.56
B to C 0.62
A to C 0.59

Readings taken from a new 7805 (acknowledging that the PCB has other components that will affect the previous readings)
Resistance (Ohms)
+ve to -ve
A to B 4.6K
B to C 1.2M
A to C 9.3M

-ve to +ve
A to B 4.6K
B to C Open
A to C Open

Diode test (Volts)
+ve to -ve
A to B 1.2
B to C 0.54
A to C 0.56

-ve to +ve
A to B 0.6
B to C 0.0
A to C 0.0


Whopper.

Dave wrote:If there is a wire link, even with an external 5V supply, it still could be shorting 9V QL power to the 5V line.

can you check across the outside two pins

Opps. Didn't see this until I'd done the previous table

Well, you've ruled out the most disastrous scenario, so that's something

When you say it doesn't work - in what way does this exhibit itself.

THe SGC is fairly reliable - in order what I would check:

a) Has the 5V regulator been bypassed (or removed) ?
b) Are any of hte pins bent inside your QL expansion connector ? That is frequently the problem when an interface does not work
c) Remove the memory chips on the SGC and put them back - I had one where I removed the memory chips and was struggling to put them back in - only then did I realise the problem all along - one of the legs from the RAM chips was still in the hole !!
d) It could be a blown INGOT chip, in which case you are in trouble.... Just in case send it to someone else with a QL to try...

Also watch out if you use surge protected sockets, my SGC card would need a reset on the QL to work.

vanpeebles wrote:Also watch out if you use surge protected sockets, my SGC card would need a reset on the QL to work.

Mains sockets?
Expansion sockets?
IC sockets?
Glove box puppets?

Mark

4 way mains sockets