From post "Access Ext3/Ext2 file system" link
Sunday, July 15, 2012
SD card setup on Mac for RP
From xterm run
df -h
to get
/dev/disk1s1 3.8Gi 124Mi 3.7Gi 4% /Volumes/CASIO-DSC
Check where the img file is...
ls ~/Downloads/debian6-19-04-2012
debian6-19-04-2012/ debian6-19-04-2012.zip
Unmount the SD card
diskutil unmount /dev/disk1s1
use dd to copy image to SD card
sudo dd bs=1m if=~/Downloads/debian6-19-04-2012/debian6-19-04-2012.ig of=/dev/rdisk1
link to relevant eLinux.org post
df -h
to get
/dev/disk1s1 3.8Gi 124Mi 3.7Gi 4% /Volumes/CASIO-DSC
Check where the img file is...
ls ~/Downloads/debian6-19-04-2012
debian6-19-04-2012/ debian6-19-04-2012.zip
Unmount the SD card
diskutil unmount /dev/disk1s1
use dd to copy image to SD card
sudo dd bs=1m if=~/Downloads/debian6-19-04-2012/debian6-19-04-2012.ig of=/dev/rdisk1
link to relevant eLinux.org post
Thursday, December 29, 2011
Wednesday, July 27, 2011
Notes on troubleshooting Apple Macs
Eject disk in DVD drive: hold eject button on startup or restart
Force Quit [Option][Command][Escape]
Restart [Control][Command][Power]
Force Shut Down: press the power button for 10 seconds
PRAM reset [option][command][P][R]
Safe mode [shift] on startup
Safe mode with console [shift][command][V] on startup
SMC reset: shutdown, power cord out, hold power button for 5s, cord back in, restart]
The nuclear option [command][R] to initiate OS X Recovery...
AppleCare support in Dublin: Typetec, Unit G6, Calmount Business Park, Ballymount D12. ph: 5009000
Links to relevant stuff.
support.apple.com/kb/HT1149#trouble1 (basic information)
https://discussions.apple.com/docs/DOC-4571 (very informative if a bit old)
www.apple.com/support/mac101/help/ (for complete novices)
Force Quit [Option][Command][Escape]
Restart [Control][Command][Power]
Force Shut Down: press the power button for 10 seconds
PRAM reset [option][command][P][R]
Safe mode [shift] on startup
Safe mode with console [shift][command][V] on startup
SMC reset: shutdown, power cord out, hold power button for 5s, cord back in, restart]
The nuclear option [command][R] to initiate OS X Recovery...
AppleCare support in Dublin: Typetec, Unit G6, Calmount Business Park, Ballymount D12. ph: 5009000
Links to relevant stuff.
support.apple.com/kb/HT1149#trouble1 (basic information)
https://discussions.apple.com/docs/DOC-4571 (very informative if a bit old)
www.apple.com/support/mac101/help/ (for complete novices)
Tuesday, July 26, 2011
Monday, June 13, 2011
Sessionette 75 fuse burn out (part b)
Note, the following steps involve live 240v AC connected tests and are dangerous. Safety precautions essential, Live AC power can KILL. Be careful.
Continuing from STEP 3
Well, following up on earlier step 3 I de-soldered the transformer from the power amp board (safely isolated the secondary wiring because it could be LIVE)
... and guess what? The fuse still burns out.
What does that tell me? It tells me there is a short in transformer. There must be a short in either the primary or secondary coils.
The transformer is an ILP Type No 4UR36, batch no. 46240. ILP don't appear to stock it anymore, an Australian electronics distributor had some detail on the spec (link now apparently defunct) as follows...
Part No. 4UR36. 120 VA (Two Secondaries 60 VA per Secondary)
Secondary = dual winding
Output Volts for input of:
220V 230V 240V
34.43 36.00 37.57
RMS Current Per Winding: 1.67
Continuing from STEP 3
Well, following up on earlier step 3 I de-soldered the transformer from the power amp board (safely isolated the secondary wiring because it could be LIVE)
... and guess what? The fuse still burns out.
What does that tell me? It tells me there is a short in transformer. There must be a short in either the primary or secondary coils.
The transformer is an ILP Type No 4UR36, batch no. 46240. ILP don't appear to stock it anymore, an Australian electronics distributor had some detail on the spec (link now apparently defunct) as follows...
Part No. 4UR36. 120 VA (Two Secondaries 60 VA per Secondary)
Secondary = dual winding
Output Volts for input of:
220V 230V 240V
34.43 36.00 37.57
RMS Current Per Winding: 1.67
Wednesday, May 25, 2011
Sessionette 75 fuse burn out
I bought this DOA on gumtree.ie for the price of the speaker really, knowing the fuse was blowing.
So, the fuse keeps blowing, I'm guessing I need a new power supply! What to do?
Award-Session say they stopped production of the Sessionette:75s in October 1988 and the company stopped making guitar amplifiers of any kind in 2007. No amps left, no parts left, no technicians who know their way around this piece of kit in Dublin. The original Sessionette:75 PSU was known to fail. A replacement PSU (the PM120 power module) used to be sold but is now no longer available.
The PSU in my kit has PM120 printed on it. I wonder if has my box had a replacement power module fitted before? Everything on the inside is tidily soldered and attached, it looks like a production version.
Symptom:
Turning on the power, indicator light (red) glows briefly (1s) then slowly fades. Power fuse is blown. Repeat, same. Switch power on/off quickly, same result. No obvious heat smell.
Conclude: Something is shorting.
Step 1
Inspect the circuit boards visually front and back to spot anything obvious.
Don't forget to use the nose to smell a burn.
Any discolouration on components? Nope, except perhaps a tarnish on one of the balanced power op amps (mj11015 pnp and mj11016 npn op amp). Note: can source the mj11015 and mj11016 from www.awatronic.fr at reasonable prices if needed.
(mj11015: Transistor PNP Darlington 120V 30A 200W TO-3 MOTOROLA (Equivalent: BDX68C) - Diode de protection intégrée)
(mj11016: Transistor NPN Darlington 120V 30A 200W TO-3 MOTOROLA (Equivalent: BDX69C) - Diode de protection intégrée
Conclusion? Nothing obviously wrong.
Step 2
Poke around with a multi-meter (MM) looking for shorts/continuity in unexpected places. No luck with this on either the power amp circuit or the pre amp circuits.
An observation, with everything soldered in place, I can't assess circuit behaviour without power. Why? Because (for example) discharged capacitors are shorts (for a while) until they charge up (sucking charge from the MM).
Continuity tests aren't that useful unless there's a smoking gun (burn out somewhere). Continuity is more for finding breaks (i.e. no continuity) as opposed to shorts (too much continuity).
Question? WHAT is the metal box on the inside of the cabinet connected to the pre amp by two signal cables (co-ax plugs)?
Answer? It's a three spring reverb effect from Accutronics (www.accutronicsreverb.com/). See www.amplifiedparts.com/ for an Excellent explanation of spring reverb effect box design and theory written by Kurt Prange.
Conclusion? Nothing obviously wrong.
Step 3
Hmm, isolate sections and inspect for expected/unexpected behaviour.
This is going to be difficult without a bench supply, an oscilliscope, and other stuff.
So, the fuse keeps blowing, I'm guessing I need a new power supply! What to do?
Award-Session say they stopped production of the Sessionette:75s in October 1988 and the company stopped making guitar amplifiers of any kind in 2007. No amps left, no parts left, no technicians who know their way around this piece of kit in Dublin. The original Sessionette:75 PSU was known to fail. A replacement PSU (the PM120 power module) used to be sold but is now no longer available.
The PSU in my kit has PM120 printed on it. I wonder if has my box had a replacement power module fitted before? Everything on the inside is tidily soldered and attached, it looks like a production version.
Symptom:
Turning on the power, indicator light (red) glows briefly (1s) then slowly fades. Power fuse is blown. Repeat, same. Switch power on/off quickly, same result. No obvious heat smell.
Conclude: Something is shorting.
Step 1
Inspect the circuit boards visually front and back to spot anything obvious.
Don't forget to use the nose to smell a burn.
Any discolouration on components? Nope, except perhaps a tarnish on one of the balanced power op amps (mj11015 pnp and mj11016 npn op amp). Note: can source the mj11015 and mj11016 from www.awatronic.fr at reasonable prices if needed.
(mj11015: Transistor PNP Darlington 120V 30A 200W TO-3 MOTOROLA (Equivalent: BDX68C) - Diode de protection intégrée)
(mj11016: Transistor NPN Darlington 120V 30A 200W TO-3 MOTOROLA (Equivalent: BDX69C) - Diode de protection intégrée
Conclusion? Nothing obviously wrong.
Step 2
Poke around with a multi-meter (MM) looking for shorts/continuity in unexpected places. No luck with this on either the power amp circuit or the pre amp circuits.
An observation, with everything soldered in place, I can't assess circuit behaviour without power. Why? Because (for example) discharged capacitors are shorts (for a while) until they charge up (sucking charge from the MM).
Continuity tests aren't that useful unless there's a smoking gun (burn out somewhere). Continuity is more for finding breaks (i.e. no continuity) as opposed to shorts (too much continuity).
Question? WHAT is the metal box on the inside of the cabinet connected to the pre amp by two signal cables (co-ax plugs)?
Answer? It's a three spring reverb effect from Accutronics (www.accutronicsreverb.com/). See www.amplifiedparts.com/ for an Excellent explanation of spring reverb effect box design and theory written by Kurt Prange.
Conclusion? Nothing obviously wrong.
Step 3
Hmm, isolate sections and inspect for expected/unexpected behaviour.
This is going to be difficult without a bench supply, an oscilliscope, and other stuff.
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