This is the 6th papa type class A amp I’ve built, and I’m still dodo that can follow instructions.
The biggest problem is the 12 months from last build.
D-S measures 0r4 without power, and 0m1 with -9V to grid, 1K, source.
Is there any other tests I can do while Fets are removed?
"m" is mili
or
"m" is Mega?
I’m thinking hall1 L is dead because L+ has 0R to GND. A dead short
ignore LTSpice schematics ( they're always just illustration of work with developing tool) in all cases when you have proper schematic
in case you spoke of , 7805 also can be suspicious
Ok, so after scratching my head all morning I decided to redo the Tokin Drain connection, scratch and clean all the close solder connections on the board. So after all that I’ve reinstalled Fets and powered it up with 60w bulb And 3A fuse. The bulb lights up and goes dim.
Offset measured 10V, draw across 0R1 was 60ma.
I’ve done the work to both boards but only powered up one.
What should I try or measure now?
Offset measured 10V, draw across 0R1 was 60ma.
I’ve done the work to both boards but only powered up one.
What should I try or measure now?
Powered it up and small puff of smoke around hall devices and dead 9240.
I will check resistances on hall devices to see if any are different.
The left hall has very little gat between the lower center pins.
I think there was a small puff of smoke from this general area.
I will check resistances on hall devices to see if any are different.
The left hall has very little gat between the lower center pins.
I think there was a small puff of smoke from this general area.
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yeah , check that
I'm checking for shorts after soldering Halls, with 17 lenses and MW light , in same time checking orientation of halls
while developing , I had rotated Hall , I had rotated 7805 and I had small wandering solder blob/ball wandered from who knows where , ending where I didn't need it at all
that's why I'm hysteric in checking every Hall , also after soldering PSU wires , when making an amp
however - as I'm always blaming Pa , feel free to blame me , if you find shorted Hall
sole good thing is - it can't be destroyed if there is short , exacto knife is enough to cure it, if you're rather using it than solder tip
and , if doing those wires again , be gentler than you did
I'm still waiting for explanation of terms you used describing SIT measurements
I'm checking for shorts after soldering Halls, with 17 lenses and MW light , in same time checking orientation of halls
while developing , I had rotated Hall , I had rotated 7805 and I had small wandering solder blob/ball wandered from who knows where , ending where I didn't need it at all
that's why I'm hysteric in checking every Hall , also after soldering PSU wires , when making an amp
however - as I'm always blaming Pa , feel free to blame me , if you find shorted Hall
sole good thing is - it can't be destroyed if there is short , exacto knife is enough to cure it, if you're rather using it than solder tip
and , if doing those wires again , be gentler than you did
I'm still waiting for explanation of terms you used describing SIT measurements
I think ZM is being kind. It looks like you've used quite a bit of solder around those legs. Good news per ZM - just clean it up.
I'd hate to think one of your SITs is shot.
Are you absolutely sure, you've read post #8 and followed Ben Mah's recommendation to the letter? I only ask b/c I'd hate to see you toss away a good SIT, you measured it incorrectly once already, and your description about how you measured it is a bit unclear.
Per Ben Mah - you should have:
Battery with 1K resistor in series, positive to S and negative to G. Measure resistance D-S. Should show high resistance.
You said...
D-S measures <snip> 0m1 with -9V to grid, 1K, source
This is unclear - Did you put the 1K resistor in series with the battery or between the gate and the source? Not to be a pain, but perhaps try again and take a picture? Be clear on your units. Use M for Mega and m for Milli with no abbreviations. Or, just type it out for clarity - 0.1 milliohms vs. 100,000 ohms. My guess is 0.1 milliohms, but try again with the measurement just for 100% confidence maybe.
Those pucks are expensive.... I hope it's still good.
I'd hate to think one of your SITs is shot.
Are you absolutely sure, you've read post #8 and followed Ben Mah's recommendation to the letter? I only ask b/c I'd hate to see you toss away a good SIT, you measured it incorrectly once already, and your description about how you measured it is a bit unclear.
Per Ben Mah - you should have:
Battery with 1K resistor in series, positive to S and negative to G. Measure resistance D-S. Should show high resistance.
You said...
D-S measures <snip> 0m1 with -9V to grid, 1K, source
This is unclear - Did you put the 1K resistor in series with the battery or between the gate and the source? Not to be a pain, but perhaps try again and take a picture? Be clear on your units. Use M for Mega and m for Milli with no abbreviations. Or, just type it out for clarity - 0.1 milliohms vs. 100,000 ohms. My guess is 0.1 milliohms, but try again with the measurement just for 100% confidence maybe.
Those pucks are expensive.... I hope it's still good.
Rabbit Season!
Exactly who are you answering?
With kindest respect, saying "Open circuit" does no one any good. Do you mean when measuring exactly per guidance on your SIT that your ohmmeter is now showing Over Limit => Open Circuit vs 0.1 milliohms?
I'll leave it to better minds. I truly hope you get it working and wish you best of luck. My kindest recommendation (repeated) is to simply quote the exact suggestion you're trying to replicate and provide an answer below it with the measurement you've taken. Better yet, back it up with a photo. I can't make heads or tails of what you're doing. Perhaps others can.
Time for a beer.
SITs are tough buggers , you can kill 'em pretty much only if you use it heatsinkless for prolonged time and if you zap it's gate with substantial neg voltage , ref. to source
Buddy of mine had a mishap , while testing them he was using Lab PSU directly for gate control ( not fixed voltage varied with external pot) , and pot on Lab PSU wasn't flawless ...... result - Dodo THF51S
hate to even think of that ....... though - I can ask him to give it to me , so I can use it as dingldongl at back mirror in my car
Buddy of mine had a mishap , while testing them he was using Lab PSU directly for gate control ( not fixed voltage varied with external pot) , and pot on Lab PSU wasn't flawless ...... result - Dodo THF51S
hate to even think of that ....... though - I can ask him to give it to me , so I can use it as dingldongl at back mirror in my car
If you tie gate to source with an alligator clip cable, you can measure Rdson with a DMM. Measure from the gate to the other terminal comprised of the shorted gate to source. What you get is Rdson at Vgs = 0.
I did this with your SIT that you are loaning me and the Rdson at Vgs = 0 is about 0.8 ohms.
You need a DMM with remote sense; a good quality bench DMM.
Gate leakage with the device powered on is from 200nA to 800nA.
I did this with your SIT that you are loaning me and the Rdson at Vgs = 0 is about 0.8 ohms.
You need a DMM with remote sense; a good quality bench DMM.
Gate leakage with the device powered on is from 200nA to 800nA.
@woofertester - The good news is that the one I hooked up ***-backwards (for just a brief moment) is in a fully functioning SissySIT at the moment. The ones you have were delivered by Tibetan virgins in a pristine state.
Fabulous guidance also, BTW - thanks! I'm following the other thread with great interest.
Fabulous guidance also, BTW - thanks! I'm following the other thread with great interest.
What confuses me is how I pass the dim bulb test for 30seconds+ and then go direct and get huge amp draw and fry the 9240 in less than a second. I’m on my 5th one and the heat from unsoldering is taking a tole on the pcb. One of the barrels came out this time.
I think there’s a bridge in the middle here. It’s tucked under the hall devise.(shiniest jewel) I’ll have to remove the cap to get between. This stuff is so tight A knife will make a mess. I’ll just keep taking photos to get “eagle eye”.... I’ll also check pinout of hall to understand effect of a bridge in this location.
Yes I to think Tokin is ok, it conducts and closes. 9240 just conducts on every pin. I will have to make artwork from dead bugs.
Sorry for the poor answers. My volt meter just says m so milli or mega I’m dodo. But it was changing from OL to 0.1 m so that’s why I said Open Loop. I didn’t realize there was m and M.
Honestly, it’s getting terrifying to try full power. I’m starting to cringe and use special words. Almost good enough for you tube. Titled (Full grown tantrum)
Time for Baltimore egg nog, I just need a nice bourbon....
So after looking at schematic that jumper puts 5v on Vout of hall device. Will that kill 9240?
I think there’s a bridge in the middle here. It’s tucked under the hall devise.(shiniest jewel) I’ll have to remove the cap to get between. This stuff is so tight A knife will make a mess. I’ll just keep taking photos to get “eagle eye”.... I’ll also check pinout of hall to understand effect of a bridge in this location.
Yes I to think Tokin is ok, it conducts and closes. 9240 just conducts on every pin. I will have to make artwork from dead bugs.
Sorry for the poor answers. My volt meter just says m so milli or mega I’m dodo. But it was changing from OL to 0.1 m so that’s why I said Open Loop. I didn’t realize there was m and M.
Honestly, it’s getting terrifying to try full power. I’m starting to cringe and use special words. Almost good enough for you tube. Titled (Full grown tantrum)
Time for Baltimore egg nog, I just need a nice bourbon....
So after looking at schematic that jumper puts 5v on Vout of hall device. Will that kill 9240?
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