So I ordered one of the STA-45 kits from Lighthouse Electric a little while ago. Ended up getting here on Thursday and I've been putting it together on and off during the weekend.
I'm pretty sure that the kit didn't include all the right parts... looked like I had a few too many of one type of resistor and not enough of another, and I had a missing stand-off screw, but that wasn't too big of a deal.
In any case, a couple trips to radio shack to refill my supply of spare resistors and misc. wiring/etc., many hours, and a lot of profanity later, I get to the point where I can try to start running some tests with the multimeter while it's plugged in and live.
Get through about halfway, and much to my surprise, everything is checking out. "Sweet! It's all down hill from here, I'll be listening to some sweet, sweet, tube goodness in no time flat!" I say to myself.
Next test, put the probes in the right place, flip the power switch, flip the standby... *pop* down one fuse.
Checked a few other things, re-did a few connections just to be sure, wash, rinse, repeat... and I kiss the four extra fuses I picked up earlier goodbye.
Of course, about two seconds after I toss the last fuse out, I notice that I had a wire very obviously soldered into the wrong place that I had missed before somehow.
I'm pretty sure that woulda fixed it, but radio shack is closed and I'm out of fuses
*sigh* There's always tomorrow...
I'm pretty sure that the kit didn't include all the right parts... looked like I had a few too many of one type of resistor and not enough of another, and I had a missing stand-off screw, but that wasn't too big of a deal.
In any case, a couple trips to radio shack to refill my supply of spare resistors and misc. wiring/etc., many hours, and a lot of profanity later, I get to the point where I can try to start running some tests with the multimeter while it's plugged in and live.
Get through about halfway, and much to my surprise, everything is checking out. "Sweet! It's all down hill from here, I'll be listening to some sweet, sweet, tube goodness in no time flat!" I say to myself.
Next test, put the probes in the right place, flip the power switch, flip the standby... *pop* down one fuse.
Checked a few other things, re-did a few connections just to be sure, wash, rinse, repeat... and I kiss the four extra fuses I picked up earlier goodbye.
Of course, about two seconds after I toss the last fuse out, I notice that I had a wire very obviously soldered into the wrong place that I had missed before somehow.
I'm pretty sure that woulda fixed it, but radio shack is closed and I'm out of fuses
*sigh* There's always tomorrow...
andry1 said:So I ordered one of the STA-45 kits from Lighthouse Electric a little while ago. Ended up getting here on Thursday and I've been putting it together on and off during the weekend.
I'm pretty sure that the kit didn't include all the right parts... looked like I had a few too many of one type of resistor and not enough of another, and I had a missing stand-off screw, but that wasn't too big of a deal.
In any case, a couple trips to radio shack to refill my supply of spare resistors and misc. wiring/etc., many hours, and a lot of profanity later, I get to the point where I can try to start running some tests with the multimeter while it's plugged in and live.
Get through about halfway, and much to my surprise, everything is checking out. "Sweet! It's all down hill from here, I'll be listening to some sweet, sweet, tube goodness in no time flat!" I say to myself.
Next test, put the probes in the right place, flip the power switch, flip the standby... *pop* down one fuse.
Checked a few other things, re-did a few connections just to be sure, wash, rinse, repeat... and I kiss the four extra fuses I picked up earlier goodbye.
Of course, about two seconds after I toss the last fuse out, I notice that I had a wire very obviously soldered into the wrong place that I had missed before somehow.
I'm pretty sure that woulda fixed it, but radio shack is closed and I'm out of fuses
*sigh* There's always tomorrow...
With new builds you have to check and check again all components and connections. Its tedious but saves on blown up components and fuses.
Lol... I have to admit, in the true spirit of diy I considered "just making it work," so to speak, but as it was getting late and I had been staring at (by my estimation) 1.8 quadrillion tiny little wires soldered to an equal number of tiny little terminals and had managed to miss a fairly obvious mis-wiring problem... Well, I decided discretion was the better part of valor, and decided to just hit radio shack on the way home from work today
In my days as a repair tech at a stereo store I made the discovery that a volume control shaft fits perfectly. Clarostat made replacement controls with scored shafts that could be snapped off at most of the common lengths. The leftover portion was exactly the same length and diameter as a fuse. I used one to find the intermittent short in my old Pontiac. After the fire gods danced around on the AC fan speed switch it was obvious where the short used to be.
Note: I was young and stupid when I did this. I am not young anymore!
Pyre,
.22 cartridge as a fuse !!!!
The previous owner of your truck obviously missed the "Myth Busters" episode where they showed that a .22 cartridge used as a fuse DOES fire in a fault current situation. A "Self Annunciating" fuse.
As my reactionary old coot of a grandpa used to say, someone should have put a "Warning Shot" through his ears.
As they say on all those shows:
"Kiddies - DO NOT TRY THIS AT HOME".
Jokes aside - this is incredibly dangerous. Given a short circuit in that line the bullet WILL explode.
Cheers,
Ian
.22 cartridge as a fuse !!!!
The previous owner of your truck obviously missed the "Myth Busters" episode where they showed that a .22 cartridge used as a fuse DOES fire in a fault current situation. A "Self Annunciating" fuse.
As my reactionary old coot of a grandpa used to say, someone should have put a "Warning Shot" through his ears.
As they say on all those shows:
"Kiddies - DO NOT TRY THIS AT HOME".
Jokes aside - this is incredibly dangerous. Given a short circuit in that line the bullet WILL explode.
Cheers,
Ian
gingertube said:
Probably that's why modern fuses for cars have so different shape.
When I was a kid there were books for DYIers with tables of correspondence of wire diameters to currents, so it was easy to make a fuse from scratch... I remembered lot of useful numbers... However, when I got my MS EE diploma I forgot all that simple tables...
Well I sure am glad I didn't have any .22 cartridges lying around
On the upside, I hit Radio Shack on the way home last night and I think bought every 0.5 amp fuse they had "just in case" (knowing full well that by doing so I'd only need the one).
And, of course, I only needed the one.
So now I have a working STA-45 amp! Well... one channel's worth, anyway. I've got a short in one of the RCA jacks (I'm about 99% sure that's what it is, anyway). Not surprising given that in order to connect it to the pots and pre-amp board it involves soldering this impossibly thin, stranded speaker wire and it's even more impossibly thin, stranded shielding to two bits of the back of the jack that are about half a nanometer apart. That shielding tends to get unruly and go everywhere.
I was thinking of just redoing all the runs that involved the shielded speaker cable that came with the kit with CAT5, which I have tons of lying around the house and is serving as pretty decent speaker cable elsewhere in my system right now.
Anyone ever tried that? If I'm going to be building more of these sorts of things in the future, I'd definitely like to find an alternative to the audio signal wire that came with this kit that would prove to be a little easier to work with.
On the upside, I hit Radio Shack on the way home last night and I think bought every 0.5 amp fuse they had "just in case" (knowing full well that by doing so I'd only need the one).
And, of course, I only needed the one
.So now I have a working STA-45 amp! Well... one channel's worth, anyway. I've got a short in one of the RCA jacks (I'm about 99% sure that's what it is, anyway). Not surprising given that in order to connect it to the pots and pre-amp board it involves soldering this impossibly thin, stranded speaker wire and it's even more impossibly thin, stranded shielding to two bits of the back of the jack that are about half a nanometer apart. That shielding tends to get unruly and go everywhere.
I was thinking of just redoing all the runs that involved the shielded speaker cable that came with the kit with CAT5, which I have tons of lying around the house and is serving as pretty decent speaker cable elsewhere in my system right now.
Anyone ever tried that? If I'm going to be building more of these sorts of things in the future, I'd definitely like to find an alternative to the audio signal wire that came with this kit that would prove to be a little easier to work with.
You really shouldnt be blowing any fuses if you follow a logical testing procedure.
1/ Test transformer on its own.
2/ Check bridge rectifier for shorts
3/ Check power supply caps for a short.
4/ Check output transistors for a short.
5/ Check driver board for shorts.
I would then leave the output transistors disconnected and fire up the driver board with the output fed back into the LTP.
I would set the bias to a minimum.
Once I am convinced the driver board is OK would I consider reconnecting the output transistors.
1/ Test transformer on its own.
2/ Check bridge rectifier for shorts
3/ Check power supply caps for a short.
4/ Check output transistors for a short.
5/ Check driver board for shorts.
I would then leave the output transistors disconnected and fire up the driver board with the output fed back into the LTP.
I would set the bias to a minimum.
Once I am convinced the driver board is OK would I consider reconnecting the output transistors.
Oh, I'm not blowing any fuses anymore (not sure if you were responding to my last message or not). Corrected a minor wiring SNAFU that was causing the original fuse blowage -- took me about two minutes to do after I got back from Radio Shack last night with my big bag full o' fuses (of which I only needed one).
Amp works fine now, no fuses blowing, pretty glowing tubes on top, etc. I'm just only getting output from one channel due to some "icky" wiring on the RCA input jacks.
Should take me about two seconds to fix, just didn't feel like popping the tubes out again last night to flip it over and correct it since I wanted to get around to installing/aligning the new phono cartridge that arrived yesterday.
Was just thinking about rewiring some or all of the audio signal paths using CAT5 instead of the 'shielded audio wire' that came with the kit, which I'm not overly fond of for various reasons.
I'm sure it will shock all of you to hear that this is the first time I've built one of these things, so I was curious if there was any particular reason why I shouldn't swap the internal audio wiring with CAT5. I can't see any reason why it wouldn't work just fine, but hey, I have been known to be wrong once or twice before
Amp works fine now, no fuses blowing, pretty glowing tubes on top, etc. I'm just only getting output from one channel due to some "icky" wiring on the RCA input jacks.
Should take me about two seconds to fix, just didn't feel like popping the tubes out again last night to flip it over and correct it since I wanted to get around to installing/aligning the new phono cartridge that arrived yesterday
.Was just thinking about rewiring some or all of the audio signal paths using CAT5 instead of the 'shielded audio wire' that came with the kit, which I'm not overly fond of for various reasons.
I'm sure it will shock all of you to hear that this is the first time I've built one of these things, so I was curious if there was any particular reason why I shouldn't swap the internal audio wiring with CAT5. I can't see any reason why it wouldn't work just fine, but hey, I have been known to be wrong once or twice before
I've used individual wires pulled from Cat 5 cables for audio signal wiring in SS amps but haven't tried it in a tube amp. You have to be very carefull about wire routing, crossing wires at right angles etc to avoid hum pickup AND occassionally you will find a particular signal line that just has to be done with shielded cable. If you are using Cat 5 wires from the RCA Input connectors to the 1st tube then twist the signal and the 0V wires together, 3 to 5 twists per inch.
There are 2 grades of Cat 5 cable - one (the cheap stuff) has PVC insulated wires, the better grades have teflon insulation. It is this latter one you want to use.
For my tube amp builds, most times now I use thin tinned copper wire which I pass down the centre of some teflon tubing for these feeds. This is much the same thing.
I've listened to some speaker cables made up of multiple Cat 5 wires plaited together. I did'nt care for them that much but some others have "raved" about them.
Cheers,
Ian
There are 2 grades of Cat 5 cable - one (the cheap stuff) has PVC insulated wires, the better grades have teflon insulation. It is this latter one you want to use.
For my tube amp builds, most times now I use thin tinned copper wire which I pass down the centre of some teflon tubing for these feeds. This is much the same thing.
I've listened to some speaker cables made up of multiple Cat 5 wires plaited together. I did'nt care for them that much but some others have "raved" about them.
Cheers,
Ian
I thought the "problem" with using shielded speaker cable was its inherent capacitance (per inch). It ends up being in parallel with the input, and shorts a small amount of high frequency material to ground. The high frequency roll-off you get might vary if you have a voltage divider on the input (a.k.a., the volume pot). You're better off if you keep the total impedance of the volume pot small (use a 100k pot instead of a 500k) and keep the shielded wiring as short as possible.
Am I mistaken?
Am I mistaken?
I also orderd the lighthouse electric sta-45 and also found that more than half of the parts were not the same as the parts list. This was the first tube amp kit that I had built. I couldnt ever get to work...only a faint sound that you could hardly hear. It will make a nice paper weight until I can get some help with it.
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