Hi Chuck,
LOL HIL - I like that one. Since I haven't heard a name for this "process", I'll use your suggestion.
Hi Stocker,
I have tried everything on PCB's for cleaning over the years. For flux removal, the best stuff attacks most plastics. ElectrO-WasH PX (Chemtronics) is my current "best" (use a toothbrush) followed by lacquer thinner. I have used both methyl hydrate and isopropyl alcohol (not as good) to clean flux off. The alcohols tend to leave residues and require much more volume to clean.
Repairing smt stuff, my first two picks are way out front. I end up with a new looking pcb before installing the new parts. Most times you can't tell I've been there after the job is done (by hand). I have not found a single instance where lacquer thinner has caused any damage at all. If you haven't tried it yet, give it a shot. It's not expensive at all.
Mike,
You have to give Clem credit for the PCB, he made them and shipped a pair to me. Also, I used a 35V unit for C19 as it measured better than the 16V examples I had (DA and ESR). This may make a positive difference in the sound given the location of the capacitor.
-Chris
LOL HIL - I like that one. Since I haven't heard a name for this "process", I'll use your suggestion.
Hi Stocker,
I have tried everything on PCB's for cleaning over the years. For flux removal, the best stuff attacks most plastics. ElectrO-WasH PX (Chemtronics) is my current "best" (use a toothbrush) followed by lacquer thinner. I have used both methyl hydrate and isopropyl alcohol (not as good) to clean flux off. The alcohols tend to leave residues and require much more volume to clean.
Repairing smt stuff, my first two picks are way out front. I end up with a new looking pcb before installing the new parts. Most times you can't tell I've been there after the job is done (by hand). I have not found a single instance where lacquer thinner has caused any damage at all. If you haven't tried it yet, give it a shot. It's not expensive at all.
Mike,
You have to give Clem credit for the PCB, he made them and shipped a pair to me. Also, I used a 35V unit for C19 as it measured better than the 16V examples I had (DA and ESR). This may make a positive difference in the sound given the location of the capacitor.
-Chris
Cleaning boards
Hi guys
I've been cleaning my boards and removing flux with some
stuff that I found at Home Depot called LECTRA CLEAN, heavy
duty degreaser. It's very efective and leaves the boards
spanky clean, I've been using it for 2 / 3 years, it's cheap ($3/4)
and you can clean just about everything with it.
Even to wipe off the residue of paper on the boards right
before etching is extremly effective.
Hi guys
I've been cleaning my boards and removing flux with some
stuff that I found at Home Depot called LECTRA CLEAN, heavy
duty degreaser. It's very efective and leaves the boards
spanky clean, I've been using it for 2 / 3 years, it's cheap ($3/4)
and you can clean just about everything with it.
Even to wipe off the residue of paper on the boards right
before etching is extremly effective.
True, but we are talking about cleaning the underside (foil), not the component side. I clean "topside" with a "Q-tip", or cotton swab. It's not on long either. I have never seen any harm come to circuit board material, or components where it has leaked through a hole.
Lacquer thinner works very well on P to P terminal strips and tube sockets. I don't use it on controls, pots or switches.
-Chris
My silver-zinc solder instruction indicates that water can be used to remove residue. I was able to clean pretty well by brushing the solder side with small amount of soap water and dry it with tissue paper. Then I use my fingers to wet the solder side surface (face down) with some water and dry it again with tissue paper. I was surprised that it cleaned much better than using iopropyl acohol for me.
Hi MikeB:
I made good progress on parts and assembly. I am too cheap to buy a digital camera and could not show you a picture. Maybe I will get a USB camera soon for the purpose.
I need you opinion on the choice of power capacitors. I wanted to use 4 x 62,000UF computer grade capacitors, but my case is a bit cramped. Do you think using 4 x 10,000UF will make any difference?
I made good progress on parts and assembly. I am too cheap to buy a digital camera and could not show you a picture. Maybe I will get a USB camera soon for the purpose.
I need you opinion on the choice of power capacitors. I wanted to use 4 x 62,000UF computer grade capacitors, but my case is a bit cramped. Do you think using 4 x 10,000UF will make any difference?
No. Pulse current that recharges the capacitor bank is proportional to capacitor value (I speak about steady-state, not only the turn-on current surge current). For large capacitors you get very high peak values to charge the capacitors - everyone should make an analysis before making decision about the capacitor value. It is very easy to simulate this situation.
Hi Tim, i have no experience with different types of rectifiers, i simply use metal bridges, they showed no problems, are cheap and tough with a 25A rating. There are hot debates about the use of high speed diodes for rectifying, NP for example does not like them, the chipamp section swears on them...
Chris, have you already been able to fire up a symasym, or are you too busy with cleaning up the SKA-thread ?
Mike
Chris, have you already been able to fire up a symasym, or are you too busy with cleaning up the SKA-thread ?
Mike
Hi Mike,
Darn - You've been watching!!
Yes, that was taking up some time. I am just hunting down some components to complete the first board and test it. This is a perfect power range for some small amplifiers I need to make for various wall speakers around the house. So either way they will be used. I have high hopes for them.
I will try to change the diff pair as we discussed earlier. I am very curious what they will sound like with a fet diff pair. I'll have to clamp the drain voltages for that, so that's another mod to make to compare with bipolars on an even footing.
I was attempting to use my sound card to get more info in tests, but I don't like what my SB 24 bit Live! is doing. PM if you have any input. I already made compensated dividers to drop the output level. Man would I love to have an AP system!!!!
-Chris
Darn - You've been watching!!
Yes, that was taking up some time. I am just hunting down some components to complete the first board and test it. This is a perfect power range for some small amplifiers I need to make for various wall speakers around the house. So either way they will be used. I have high hopes for them.
I will try to change the diff pair as we discussed earlier. I am very curious what they will sound like with a fet diff pair. I'll have to clamp the drain voltages for that, so that's another mod to make to compare with bipolars on an even footing.
I was attempting to use my sound card to get more info in tests, but I don't like what my SB 24 bit Live! is doing. PM if you have any input. I already made compensated dividers to drop the output level. Man would I love to have an AP system!!!!
-Chris
Hi bodopriva, thanks for the interest, unfortunately you would have to order them yourself from a PCB manufacturer, you can download gerber & excellon files on my website. Also you could wait for a groupbuy or you might be lucky that someone has some boards left. Sadly i have not enough time to handle kits.
Chris, yes i was watching...
The symasyms should be small enough to fit into wall speakers and are reasonably cheap. The most expensive will be a PSU for each of the wall speakers...
If you lower the supply voltage a bit you should be able to simply use the sk170 without further modification. As i remember, jfets don't like too high Vds ? The sk170 has a 40v rating.
I already tried the re's in input ltp (47ohms), but did not perceive an advantage.
Measuring an amp with a soundcard is not easy, you have to fight many grounding problems unless you have a soundcard with balanced inputs/outputs like the ESI Juli@. I used a plain resistor divider (5:1) in paralell to a dummy load but was plagued with induced distorted 50hz caused by some strange groundloop.
For some reason i can't remember i decided against the Julia and bought the m-audio 24/96, dumb me...
You can also add a balanced to unbalanced buffer between amp and soundcard input, otherwise you will connect power-gnd and signal-gnd. I got best results by using a CD-player as signal source. But i gave up and will never be able to measure like Pavel can...
Mike
Chris, yes i was watching...
The symasyms should be small enough to fit into wall speakers and are reasonably cheap. The most expensive will be a PSU for each of the wall speakers...
If you lower the supply voltage a bit you should be able to simply use the sk170 without further modification. As i remember, jfets don't like too high Vds ? The sk170 has a 40v rating.
I already tried the re's in input ltp (47ohms), but did not perceive an advantage.
Measuring an amp with a soundcard is not easy, you have to fight many grounding problems unless you have a soundcard with balanced inputs/outputs like the ESI Juli@. I used a plain resistor divider (5:1) in paralell to a dummy load but was plagued with induced distorted 50hz caused by some strange groundloop.
For some reason i can't remember i decided against the Julia and bought the m-audio 24/96, dumb me...
You can also add a balanced to unbalanced buffer between amp and soundcard input, otherwise you will connect power-gnd and signal-gnd. I got best results by using a CD-player as signal source. But i gave up and will never be able to measure like Pavel can...
Mike