Prototypers wanted

[Pars]

I assume the Fairchild 512-MJE350STU may be used in place of the ST parts in the Mouser BOM that are backordered? After my recent experience with ST regulators, I avoid them like the plague

Also, the 33uf / 50V cap listed in the BOM is backordered as well. I haven't measured the LS on the board, but from the pic I assume that 5mm won't work (Mouser stocks the Pana FC in this value, but it is 5mm instead of 2.5mm LS).

[luvdunhill]

I assume the Fairchild 512-MJE350STU may be used in place of the ST parts in the Mouser BOM that are backordered? After my recent experience with ST regulators, I avoid them like the plague

Also, the 33uf / 50V cap listed in the BOM is backordered as well. I haven't measured the LS on the board, but from the pic I assume that 5mm won't work (Mouser stocks the Pana FC in this value, but it is 5mm instead of 2.5mm LS).

check Doug's post above, it should help you out.

[Pars]

Also, C1L/R: I assume 250V is too low for these in case Q1/Q2 were to blow. I have a ton of MKP10 0.1/250V around.

[kevin gilmore]

oops just notice the mje350's were backordered.

i think i have some original motorolas at work otherwise 2sa1156 or 2sa1486 would be identical

and probably slightly better replacements.

[dsavitsk]

Right now I'm trying to avoid the compulsion to upgrade the output trafos with the eprint units that Doug hinted at.

Jack and I are still finalizing designs, so I don't actually have any to send you. And, if it helps relieve the compulsion, a pair will cost more than the rest of the kit -- way more that the rest of the partial kit.

I assume the Fairchild 512-MJE350STU may be used in place of the ST parts in the Mouser BOM that are backordered? After my recent experience with ST regulators, I avoid them like the plague

Mouser lists 4 different MJE350's -- any of them will work, but check the pinout carefully. There's SOT-32, TO-225, and TO-126 and while the cases are the same, the pinouts are different.

Also, the 33uf / 50V cap listed in the BOM is backordered as well. I haven't measured the LS on the board, but from the pic I assume that 5mm won't work (Mouser stocks the Pana FC in this value, but it is 5mm instead of 2.5mm LS).

Literally anything from 0.1 to 1000u is probably fine. Just find something that fits. We don't care about performance as this is just for the heater supply.

Also, C1L/R: I assume 250V is too low for these in case Q1/Q2 were to blow. I have a ton of MKP10 0.1/250V around.

These will see full unloaded B+ at startup until the tubes start conducting, so 300V is minimum -- use the spec'd parts here. One thing -- if you have everything else except these, don't sweat it -- it will probably run fine without them.

[kevin gilmore]

The mains transformer can be put in backwards. So pay attention to the wiring of the transformer and

compare to the board. Also the shield is soldered to a pin which really should go to circuit ground.

too bad there aren't any connex 7 pin teflon sockets.

very hard to tell the direction of the led's, so first test the led to make sure of direction, then

look at the schematic to make sure you insert it right.

I'm as far as i can go until the rest of the parts show up.

Should take no more than 2 hours to fully stuff it.

Cutting the holes in the back and front are going to take more time.

as far as i can tell all of the mje350's are BCE across the plastic front...

Edited June 30, 2010 by kevin gilmore

[kevin gilmore]

lets try that again

mje350 ECB across the plastic front.

[luvdunhill]

The mains transformer can be put in backwards

you'd have to be pretty damn determined to do that

[dsavitsk]

The mains transformer can be put in backwards.

I sure hope not. If that's the case, you got one on the wrong bobbin and it should not fit the board at all. Pin 1 is offset.

Also the shield is soldered to a pin which really should go to circuit ground.

Yes -- the PCB was designed before we knew which pin would be the shield. So, solder it without connecting it and check for hum. If there is a little, connect it and it should go away (on breadboard, the spacing of the transformers was just enough to eliminate it, but even a 1/2" closer made it audible) -- but, if we can get away without the shield, it saves everyone $6 per kit on the finals

very hard to tell the direction of the led's, so first test the led to make sure of direction, then

look at the schematic to make sure you insert it right.

All cathodes go toward the middle of the PCB. What, you can't read my mind?

as far as i can tell all of the mje350's are BCE across the plastic front...

The order of B-C-E seems consistent across devices. But, on the SOT-32s, pin one is B while on the TO-225 and TO-126 pin 1 is E. I find figuring out which pin is 1 on these things tough enough, so this extra wrinkle is a real pain. Most likely, we'll supply devices that are labeled.

-d

[Pars]

lets try that again

mje350 ECB across the plastic front.

The order of B-C-E seems consistent across devices. But, on the SOT-32s, pin one is B while on the TO-225 and TO-126 pin 1 is E. I find figuring out which pin is 1 on these things tough enough, so this extra wrinkle is a real pain. Most likely, we'll supply devices that are labeled.

-d

All of the ones that Mouser carries are E-C-B. ON, STM and Fairchild. ON and STM have the pictures in their datasheets showing the back (metal tab), but when looking at the plastic front, are consistent in pinout.

Parts are on order. I take it the preferred build is with the C-L-C filter in the PSU instead of the C-R-C, and to use the CCS? Hammond choke ordered from RadioDaze. We'll see how fast they are. I also had Craig order the Pana TS-HC caps from Mouser. They do carry the TS-HA as well, but do not have them yet and delivery was early August (8-9-2010). I substituted a 47uf cap of the same series as the 33uf one that was backordered also (C5 IIRC).

Edited June 30, 2010 by Pars

[n_maher]

It would appear that Radiodaze is the only place in the states that has the choke, or at least lists the choke on their site. I suppose I'll just go the cheap/simple route to start and go from there.

[kevin gilmore]

I sure hope not. If that's the case, you got one on the wrong bobbin and it should not fit the board at all. Pin 1 is offset.

Well it is soldered in, so if there was an offset i got it right, but i did try it first, and it fit both ways.

The output transformers are definitely offset and can't be put in backwards.

[luvdunhill]

Well it is soldered in, so if there was an offset i got it right, but i did try it first, and it fit both ways.

The output transformers are definitely offset and can't be put in backwards.

given the board footprint for the power transformer, the only way you could have a transformer that could be put in backwards, is if you were missing two pins, specifically the key and the one diagonally across from it... unless I'm missing something.

[n_maher]

I sure hope not. If that's the case, you got one on the wrong bobbin and it should not fit the board at all. Pin 1 is offset.

Yes -- the PCB was designed before we knew which pin would be the shield. So, solder it without connecting it and check for hum. If there is a little, connect it and it should go away (on breadboard, the spacing of the transformers was just enough to eliminate it, but even a 1/2" closer made it audible) -- but, if we can get away without the shield, it saves everyone $6 per kit on the finals

<snip>

My 2

[TomB]

It would appear that Radiodaze is the only place in the states that has the choke, or at least lists the choke on their site. I suppose I'll just go the cheap/simple route to start and go from there.

It looks like PartsConnexion has them in stock. I entered up to 100 and never got an "out-of-stock" notice. Whether their website is sophisticated enough to account for their inventory, I don't know - but it seems a good bet they have several.

Newark says they have 31.

Mouser's lead time is only two weeks - it might be faster than that at Allied and DigiKey ~10 days.

[n_maher]

Thanks Tom, I'll do some more hunting during lunch.

My experience with PCX and Hammond items is that a lot of the time once you place your order they place an order with Hammond and it delays shipment a few days. Not a big deal, but for most of those items I think it's rare that they actually have stock. I've experienced the same thing with Angela as well.

[Pars]

The order acknowledgment that my brother got from RadioDaze included the following:

*If you have ordered a Hammond product there will be some additional time needed to get it from them or have them ship it to you, so please be aware.

So I am guessing they do the same thing. I ordered enough resistors that I can do R2 until the choke shows up. I suppose the footprint, etc. on these is proprietary, so no alternate part/supplier other than Hammond.

Edited June 30, 2010 by Pars

[TomB]

Yep. Just an FYI, but Hammond won't let you order the chokes directly from them - even if you're a dealer. Their transformers and chokes are governed through strict distribution arrangements - been there, tried that.

[Nebby]

Last parts are in, any particular sanity checks to do prior to power on?

[dsavitsk]

Last parts are in, any particular sanity checks to do prior to power on?

One thing that I am not sure has been said yet -- the mounting holes are all ground -- make sure that at least one of these is making good contact with the case (with a screw and metal standoff and lock washers) such that the case is well connected to safety ground.

[Nebby]

Measuring between the G and B+ points results in 1.58V, so it's obvious I screwed up somewhere. I've taken some pictures in case my mistake is painfully obvious. I'm going to go back through the part list and try to find out what I messed up on. I guess I can be the "complete noob" prototype test case.

[n_maher]

Check the output at the IEC, you're sure you've got a fuse in there (if it's required) right?

[Nebby]

Yup, fuse is in there and voltage in is 121V; the pins on the other side of the transformer read ~26V

[kevin gilmore]

Measuring between the G and B+ points results in 1.58V, so it's obvious I screwed up somewhere. I've taken some pictures in case my mistake is painfully obvious. I'm going to go back through the part list and try to find out what I messed up on. I guess I can be the "complete noob" prototype test case.

You forgot to jumper the primaries on the transformer

A to B and C to D

[n_maher]

Check for a backwards cap or rectifier diode next.