Khron

Re: TC Electronic problems...
« Reply #100 on: May 16, 2020, 09:51:43 AM »
The "right" parts might depend on your choice of distributor - not all of them carry all the inventory from all the silicon manufacturers. But since these are simple semiconductors (as opposed to opamps and everything "above" those), the options are indeed multiple.

Is the 2SA1012 in normal TO220-packaging, or the isolated version?

Ordering them by price at Mouser for example, and keeping an eye on the hFE (gain) of the PNP's, 2SA2222G would seem to be an option, as could 2SA2207, both in isolated TO220 packaging. 2N6491 is way down on gain (minimum 20, typical "barely" 150).

IPA70R900P7S, IPA70R750P7S seem to be the cheapest 6-700v MOSFETs at Mouser, rated for 6A and above (0.9 and 0.75ohms Rdson respectively), loads of other options to choose from.

I take it the "F10P04" is also a dual 10A Schottky diode, possibly 40v rated?
MBR2045CT and up (the "45" bit being the rated reverse voltage, going up to 100), SBR1040CT to -10100CT, SDT20100CT etc should do just fine.
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drpat

Re: TC Electronic problems...
« Reply #101 on: May 16, 2020, 06:02:04 PM »
Is the 2SA1012 in normal TO220-packaging, or the isolated version?

Ordering them by price at Mouser for example, and keeping an eye on the hFE (gain) of the PNP's, 2SA2222G would seem to be an option, as could 2SA2207, both in isolated TO220 packaging. 2N6491 is way down on gain (minimum 20, typical "barely" 150).

The 2SA1012Y is not the isolated version. Was really hung up on if the hFE should be the same, or as high as possible for a SMPS. Stuck the 2SA2222SG non-isolated version in my cart.

IPA70R900P7S, IPA70R750P7S seem to be the cheapest 6-700v MOSFETs at Mouser, rated for 6A and above (0.9 and 0.75ohms Rdson respectively), loads of other options to choose from.

To make things a little clearer, I'm working on two of these power supplies, so these are 6 different part numbers for the same 3 spots (Q1, Q4 and D5). Looks as if I may need to choose different MOSFETS for each of the two supplies based on the Rdson specs. Am I on the right track? Or should I just go for the lowest Rdson (0.75ohms) for both units and call it a day?

I take it the "F10P04" is also a dual 10A Schottky diode, possibly 40v rated?
MBR2045CT and up (the "45" bit being the rated reverse voltage, going up to 100), SBR1040CT to -10100CT, SDT20100CT etc should do just fine.

You are correct... also a schottky. Couldn't find a data sheet for that one either. I originally asked about the RB225T100 because it SEEMS like a more robust part in the same isolated TO-220 package. Could I be looking at this wrong?

Oh, and thank you for holding my hand on this. It's been a fun learning experience, to say the least.
I use the LA2a on very hot signals like lead vocal.

Khron

Re: TC Electronic problems...
« Reply #102 on: May 16, 2020, 07:21:58 PM »
Looking at the specs, the "pairs" of components are pretty much interchangeable, no meaningful differences between them.

Pretty sure the MOSFET is the switching element on the primary (and yes, lower Rdson is generally better, but you'll wanna keep the gate capacitance in the same ballpark figure).

Any idea what that PNP does, in the circuit? Is the PNP part of a discrete regulator on the secondary side, or..?

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drpat

Re: TC Electronic problems...
« Reply #103 on: May 17, 2020, 07:01:01 AM »
Pretty sure the MOSFET is the switching element on the primary (and yes, lower Rdson is generally better, but you'll wanna keep the gate capacitance in the same ballpark figure).

You are correct. The MOSFET (Q1) is located on the primary side.

When you refer to "gate capacitance", the only specs i can find for capacitance on the data sheets for the 2SK1118 and the 2SK2545 are the following:
- input capacitance (Ciss)
- reverse transfer capacitance (Crss)
- output capacitance (Coss)

Any idea what that PNP does, in the circuit? Is the PNP part of a discrete regulator on the secondary side, or..?

I can't find a schematic for this power supply, but the PNP is definitely on the secondary side. The Emitter is directly connected to the standby wire (SB-VCC) that's going from the power supply to the main board. It also leads to the tiny sub-board that contains the PWM chip and opto-isolator chip, but without a schematic, I can't tell exactly where it's connected on the sub-board.
I use the LA2a on very hot signals like lead vocal.

Khron

Re: TC Electronic problems...
« Reply #104 on: May 17, 2020, 07:10:52 AM »
That'll be the input capacitance, then. Stay under 2nF or so and it should be fine (stock was 1.3-1.5nF or so, iirc?).

Sounds like the PNP's either a discrete regulator pass element, or just a high-side on/off switch. Either way, higher gain's never a bad thing, it only makes the transistor easier to drive.
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drpat

Re: TC Electronic problems...
« Reply #105 on: May 17, 2020, 09:46:05 AM »
OK, so here's what I have in my Mouser cart:

(Q1) MOSFET - IPA70R900P7S
Package – TO-220 (isolated)
Type - N-Channel
Drain-Source Voltage (Vds) – 700V
Drain Current DC (Id) - 6A
Drain-source on-state resistance(Rdson) – 0.9ohms (max)
Input Capacitance (Ciss) – 211pF

(Q4) BJT - BD912
Package – TO-220 (Non-Isolated)
Polarity – PNP
Collector to Emitter Voltage (Vceo) - 100V
Collector Current (Ic) - 15A
hFE (gain) – 40~250

(D5) Dual Schottky - RB225T100
TO-220 (isolated)
110V
30A
Common Cathode

Anybody see any issues before I pull the trigger?

I will also update my first post with all of the major parts and part numbers for this SMPS once I test these.
« Last Edit: May 17, 2020, 09:49:26 AM by drpat »
I use the LA2a on very hot signals like lead vocal.


 

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