Does the 2SK180 fit any version of a UMS hole specification? It doesn't look like it, but am wondering if I am missing something. The specs in the Yoshino 2SK180 pdf show that the distance between mounting holes is 43mm and I don't see that value anywhere on the UMS spec... Thanks! (How did I wander down this road? Modushop has a "substitution" heatsink for the 4U 400 chassis.)
You will need to drill and tap a hole.
But that would apply to the THF-51S if it is attached directly to the heatsink.
The 2SK180 has its pins protruding from the bottom of its case so it cannot be easily mounted directly to the heatsink. The usual practice is to mount it on a tee or angle, and then mount the tee or angle to the heatsink. The UMS dimensions may then be used for the tee or angle.
But that would apply to the THF-51S if it is attached directly to the heatsink.
The 2SK180 has its pins protruding from the bottom of its case so it cannot be easily mounted directly to the heatsink. The usual practice is to mount it on a tee or angle, and then mount the tee or angle to the heatsink. The UMS dimensions may then be used for the tee or angle.
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To calculate the fuse value you need to know the rated power of the transformer. The should be on the label of the transformer.
The fuse value in Amperes = P/V
where P = transformer rated power in VA, and V = wall AC voltage (transformer primary voltage)
Have you purchased the transformers? What are the VA of your transformers?
The fuse value in Amperes = P/V
where P = transformer rated power in VA, and V = wall AC voltage (transformer primary voltage)
Have you purchased the transformers? What are the VA of your transformers?
Ben, could you please tell me why you chose 62V Instead of the 80V in the PS for the FE22?
Does 62V change any values? Resistor or caps?
And could you show me pictures of the inside of the FE22?
Where to put the power transformer / PS / boards?
I received the Circuit boards today.
I did not order the power transformers yet. First I want to be sure about the correct values.
And I wait for some resistors an papacitors to arrive.
Does 62V change any values? Resistor or caps?
And could you show me pictures of the inside of the FE22?
Where to put the power transformer / PS / boards?
I received the Circuit boards today.
I did not order the power transformers yet. First I want to be sure about the correct values.
And I wait for some resistors an papacitors to arrive.
For my DIY FE 2022 build, see my posts in the DIY FE 2022 thread, starting with this post: https://www.diyaudio.com/community/threads/diy-front-end-2022.394339/post-7312224
For the 62V power to the FE, 35V capacitors were chosen for C4 and C5.
For the amplifier circuit board, use the Kicad schematic for stuffing the board. The other schematic was from LTSpice simulations where RV1a and RV1b together represented RV1.
For the 62V power to the FE, 35V capacitors were chosen for C4 and C5.
For the amplifier circuit board, use the Kicad schematic for stuffing the board. The other schematic was from LTSpice simulations where RV1a and RV1b together represented RV1.
@Ben Mah, I am almost there with my right channel. I have two more questions before I start with power:
Adrian
- For grounding: my previous drawing was wrong, I've attached an updated one. Should the Input - (negative of RCA) connected to the chassis?
- I got a Variac as they aren't that expensive. Would slowly increasing the AC voltage make sense, or should I stay with only the dim light bulb test?
- I haven't connected the ground to the chassis yet.
- I haven't connected the RCA input yet.
- I've drilled much more holes in the floor for cooling.
- I am using crimp and WAGO connectors, after crimping I soldered the wire to the crimp connector. As for the WAGO connectors, let me know if you would change them to something else once I know everything works.
- Snubber circuit is under the heat shrink.
- The trim potentiometer has 21 turns, I wish I would have chosen one with less turns
- Bulb tester is ready, I got some inspiration from the web.
- There is some aluminium scrap from drilling in the picture, I'll clean of course everything before I start plugging it in.
Adrian
Hi Adrian,
It's great to see that you are close to powering up for the first time.
I looked at your previous power supply diagram and from a schematic point of view it is probably more correct. The IEC power ground wire should be connected directly to the chassis, with star washer against the chassis, ring connector on the ground wire, lick washer, and double nuts. The ground wire connection to chassis should be very secure and be difficult to be accidentally removed.
The transformer screen wire and power supply ground lift thermistor may be connected to the chassis in a similar manner to another screw next to the safety ground screw., using ring connectors.
The input signal and ground wires should be twisted together and soldered to their Input+ and Input Gnd pads on the PCB.
I have never used Wago connectors so I have no experience with them. However if they are insulated and cannot short out against the chassis, they are probably not a problem for wire connections. However you should be careful with the thermistors in the AC lines as they will heat up when the amplifier is on and current is flowing. For connection of components such as thermistors, I prefer to use terminal blocks screwed to the chassis so that the components are not floating and free to move around.
At the back panel I see that the AC hot and neutral wires are not twisted, and the wires from PCB to SIT drain and source are not twisted. It is best to twist them.
You can use the DBT for first power up or the variac.
The power supply should be tested by itself first. Without the amplifier board attached, the voltage should be a few Volts higher. The DBT is probably best for this. The bulb will glow bright for a short period of time as the capacitors charge. Then it will go dark. If the bulb stays on, then there is a problem.
For full power up tips, see https://www.diyaudio.com/community/...-choke-loaded-2sk180-lamp.366312/post-7270513
Be sure to double check all wiring. Be sure that all power supply wires to the amplifier PCB are correct for power supply polarities, and all other wires are in their correct locations on the PCB.
I had a look at powering up with a Variac and I do not think it is a good idea. The reason is that SITs need gate voltage to control their drain current. If a Variac is used, the SIT gate voltage starts out at a very low value, allowing high current to flow. So I recommend using the DBT for first full power up.
Before powering up, be sure that the trimmer resistor is set to fully counterclockwise, and have a meter set to VDC connected to T.P. Choke 1 and T.P. Choke 2. This is to monitor the SIT drain current. The DCR of the 193V is 1 Ohm, so 1V = 1A. See above mentioned power up tips.
Edited: Variac not used for full power up.
It's great to see that you are close to powering up for the first time.
I looked at your previous power supply diagram and from a schematic point of view it is probably more correct. The IEC power ground wire should be connected directly to the chassis, with star washer against the chassis, ring connector on the ground wire, lick washer, and double nuts. The ground wire connection to chassis should be very secure and be difficult to be accidentally removed.
The transformer screen wire and power supply ground lift thermistor may be connected to the chassis in a similar manner to another screw next to the safety ground screw., using ring connectors.
The input signal and ground wires should be twisted together and soldered to their Input+ and Input Gnd pads on the PCB.
I have never used Wago connectors so I have no experience with them. However if they are insulated and cannot short out against the chassis, they are probably not a problem for wire connections. However you should be careful with the thermistors in the AC lines as they will heat up when the amplifier is on and current is flowing. For connection of components such as thermistors, I prefer to use terminal blocks screwed to the chassis so that the components are not floating and free to move around.
At the back panel I see that the AC hot and neutral wires are not twisted, and the wires from PCB to SIT drain and source are not twisted. It is best to twist them.
You can use the DBT for first power up or the variac.
The power supply should be tested by itself first. Without the amplifier board attached, the voltage should be a few Volts higher. The DBT is probably best for this. The bulb will glow bright for a short period of time as the capacitors charge. Then it will go dark. If the bulb stays on, then there is a problem.
For full power up tips, see https://www.diyaudio.com/community/...-choke-loaded-2sk180-lamp.366312/post-7270513
Be sure to double check all wiring. Be sure that all power supply wires to the amplifier PCB are correct for power supply polarities, and all other wires are in their correct locations on the PCB.
I had a look at powering up with a Variac and I do not think it is a good idea. The reason is that SITs need gate voltage to control their drain current. If a Variac is used, the SIT gate voltage starts out at a very low value, allowing high current to flow. So I recommend using the DBT for first full power up.
Before powering up, be sure that the trimmer resistor is set to fully counterclockwise, and have a meter set to VDC connected to T.P. Choke 1 and T.P. Choke 2. This is to monitor the SIT drain current. The DCR of the 193V is 1 Ohm, so 1V = 1A. See above mentioned power up tips.
Edited: Variac not used for full power up.
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I'd put some heatshrink or similar insulation over the gate resistor to prevent it from accidentally shorting to nearby pins or parts.
Thanks @Ben Mah. I'll change the grounding setup to as you have described. I got the RCA input (neutrik) as below which will result in the negative input to make contact with the chassis. I'll look for another input jack.
@mbrennwa I'll also cover that gate resistor with heat shrink. I thought it would be useful to show in the picture.
@mbrennwa I'll also cover that gate resistor with heat shrink. I thought it would be useful to show in the picture.
Check to see if the red and white washers are shoulder washers. The washers would go on each side of the chassis insulating the jack from the chassis. You would need an oversized hole to fit the shoulder washers. The ground tab can go between the jack nut and the white washer.
What pinholer said re: RCA input jack.
One of the washers is usually a shoulder washer. The washers are also usually the same colour as the colour band around the RCA jack. So the RCA jack with the red band should have two red washers and the RCA jack with the white band should have two white washers.
One of the washers is usually a shoulder washer. The washers are also usually the same colour as the colour band around the RCA jack. So the RCA jack with the red band should have two red washers and the RCA jack with the white band should have two white washers.