SP14 - Tips and Tricks requested

Hello fellow tube lovers,

I am about to start putting an SP14 kit together. Are there any tips and tricks that you are willing to share? Any pitfalls? I am more or less a newbie in the field and do not have any engineering background either. I am learning as I go along and depend on help from the community.

Thanks a lot for any input.

Michael

Ps: I will document my build and post here

check out the two or three links to builds on my website at www.tubes4hifi.com/SP14.htm

Thank you guys. I have looked at the link earlier, of course I was more looking for mistakes or obstacles that other have made or come across and a tip how to avoid those.

Michael

Zimmer64 wrote:Thank you guys. I have looked at the link earlier, of course I was more looking for mistakes or obstacles that other have made or come across and a tip how to avoid those.

Michael

I just put mine together last night. Some possible pitfalls.

1) When soldering components - solder from the bottom and check from the top to ensure the join is correct/solid.
2) When soldering diodes verify the direction of the diode. The side with the band should match the the box on the board schematic.
3) When soldering the electrolytic capacitors the long wire is positive and goes in the square hole (be sure it matches the + lead on the schematic.
4) Presort your resistors so they match based on labels and color bands.
5) Identify the resistors based on labels and solder them first (easiest to identify)
6) Identify the resistors based on bands next - several are easily identifiable (like 330, or 470)....once identified solder to the board - work backwards (if its known solder it). It helps identify the parts.
7) periodically check your work against the photo's Roy posted above.

Once the board is soldered you can start work on the wiring and jacks - this is the stage I'm at now (just waiting for some parts in the mail).

For resistors I use http://www.elexp.com/t_resist.htm to identify the color codes.

David

don't relay on color codes, just sort the resistors by colors, and then DOUBLE CHECK THEM with a meter !!!!

Thanks guys. I started the build today. I checked all resitors with my meter and put them onto the board following the schematics, but did not solder yet. I will double check tomorow before I solder.

One question tough. Compareing to the pics on Roy's website, there seems to be a difference. I dont see the 100 Ohm resistors R11 - R12 on the pictures. Have I made a mistake or is mine a different version of the board?

Best

Michael

Michael, the pics on the website are an older version, R11 and R12 are there, closer to the rectifier tube

Thanks guys. I started the build and made good progress. The board is mostly a mirror image for each channel. Except two resistors! I almost fell for it. Be carefull where R20 and 21 goes. Those two buggers change the sort order

I double checked and measured every component before I soldered (I hate to de-solder......).

Best

Michael

Hey Michael - looks just like mine (except for the Cap upgrade).

David

Looks like you are well on your way there. The power supply area is not a mirror image as I recall.

Looking forward to seeing it come together.

The schematic/documentation doesn't seem to cover the relay board.

Based on what I can see in the sample builds I think it is as follows:

1) High voltage +- to the relay board (230/240V) - High voltage from transformer. If you got a discrete 115/230V high voltage transformer remember that it needs to be wired in SERIES to get the right voltage.
2) L/R Out goes to input on board
3) S1-S5 goes to pins 1-5 on the selector switch
4) S0 goes to pin A on the selector switch
5) Ground to common Ground

Not really sure how to wire tape switch if you are using the relay.

David

Thanks Dave. I do not use a tape switch, but I actually struggle a bit with the relay board. I dont think the input selector relays work with high voltage. I also struggle a bit with the toroids. Question is where to solder the secondaries to.The schematics are showing different toroids. I have 3 toroids with secondarie 2x115, 2x18 and 2x6 volt. I am aware, that I have to wire the primaries of the toroids in series for 240 volt operation. I also did not figure out where to wire the LED. I have sent a couple of questions to Roy re this and await his reply. I will keep you posted.

Michael

Roy just replied. Here is an updated schematic: