Jump to content

The ultimate DIY? A Stax SRM-T2!


spritzer

Recommended Posts

secondhand, I wasn't sure if the strip alignment was uniform for the whole series. the casing looks pretty shitty too so I should have been more suspicious.

fuck

what's a good way to desolder these without opting for a second iron? I don't want to fuck up the board too much but I've only one iron at the moment

Link to comment
Share on other sites

I've used a hot air station to desolder caps before.  Need to be careful not to burn the PCB by holding in one position for too long.

That is a good idea, use hot-air to preheat the joint and adjoining PCB area slowly, once the solder starts to melt use a desolder gun or one of the solder suckers mentioned earlier.

Always keep the wand moving and never leave it in more than 1 spot for more than 2-3 seconds. I set my air temps to 350-380degF

Be careful to not pull out the plated sleeve that connects both sides of the board.

Link to comment
Share on other sites

I was able to get it out cleanly by slowly rocking it out of place by heating and reheating the joints.

I just found out my octal sockets don't fit, does anyone have a link to what they know fits the board?

Also looking at the Bakelite sockets, what are the dis/advantages of this over ceramic/teflon?

Link to comment
Share on other sites

Today I triggered my PSU.

Before I had a chance to measure high voltages, I heared something boiling. The two 4700µF were hot and their tops are now convex.

Sounds like an overvoltaged cap, right ?

Maybe the center tapping is confusing me, but why a 25v rating for those ? Isn't the 30-0-30 rectified to 42v ? This way 50v seems to be the minimal requirement...

 

Any thought ?

Edited by G600
Link to comment
Share on other sites

OK, there is the culprit.

So I jumped both feet into Lil Knight's error (boards markings, etc...).

Would you share a solution, other than reworking the secondary ?

I could put 63V caps, but max DC for the 7X12 is 35V...

Edited by G600
Link to comment
Share on other sites

So I've now been able to replace the 10k trimmers with PTF56 resistors. The batteries adjusted just fine too. However the background noise is still there. Could the PSU be the culprit somehow?

Probably the noise from the current source 2sk246 - 10k. Test it: touch a isolated metal screwdriver to 10k pot and also the circuit between 10k and 2sk246 (don't touch the soldering place). Noise should disappear or minimize by touch one battery and maximize in other battery.

 

And do not forget to change resistors R24, R31 to 20 ohm in PSU.

Edited by 8street
Link to comment
Share on other sites

Yea, I ordered some 22ohm resistors to put in the -500V supply as well. I assume you mean touch the legs of the 10k PTF56 or the 2SK246 and not the point where it's soldered, right? Do you mean the noise would maximize in the other channels batteries, or in the other battery in the same channel? Either way it sounds like I'm looking for a change in the noise by touching these points.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.