CHANGSTAR: Audiophile Headphone Reviews and Early 90s Style BBS
Lobby => DIY => Topic started by: MisterRogers on May 01, 2015, 12:53:43 PM
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Hey Mates,
As some of you know, I recently upgraded my S7 (Anax's beast) with a Belleson Super Regulator on the DC heater pins of the driver tube. While a bit tricky to install, I'm finding this to be a fantastic upgrade (increased sound stage precision, plankton). It does not make the S7 a BA, but it does move it a bit closer.
I thought I'd ask of any of you S7 owners would be interested in a short writeup / images / 'how to'. I'm a bit insane when it comes to wringing out the best possible performance; it may not be worth it to most. But... thought I'd check. Chime in if there's interest.
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Hell, yes! :)p6
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Ha! Ok! I'll list a BOM this weekend of what you'll need, followed by some instructions.
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alas, I suppose it wouldn't hurt.
Cheers ;D
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Ok. You'll need a few things to get this going:
* A new smoothing capacitor; you'll need a new one as the old will need to be removed for access, and the new installed on an angle (you'll need the full length of the leads).It's a Nichicon 25V 4700uF, part number UPWIE472MHD. There's not much benefit in upgrading this cap - this part is will suited for the application.
* A Belleson SPJ 6.25V regulator. Order the 317 pin compatible one. The SPJ can handle 2A, which give a bit of headroom for tubes that draw 1.5A.
* Small diameter heat shrink tubing; about 2 inches length. The diameter should be just enough to fit the capacitor leads in.
* A .50mm, right angle, 3 pin male connector. I'll try and dig up a part number for this. It's needed to mount in the Belleson.
* Thermal isolation pad for heat transfer; paste is currently used and would suffice.
Also and not specifically just for this project, you'll need:
* Soldering station / rework / pencil.
* Solder wick.
That'll let you get the Belleson and capacitor ordered. Let me try and dig up the connector part number.
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OK - LET'S GET STARTED!
Well, almost. Before diving in, I need to lay out the usually disclaimers. Bottom line: Do not endeavor to perform this mod unless you know what you're doing. You assume full responsibility for any damage that may be caused by doing this. I'd consider this an intermediate level mod; it require basic rework skills. As with most tube amps, S7 is medium / high voltage, and poses a significant shock hazard if care is not taken. I'm happy to share what I've done, and am happy to support suitably skilled pirates with related answers. That offer of help does NOT extend to those without intermediate skills, or any further related or unrelated modifications.
Whew. OK. While the above needed to be said, I don't want to discourage those with suitable skills. The work is straightforward and the results are beneficial (IMO).
Step 1
Organize your workbench. You'll want to have the following handy:
* Soldering station. Tip of your choice - I use a suitably sized chisel tip.
* Soldering wick. A solder removal gun / pump can also be used, assuming it's able to access the rework area of the board.
* Necessary parts.
* Containers for screws you'll remove.
* Whatever else you need / use. I'm old, so I rely on a large, magnifying bench light.
Step 2
* Power down your S7. Let it sit for 5 / 10 minutes to be sure output caps have dissipated.
* Move to your workbench.
* Remove tubes. If you want / need to, take a photo or write notes indicating correct tube positions - if it matters.
* Remove the two side plates, placing screws in a container / wherever they're safe. Set the two side plates aside - don't want to scratch / damage them.
* Unscrew the top plate, placing screws in a container / wherever they're safe. Lift top gently; you'll have multiple connections to PCB from transformers, pot, etc.
* With S7 front towards you, tilt the top to the left and take photos / notes of the correct wire connections to the mother board. You'll need to assemble, so insure you know how to connect it back up.
* Before removing the top plate, remove the volume knob, and the potentiometer from the top plate. Place the knob and screws in a container. Take care not to scratch the top plate or knob.
* Tilt the top plate to the left again, and CAREFULLY remove the connectors from the PCB. There's a pressure tab on one side, but with a firm wiggle / pull motion, they'll slide off. Take note of the pressure tab; when reassembling, you'll want to be sure it's facing the inside of the connector.
* With Pot and connections removed, you should be able to lay the top on the left, face down. You may find it necessary to carefully cut some zip ties. Carefully - you don't want to cut into / nick the insolation of the wires being held by the zip ties.
* Now, you can remove the 4 screws that secure the PCB to the top plate. Place them into a container. You'll probably find a wire without a connector (green I think) that runs from the PCB to the power transformer. You can remove it if you like (if you do, take photos, make note of connect reconnection), but there's enough length to it that I was able to perform mods without removing it.
* Depending on any other capacitor mods you may have performed, you may need to remove flying wires for both interstage and output capacitors. You'll want to remove these; it's important for you to be able to flip the PCB front to back as you do the rework.
At this point, you have have the PCB loose and ready to work. Think about how you can work with it; if you still have wires running to the transformer, you'll need to work out how to perform your work next to, or on top of the S7 case. This is what I did - I covered the case / transformers with some clean work rags and laid the PCB on top. I was able to easily flip it as needed. If your PCB is 'free' of the amp, then work on it as you would any other board.
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Step 3
* Now we need to remove the old components:
1. Switching Capacitor
2. LM317 Regulator
3. Two voltage adjustment resistors (Classically R1 & R2 in *317 spec sheets).
(http://www.prettygoodsoftware.net/DIY/S7Mod-RepParts.png)
Do NOT remove the heatsink; we can do this without taking it off, and removing heatsinks can be a real pain in the arse. Just cut the leads of the regulator and remove a pin at a time. So remove all of these parts (reg, 2 resistors, capacitor), and clean up the board - get it ready to install new parts.
Note: The photos shown are from my amp after modification. This is the only picture I took, so we'll have to work with it.
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Step 4
1. You'll want to prepare your parts - specifically the capacitor and the Belleson regulator.
2. For the capacitor, you'll want to bend the leads in an arch, as to position them close to a 90deg angle.
3. Use some small diameter heatsink tubing to protect the leads. We'll likely not have any parts touching them, but it's good form.
(http://www.prettygoodsoftware.net/DIY/S7Mod-Leads.png)
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Pretty nice of them to put Duelund caps in their amps without telling anybody p:3
This Nichicon thing seems a bit lost in this posh meeting
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Pretty nice of them to put Duelund caps in their amps without telling anybody p:3
This Nichicon thing seems a bit lost in this posh meeting
That's just Anax's modified one. Mine is modified with Jantzen caps. This regulator mod does seem interesting though.
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Just be sure you know exactly what you are doing. Don't call anyone at EC if you need help on the regulator mod or the regulator mod breaks something else. We won't service or field questions on modded amps.
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Just be sure you know exactly what you are doing. Don't call anyone at EC if you need help on the regulator mod or the regulator mod breaks something else. We won't service or field questions on modded amps.
That's certainly fair. I was one of those dummies that forgot to label the internal cables before messing around inside. Let's just say..bad things happened. Ended up finding a guy to fix it at my own expense who used to be a tech for Cary Audio. All that ended up wrong with it was a blown Zener dioide. A testement to the practicality of Craig's designs.
But I ended up doing to the cap mod successfully on my own. May want to put that disclaimer in the Super 7 Mod thread as well if you haven't already.
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We have it in the Eddie Current FAQ: http://www.eddiecurrent.com/FAQ.html (http://www.eddiecurrent.com/FAQ.html)
Will you service an Eddie Current amp that was modified by Maestro-Modders?
Modifying your Eddie Current amp will not only immediately and permanently void the warranty, but also ensure that we will never touch your amp ever again. Trying to figure what other people may have done is a pain in the ass.
You won't believe what we've seen or have been asked to fix.
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Hey jwahl - Merv's warning is certainly not to be taken lightly. Diving into modding electronics is risky, more so with tube amps.
Warning aside though, this particular mod isn't super difficult and really made an overall improvement to the S7 performance. If / when you (or others) decide to attempt this, feel free to reach out if I can be assistance. Don't get me wrong - you assume the risk, but always ready / willing to share my experiences with fellow pirates.