Got a question for ya

[spider]

I found a mod for an epiphone valve jr that I wanted to try. Im not exactly sure how read or say the information to the electronics store without confusing them. So if anyone can help me figure out what I need to fit the board it would be greatly appreciated.

I want to change C4 to a +220 mfd(bfg) or early .68 cap. What would the voltage and tolerance be for this? I cant reach the original modder and can only find this information that he listed years ago. I assume its a radial capacitor but not sure the voltage or tolerance. Anyone help me out with what would fit best here?

The other part is changing C1 to .002 again no other information is listed and Im kinda lost and working in the dark with finding out what is needed in voltage/tolerance?

And last is C7 changing it to a 4.7 mfd Max 10 mfd. Would 10 be 10% tolerance? Again not sure of the voltage. This one I know is a radial capacitor.

Any help would greatly be appreciated in figuring it out.

[turtle441]

So, a few comments:
1. Best resource for getting questions answered on the VJ is over at www.sewatt.com. They've got a whole board devoted to it. There's hella smart people here, and alot of the original mods came from here back in the day, but the most active discussion is over there.

2. The available schematics for the VJ on sewatt list all the required specs, and don't even require a sign-in. Check here: http://www.sewatt.com/node/16248

3. With that said, C1 is a coupling cap, the schematic lists 400V. Any of the common coupling cap sources (Mallory 150's, Orange drops, etc.) should work fine. C4 is a cathode bypass cap (needs to be electrolytic). Schematics on sewatt list it as 50V, although I've seen 65V used in other amps. I would not assume it's a radial cap. Find it on the pcb and look at it to confirm. (Last I remember, the filter caps are radial, but some of the bypass caps are axial on the VJ... but I could be wrong.) C7 is a power filtering capacitor (also needs to be electrolytic). Schematic lists 450V, which is pretty standard.

4. I can't speak to the specific changes. A couple of the numbers you've listed seem a bit different from what I've seen in the past on the VJ. But different doesn't necessarily mean bad... just different. FWIW, I think the best mod to the VJ is swapping out the undersized OT for a 125DSE or 125ESE. Really opens up the amp and improves bass response.

5. If you feel like you're not sure how to speak to someone at the electronics store, I feel like I have to put out the caveat, make sure you are confident in your ability to work around high voltage and filter capacitors. (Read the warnings on any/all of the various diy amp forums and know how to discharge capacitors.) Even small amps like a VJ can reach out and bite you if you're not careful.

[spider]

Thanks turtle441. I appreciate your response & information. As for me not knowing how to talk to these guys, Im not so sure its on my part? In the past, I use to just ask them my questions(which werent that hard to understand) and never got any attitude. Some of the employees changed hands and now have rude personalities esp. one of them. So asking a question or advice seems to get him annoyed.He just seems to be the type of person that is sarcastic with everything. Maybe to use to knowing about a certain subject. For me, I was always kind and happy to help someone that had a question on something they weren't totally sure about. After all isnt that what life is suppose to be about? We all dont know everything. Just my opinion.

I had a friend that emailed me years ago that guided me on how to mod my old marshall. I knew less back then. He recommended I did build a power bleeder with ceramic resistors which I did. So I knew the amps needed to be drained of power before any type of work is performed on them. I just wasnt sure exactly how to drain these types of 450v filter caps since they are on a pcb board and have no leads sticking out. So Im researching that as much as I can & finding out that my amp is V3 and has a resistor on it to help bleed the power when turned off. Not that I wouldnt check before I worked on it anyway. When I dont know something I research it before I do anything to it.

As for the V3 and the updated output transformer, Ive read swapping in a Heyboer would get it to sound alot better. Even better than a Hammond OT. Would you know if there is any truth to this? It sounds like they worked some bugs out with the v3 and the output trans was one of those bugs. Just curious to know if the swap was worth it or not? One video I watch I heard a noticeable difference with the swap but its not like being there in front of it either. I know you mentioned swapping out the OT for a Hammond and I have not squabbles on that Im just wondering how the v3 OT is and if it really needed to be swapped. Im currently looking for a used one or even a new one but the Heyboer one as from what Ive read it was the "one" to use.

I also saw a few people putting the old mustard caps in them as well. Again my question would be is there any benefit to this as well? I saw a guy swapping two stock caps for two old mustard caps(.022 uf 400v) on c9 & c10 of the board. But then I questioned if just using Sozo's as a replacment would be just a suitable since they would be a bit cheaper and for what the amp is......

Not sure myself so would love to hear your thoughts.

[geoff 1965]

spider,
regarding the mustard caps,i've done a lot of testing in this area when i was doing the parallel/cascade mod.the old mullard mustards are good but you need to be able to test them for leakage even if they are NOS or you might get problems. mallory 150's,mojo dijon and SoZo are all very good in fact i have all 3 in my circuit and have slight differences i.e. the mojo's are a bit brighter than the SoZo's,if you want to get near the old mullards then you can't go wrong with the SoZo Nexgens.

[spider]

Awesome, Thanks Geoff 1965. I wasnt aware of the dijon or mojo caps. Ill definitely keep those in mind but it sounds like Im gonna go after the Sozo Nexgen for sure. . That is the tone that always talks to my ears the most. Cant thank you enough for responding.