Wild Bill, Let's get my Plexi 1987x back up and running!

[Kapo_Polenton]

This thing has been the amp from hell for me.. it started as a Weber 6m45p which i had working till something blew. It was soo messy the first time i did it (thanks to small box) that I decided to rebuild it to the proper 1987x specs. Its still a tad crowded as i had to find ways to fit in the 50/50 filter caps, but I got her all done. The problem I am having besides the fact that it looks like a franken Marshall, is that it ain't workin! I have been up and down this thing with the help of an old feller who used to build tube radios. He said everything in sight and based on the schematic we verifed, looked fine.The problem however is the following:

- Right now, only one power tube is lighting up

- I'm getting about 434 DC on pin 4 of my EL34 V5 BUT I also see this at pin 1 of the first preamp tube??

- heater wiring all registers 3.15 AC on each preamp and output tube. (maybe i blew the other tubes from excessive voltage at that first stage?) The schematic leads back to that first 50/50 uf filter cap but i verified that it is wired properly as well.

- no sound (the biggest problem)


This is obviously wayyyy too high and i wonder if it is the result of a component failing somewhere? How do I figure this out? I thought I would post here as it is a smaller community. People have less attitude and I am tired of the " you shouldn't be building if you don't know what you are doing.." well news flash, its built so kinda late for that lol.

Anyway thought maybe you could help me out. The reason I refuse to give up on this amp is that when I had it running it sounded soo f_cking good. I want it back.

[nonreverb]

I might be able to help you out...since we're in the same city:smile:

[Milkman]

I might be able to help you out...since we're in the same city:smile:

6 hammonds and a bunch of Leslies



I hate you


I would LOVE to have ONE B3. We do drag around a nice old Leslie 147 to which we've added nice handles and casters.


Ah the mighty B3. Accept no substitutes.

[Kapo_Polenton]

nonreverb, I'm game if you have the time at some point.. I'd love to get this bastard back up and running.

[nonreverb]

6 hammonds and a bunch of Leslies



I hate you


I would LOVE to have ONE B3. We do drag around a nice old Leslie 147 to which we've added nice handles and casters.


Ah the mighty B3. Accept no substitutes.

They're still out there...difference is I bought most of mine before the ebay insanity when people were selling them at reasonable prices...but there are still deals to be had..they're just harder to find:smile:

[nonreverb]

Sent you PM

nonreverb, I'm game if you have the time at some point.. I'd love to get this bastard back up and running.

[Wild Bill]

This is absolutely great! When I first found this board I noticed how there was very little tech stuff to help folks.

So I jumped in and the word spread quickly. Soon GC gave us our own tech forum. More tech guys started pitching in and helping out.

Someone starts a thread addressed to me for help and before I can answer he's already had a kind offer from someone local to him!

Keep the flame burning! Tubes forever - transistors never!:rockon2:

:food-smiley-004:

[bcmatt]

Keep the flame burning! Tubes forever - transistors never!:rockon2:

:food-smiley-004:

Haha! I love that! Wild Bill, you have so many great quotes. I'll be using this one, and your name shall live on.

[nonreverb]

I hope you don't mind me asking him Bill. I'm not trying to interfere..the guys close to me and I thought I could help him out:smile:

This is absolutely great! When I first found this board I noticed how there was very little tech stuff to help folks.

So I jumped in and the word spread quickly. Soon GC gave us our own tech forum. More tech guys started pitching in and helping out.

Someone starts a thread addressed to me for help and before I can answer he's already had a kind offer from someone local to him!

Keep the flame burning! Tubes forever - transistors never!:rockon2:

:food-smiley-004:

[Wild Bill]

I hope you don't mind me asking him Bill. I'm not trying to interfere..the guys close to me and I thought I could help him out:smile:


Mind? I'm tickled pink!

I had been hanging out on some great techie boards from the states before I found this one. I was really hoping that this board could offer some good help with a Canadian focus. A number of guys like yourself have jumped in to lend a hand.

It's exactly what I was hoping! In the words of the song from that immortal band "Strange Fruit": "The flame still burns!"

:rockon2:sdsre:smilie_flagge17:

[Kapo_Polenton]

Props to nonreverb, I never thought of checking the pheripherals for issues but he found that the OHm switch was faulty. the whole time the amp worked in 4 and 16 but not at the 8 ohm setting. Soo much for expecting quality parts to work eh?! I was all proud of myself for updating that switch too.. (the old crappy one worked just fine). The pots are not the best either but that is easy enough to fix. You'd think I've learned not to build amps from this experience but I think I'll have another go this summer because its damn fun.

Back in business! :rockon2:

Any of you guys need servicing or work done to your amp in Ottawa, contact Richard/nonreverb. Great guy to deal with and knows his $hit.

[bagpipe]

He fixed it over the phone, or via email/PMs? If so, thats pretty impressive. :bow:
If I ever need work done on my amp, I'll know who to contact.

[Kapo_Polenton]

Nope, not quite that simple.. I had to bring it to him but it was well worth the use of my lunch hour.:) With tube amps it could be the smallest of detail you've overlooked. Almost impossible to do that over the phone or by pm. Nothing beats someone who is qualified as they have a better sense of where the trouble may be.

[shoretyus]

Nope, not quite that simple.. I had to bring it to him but it was well worth the use of my lunch hour.:) With tube amps it could be the smallest of detail you've overlooked. Almost impossible to do that over the phone or by pm. Nothing beats someone who is qualified as they have a better sense of where the trouble may be.

I can never stay for just one potato chip.... Rich is one of those 5 star type guys.

If you get a chance ask to see the B-hive :wave:

[nonreverb]

Nope, not quite that simple.. I had to bring it to him but it was well worth the use of my lunch hour.:) With tube amps it could be the smallest of detail you've overlooked. Almost impossible to do that over the phone or by pm. Nothing beats someone who is qualified as they have a better sense of where the trouble may be.

Thanks for the feedback my friend...I'm glad I was able to help you out:food-smiley-004:

[Kapo_Polenton]

Nonreverb has really helped me out soo far with this plexi of mine and I am almost there.. thought I would post a clip of it for you guys. Currently, it sounds like $hit lol! Its flubby. I am not sure if this is because of a bad filter cap or what... but anyway, here it is. The overdrive pedal kicks in after the open E palm muting. http://media.putfile.com/Plexi-II Maybe with a bit more patience and research I'll get it. I'm learning some really useful stuff though.. just sucks its taken me a year to get it finished and now troubleshooted. :bow:

[Kapo_Polenton]

Hey guys if you have heard this type of tone before and know what it stems from, don't be shy in piping up. Right now to me it sounds like i am playing a fuzz pedal.. it seems like ther eis a lot of preamp gain or that the circuit is being pushed. Altering the bias may help but i'm open to the craziest of suggestions. Besides it will allow us to go through more stuff before I bring it back in to the shop for Richard! ;)

[Kapo_Polenton]

Got her runnin... needed an extra .68uf cap to tighten the bass up and one of my tube sockets has lose pins that need tightening. CAse closed. KT-77's are bassier than EL34's though, I'm running this with the bass at around 2 presence almost full as i snippd my bright cap. Stay tuned for a sound clip.