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Author
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Topic: Session 400 spitting/distortion
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Dave Ristrim
Member From: Whites Creek, TN
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posted 26 March 2005 05:18 AM
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Okay, I now have 3 older Peavey Session 400's that all have the same problem. When I give them a strong signal, they spit. By spit, I mean they breakup in a harsh "digital distortion" kind of way. It's not the speakers, is it the output transitors? It happens with steel as well as electric guitar. These amps should sound louder and cleaner than they are, I think...
Man, this is driving me crazy. Maybe I'll send one back to Peavey, let them fix it and repeat the fix on the other 2? Any help would be much appreciated. If you think you have the answer, e-mail me your phone number and I'll call you and be forever in your debt.
Dave Ristrim |
LARRY COLE
Member From: COLUMBUS, OHIO, USA
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posted 26 March 2005 05:48 AM
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Dave, this sounds like the problem that is common on the Nashville 400. The power amp in jack gets dirty where it makes contact when there is nothing pluged into it. If this amp has preamp out and poweramp in, plug a cord from pre amp out to power amp in. If this clears up the problem the jack needs cleaned or replaced. I just bought some switchcraft jacks to change in my Nashville and two for a friend. Let us know if this is the problem.------------------
Playing For JESUS,LC. WILLIAMS U12,SHO-BUD PRO1,CARVIN TL60,GIBSON LES PAUL CUSTOM,YAMAHA L-10A ACOUSTIC,ROLAND JW-50 KEYBOARD,G&L AND BC RICH BASS'S
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Mike Wheeler
Member From: Columbus, Ohio, USA
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posted 26 March 2005 05:55 AM
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Hi Dave,I had a 400 years ago that developed the same problem...and I understand a few others have as well. Aside from the usual suspects, ie; reverb connector loose, 1/4 in. jacks intermittent, junk in BW gap, it would most likely be a cold solder joint. These amps are often subjected to a lot of low frequency vibration from our steels. That promotes cold joints, and the sound you hear is caused by the bad connection being "shaken". The location of the bad joint is often very difficult to find without some test equipment, but, sometimes a good visual inspection can locate it (could be more than one)...it can be hiding UNDER a solder bubble and you won't see it at all! With my 400, I had the time and just went thru EVERY solder point and cleaned the old solder off, then applied new....problem solved....but never did figure out which one was the bad one. If you've checked the usual suspects and can't find a cause, and you're not into a lot of soldering, I'd suggest sending it to Peavey. I'm sure they've dealt with this problem many times. ------------------
Every day is a Great day,
Mike
(aka Sideman) |
Ken Fox
Member From: Ray City, GA USA
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posted 26 March 2005 06:16 AM
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Have them replace the filter caps and go thru the amps! They will be ready to rock for another 20-30 years. You can't beat the service, quality of work and cost of a Peavey factory repair. |
Dave Ristrim
Member From: Whites Creek, TN
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posted 26 March 2005 07:06 AM
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I will take some time and re-do the solder joints and check the jacks. I also have a re-cap kit from Brad Sarno that I will install. At each step, I am going to re-try the amp and see what fixes it. If none of these fix it, I will send one of them to Peavey and let them give it a go. I will ask them for an explanation if possible. Any other suggestions are still welcome. This is what this froum is all about.
Thank you,
Dave Ristrim |
Bill Terry
Member From: Bastrop, TX, USA
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posted 26 March 2005 09:13 AM
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I've fixed similar solder joint problems on my Session 400, and various Nashville 400's etc. One way to help isolate a bad solder joint is to power up the amp with the chassis out and (carefully) tap around on the PCB with the eraser end of a pencil, listening for noise.A lot of times you'll be able to narrow down the area with the problem as it will be more sensitive to the tapping. |
Tony Palmer
Member From: Lincoln, RI USA
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posted 31 March 2005 10:47 AM
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Dave,
A friend of mine had the same problem and it was not what usually happens...it was his George L cords...he had to tighten one of the cord ends to fix the problem.
The fact that it's happening on all 3 of your amps makes the cords suspect... |
Dave Ristrim
Member From: Whites Creek, TN
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posted 31 March 2005 02:38 PM
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No problems with cords. I have a good supply of the best, and when I get a bad one, I cut the ends off to use later if I need them. Thanks for the input though. I am hopefully going to start a re-solder on one of them and see what happens. It's driving me crazy. I even took the :head" into a shop here in the Nashville area and they couldn't fix it. Maybe it's just me?
Dave |
Mike Wheeler
Member From: Columbus, Ohio, USA
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posted 31 March 2005 05:54 PM
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I know what you mean Dave, I used to be one of those shops in Nashville. A tech will often look for the most common causes and work down toward the more complex. Given that he has to maintain an income per hour rate, he may not go to every length to accomplish a repair. A cold solder joint can be a bear to find when you are on a time constraint. Not justifying, just giving insight.Anyway, good luck on the solder job...and take your time to do it right the first time. Doing it the second time really sucks! lol |
Dave Ristrim
Member From: Whites Creek, TN
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posted 31 March 2005 07:08 PM
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Hi Mike,
You're right about repair shops spending time on items that are hard to figure out where the source of the problem is. I just was bummed out, because both my amps at the time, Vegas 400 and Session 400 head were having problems. I normaly can fix my own amps if it's something not too difficult, but felt maybe someone else should fix these. Well, I took them in, explained both problems and said not to spend any time on other issues, just the problems I described. A month later when my amps were "done" I excitedly picked them up, took them home, plugged them in and was hearing the same problem they had before I took them in. So I guess I payed the guys $125 to just clean the pots, which I told them not to do.
I'm over it. They are nice guys and I hear they do do good work. Wow, I feel better.
Thanks for listening,
Dave |
Mike Brown
Member From: Meridian, Mississippi USA
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posted 04 April 2005 11:30 AM
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Let me know if I can assist. |
Ken Fox
Member From: Ray City, GA USA
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posted 07 April 2005 09:54 AM
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I have a similar problem with a Session 400. I am a tech and it still has driven me nuts! Mine is in the power amp board, as I can disconnect the prremp from it completely and it still has the noise. I have chased it with a heat gun and with a can of freeze. I have changed the common problem, the long-tailed pair at the front of the chain! I have spoke at length to Peavey on their Forum and they agree it is one of the hardest to trouble shoot, as it shows up everywhere in the circuit (feedbacks circuits all over in there). Breaking the circuit apart is one way but the amp can go nut when you do that and burn out a speaker! Best way is with a dummy load, still it can destroy output transistors if it gets too unstable! This one is may end up back at Peavey, as I just can't get a handle on the problem. |
Mike Wheeler
Member From: Columbus, Ohio, USA
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posted 08 April 2005 06:34 AM
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I hear you Ken! Been there many times...And I have the gray hair to prove it!!I used to first, analyze the hum signal itself to determine if it was truly 60 cycle related, was there any digital trash on it, or other switching noises, etc. It usually was 60 cycle hum, so power supply caps were probably bad..BUT, when, in cases like you describe, I'd take a deep breathe,then proceed. When the usual hot/cold tests wouldn't turn up anything, I'd start tracing with my O-scope watching the hum voltage very closely. IF I could narrow down to an area with slightly higher hum voltage, I'd start replacing small filter caps in that area. They can play havoc with signal paths...I know, some just filter the digital trash off the low voltage lines, but they also provide for some circuit isolation. Anyways, a bad one, in just the right place, can result in what sounds like hum...then there's off value resistors, and so on. What a headache these are. I'm gettin' one just thinkin' about it!! Just a thought....I hated chasing these buggers down, too.[This message was edited by Mike Wheeler on 08 April 2005 at 06:36 AM.] |
Dave Ristrim
Member From: Whites Creek, TN
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posted 08 April 2005 06:56 AM
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Wow. The more I think about it, I should just take the worst one and send it to Peavey. I will try them out, box and ship one in a couple weeks. You'll hear the results here.
Dave |
Ken Fox
Member From: Ray City, GA USA
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posted 08 April 2005 07:15 AM
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Mine is not hum. Intermittent spitting sound, just like an old Fender with bad plate load resistors. It is in the power board. All electrolytic caps are new, I replaced them all myself. I think I narrowed it down to one of the dual diodes in the bias lines. It is intermittent, does not respond to heat or cold. I also resoldered ever connection on the power board yesterday. Sometimes it can go an hour and never make a peep. Other times it is noisy for an hour! It appears everywhere with a scope! Truly a challenge. I sure love this amp and I will overcome this problem!!!! |
Dave Ristrim
Member From: Whites Creek, TN
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posted 08 April 2005 08:49 AM
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Ken, when you find the problem, please let me know. It sounds like the same problem I have.
Dave |
Marty Pollard
Member From: a confidential source
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posted 08 April 2005 09:44 AM
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My Session 500 started spitting loud, freaky distortion at power up. If I smacked the cabinet I could make it happen. It happened w/all the controls in the off position. Naturally it started at a high-profile job!Unplugging the speaker was the only way to stop the noise but I could still see the clip light activating. Problem would stop after 4-5 minutes. Sent it to Peavey and asked for the mod at the same time. Works perfectly now... |
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