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Author
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Topic: Session 500 distortion: a common failure?
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Eugene Cole
Member From: Washington Grove, MD, USA
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posted 08 December 2005 04:37 PM
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When I turned on my Session 500 (Peavey) tonight and started to play through it I was hearing a conspicuous amount of distortion. I have not yet done determined if the distortion is coming from the preamp or power amp portion of the signal path. I will do this tomorrow. Diagnostically I have only performed the following diagnostics at this time.
1. Disconnected everything from the eternal signal loops.
2. Tried 3 different instrument cables.
3. Tried 3 different instruments with the various instrument cables.
4. Connected it to a different system via the XLR jack (I heard no audible distorion). I have concluded that the distortion is coming from from the amps power-amp stage.
Question: Are their components which are know to be prone to failure on these amps?
Update:
The problem is in the Power Amp section of this amp.
------------------
Regards
-- Eugene at FJ45.com
 Click Here
Sierra U14, MSA D10, and almost nothing in the Bank. 8^)
[This message was edited by Eugene Cole on 19 December 2005 at 07:01 PM.] [This message was edited by Eugene Cole on 20 January 2006 at 01:11 PM.]
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Jack Stoner
Sysop From: Inverness, Florida
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posted 09 December 2005 03:18 AM
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Going by the age of Session 500's, if the power supply filter caps have never been replaced that would be the first place to start. If the power supply voltages are off that will cause distortion. Happened in the 500 that I had and to a couple others that I know of. There may be other issues but the first thing is the filter caps. |
Donny Hinson
Member From: Balto., Md. U.S.A.
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posted 09 December 2005 07:21 AM
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Could be just a dirty pot. Cycle all the pots on the amp back and forth about 15-20 times to "clean out the cobwebs".  |
Bob Hamilton
Member From: Atascadero, California, USA
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posted 09 December 2005 07:27 AM
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Make sure the "String Effect" switch is off.... |
Mike Brown
Member From: Meridian, Mississippi USA
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posted 09 December 2005 08:52 AM
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Ditto to Bob's comment. Then proceed with the caps. |
Jack Stoner
Sysop From: Inverness, Florida
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posted 09 December 2005 08:56 AM
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Also, send it to Peavey for repair if it's not something obvious like the string effect. For 99% of needed repairs that is the best place to go. Call Mike first, before shipping it to get the needed info. |
Mike Brown
Member From: Meridian, Mississippi USA
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posted 12 December 2005 08:54 AM
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Thanks Jack. Our service address is;
Peavey Service Center
Attn; Repair Department
412 Hwy. 80 East
Meridian, MS 39301Please include a note of symptoms as well as your daytime phone number. Mike Brown
Peavey USA |
Eugene Cole
Member From: Washington Grove, MD, USA
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posted 19 December 2005 06:11 PM
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The problem is in the Power Amp section of this amp. In the interim I have a Peavey Combo 300 which has been on loan to someone for a long while. It will be returned to me in a few days. As I recall I prefered the Session 500 to this amp because it has a balanced line out which allowed me to use its POST gain control to set my "instrument-monitor" level myself and got rid of all of the issues related to miking a speaker cabinet. I think that the Combo 300 has a 5 band non-parametric EQ, no onboard Reverb, it lacks the "String" circuit which I never used because it introduced a conspicuous amount of distortion. ------------------
Regards
-- Eugene at FJ45.com
Click Here
Sierra U14, MSA D10, and almost nothing in the Bank. 8^)
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David Wren
Member From: Placerville, California, USA
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posted 20 December 2005 02:32 PM
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I picked up a session 500 which had been in storage (damp) for some period. The distortion in this case only occurs > about 1/2 volume, and sounds like signal over- driving (strong picking action on the string will produce the distortion).
In my case I know it is in the pre amp, and not speaker or power amp. I also heard some noise in the freqency shift pot. I'm going to clean the pots well next, but could this be a candidate for filter caps as well? And is there a way to by-pass EQ in the pre amp?------------------
Dave Wren
'95Carter S12-E9/B6,7X7; Session500; Hilton Pedal
www.ameechapman.com |
Mark Fasbender
Member From: Salt Lake City,Utah
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posted 20 December 2005 06:25 PM
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If it were my amp I'd check the pedal I-O jacks and all the other normalled-thru jacks on the amp. When not in use, these jacks pass signal through small contacts and can cause lots of trouble when the contacts are dirty or whatever. Distortion and cutting in and out are very common.
It's also the easiest thing to fix- either use a good contact cleaner (blow - off) or burnish the contacts in severe cases.
Good luck.  ------------------
Got Twang ? Mark |
David Wren
Member From: Placerville, California, USA
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posted 22 December 2005 09:38 AM
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Thanks for the advice, I'm armed with a brand new can of cleaner, and today's the day. Hope you get your 500 working too Eugene..... sounds like your preamp and my power amp would make a good unit :-)Merry Christmas everyone. ------------------
Dave Wren
'95Carter S12-E9/B6,7X7; Session500; Hilton Pedal
www.ameechapman.com |
Mark Fasbender
Member From: Salt Lake City,Utah
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posted 22 December 2005 12:12 PM
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Dave............. In the case of an amp thats been in damp storage be sure to clean and tighten EVERY connector you can find. EVERY jack too. Also the connectors between the pre section and the power section (Session 500). I love 500's and 400's and they are great with a little tlc. Good luck.------------------
Got Twang ? Mark |
Eugene Cole
Member From: Washington Grove, MD, USA
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posted 20 January 2006 12:57 PM
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At this point I am pondering shipping it to Peavey for servicing.If I decide to ship it: How should it be packed for shipment? ------------------
Regards
-- Eugene at FJ45.com
 Click Here
Sierra U14, MSA D10, and almost nothing in the Bank. 8^) |
Eugene Cole
Member From: Washington Grove, MD, USA
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posted 20 January 2006 01:47 PM
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I have not yet pulled the components out of the cabinet to inspect them but I will do so prior to shipping it off to Peavey. The answers to some of my questions may become apparent after I inspect the cicuit boards. I tried locating the documentation for this amp on the Peavey web site. But it appears that the only documentation which is still available for this (20+ year old) amp are realated to the "tone enhancement kit" which is limited to the pre-amp section.
All of my copies of these files (PDF files as I recall) probably disappeared 12 to 24 computers ago. The information about the tone enhancement kit did reveal that the preamp section requires a +15 & -15 power input. However I have no idea what the voltages going to the power amp section are supposed to be. If any of you still have your downloaded copies of any of the documantation; particularly the schematics or the owners manual please email either them or the URL's for them to me directly. ------------------
Regards
-- Eugene at FJ45.com
Click Here to visit my FJ45 site.
Sierra U14, MSA D10, and almost nothing in the Bank. 8^) [This message was edited by Eugene Cole on 20 January 2006 at 01:51 PM.]
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