| Quad 100 DFXWT "special edition" - repairs [message #25371] |
Sun, 07 August 2016 10:36  |
ghramsey
Messages: 3
Registered: July 2016
Location: Houston, TX - USA
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Junior Member |
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My buddy got this amp from his ex-girlfriend it is a Kustom Quad 100 DFXWT "Special Edition".
The amp has a short somewhere that is making the sound cut out.
Banging on it near the effects circuit board would make the sound come back on or any sound transient input such as
bashing strings on a guitar or tapping a mic makes the sound come back on briefly only to cut off again.
I pulled the main circuit board and found the effects switch was extremely loose and four of the eight solder joints had
pads that seemed to be lifting from the board. This is a BCD switch to select which effect is put into the audio path
I think.
I tried to secure it and tried to re-flow the joints using a low-watt pencil iron, but the pads were just totally
broken from the board as I had originally suspected. I think there are only 4 connected traces and the other four
are to secure the switch to the board. These are the ones that are completely lifted. I suspect a prior repair attempt
based on how badly the pads were lifted. The amp was reportedly dropped while moving from AZ to TX.
Looking at the schematic for this amp it doesn't even look like that switch is even in circuit when the effects are turned off.
The other controls seemed to be OK and I re-flowed solder on one other control where the solder joints were moving when I wiggled the switch.
I reassembled the amp and the issue remains. It still just stops unless it receives a large transient signal.
I did not see any other cracked traces, but I supposed there might be plenty I missed.
I was appalled at how flexible the circuit board is.
Is there any way to fix this amp or is it just a pile of junk now?
What else should I try to look for that might be causing the sound to stop?
Can I buy a replacement circuit board somewhere?
I realize this is a forum for vintage amps. Is there one for more modern Kustom amps?
Any help will be appreciated.
Henry
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| Re: Quad 100 DFXWT "special edition" - repairs [message #25377 is a reply to message #25375] |
Sun, 07 August 2016 20:10  |
ghramsey
Messages: 3
Registered: July 2016
Location: Houston, TX - USA
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Junior Member |
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stevem wrote on Sun, 07 August 2016 18:21Many times the switch contacts within the jacks themselves in these effects loop sections become tarnish and or dirty and need to be cleaned.
Without go closure cionnectiions in these Jack when there is nothing plugged in the signal can not get thru to the driver stage and then on to the output stage.
If you take a cord and plug it in to jump those jacks is the amp ok?
If not the amp could have other bad connections due to being dropped and its flimsy build!
If you contact Kustom for a schematic and post it up,here we may be able to help you further .
I cannot post a link to the schematic I got nor attach it to this post since I do not have enough posts.
I see what you are saying about the effects loop. It connects to a buffer circuit which goes
to power amp board. I am not 100% certain that schematic is same as for this amp though.
Difference is this one says "special edition" the circuit diagram does not.
I will check out the effects loop however and I need to find a way to try both the CD input and the XLR line out.
I don't have an XLR cable, but my friend who's amp this is will have one.
[Updated on: Sun, 07 August 2016 20:12] Report message to a moderator |
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| Re: Quad 100 DFXWT "special edition" - repairs [message #25379 is a reply to message #25371] |
Mon, 08 August 2016 06:13 |
stevem
Messages: 4774
Registered: June 2004
Location: NY
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Senior Member |
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You can jump failed circuit board traces with wire once you scrape off the soldering mask that boards have.
I use a small wire wheel attachment in my Dremel tool or a Xacto knife.
On any tube amp I work on I jump out all the connections on the output tubes even if they are good to prevent a future issue and you may have other broken board traces than need to be found and using you meters continuity ring tone mode will help you do such !
Just put up enough post that say " test" until you can post up schematics or what not and then latter I will delete them from this string!
[Updated on: Mon, 08 August 2016 06:16] Report message to a moderator |
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| Re: Quad 100 DFXWT "special edition" - repairs [message #25390 is a reply to message #25379] |
Mon, 08 August 2016 07:07 |
GHR1227
Messages: 1
Registered: July 2016
Location: Houston, Texas USA
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Junior Member |
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This is where I got the schematic from:
http://music-electronics-forum.com/t28128/#post372832
I'm uncertain it is actually correct one other than being for Quad 100 model.
This amp I have says special edition and the schematic doesn't.
How do I make a file attachment? There is still no option to do that even after 10 posts.
I see what you are saying about jumping the traces. That could work, but I need really thin insulated wire.
The smallest wire I have here is bare 20 gauge. I have not worked much on PCB stuff like this.
All my electronics experience is with home brew tube based guitar amps for my own use.
Maybe building some pedals. So I'm not inexperienced generally.
It's funny about 20 years ago I got a "luggable" style computer and it had bunches of traces which were
jumped in the same manner. Solid core 26 or maybe smaller gauge wire.
Money Talks!? All it ever says to me is "Goodbye!"
[Updated on: Mon, 08 August 2016 07:18] Report message to a moderator |
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