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Post new topic Matchbox mysteries (and a problem)
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Author Topic:  Matchbox mysteries (and a problem)
Dan Beller-McKenna


From:
Durham, New Hampshire, USA
Post Posted 18 Mar 2017 9:57 am     Reply with quote

In my quest to completely duplicate my equipment (so as not to drag everything from my study to the room on the other side of the house where my band rehearses), I recently picked up a second matchbox. This one is a 7a, the one I already had is a 6a. Right off the bat I noticed that they behaved decidedly differently. The 7a was way hotter. With a little more experimenting I noticed that the the Gain control on the 7a added gain to the signal; turned fully counter-clockwise, it allowed the regular signal through, boosting as it was turned clockwise. Quite otherwise, on my 6a it is a pure and simple volume control: fully counter clockwise = no signal; fully clockwise = full signal.

I was wondering whether the batteries in the 6a had gone south (although I checked them a couple of months ago.) When I opened up the two units, I found the board in the 7a to be way more loaded than that in the 6a.







Some of this certainly has to do with the on/off switch, which is not present in the 6a. I had read in several places that that was, in fact, the only difference between them; but there are several more components on the 7a board. I don't know much about electrical circuits, so perhaps these are necessitated by the on/off switch.

You may notice that there are the same mismatched pairs of batteries in each units. The newer 9vs in the 7a measured at 9.5, while the older ones in the 6a measured 8.5. I thought "balancing" them might get the two units to act somewhat more similarly. No.

Here's where things get more interesting (and not in a good way). Somehow, by opening up the 7a and swapping a battery, I introduced a couple of problems; hoping some of you will recognize these and know a quick, silver-bullet solution.

1) The 7a now makes a very loud pop when the unit is turned on from the toggle switch. Very loud. Unplugging the chord from the amplifier (not from the 7a) has the same effect. Sounds like a solder joint and/or grounding problem. I did find a very old post that may relate: http://steelguitarforum.com/Forum11/HTML/002389.html Any thoughts? I will try retensioning the various items mentioned in that thread.

2) Much stranger: the tone pot now does absolutely nothing. The signal goes through it (because it goes to the amp and is affected by the gain pot), and the pot shows changes in resistance on my multi-meter when I turn it, but there absolutely no change in tone, volume, etc. Could I have messed up a ground somewhere that is causing the signal to go straight past the tone pot? Could that be directly related to the popping? Inquiring minds want to know.

For what it's worth, the 7a spent some quality time (15-20 minutes) in a snowbank on Wednesday. It was well insulated from the snow (very well packed by the seller) and inside a plastic bag. But the ever resourceful Fedex guy, encountering our driveway with a fresh 14" of snow from the night before, put the item in the plastic bag and tossed it over the "plow wall." March in New Hampshire: good times, good times.

Thanks,

Dan


Last edited by Dan Beller-McKenna on 18 Mar 2017 4:38 pm; edited 4 times in total
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Dan Beller-McKenna


From:
Durham, New Hampshire, USA
Post Posted 18 Mar 2017 11:36 am     Reply with quote

Retensioning the battery terminal receptors did cure the loud pop. No progress on the ghost tone control, though.
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Dan Beller-McKenna


From:
Durham, New Hampshire, USA
Post Posted 20 Mar 2017 7:22 am     Reply with quote

TTT

Anyone have any ideas?

Thanks.
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Jon Jaffe


From:
Austin, Texas
Post Posted 20 Mar 2017 4:27 pm     Reply with quote

I have a Goodrich Steel Driver, older than the Matchboxes, that died. I sent it to Goodrich and they sent it back with my money saying they could not fix it. One of Austin's great drummers, Terry Kirkendall, who also QCd and repaired circuit boards for AMD, I think, fixed it in a day (30 minutes). He said it was a bad solder that was not visible. It's a long shot, but if you know someone who is facile with soldering, give it a try.
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Dan Beller-McKenna


From:
Durham, New Hampshire, USA
Post Posted 20 Mar 2017 5:28 pm     Reply with quote

Thanks, Jon. I might just send it to Kevin at Steel Guitars of North County. It is probably something simple like that.
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Carl Mesrobian


From:
Salem, Massachusetts, USA
Post Posted 31 Mar 2017 5:09 pm     Reply with quote

Dan poke around with a chopstick. I had a Matchbro that had a loose hex nut stuck under a board.

A good visual check can sometimes be all you need.
_________________
--carl

"Just because I'm not paranoid doesn't mean they're not out to get me!" --Pat Farrell, Salem, MA
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kevin ryan


From:
San Marcos, California
Post Posted 1 Apr 2017 7:35 am     Reply with quote

Hey Dan, By looking at the picture I can tell its probably one of the early 7A's produced by Goodrich. One thing I have found with all the Goodrich stuff is that it gets used a lot and with that comes many hours of wear and tear. The stuff that comes in here at Goodrich is almost hilarious how much these things get bounced around and keep on ticking. With that, you can send that device in and I will take a look at it no charge, probably something simple .... and or we can put all new guts in it for you and it will be brand new... Just let us know
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Dan Beller-McKenna


From:
Durham, New Hampshire, USA
Post Posted 1 Apr 2017 7:44 am     Reply with quote

Thanks all for the ideas;

Carl: that is a good point. I did give it a good look under and around stuff (short of taking the board off completely. I think it's something electrical, probably a solder joint come loose.

Kevin: thanks,that's what I've been planning to do (send it to you). Things have been a bit to zooey the last few weeks to find time to pack it up etc. My life gets a lot simpler after next weekend, and I'll send it along then. Glad to have you taking care of all us Goodrich users!

Dan
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Jim Reynolds


From:
Franklin, Pennsylvania
Post Posted 7 Apr 2017 2:22 pm     Reply with quote

Jon, I'm surprised a cold soldier joint wouldn't have showed up long before 2017. No pun intended, but just seems that way. My first Matchbox was bought in 1984, when Jeff first said "You have to have one". Used one ever since, and wouldn't play with out, but don't ask me why. hahaha.
_________________
Carter U-12, Black Mullen S-10 Discovery, Zum StageOne
, Morrell 8 String Lap Steel, Morrell Dobro, 2 Peavey Nashville 112, Ibanez DD700, Every Lesson Jeff Newman made. 1947 SJ Gibson Guitar, Washburn Special Edition Guitar, 1963 Original Hofner Beattle Bass bought in Germany 1963, and a 1973 Framus Bass.
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Erv Niehaus


From:
Litchfield, MN, USA
Post Posted 8 Apr 2017 8:19 am     Reply with quote

I just like to have a tone and volume control right at my fingertips. Very Happy
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