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Ol' Sidewinder [message #23797]

Thu, 10 September 2015 19:30

Mrd34d
Messages: 9
Registered: September 2015

Junior Member

Hey this is my first post; hello.

So I've recently acquired a Sidewinder combo Model 24-C, serial: 37243. Long story short, it is a god awful mess. There's no speaker, the castors are are rusted & cracked, the handle is rusted, the bottom of the TNR is shredded, and more importantly; the doesn't work.

There was a resistor fire (R18), and it took out a few others around it. Also the pilot light is missing the bulb. It also needs the obvious 3-prong conversion.

I plan on building a new cabinet (and learn how to do TNR ) for it and making it a head unit. I'm gonna give it clearance for air flow, try to use the old speaker screening, tinsel spline and logo as to maintain the original look.

I'm hoping someone can give me some insight into what light bulb this thing needs, if there's a problem that's common among these amps that could've caused the resistor fire, and perhaps some info on when it was made.

Also many websites & old ads show this amp as a 150watts...but it says 75watt RMS on it...so which is it?

Thanks

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Re: Ol' Sidewinder [message #23798 is a reply to message #23797]

Thu, 10 September 2015 21:51

pleat
Messages: 1454
Registered: June 2004
Location: Belding, Mi

Senior Member

Welcome to the site. Kustom rated their amps a peak power so the sidewinder would be half of the 150 watts PP or 75 watts RMS driving a 8 ohm speaker.
A few things that might work. If the majority of the T&R from the bottom is really toast. Is the top part of the T&R good? If so, you might want to make it into a piggyback amp head. Remove the speaker baffle board, and I'd count down 4 T&R from the top down each side and cut the sides off. You will have to un-staple a few row's of T&R and cut the sides again flush with the shelf that the amp sits on. Re upholster the bottom sides with the original excess material from cutting it long at the start.

I bought a red K50 that had been chopped and converted into a piggyback head. Amp had sat in a foot of water and ruined most of the amp cabinet. Who ever did the conversion did a great job and if you saw it, you'd swear it was done at the factory.

The problem with starting from scratch in sewing a new T&R covering is the foam. Kustom used a V cut foam that was sewn into the strips of the naugahyde. We've had car upholsters that say they can duplicate it and some get it close, but I've never seen a perfect match to the original.

I'll leave it up to the tech guys on the amp issue, but you can find the schematics for your amp in the technical tab on the left side of the site.

pleat

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Re: Ol' Sidewinder [message #23799 is a reply to message #23797]

Thu, 10 September 2015 23:31

chicagobill
Messages: 2006
Registered: April 2003

Senior Member

Yes, welcome to the site. I love that series of amps. Just enough power for small gigs, great effects and look good too.

If you are talking about R18 on the power amp board, you probably have some shorted transistors in there.

The light bulb is a 28 volt bulb #335. They are still available from larger electronics supply houses. If you are planning on repairing the amp yourself, you may want to start a parts order list.

What are your technical abilities and what sorts of test equipment do you have access to?

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Re: Ol' Sidewinder [message #23800 is a reply to message #23798]

Thu, 10 September 2015 23:46

Mrd34d
Messages: 9
Registered: September 2015

Junior Member

pleat wrote on Thu, 10 September 2015 21:51

Welcome to the site. Kustom rated their amps a peak power so the sidewinder would be half of the 150 watts PP or 75 watts RMS driving a 8 ohm speaker.
A few things that might work. If the majority of the T&R from the bottom is really toast. Is the top part of the T&R good? If so, you might want to make it into a piggyback amp head. Remove the speaker baffle board, and I'd count down 4 T&R from the top down each side and cut the sides off. You will have to un-staple a few row's of T&R and cut the sides again flush with the shelf that the amp sits on. Re upholster the bottom sides with the original excess material from cutting it long at the start.

I bought a red K50 that had been chopped and converted into a piggyback head. Amp had sat in a foot of water and ruined most of the amp cabinet. Who ever did the conversion did a great job and if you saw it, you'd swear it was done at the factory.

The problem with starting from scratch in sewing a new T&R covering is the foam. Kustom used a V cut foam that was sewn into the strips of the naugahyde. We've had car upholsters that say they can duplicate it and some get it close, but I've never seen a perfect match to the original.

I'll leave it up to the tech guys on the amp issue, but you can find the schematics for your amp in the technical tab on the left side of the site.

pleat

Great advice! Thank you!

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Re: Ol' Sidewinder [message #23801 is a reply to message #23799]

Thu, 10 September 2015 23:53

Mrd34d
Messages: 9
Registered: September 2015

Junior Member

chicagobill wrote on Thu, 10 September 2015 23:31

Yes, welcome to the site. I love that series of amps. Just enough power for small gigs, great effects and look good too.

If you are talking about R18 on the power amp board, you probably have some shorted transistors in there.

The light bulb is a 28 volt bulb #335. They are still available from larger electronics supply houses. If you are planning on repairing the amp yourself, you may want to start a parts order list.

What are your technical abilities and what sorts of test equipment do you have access to?

I can solder no problem (I do all of my guitars, have modded gaming systems, wired motorcycles), schematics I understand for the most part if I have a symbol legend near. Anything I don't understand, I research the hell out of before proceeding.

As for test equipment; I've got a couple of multimeters. And ya, I was looking to tackle this myself. See when I got the amp, I found a mouse nest sitting on the power amp board. My theory is that the first owner put it away for a while, a critter got in there, did its thing and left. Owner A then gave it to owner B who tried to power it up and fried it (not knowing about the nest), then sold it to me. I knew it didn't work but didn't know why until I got it home.

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Re: Ol' Sidewinder [message #23802 is a reply to message #23797]

Fri, 11 September 2015 00:15

chicagobill
Messages: 2006
Registered: April 2003

Senior Member

Yeah, mice will do a real number on electronics. As I understand it, it is worse now due to the use of soy based plastic insulated wires.

If you need any help, feel free to ask.

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Re: Ol' Sidewinder [message #23805 is a reply to message #23802]

Fri, 11 September 2015 01:04

Iowa Boy
Messages: 767
Registered: June 2014

Senior Member

As to the tuck and roll.....a guy here did a sample of T&R for me and I couldn't tell the difference between the original and what he did. He tried cutting the V in the foam but was very time consuming and didn't look quite right. He then just folded the foam with the material and made the pleat. You couldn't tell the difference, was a perfect match in every way. He wants $150 just to do an amp head but from what I saw, it's worth every penny. He cranked out 8 pleats the exact size of the amp head in less than 10 minutes and that included marking the foam where the stitching was to go. So there are people out there who can do it.....ask for a sample first before having it done just so you can see what your paying for.

Welcome to the wonderful world of Kustom......you're in for a great ride.

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Re: Ol' Sidewinder [message #23813 is a reply to message #23805]

Fri, 11 September 2015 19:43

pleat
Messages: 1454
Registered: June 2004
Location: Belding, Mi

Senior Member

Let us know how it turns out. I saw one that was really well done, but when you counted the T&R on the sides on a 2x15 cab, should be 18 from the factory and his was 19. Also the corners were not to factory appearance. The odd part is, each T&R measured 2".
pleat

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Re: Ol' Sidewinder [message #23815 is a reply to message #23813]

Fri, 11 September 2015 20:05

Iowa Boy
Messages: 767
Registered: June 2014

Senior Member

I'll bet the material wasn't stretched like it was done in the factory. I remember hearing that the women who did the T&R would complain about their hands hurting at the end of the day from stretching the material to make it fit. Probably explains why on some cabinets the stitching now shows at the pleats.......realize there was shrinkage with time, but was also probably stretched maybe a little too much.

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Re: Ol' Sidewinder [message #23820 is a reply to message #23797]

Sat, 12 September 2015 07:40

Mrd34d
Messages: 9
Registered: September 2015

Junior Member

well I've got a parts list together based on the help from here and at talkbass.com forums. I still need to get the values for the two transistors. Would I be missing anything?

Kustom sidewinder resistor values

Resistor - "R26" - 510, 5% 1/2w
Resistor - "R18" - 1K 1/2w
Resistor - "R25" - 150 1% 1/2W
Resistor - "R24" - 0.51 5W

Diode - "CR2" - 1N4007
Diode - "CR1" - 1N4007

Wire wound sand resistor - "R21" - 510(0.51ohm), 5% 5W

Q5 - transistor
Q7 - transistor

Light bulb - 28v #335

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Re: Ol' Sidewinder [message #23827 is a reply to message #23820]

Sat, 12 September 2015 12:18

chicagobill
Messages: 2006
Registered: April 2003

Senior Member

I've responded to your other posts in the replacement parts section, but as far as I can see the only problem is that you have listed R21 as a 5 watt power resistor, which is what R24 is.

R21 is the same as R26 510 ohms 1/2 watt 5% tolerance.

Have you tested all of the transistors on the board as well as the two main power transistors mounted to the chassis? Q7 is the one of the protection transistors and was originally a 2N3638.

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Re: Ol' Sidewinder [message #23832 is a reply to message #23797]

Sat, 12 September 2015 19:59

Mrd34d
Messages: 9
Registered: September 2015

Junior Member

ya I think I updated the list since; I caught the error.

There's been a new development...the smaller Transformer has been bypassed. Green, Red, green/yellow, and red/yellow wires were cut from the transformer, and spliced together. Green to green/yellow and Red to Red/yellow.

Why would this be done? Should I set it back? Could it be the cause of the blown resistors on the power amp circuit?

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Re: Ol' Sidewinder [message #23834 is a reply to message #23797]

Sat, 12 September 2015 20:25

chicagobill
Messages: 2006
Registered: April 2003

Senior Member

The smaller transformer is a dual section choke (inductor). I don't know why it was removed, it is there to help stabilize the power supplies. It would not be the cause of the burned resistors in the power amp.

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Re: Ol' Sidewinder [message #23835 is a reply to message #23834]

Sat, 12 September 2015 20:59

Mrd34d
Messages: 9
Registered: September 2015

Junior Member

chicagobill wrote on Sat, 12 September 2015 20:25

The smaller transformer is a dual section choke (inductor). I don't know why it was removed, it is there to help stabilize the power supplies. It would not be the cause of the burned resistors in the power amp.

Should I hook it back up then? I had planned on it, but thought I'd ask first

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Re: Ol' Sidewinder [message #23836 is a reply to message #23797]

Sat, 12 September 2015 22:33

chicagobill
Messages: 2006
Registered: April 2003

Senior Member

I guess that you should try testing it first. There may be a reason that it was removed from the circuit.

The main thing would be to see if both coils are still intact and are not shorted to the core lamination.

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