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Kustom Sidewinder [message #13417] Mon, 19 April 2010 01:03 Go to next message
Goonak is currently offline  Goonak
Messages: 19
Registered: April 2010
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Hello - can anyone direct me to the correct reverb tank for the Kustom Sidewinder please? There is an Accutronics tank that came with the amp when I bought it about 5 years ago, but I'm not sure it's the right one. The number is 4FB2A5C. The reverb has never worked on this Sidewinder amp since I've had it.

BTW, I also have a Kustom 150 and a 250, and both of those amp heads have Gibbs tanks in them and work fine. I'm hoping that maybe there's just the wrong tank in the Sidewinder?

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Re: Kustom Sidewinder [message #13419 is a reply to message #13417] Mon, 19 April 2010 05:51 Go to previous messageGo to next message
stevem is currently offline  stevem
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Get some long RCA cables from radio shack and patch in the tank from one of you other amps so you can confirm that the rest of the sidewinders reverb circuit is ok.
Its hard to get at those pan connections on the 150 and 250 models so you might also pick up to female to female RCA unions so you can just unplug the cables at the cicuit board side and not struggle with the pan side.
You can make a mistake and plug the test pan in to the sidewinder the wrong way and not hurt the amp, but you will have no reverb eitheir.

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Re: Kustom Sidewinder [message #13425 is a reply to message #13417] Mon, 19 April 2010 12:12 Go to previous messageGo to next message
chicagobill
Messages: 2005
Registered: April 2003
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Welcome!
According to the schematic, the Sidewinder uses the same effects board as the 150 and 250 metal fronts, PC5068. So they will use the same tank, Kustom part #031-0047-00.

Maybe one of the other guys here has the tank codes handy, but if they don't, I'll dig up the correct Accutronics code number for the tank. The tank you have is not original and has a grounded input jack.

The correct tank should have an isolated input jack and a grounded output jack, so the 5th letter in the tank code should be "C" and not "A".

Hope this helps.

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Re: Kustom Sidewinder [message #13428 is a reply to message #13417] Mon, 19 April 2010 12:19 Go to previous messageGo to next message
Van
Messages: 134
Registered: April 2004
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Try this place: http://www.tubesandmore.com/
Type "reverb tank" in their search box.
They have a few NOS Kustom reverb tanks available.

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Re: Kustom Sidewinder [message #13432 is a reply to message #13417] Tue, 20 April 2010 00:26 Go to previous messageGo to next message
Goonak is currently offline  Goonak
Messages: 19
Registered: April 2010
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Thank you all for the help / suggestions.

I tested the reverb tanks of the 150 and the 250 heads through the Sidewinder, but got nothing, no reverb through the Sidewinder. That was disheartening, but I think I have a bigger problem which also may be causing the reverb issues. When I opened the chassis to check the reverb wire connections (and to replace the 335 pilot bulb) I realized that the entire power amp section has been rebuilt and/or modified. The original board is not in the amp. Can I post a picture on here?

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Re: Kustom Sidewinder [message #13433 is a reply to message #13432] Tue, 20 April 2010 00:28 Go to previous messageGo to next message
Van
Messages: 134
Registered: April 2004
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Yes, you can post a picture.
Upload it to a host (photobucket, etc.) and then use the img tags.

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Re: Kustom Sidewinder [message #13434 is a reply to message #13433] Tue, 20 April 2010 00:31 Go to previous messageGo to next message
Goonak is currently offline  Goonak
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OK cool, thanks. I will work on that now!

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Re: Kustom Sidewinder [message #13435 is a reply to message #13434] Tue, 20 April 2010 01:06 Go to previous messageGo to next message
Goonak is currently offline  Goonak
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Registered: April 2010
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OK, here's some pics. The "Tape" output jack has also been eliminated:

http://i778.photobucket.com/albums/yy62/goonak/Kustom%20Sidewinder/DSC03002.jpg

http://i778.photobucket.com/albums/yy62/goonak/Kustom%20Sidewinder/DSC03014.jpg

http://i778.photobucket.com/albums/yy62/goonak/Kustom%20Sidewinder/DSC03015.jpg

http://i778.photobucket.com/albums/yy62/goonak/Kustom%20Sidewinder/DSC03006.jpg

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Re: Kustom Sidewinder [message #13436 is a reply to message #13435] Tue, 20 April 2010 01:15 Go to previous messageGo to next message
Van
Messages: 134
Registered: April 2004
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That looks a lot different than my 250-4.
Maybe someone here with a bit more expertise can help you.

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Re: Kustom Sidewinder [message #13437 is a reply to message #13436] Tue, 20 April 2010 01:20 Go to previous messageGo to next message
Goonak is currently offline  Goonak
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I hear ya. I took a look inside my 150 for comparison and the 150 looks nothing like this section of the Sidewinder. I'm wondering why someone would do this kind of mod? Where the heck did that board come from? But I guess the bigger question would be is it possible for me to even get the Sidewinder back to it's original state?

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Re: Kustom Sidewinder [message #13438 is a reply to message #13417] Tue, 20 April 2010 05:55 Go to previous messageGo to next message
stevem is currently offline  stevem
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That looks like the driver/output section from a stereo or a sub woffer amp, and its not all that new eitheir as it is employing T066 type driver transistors!
I do not think that this is having any thing to do with your reverb problem however.

If you go back and look in this section to postings titled reverb issue you can find out how to test if the amps reverb driver and recovery stages are working or not.
This post was in regards to a K200 amp, but the general test out is the same.

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Re: Kustom Sidewinder [message #13442 is a reply to message #13417] Tue, 20 April 2010 11:55 Go to previous messageGo to next message
chicagobill
Messages: 2005
Registered: April 2003
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That's quite a mod there. I guess the original power amp died and rather than rebuild it, someone decided to replace it.

In order to restore it, you would need a power amp PC board, an aluminum channel for mounting the output transistors and a thermal cut off switch. Unfortunately the only place you will get these items is from another Kustom amp.

Kustom used a modular approach to building these amps, so the power amp board in your amp is the same as in a 150 metal front as well as a few others. You may be able to find a donor head out there and steal the parts that you need.

As for the original question, the correct tank for your amp is an Accutronics 4BB2C1D. If you still get no reverb with the correct tank, then do as Steve mentioned and see some of the other posts to find out if the problem lies in the drive or the return side of the amp.

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Re: Kustom Sidewinder [message #13444 is a reply to message #13417] Tue, 20 April 2010 17:04 Go to previous messageGo to next message
pleat is currently offline  pleat
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Location: Belding, Mi
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Chicago Bill is right, kustom was doing the modular circuit boards back then, the Charger, Hustler, Commander and Sidewinder amps used the same circuit boards as the K150-1 and K150-2 heads. I have a black working K150-2 head I was thinking of parting out. I personally don't care for any of the slant metal face amps, but would prefer to sell as a working unit. 150.00
pleat

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Re: Kustom Sidewinder [message #13445 is a reply to message #13438] Tue, 20 April 2010 19:11 Go to previous messageGo to next message
Goonak is currently offline  Goonak
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I will go back and re-read the posts regarding reverb.

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Re: Kustom Sidewinder [message #13446 is a reply to message #13445] Tue, 20 April 2010 21:13 Go to previous messageGo to next message
Goonak is currently offline  Goonak
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I haven't been able to find any 4BB2C1D tanks yet, but I have found 4BB2C1A and 4BB3C1D available. If need be, one of these two options could work, right?

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Re: Kustom Sidewinder [message #13447 is a reply to message #13417] Wed, 21 April 2010 11:51 Go to previous messageGo to next message
chicagobill
Messages: 2005
Registered: April 2003
Senior Member
Either one of those tanks will work for you. Antique Electronics is having a sale right now and the tank is selling for $17 right now.

If you go to the Accutronics site, there is page of code numbers that will explain the different parts of the coding system. The two most important parts of the code for any Kustom amp is the input impedance and whether or not the RCA jacks are both grounded or not.

Kustom used a number of different tanks through the years for different eras and models. The main difference was in the input jack grounding. For example a K100B or K200B series amp must have a grounded input and output jack or it will not work at all. While on a 150 or 250 metal front the input jack must not be grounded for it to work. Your amp needs an ungrounded input which is designated by the 5th digit "C", so either one of the two you have found will work correctly.

The other differences in the two tanks, is in how long the delay is and how it was designed to be mounted.

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Re: Kustom Sidewinder [message #13448 is a reply to message #13447] Wed, 21 April 2010 12:54 Go to previous messageGo to next message
Goonak is currently offline  Goonak
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Great - thanks! That's what I hoped. I did go to the Accutronics page yesterday and printed out the reverb chart. That's why I guessed one of those two tanks would work.

I figured if the 2nd, 3rd, and 5th characters matched, the mounting (7th) character wasn't quite as important on the Sidewinder. So then it basically comes down to whether I want to spent a few more dollars for a longer reverb decay.

Considering there's nothing wrong with the amps reverb circuit which I still need to successfully test.

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Re: Kustom Sidewinder [message #13449 is a reply to message #13417] Wed, 21 April 2010 13:25 Go to previous messageGo to next message
chicagobill
Messages: 2005
Registered: April 2003
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The fastest test for your reverb is to take the RCA cable that connects to the tank and touch the tip of each connector with the amp on and the reverb control turned up. One is the send side, and the other is the return. Touching the return cable tip should cause a loud buzz in the amp that is controlled by the reverb controls on the amp.

If you hear the buzz, your return circuit is working, and the problem is in the drive side. If you don't hear the buzz, then the return circuit needs repair.

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Re: Kustom Sidewinder [message #13452 is a reply to message #13449] Wed, 21 April 2010 18:41 Go to previous messageGo to next message
Goonak is currently offline  Goonak
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OK, I just did the test and I do get a "buzz" from the tip of the RCA cord that can be controlled by the reverb controls. So the return circuit is working. How involved is it to check the drive side?

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Re: Kustom Sidewinder [message #13454 is a reply to message #13417] Thu, 22 April 2010 10:01 Go to previous messageGo to next message
chicagobill
Messages: 2005
Registered: April 2003
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You could try testing it by taking a cable from the send jack and plugging it into the input of another amp.

If you do this be certain that the two amps are grounded exactly the same before connecting the wire, as there is a slight chance of causing damage to the amps if the grounds are mis-wired. The safest choice would be a small battery operated amp or a headphone amp.

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Re: Kustom Sidewinder [message #13455 is a reply to message #13417] Thu, 22 April 2010 10:20 Go to previous messageGo to next message
stevem is currently offline  stevem
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Good point Bill!

If you have a volt meter, set it for AC volts and hook it up between the RCA cables ground/shell and the second amps input ground and if you get a voltage reading you need to revrse the ground on one amp.

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Re: Kustom Sidewinder [message #13456 is a reply to message #13455] Thu, 22 April 2010 12:53 Go to previous messageGo to next message
Goonak is currently offline  Goonak
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OK, thank you. I will work on setting up and completing that test.

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Re: Kustom Sidewinder [message #13463 is a reply to message #13456] Sun, 25 April 2010 00:54 Go to previous messageGo to next message
Goonak is currently offline  Goonak
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OK I did the test and I got no sound coming from the reverb section through to the 2nd amp. How would I proceed now?

Also, although I'm an electronics novice I have been studying the schematics of the Sidewinder. I'm wondering why the black wire (#2) from the specical effects board is not connected anywhere. I believe it's supposed to go to ground.

According to the schematic, the orange wire (#3) and the black wire (#2) connect to the power amp section. Whenever the power amp section was replaced on this amp the orange wire was connected, but the black wire was left hanging. Could this have something to do with the reverb not working?

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Re: Kustom Sidewinder [message #13465 is a reply to message #13463] Mon, 26 April 2010 12:02 Go to previous messageGo to next message
chicagobill
Messages: 2005
Registered: April 2003
Senior Member
Goonak wrote on Sat, 24 April 2010 23:54

...the black wire was left hanging. Could this have something to do with the reverb not working?


It might, but I'd doubt it. If the board was not grounded there would be no signal at all going through the amp. The black wire is the ground connection for the original power amp. Let me ask this, does the trem/vib work on the amp?

The reverb send is driven by one half of IC3, a very common dual opamp. The only thing between the chip and the tank are a couple of resistors and the cables. Did you check the cables for continuity and for shorts? Use your meter and check resistors R11, R12 and R13. Also check to be sure that there are no bad solder joints or bridges on the PC board.

If all of this checks out, the only other thing to try is to replace the chip. Almost any dual opamp will work in this circuit, how are your soldering skills?

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Re: Kustom Sidewinder [message #13469 is a reply to message #13465] Tue, 27 April 2010 00:36 Go to previous messageGo to next message
Goonak is currently offline  Goonak
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OK, well first off, I did connect the black wire (#2) to ground and nothing major happened. Still no reverb.

Yes, the trem/vib does work on the amp.

The reverb cables are good, continuity checks out. Solder joints look OK, no bridges, and R11, R12 and R13 check out OK too. But what about C8? Could that be an issue?

Also, the more I look at the board the more I'm convinced that IC3 has been changed out once before. The solder connections are not as clean as the IC6 that's on the board. Plus there are scratches between the pinouts for IC3, so someone was trying to clean up the area previously.

There's an LM1458 currently installed for IC3. I may have an extra one of those around. If not, I can get one. My soldering skills are pretty good. I've repaired and built some effects pedals, just never worked on an amp before.

Anyway, pinout 7 on IC3 powers the reverb "send" correct? I can change out this op amp like you suggest, but before I do, can't I test whether or not both halves of the currect 1458 are working right? How would I test pinout 7?

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Re: Kustom Sidewinder [message #13471 is a reply to message #13417] Tue, 27 April 2010 06:04 Go to previous messageGo to next message
stevem is currently offline  stevem
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If there is a radio shack near by I would pick up an IC socket and solder it in so that it is the last time you have to touch a iron to that circuit board in that area and then try out the new IC chip.
Unless C8 is a ceraimic disc type type cap ( not one of the orange or blue ones) I dought its bad, but pulling out whatever cap is used to check it for a short might be worth the effort anyway.
If you can scan and email, or fax me that boards schematic I can tell you if a 1458 chip is a good sub for the original.

Steven.Magnotti@avispl.com
fax 914 662 3735

[Updated on: Tue, 27 April 2010 06:04]

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Re: Kustom Sidewinder [message #13474 is a reply to message #13417] Tue, 27 April 2010 11:52 Go to previous messageGo to next message
chicagobill
Messages: 2005
Registered: April 2003
Senior Member
First off, if you look at the board there is a metal bracket that the pots mount through. This bracket is soldered to the ground trace on the PC board. So when the board is mounted to the chassis, the ground circuit is complete. The black wire actually grounds the original power amp board to the front panel, eliminating a potential ground loop.

Yes, C8 is involved in the send to the tank, but as it parallels R13, which takes most of the load, it really only adds a bit more high frequency to the signal going to the tank. Test it to be thorough. In looking at the schematic the input cap C6 and resistor R10 should be checked as well.

Well, you know that at least one half of the chip is ok as it functions as the output buffer for the FX board. Test IC3 by reading the voltages on the pins. There should be +12 volts dc on pin 8 and -12 volts dc on pin 4. There should be nearly 0 volts on all of the other pins. If there are a few mVs on any of the pins, that's ok. That being said, even if the voltages read ok there may still be a problem with the chip.

This circuit design places the tank in the feedback loop of the driver chip, so neither side of the input coil is grounded. Your amp came with the wrong tank which would have grounded the output of the chip, which may have caused it to fail. This is pure speculation on my part, but it is something to look into.

Steve's suggestion of adding a socket is fine, as that will make any later chip replacement a snap. The original IC was a 5558, which is basically the same as the 1458 chip that is in there.

Steve: This amp uses a PC5068 FX board just like what's in a metal front series head. If you don't have a copy of the schematic, let me know, and I'll email one to you.

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Re: Kustom Sidewinder [message #13476 is a reply to message #13417] Tue, 27 April 2010 12:33 Go to previous messageGo to next message
stevem is currently offline  stevem
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Thanks for that PC # info Bill.

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Re: Kustom Sidewinder [message #13497 is a reply to message #13476] Thu, 29 April 2010 20:55 Go to previous messageGo to next message
Goonak is currently offline  Goonak
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Sorry for the delay here - I haven't had time until tonight to work on the amp. But good news! It looks like it was the chip after all. I tested the 1458 in question and got the following readings on the pinouts:

1 = 35.3 mV
2 = 35.3 mV
3 = 33.8 mV
4 = -12.33 v
5 = 0
6 = 0
7 = 0
8 = 11.85 v

So I desoldered the chip, installed a socket and another 1458 I had available. I didn't write down the test readings from the new chip, but I did get some mVs from pins 5, 6, and 7. Encouraged, I did the reverb RCA out test to another amp and this time I got a strong signal going to the other amp. Now I can buy the correct reverb tank and I should be good to go!

Bill and Steve - thank you both for your help on this.

But one more question regarding this Sidewinder: on the preamp board, I noticed that C16 and C26 are gone (leads snipped clean off at the board). The preamp board is PC5093. My question is do I need to replace these caps? What do C16 and C26 do in this circuit?

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Re: Kustom Sidewinder [message #13500 is a reply to message #13417] Fri, 30 April 2010 05:45 Go to previous messageGo to next message
stevem is currently offline  stevem
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Sorry, but I do not have pc5093 layout to anwser your question.

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Re: Kustom Sidewinder [message #13507 is a reply to message #13417] Fri, 30 April 2010 12:45 Go to previous messageGo to next message
chicagobill
Messages: 2005
Registered: April 2003
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Great to hear of your progress!

The two caps C16 and C26 are compensation caps for the uA739 chip. If the preamp is working, I wouldn't worry about replacing them.

Is the chip the original 739 or has it been replaced with a 4739 chip? The newer 4739 didn't need the external compensation parts that the original 739 did.

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Re: Kustom Sidewinder [message #13508 is a reply to message #13507] Fri, 30 April 2010 13:20 Go to previous messageGo to next message
Goonak is currently offline  Goonak
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(SteveM, I need to get my scanner working so I can email you the schematic.)

Bill, I'm not sure. The current preamp chip is marked as SL14228. It doesn't look new, but I haven't pulled the board to check the solder connections underneath.

Also, someone used a hot glue-gun at some point and put glue under 5 of the larger caps. Don't know why, but it looks intentional. Should I remove this glue?

Since the preamp is indeed working, I'm inclined to leave well enough alone, but since the effects board was tinkered with, I figured I'd check the preamp board too.

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Re: Kustom Sidewinder [message #13510 is a reply to message #13417] Fri, 30 April 2010 13:25 Go to previous messageGo to next message
stevem is currently offline  stevem
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leave it the way it is, the glue is to stop vibrations from degreading the solder connections.

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Re: Kustom Sidewinder [message #13511 is a reply to message #13508] Fri, 30 April 2010 13:27 Go to previous messageGo to next message
pleat is currently offline  pleat
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Location: Belding, Mi
Senior Member
The glue was something that Kustom did to help secure the larger caps to the board to prevent vibrations from breaking the leads and causing a failure.
pleat

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Re: Kustom Sidewinder [message #13512 is a reply to message #13511] Fri, 30 April 2010 13:30 Go to previous message
Goonak is currently offline  Goonak
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Registered: April 2010
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OK - thanks Pleat & SteveM!

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