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| Re: Reverb K50-2 Reverb Repair [message #28562 is a reply to message #28559] |
Wed, 27 April 2022 12:18   |
chicagobill
Messages: 2006
Registered: April 2003
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Senior Member |
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If the tank makes a good loud spring splash sound when the chassis is moved, then the return circuitry is working properly. There may be a problem with the drive circuit or the input of the tank.
If you switch the reverb cables at the board and shake the chassis and still get a strong splash sound, you can assume that the input transducer is working well enough.
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| Re: Reverb K50-2 Reverb Repair [message #28564 is a reply to message #28559] |
Thu, 28 April 2022 00:53 |
chicagobill
Messages: 2006
Registered: April 2003
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Senior Member |
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I think that your tank is fine, as are the cables, etc.
The drive circuit is centered around Q20, Q21 and Q22. It's basically a small power amp with a differential pair input. If anything goes wrong there will be less signal sent to the tank and therefore less reverb signal. When there is less input signal going into the tank, you need to turn up the reverb control to compensate. The problem with that is, turning up the return will start to cause the tank to feedback.
I'd check the transistors and the caps in the circuit.
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| Re: Reverb K50-2 Reverb Repair [message #28565 is a reply to message #28562] |
Fri, 29 April 2022 18:11 |
jammy5152
Messages: 62
Registered: May 2018
Location: Georgia
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Member |
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chicagobill
I removed the amp and set on work bench
I did as you said and shook the amp and it made a huge splash...
Switched the cables at the board and shook the amp....NO SPLASH....
So I guess the INPUT transducer ( coil ) is bad ???
Any ideas?. Can transducer be found?? Or tank replacement?
If tank replacement what would be the correct one as far as electronics/ ohms/ or ??
Thanks
[Updated on: Fri, 29 April 2022 18:40] Report message to a moderator |
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| Re: Reverb K50-2 Reverb Repair [message #28566 is a reply to message #28559] |
Sat, 30 April 2022 07:28 |
stevem
Messages: 4775
Registered: June 2004
Location: NY
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Senior Member |
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Do not give up on that tank yet!
75% of the time either end of a tank does not work because one of the very fragile wires at RCA jack have broken off due to vibration .
Peal back the tank cover and look close at the wires , and you may have to look real close as many times they appear to be ok, but are not!
If this is your issue then once soldered back up apply some bath tub caulk or hot glue to the wires and on the metal fold over that is not doing it's job to hold the wires.
Do this on both jacks while you are in there to eliminate this issue from taking place again .
When I am working on any of my amps or customers amp with a reverb tank this is what I do, only I use automotive silicone gasket maker since I always have this on hand.
Should that transducer be open then the replacement tank you need is a 4FB3C1A model.
Yes I know the input on this model tank is grounded and the schematic's do not show such, but this is what the original tank is in my K100-8, and the K50 is no different.
If you get a new tank do the glue down thing to wires before you install it.
[Updated on: Sat, 30 April 2022 07:37] Report message to a moderator |
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| Re: Reverb K50-2 Reverb Repair [message #28569 is a reply to message #28566] |
Sat, 30 April 2022 16:51 |
jammy5152
Messages: 62
Registered: May 2018
Location: Georgia
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Some of the major differences between the MOD®s and other reverb tanks are that the Transducers are wired directly to their respective RCA jacks as opposed to current production tanks where Transducers are connected by a detachable plug to their respective RCA jacks. This makes the tanks less receptive to any outside interference. The original Hammond Accutronics tanks from the 1960s were also wired directly to their respective RCA jacks. In addition very close attention has been paid to the spacing and size of the lamination of the Transducers resulting in a more vintage like tone.
#50820 - Replacement Reverb Tank for ....4AB3C1B....
Solid, Sturdy Construction
Long (16 ¾") 2 Spring Unit , Long Decay (2.75-4.0 seconds)
Input Impedance 8 Ohms, Output Impedance 2250 Ohms
Input Insulated/Output Grounded
Horizontal,Open Side Down Mounting Plane
Used in Fender™amps with tube reverb from 1963-1990 such as the Princeton Reverb , Vibrolux Reverb , Deluxe Reverb , Super Reverb , Pro Reverb , Twin Reverb , Quad Reverb , Super Six Reverb, Vibrosonic Reverb. This also includes all reissue equivalents.
Other compatible amps include: Fender™ '63 Reissue Reverb Unit, Fender™ Concert II , Mesa Boogie™ MK2C plus other models, LAB™ Series L5, L7, L9, Koch™ Powertone I , Ampeg™VT-40 and Super Rocket SR212 , B-52™ AT-100.
This I found on the web...is this compatible??
[Updated on: Sat, 30 April 2022 16:52] Report message to a moderator |
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| Re: Reverb K50-2 Reverb Repair [message #28572 is a reply to message #28559] |
Sun, 01 May 2022 14:59 |
chicagobill
Messages: 2006
Registered: April 2003
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Senior Member |
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The input impedance of the tank that you listed is 8 ohms, much too low for a Kustom amp. Also the input is isolated from ground. The Kustom amp needs to have both input and output grounded.
Check the tank that Steve listed and see if it meets the requirements.
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