UncleSpot Messages: 2 Registered: November 2012 Location: Lodi, California
Junior Member
'been working on tube amps since 1968. 'seen most problems, never NOT been able to fix...
'have 11 Kustoms, and just acquired a K100, model 2 piggyback (2x12). The problem: the reverb is ON (sounds like it's turned up 1/2 way!) when the pot (R171) is all the way down. When you turn the reverb up it goes WAY past "surf music".
If the chassis is LIGHTLY touched it makes the "reverb explosion" like it was kicked (HARD).
Pulled EVERY xstr and put them on my curve tracer and they're all functioning like they're suppose to. Checked all caps to make sure the ESR is not high and they're within spec. Changed out the reverb tank with 3 others: NO change. WTH am I missing? I can NOT use this amp ANY where with this problem. I have a schematic, but it doesn't exactly match the PCB104 in the amp. I've never heard of this kind of problem...
TIA,
Ron
stevem Messages: 4728 Registered: June 2004 Location: NY
Senior Member
I will dive into my k100 tonight and post you some info and things to check, also what does the input and output of the other pans you tyred out check at resistance wise?
stevem Messages: 4728 Registered: June 2004 Location: NY
Senior Member
Ok, they should have all worked out for you, check out the info Pleat ia sending on the after production factory mods that Kustom dealers where sent for a fix.
Let us know how you make out,if need be I will dive into one of mine and give you drive voltages and rcovery gain specs for the reverb stage.
stevem Messages: 4728 Registered: June 2004 Location: NY
Senior Member
Hi, put my K100-2 on my test bench last night and heres what I found.
With the volume set on marking two(9:00) and the bass a treble set to full on I drove the input with a a 1k test tone at .116 mv.
This producded a input level to the pan of 5.30 volts.
This was measued between the tip of the RCA jack and CHASSIS ground,not the RCA sheild.
I then checked the output side of the pan between tip and chassis ground and it was at 5.30 volts also.
I then set out to drive the output end of the pan (recovery amp) and found it to be quite sensivtive, to the point that a -60 db input level would drive the amps output stage to a 17 volt level into a 8 ohm load.
Hope helps you out if you are still working on the problem!
I'm resurrecting this thread, I also have a Kustom 100 with that exact reverb problem! M techs say it appears that the ampand reverb are operating the way it was designed, although none of my other Kustoms do that. Can someone send me the "revision" of what Kustom did to correct this?