| Frankenstein L795 RV issues [message #26978] |
Wed, 19 September 2018 23:43  |
Lovguitar
Messages: 15
Registered: August 2018
|
Junior Member |
|
|
I've managed to get the "Kustom Bug" and bought a cool looking Frankenstein head (L795RV)from ebay. It was advertised for parts or possible repair and the price was reasonable. I opened it up tonight and took a look inside before powering up. It looks to be in largely original condition -- no overt evidence of hacked repairs, burnt components, etc. I re-did a few flaky looking solder joints and cleaned the pots. I powered it up with a bulb limiter, and there was no drama. I removed the limiter and powered it up and discovered that it does work but the volume is substantially lower - on both channels - than I would expect. It has significantly lower volume than the K100s I've worked on and I believe that this is equivalent to a K200, with 100 watts rms. When I turn it all the way up it sounds distorted and thin. Good news -- the vibrato works BUT the reverb doesn't work at all. In fact when I turn up the reverb control, the volume drops significantly. No sounds when I bang the tank.
.
Thoughts as to what I should be looking at? I'm thinking that the low overall volume on both channels may point to a power amp issue. I will check out the K200 "wide panel" schematic. As far as the reverb, I'll substitute in a known good tank and then go from there. Since there's no sound when I bang the tank, if changing out the tank doesn't fix it, I'll trouble shoot the return side.
Any thoughts or suggestions appreciated.
Thanks
Paul
|
|
|
|
| Re: Frankenstein L795 RV issues [message #26981 is a reply to message #26978] |
Thu, 20 September 2018 17:14  |
chicagobill
Messages: 2006
Registered: April 2003
|
Senior Member |
|
|
I would suggest looking at the schematic and start by comparing voltage readings shown on the schematic with the readings that you take on your own amp.
The reverb control on this and most Kustom amps acts like a balance control. Full counter clockwise, there is only straight signal and no reverb. As you rotate the control clockwise, there is less straight signal and more reverb signal. At full clockwise rotation, there is little or no straight signal and full reverb signal. So if the reverb signal is missing, the straight signal will be reduced as you turn up the reverb control.
Yes, the tank is always the first thing to check. If there is no spring rattle when you tap on the tank, then check the small wires that connect the output transducer to the RCA jack, a known weak point.
When both channels are weak, the first place I check is for a leaky cap at the output of the preamps. If the output cap leaks any dc voltage, it will change the bias on the input transistor of the power amp and cause a loss of power and distortion that effects both channels.
|
|
|
|
|
|
VintageKustom.com
Search
Help
Members
Register
Login
Home
]