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Home » VintageKustom.com » Repairing Kustom Amps » Kustom Studio 4V - Schematic needed (Restauration of a butchered Amp)
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Kustom Studio 4V - Schematic needed [message #29255] Fri, 31 May 2024 15:12 Go to next message
electrip_flip is currently offline  electrip_flip
Messages: 2
Registered: May 2024
Junior Member
Hello,

first posting here.

I'm trying to bring a Studio 4V back to life.
Some tried to convert to EL34 and some magic smoke happened.
Chopped the combo to a headshell and painted it black.

Does anyone could supply me a schematic and maybe a connector diagramm?

It looks somewhat easy but there are modifications I want to revert back to stock
and maybe some butchering caused the trouble.

Thanks in advance and
greetings from germany

electrip_flip

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Re: Kustom Studio 4V - Schematic needed [message #29259 is a reply to message #29255] Mon, 03 June 2024 06:26 Go to previous messageGo to next message
stevem is currently offline  stevem
Messages: 4775
Registered: June 2004
Location: NY
Senior Member
Go to MusicParts.com, they list the schematic there.
You can buy right there on line and it will load to your computer so you can print it off.

Here's a guess as to what happened to the amp.
A quad of EL34s need 2.5 amps more of heater current then does a quad of 6l6tubes .
This means that the power transformer likely ran so hot that it shorted out and burned up in smoke.

Please report back with your findings and if you need help.
I quick way to test for a major short is to pull all the tubes out and install a 1 amp fuse.
If  that fuse blows at power up or when the amp is taken out of standby then you have a major short.

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Re: Kustom Studio 4V - Schematic needed [message #29260 is a reply to message #29259] Mon, 03 June 2024 08:47 Go to previous message
electrip_flip is currently offline  electrip_flip
Messages: 2
Registered: May 2024
Junior Member
Hello stevem,

already ordered the schematics.
No fuses dead.
Both PT and OT are fine.
Humdinger resistors literaly disappeared and left a black area.
Funny is Tubes are still heating.
10R Kathode resistors are gone on two tubes.

I expect only minor damages but I have to check those driver bjts.
One connector is missing. Wires were soldered on.

I have to order some parts and a set of 6L6.
Unit is set up for 220V mains,
will set up for 240V and then check heater voltage.
HT unloaded was 527V DC, 383 AC @233V mains

Will need some days for Progress.
Thanks for your Support.

electripflip

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