cjenrick 6/19/2017 2:10 PM
Carvin ST4000
working on this early Carvin solid state amp, Delco Germanium pwr transistors, with the Harmonic Sustain feature, which will get you the Spirit in the Sky fuzz like nobody's bidness when combined with the right 4 position EQ knob,

this amp is similar to the ST2400 for which there is a schematic available>


http://carvinimages.com/schematics/st2400_schem.pdf

here is a shot of the tag board for the 4000>[ATTACH=CONFIG]43827[/ATTACH]
 
cjenrick 6/19/2017 2:18 PM
 
cjenrick 6/19/2017 2:24 PM
the only other difference beside the output stage of the ST2400 and the ST4000 that we could spot was the reverb pan driver circuit, the 4000 uses a transformer/2N301 combo>

[ATTACH=CONFIG]43829[/ATTACH]
 
cjenrick 6/19/2017 2:28 PM
we spliced in the different power transistors to the 2400 drawing since there is no schemo online, Carvin in San Diego seems to have no info on this amp either.

all 6 transistors were good and even matched up pretty well with an avg Hfe of about 125 at Vce=4 v and Ic=450 ma,[ATTACH=CONFIG]43831[/ATTACH]
 
Enzo 6/19/2017 2:34 PM
Well the 2400 calls for silicon output transistors, not germanium.
 
Enzo 6/19/2017 2:36 PM
OK.

If they are OK, leave them.

Did you talk to Carvin on the phone or rely on the web site listings?
 
cjenrick 6/19/2017 2:43 PM
perhaps the reason these relic transistors are still good is due to the generous heat sinks used,

we put some new mica washers in there and got rid of the cake like dried out grease which required desoldering the emitter resistors and base wires,

[ATTACH=CONFIG]43832[/ATTACH]
 
cjenrick 6/19/2017 2:48 PM
the old filter caps had no labels on them, there was probably more capacitance used for the upgrade to 200 watts from the 2400 (120 watts ?) so we took advantage of the improved size factor of today's caps so we could match up or do better than what was in there,

we also stuck a heavy duty bridge in there>

[ATTACH=CONFIG]43833[/ATTACH]
 
cjenrick 6/19/2017 3:50 PM
Carvin has no record of that amp,