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Author Topic: Vox vt120+ combo schematic needed  (Read 355 times)

Psabin8951

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Vox vt120+ combo schematic needed
« on: September 29, 2020, 12:17:14 PM »
Does anyone have a schematic for a vox vt120+ valvetronic combo please.
Or even be able to tell me values for C184 and C185 as both are burnt out erasing markings.
Many thanks

DrGonz78

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Re: Vox vt120+ combo schematic needed
« Reply #1 on: September 29, 2020, 01:57:13 PM »
Looking through the VT80+ schematic C184 & C185 are near the speaker output. Obviously they are different circuits but I am curious where in the circuit those two capacitors are located on your amp board. Look at page 4 quadrant H2 of the VT80+ schematic and locate C184 & C185 the 0.68uf 100v film capacitors. Look on your board near the burnt out caps to locate two 1000pf 100v caps (C146 & C147) that run in parallel with those caps. May be a long shot here but perhaps these two schematics share something in common or possibly not. Can't hurt to check. 
“A person who never made a mistake never tried anything new.” -Albert Einstein

Psabin8951

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Re: Vox vt120+ combo schematic needed
« Reply #2 on: September 30, 2020, 07:13:32 AM »
Yes spot on. They are the same.
Do we think a blown valve would be likely to make C184 "explode"?

Jazz P Bass

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Re: Vox vt120+ combo schematic needed
« Reply #3 on: September 30, 2020, 11:31:14 AM »
The amp uses a surface mount TAS5615 Class D output IC.
As both of those blown capacitors are on each output rail, it is hard to see why both of them blew up.
Unless the output IC went belly up & cooked them at a high frequency.