On Mon, Jan 7, 2019 at 1:54 AM fabry891 <fabrizio.vita80@gmail.com> wrote: > > >Try to change C11 (I'm assuming you have a VIC-20CR, the one with 2 x > >6116 SRAMs and 3 x 2114 SRAMs) > >On the old VIC-20, the one with all 2114 SRAMs, it's labeled C16. If > >this doesn't solve the problem, then try changing Q1 (new VIC-20CR) or > >Q5 (old VIC-20). But you should first check that the transistor is > >really bad or if it's just a failed connection or polarization > >resistor etc... (most of the checks can be done with a simple > >multimeter). > > Yes, I've a VIC-20CR. > I measured the c11 capacitor with multimeter and its value is 1microF and no > resistance between two pole. > About transistor Q1, I measured the voltage between base-collector and > base-emitter either with red or black( > probe of the multimeter) connect to base and the results are: > base (red probe) vs collector (black robe) 0.7160 Volt > base (red probe) vs emitter (black robe) 0.7160 Volt > base (black robe) vs collector (red probe) 1.596 Volt > base (black robe) vs emitter (red probe) 1.80 Volt > This check is made withoout remove any componet from matherboard. > It doesn't work for you? It need to replace? looks all ok. Then if Q1 is polarized correctly (no resistors or solder joints failed), it must be the VIC chip that has issues (strange but can happen). > I read on the transistor C2548. > I've found on internet the wiring diagram of VIC-20, but not VIC-20CR, Where > I can find it? > Thanks 1000? http://www.zimmers.net/anonftp/pub/cbm/schematics/computers/vic20/index.html FrankReceived on 2019-01-07 10:00:02
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