TB-303 PSU issues messing up the Cpu?

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the nerd
 
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TB-303 PSU issues messing up the Cpu?

Post by the nerd »

Hi Guys,

i bought a broken 303and tried to repair the Psu. I failed and passed it to a relly good tech.
He fixed the internal psu and checked everything and he is stucked with the issue that the cpu wont give out CV/Gate data to the synthesis. Everything else works O.K. He checked the CV/Gate generator, the memory and all other parts that are responsible for the sequencer. The sequencer works. Notes can be played, sync in works etc, lights lit up, you can change the tempo and tab insert is possible, but no transmisson to the memory from the cpu...

That are my questions:

Can be the high noise on the output be a sign of a voltage problem on the psu?

Is it possible to masure CV/Gate signal on the cpu or how to masure the cpu at all?

Could it be that if there are voltage variations on the internal psu the cpu may freeze or works incorrect?

Did someone experinced the same?



Thank you for your answers in advance 8)
Last edited by the nerd on Tue Oct 25, 2011 6:19 am, edited 2 times in total.

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antto
 
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Re: TB-303 PSU issues messing up the Cpu?

Post by antto »

at least in the x0xb0x, incorrect PSU may make the x0x not run correctly (example: synth produces sounds (osc and filter are ok) LEDs light up, but sequencer doesn't respond)
tho, the x0x has a different PSU than the TB-303 .. so who knows..

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aminoacid
 
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Re: TB-303 PSU issues messing up the Cpu?

Post by aminoacid »

are you saying that everything working but no sound what so ever?

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the nerd
 
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Re: TB-303 PSU issues messing up the Cpu?

Post by the nerd »

aminoacid wrote:are you saying that everything working but no sound what so ever?

hey amino..

the synth works and can be played in full range via the keyboard and tweaked too but if you try to play the sequencer from the previously written pattern the sequencer does not response (no playback).. so the chain is that the signal from the keyboard is reconized by the cpu and the led lights up and then the created cv/gate signal will be written from the cpu to the memory to the advised memory slot. so beetwen cpu and memory happends no transmission..and everythings works. even the memory was checked O.K with a testing device.

So back to the topic.. Voltage variation affecting the function. I noticed that, even now i would like to know how to figure out if the cpu is broke?

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phono
 
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Re: TB-303 PSU issues messing up the Cpu?

Post by phono »

the short answer is yes, the cpu can be fried by the psu on the tb-303

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phono
 
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Re: TB-303 PSU issues messing up the Cpu?

Post by phono »

the nerd wrote:
aminoacid wrote:are you saying that everything working but no sound what so ever?
the synth works and can be played in full range via the keyboard and tweaked too but if you try to play the sequencer from the previously written pattern the sequencer does not response (no playback)
you should check if there is a break in the connection from the RUN signal at the SYNC socket to the CPU input at R10/R9/Q1. It could be a fractured PCB joint, or a problem with the switch contacts in the SYNC socket. The circuit trace passes very close to one of the case standoffs and can be broken if the case is put on slightly wrong.

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the nerd
 
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Re: TB-303 PSU issues messing up the Cpu?

Post by the nerd »

phono wrote:the short answer is yes, the cpu can be fried by the psu on the tb-303
ok, i wonder why then the rest of the cpu is working. If its fried it shouldnt working anymore. No led,s blinkin etc

As the seller said that the unit did stopped working from one day of the another without doin anything.

How can figure it out if its broken! Measuring points etc..

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phono
 
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Re: TB-303 PSU issues messing up the Cpu?

Post by phono »

the nerd wrote:
phono wrote:the short answer is yes, the cpu can be fried by the psu on the tb-303
ok, i wonder why then the rest of the cpu is working. If its fried it shouldnt working anymore. No led,s blinkin etc

As the seller said that the unit did stopped working from one day of the another without doin anything.

How can figure it out if its broken! Measuring points etc..
check my second answer ;)

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the nerd
 
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Re: TB-303 PSU issues messing up the Cpu?

Post by the nerd »

phono wrote:
the nerd wrote:
phono wrote:the short answer is yes, the cpu can be fried by the psu on the tb-303
ok, i wonder why then the rest of the cpu is working. If its fried it shouldnt working anymore. No led,s blinkin etc

As the seller said that the unit did stopped working from one day of the another without doin anything.

How can figure it out if its broken! Measuring points etc..
check my second answer ;)
yep I did posted it a sec after yours... thank you I forwarded your hint.

So this means that the Sequencer should be startet by a external sync right?

Is it really the Run signal when the Realime Tab is running? I guess if the Run signal is broke then it shoudnt be possible to change the tempo? ( faster blinking LED's) Or am i wrong and the clocksignal really dosn't have anything to do with the Run signal.

2nd question: Can it only be a broken cpu if its not possible to write a pattern.

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phono
 
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Re: TB-303 PSU issues messing up the Cpu?

Post by phono »

the nerd wrote:So this means that the Sequencer should be startet by a external sync right?

Is it really the Run signal when the Realime Tab is running? I guess if the Run signal is broke then it shoudnt be possible to change the tempo? ( faster blinking LED's) Or am i wrong and the clocksignal really dosn't have anything to do with the Run signal.

2nd question: Can it only be a broken cpu if its not possible to write a pattern.
that depends where the problem is, but if that line is severed it would be possible to program notes into the seq but it would not play back, which is the problem you are having so i would check that out

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