Troubleshooting the Sub Oscillator Section

My Sub Oscillator section is not working at all.?

What's the best way to go about troubleshooting the different components for failures on the board?

How do I measure the LFO IG00150 chip to see if its good or bad? Mind you, I am not an electronics guy so I would need detailed instructions. I don't have a technician anywhere near where I live so trying to do this solo.

Much appreciated.

Re: IG00150 LFO chips?

#4576

Looking for an IG00150. Synthparts does not have any. My sub section not working.

Re: CS50 blowing uppermost fuse

#4575

could i be correct in guessing that the problem couldn't be a 'blown' primary winding since the PS is blowing fuses ? i mean it shouldn't be able to bring power through the supply with a blown primary?

Re: CS50 blowing uppermost fuse

#4574

update: i haven't had much of a chance to look into this until recently- it's looking like there is an open circuit (no connection) between the BROWN and either GREY or YELLOW wires on the primary side of the transformer -? the grey and yellow have at least five ohms between them however...? i'm just wondering if it's possible the transformer somehow blew (???) - these seem very heavy duty so it seems unlikely...

thoughts?

IG00153 VCA

#4573

HI. I am needing a IG00153 VCO if anyone has any for sale?

Re: CS50 blowing uppermost fuse

#4572

Hi Florian - there are three fuses mounted on the front left of the power supply - and they are all mounted (stacked) in a? group of three horizontally - so it is the uppermost fuse... it's a 1,25A fuse that I replaced ... i hope that clarifies something? thanks

Re: CS50 blowing uppermost fuse

#4571

开云体育

Which one do you mean with "uppermost"?

On 23.07.17 05:41 , jw_dewdney@... [yamahacs80] wrote:

Show quoted text

?

My CS50 started blowing fuses. A preliminary check revealed nothing obvious in the power supply - is there a recommended routine for this? Maybe first checking for shorts in the board feeds?

Re: CS50 blowing uppermost fuse

#4570

开云体育

Find out which voltage the fuse is protecting.

Then desolder board for board all those voltages. Measure with the ohmmeter for short. Once a board shows 0 Ohm then that board has the short somewhere. Further measure out all tantalum capacitors for short as well as other capacitors. It's a bit time consuming but there is no other way to find the short. Good luck?

Csaba?

Sent from Csaba's iPhone

Show quoted text

On 23 Jul 2017, at 05:41, jw_dewdney@... [yamahacs80] <yamahacs80@...> wrote:

?

My CS50 started blowing fuses. A preliminary check revealed nothing obvious in the power supply - is there a recommended routine for this? Maybe first checking for shorts in the board feeds?

CS50 blowing uppermost fuse

#4569

My CS50 started blowing fuses. A preliminary check revealed nothing obvious in the power supply - is there a recommended routine for this? Maybe first checking for shorts in the board feeds?

Re: CS50 schematics anywhere??

#4568

well that too... though I was just referring to the quality of the scans... the CS50 documents I already had were pretty awful as far as reproduction goes

Re: CS50 schematics anywhere??

#4567

Yamaha's old service documents are among the beautifullest technical prints ever. The schematics, the graphics, the typesetting, the yellowed paper, the fold-outs, the cover, the odd metal binding... just wonderful.

I have the original CS-50 service manual, and it's easily the classiest book in my library. :-)

/mr

PS: The CS-40M document seems missing on ?

Thanks for keeping up the documentation work though!

?

Re: CS50 schematics anywhere??

#4566

those are some of the nicest PDFs i've seen in a long time from a 'vintage' source (presumably) too...

Re: CS50 schematics anywhere??

#4565

thank you!! you're a real light saber! (life saver)

Re: CS50 schematics anywhere??

#4564

开云体育

Welcome to the group! ?All the service manuals / schematics are on my website here: ?

Show quoted text

On Jun 26, 2017, at 11:11 AM, jw_dewdney@... [yamahacs80] <yamahacs80@...> wrote:

Hi all... i'm new to the group.

I have a CS50 service manual i downloaded but can't seem to find any drawings in the package - it's only a long description of the concepts of the design. I was looking for a set of schematic and board drawings. Anyone have a lead on these?

Specifically I'm trying to troubleshoot a blowing upper fuse - and it's kind of hard to figure out without knowing which of the pins in the molex connectors are what ... so i can see if there's a short ...

CS50 schematics anywhere??

#4563

Hi all... i'm new to the group.

I have a CS50 service manual i downloaded but can't seem to find any drawings in the package - it's only a long description of the concepts of the design. I was looking for a set of schematic and board drawings. Anyone have a lead on these?

Specifically I'm trying to troubleshoot a blowing upper fuse - and it's kind of hard to figure out without knowing which of the pins in the molex connectors are what ... so i can see if there's a short ...

My latest CS videos...

#4562

Here a couple of links to my latest CS videos...

Cheerz,

Tom

Re: Wah-Wah

#4561

Here is a video I made of the pedal I have come up with for controlling the "Brilliance"... using a slider from an old Yamaha organ...!

Cheers,

Tom

Re: Wah-Wah

#4560

Thanks for the idea David, but it occurred to me that?I might want to use the sub osc on one of it's waves while playing the synth and controlling the brilliance by foot...!

I already found a 10KB slider pot with a centre tap and have built my pedal by the way...:)

Cheerz,

Tom

Re: Wah-Wah

#4559

开云体育

If you’re going to do a +/-15v pedal, why not just plug it into the sub-osc external input jack, turn up the ext level knob next to the jack, and set the Sub Osc to EXT and Sub Osc VCF to max and Sub Osc VCO and VCA off. ?No circuit mods! ?I’m just not sure how much range you’ll get.

?David

Show quoted text

On Apr 23, 2017, at 12:51 PM, noddyspuncture@... [yamahacs80] <yamahacs80@...> wrote:

Again, thanks - I'll have a good look at your diagram...but I was thinking along the lines of actually over-patching the brilliance control (wire from the wiper) to a pot in a 'custom' pedal - along with +/-15 & ground.

I think it would be much simpler and would behave in the exact same way...?

Cheers,
Tom

Re: Wah-Wah

#4558

Again, thanks - I'll have a good look at your diagram...but I was thinking along the lines of actually over-patching the brilliance control (wire from the wiper) to a pot in a 'custom' pedal - along with +/-15 & ground.

I think it would be much simpler and would behave in the exact same way...?

Cheers,

Tom