Vintage Synth Repair

Out of the blue (my P600 is getting iffy too, must be the weather)my
beloved  Yamaha CS60 is blowing the 1.5 amp fuse on the power supply.
It lights the power switch and then blows it on power up.

There are two other small 0.5 amp ones, those are fine.

Help! Help!

It is especially annoying that Paige McConnell from Phish is talking
about how much he likes his in this month's Keyboard. Sigh.

The first thing you should do is disconnect the power supply from the
rest of the circuits, and see if it still blows the fuse, if it
doesn't blow the fuse, then you have a short somewhere else.
If it is the power supply, then try these tests.
Disconnect the transformer from the power supply, and check it for
shorts, if it is ok, then check the diodes for shorts. 
If everything checks out, then I would replace all the electrolytic
capacitors, I would also replace the positive and negative voltage
regulators (their cheap)
If your not sure about a part's condition, just replace it.
let us know how you make out

Dave
www.dragonslair.ca



--- In vintagesynthrepair@yahoogroups.com, "vcficus"
<mking235724MI@...> wrote:

>
> Out of the blue (my P600 is getting iffy too, must be the weather)my
> beloved  Yamaha CS60 is blowing the 1.5 amp fuse on the power supply.
> It lights the power switch and then blows it on power up.
> 
> There are two other small 0.5 amp ones, those are fine.
> 
> Help! Help!

--- In vintagesynthrepair@yahoogroups.com, "vcficus"
<mking235724MI@...> wrote:
>
> Out of the blue (my P600 is getting iffy too, must be the weather)my
> beloved  Yamaha CS60 is blowing the 1.5 amp fuse on the power supply.
> It lights the power switch and then blows it on power up.
> 
> There are two other small 0.5 amp ones, those are fine.
> 
> Help! Help!
> 
> It is especially annoying that Paige McConnell from Phish is talking
> about how much he likes his in this month's Keyboard. Sigh.
>
The previous suggestion is a good one except ( if youre using a
multimeter) to test for shorts, see what your meter reads probe to
probe first. Transformers have VERY LOW resistance even when they're good.
Seeing 2 ohms on the xformer isnt strange.So. subtract out the
probe-probe ohms for a proper reading. If your meter has a diode check
function use that for diodes.

PS: Isnt Phish dead? I know trey Pistaciao can't get enough of himself

--- In vintagesynthrepair@yahoogroups.com, "vcficus"
<mking235724MI@...> wrote:
>
> Out of the blue (my P600 is getting iffy too, must be the weather)my
> beloved  Yamaha CS60 is blowing the 1.5 amp fuse on the power supply.
> It lights the power switch and then blows it on power up.
> 
> There are two other small 0.5 amp ones, those are fine.
> 
> Help! Help!
> 
> It is especially annoying that Paige McConnell from Phish is talking
> about how much he likes his in this month's Keyboard. Sigh.
>
try this link

http://www.cs80.com/ it has related shhhhhhtuff

Scott, AudioFixation

On Thursday 30 August 2007 02:39, David Vandenberg wrote:
> The first thing you should do is disconnect the power supply from the
> rest of the circuits, and see if it still blows the fuse, if it
> doesn't blow the fuse, then you have a short somewhere else.
> If it is the power supply, then try these tests.
> Disconnect the transformer from the power supply, and check it for
> shorts, if it is ok, then check the diodes for shorts.

So far so good...

> If everything checks out, then I would replace all the electrolytic
> capacitors, 

I get really tired of seeing this -- it's not that often that necessary.

> I would also replace the positive and negative voltage 
> regulators (their cheap)

Ditto.  Those are not common failure items.

> If your not sure about a part's condition, just replace it.

And this is the worst part of the whole mess.  If you don't need to mess with 
something then don't!  Going in and changing all sorts of parts unnecessarily 
is likely to create more problems than were there to start with,  and "the 
shotgun approach" is certainly not the way to recommend to troubleshoot...

-- 
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space,  a critter that can
be killed but can't be tamed.  --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James 
M Dakin

--- In vintagesynthrepair@yahoogroups.com, "Roy J. Tellason"
<rtellason@...> wrote:

> I get really tired of seeing this -- it's not that often that necessary.
> 
> > I would also replace the positive and negative voltage 
> > regulators (their cheap)
> 
> Ditto.  Those are not common failure items.

That's funny, in the 30 years I have been restoring these old synths,
90% of the power supply problems I ran into, where either bad caps or
blown voltage regulators.

> From: Roy J. Tellason
> And this is the worst part of the whole mess. If you don't need to mess 
> with
> something then don't! Going in and changing all sorts of parts 
> unnecessarily
> is likely to create more problems than were there to start with, and "the
> shotgun approach" is certainly not the way to recommend to troubleshoot...

Amen

Any Axxe owners on the list?

I just got around to repairing an Axxe that i've had on the shelf for  
a bit.
The main issue was a broken trace in the cv memory circuit.
The keyboard now tracks correctly and the portamento works too.

The s/h circuit seems odd though
According to the service manual, when you engage the the s/h switch  
the noise source is connected to the memory circuit and key cv buss  
is routed directly to the vco mod in. all of the has the effect that  
while key presses do offset the vco pitch, that offset isn't held or  
memorized upon key release.  So when the key is released the vco then  
returns to it's base pitch which is determined by the tune knob and  
the transpose switch.

This seems so weird that I just wanted to ask if anyone else had  
noticed this.

Portamento in s/h mode doesn't behave as expected either, so maybe  
something else is broken or shorted...

jmw

Any Axxe owners on the list?

I just got around to repairing an Axxe that i've had on the shelf for
a bit.
The main issue was a broken trace in the cv memory circuit.
The keyboard now tracks correctly and the portamento works too.

The s/h circuit seems odd though
According to the service manual, when you engage the the s/h switch
the noise source is connected to the memory circuit and key cv buss
is routed directly to the vco mod in. all of the has the effect that
while key presses do offset the vco pitch, that offset isn't held or
memorized upon key release. So when the key is released the vco then
returns to it's base pitch which is determined by the tune knob and
the transpose switch.


If I recall correctly that's how it is, yes. The only solution is to set
Release to zero.


-- 
Malte Rogacki gacki@... 
----------------------------------------------------------------------------
"Don't forget to TURN ON THE SYNTHESIZER. Often this is the reason why you
 get no sound out of it." (ARP 2600 Owner's Manual)
----------------------------------------------------------------------------

On Thursday 30 August 2007 20:00, David Vandenberg wrote:
> --- In vintagesynthrepair@yahoogroups.com, "Roy J. Tellason"
>
> <rtellason@...> wrote:
> > I get really tired of seeing this -- it's not that often that necessary.
> >
> > > I would also replace the positive and negative voltage
> > > regulators (their cheap)
> >
> > Ditto.  Those are not common failure items.
>
> That's funny, in the 30 years I have been restoring these old synths,
> 90% of the power supply problems I ran into, where either bad caps or
> blown voltage regulators.

Thirty years ago (and I've been a tech somewhat longer than that,  got my CET 
in 1981!) there weren't all that many "old synths" around...

Yeah,  3-terminal regulators do fail.  Occasionally.  *Very* occasionally.  
I'd suspect a lot of other tihngs before blindly replacing those,  unless I 
had reason to suspect that the design was poor and that the device had become 
thermally stressed.

Caps are another story,  and they do need to be replaced sometimes.  But not 
blindly,  en masse,  with only a few exceptions -- those black-bodied units 
with one red end were bad news in certain Thomas organs,  ferinstance.

-- 
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space,  a critter that can
be killed but can't be tamed.  --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James 
M Dakin

>>Yeah,  3-terminal regulators do fail.  Occasionally.  *Very*
occasionally.  
I'd suspect a lot of other tihngs before blindly replacing those,
unless I had reason to suspect that the design was poor and that the
device had become thermally stressed.<<

well.... I've been in broadcast engineering for 25 years, &
electronics for slightly longer, & the three-terminal regulator (78xx,
79xx) is definitely in my top-5 of things that go wrong. 

electrolytic caps, bridge rectifiers, those racehorse transistors in
SMPSUs, tantalum caps, lithium batteries, the odd transistor, op-amps...

I have seen 78xx/79xx go open & even go short, input-to-output. this
latter happened in a moog prodigy (which survived the 17V) & a pro-1
(which didn't, needed a new VCF).

I think, with kit you don't know the full service history of, the best
approach is to suspect everything. see if the psu works on it's own,
if possible. a good sense of smell can be useful, if something's
getting too warm in a device that seems ok otherwise- you can
sometimes find that a badly-replaced reg runs hotter than it wants to
(& will fail again) because the repair-guy before you didn't have any
heatsink compound. in a symmetrical power supply, I check that the
positive & negative components are running at around the same
temperature & that the on-load volt-drop is similar.

duncan.

Hey..

i have the same problem... is this is correct ?

I have an ARP AXXE MK1.

regards,


--- In vintagesynthrepair@yahoogroups.com, John Wieczorek 
<evening@...> wrote:
>
> 
> Any Axxe owners on the list?
> 
> I just got around to repairing an Axxe that i've had on the shelf 
for  
> a bit.
> The main issue was a broken trace in the cv memory circuit.
> The keyboard now tracks correctly and the portamento works too.
> 
> The s/h circuit seems odd though
> According to the service manual, when you engage the the s/h 
switch  
> the noise source is connected to the memory circuit and key cv 
buss  
> is routed directly to the vco mod in. all of the has the effect 
that  
> while key presses do offset the vco pitch, that offset isn't held 
or  
> memorized upon key release.  So when the key is released the vco 
then  
> returns to it's base pitch which is determined by the tune knob 
and  

> the transpose switch.
> 
> This seems so weird that I just wanted to ask if anyone else had  
> noticed this.
> 
> Portamento in s/h mode doesn't behave as expected either, so maybe  
> something else is broken or shorted...
> 
> jmw
>

oxygeno,

I believe that this is the correct behavior on the Axxe.
There's only one s&h circuit inside and it's switched between the  
keyboard CV input/gate  or noise input/ LFO trig.
So there's nothing sampling or holding the key CV when the switch is on.
The thing to do is turn the release slider down when using s&h, which  
sucks.

I've thought about adding the "music from outerspace"  s&h board to it .
I haven't played the Axxe in a bit so I'll check out your other  
questions when I get home.


peace,
john

On Oct 24, 2007, at 12:39 PM, oxygeno1313 wrote:

> Hey..
>
> i have the same problem... is this is correct ?
>
> I have an ARP AXXE MK1.
>
> regards,
>
>
> --- In vintagesynthrepair@yahoogroups.com, John Wieczorek
> <evening@...> wrote:
>>
>>
>> Any Axxe owners on the list?
>>
>> I just got around to repairing an Axxe that i've had on the shelf
> for
>> a bit.
>> The main issue was a broken trace in the cv memory circuit.
>> The keyboard now tracks correctly and the portamento works too.
>>
>> The s/h circuit seems odd though
>> According to the service manual, when you engage the the s/h
> switch
>> the noise source is connected to the memory circuit and key cv
> buss
>> is routed directly to the vco mod in. all of the has the effect
> that
>> while key presses do offset the vco pitch, that offset isn't held
> or
>> memorized upon key release.  So when the key is released the vco
> then
>> returns to it's base pitch which is determined by the tune knob
> and
>> the transpose switch.
>>
>> This seems so weird that I just wanted to ask if anyone else had
>> noticed this.
>>
>> Portamento in s/h mode doesn't behave as expected either, so maybe
>> something else is broken or shorted...
>>
>> jmw
>>
>
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