Elektor Formant Modular

OK I have tidied up my Old Formant PSU, Hurrah.. looks nice, stuck my 
(misunderstood) voltmeter on the wires and I get +15 where it should 
be +5 where THAT should be.. 0 on well um.. zero.. but.. how do I 
know it the -15 is working? (tried reversing the red and black 
probes.. no effect).. Anyway seems to be working... so

I connect up an ADSR. Now thos of you that remember, I blew one, I 
think, connecting to my Blacet PSU... Now I know I blew it.. dead.. 
so I chnge the IC's (yes I had cleverly bought a bunch of spares..) 
now when I connect (and please bare in mind that THIS ADSR used to 
work on THIS PSU) I feel the IC's and sure enough.. one is heating 
up ... I pull the plug.

What do I know? My ADSR is blowing (maybe on ALL PSU's) particularly 
on one IC? Maybe the old ones are OK? (apart from this one)

Questions?

Well, How can I find out why this is happening.. believe me Ive 
stared at the circuit long enough looking for breaks and blobs etc...

maybe its time to try a different module? a VCO perhaps?

Next time I plug it in Im going to use a resistor to cushion the 
voltage

Kris, you said you may have some way of telling if modules worked? 
you said...
I think I have some test sequences in my report if you want
I'll send you it ..
er.. yes please!!

<wizard of oz mode on>

You don't need a MODULE... what you need is a dummy LOAD.

(no offense) Do you know how to use Ohms Law ???

I ask because you can calculate a number of resistive loads, and
wattages...
that you can use to safely test a power supply without blowing up
modules.
If not, contact me off/on list and I'll help you.

First of all, with the positive probe of your VOM on "0 volts" and the
negative probe on the -15V you should read "15 volts"   I'm assuming
that
you have the old meter with a pointer. Most modern ones do not care
which
lead is where, they will still read OK.

It seems like you are still missing a -15V supply.  If so fix THAT
first...

You might have two problems, a broken power supply AND a broken module.
But if the PS is not working, you will never get the module going
either.

Let me know about the load resistors.  You want to calculate some value
that
will draw some current from the supply, but not a huge amount. You need
to check
the wattage of the resistors as well.  Wirewound or Carbon Comp
resistors are very forgiving of short overloads... film resistors are
less so.

over:

H^) harry

markfrancombe wrote:

>  OK I have tidied up my Old Formant PSU, Hurrah.. looks nice, stuck my
>
> (misunderstood) voltmeter on the wires and I get +15 where it should
> be +5 where THAT should be.. 0 on well um.. zero.. but.. how do I
> know it the -15 is working? (tried reversing the red and black
> probes.. no effect).. Anyway seems to be working... so
>
> I connect up an ADSR. Now thos of you that remember, I blew one, I
> think, connecting to my Blacet PSU... Now I know I blew it.. dead..
> so I chnge the IC's (yes I had cleverly bought a bunch of spares..)
> now when I connect (and please bare in mind that THIS ADSR used to
> work on THIS PSU) I feel the IC's and sure enough.. one is heating
> up ... I pull the plug.
>
> What do I know? My ADSR is blowing (maybe on ALL PSU's) particularly
> on one IC? Maybe the old ones are OK? (apart from this one)
>
> Questions?
>
> Well, How can I find out why this is happening.. believe me Ive
> stared at the circuit long enough looking for breaks and blobs etc...
>
> maybe its time to try a different module? a VCO perhaps?
>
> Next time I plug it in Im going to use a resistor to cushion the
> voltage
>
> Kris, you said you may have some way of telling if modules worked?
> you said...
> I think I have some test sequences in my report if you want
> I'll send you it ..
> er.. yes please!!
>
>
>
>
> -----------------------------------------------------------------------
> YAHOO! GROUPS LINKS
>
>    +  Visit your group "ElektorFormant" on the web.
>
>    +  To unsubscribe from this group, send an email to:
>       ElektorFormant-unsubscribe@yahoogroups.com
>
>    +  Your use of Yahoo! Groups is subject to the Yahoo! Terms of
>      Service.
>
> -----------------------------------------------------------------------
>

Thanks for the reply harry...
> (no offense) Do you know how to use Ohms Law ???

None taken ..because.. er.. no I dont!
> It seems like you are still missing a -15V supply.  If so fix THAT
> first...

Hmm seems so... strange because it WAS ok (before I pulled the synth 
apart to fix the mess..darn it.. what did I do?)Ill go around checking 
if wires have fallen off or something...

> 
> You might have two problems, a broken power supply AND a broken 
module.

Stephen suggested earlier that...
You can insert a resistor of a few hundred ohms in the +15
and the -15 V ...

does this sound about right?

Hi,

Unfortunaelty my adsr worked fine so report was very limited with details 
about it. Is it a new module MSS2000 or the old one.

Lets take it easy and look at what you have and should have.

Power supply.
(please be aware that I am using no colours here as many people change wire 
colours.)

Get the schematic out for the powersupply you are using.
On the schematic the solder pads are labelled, If you're lucky your board 
will also be labelled.
if not match it up with the one in the book and find all your power lines.

By the sounds of things your supply has went wrong or is being connected 
wrong.

Test the wires, connect your black probe to the ground of the power supply 
to wall socket. then the red to the Ov line out. This should read 0v,

Then test +15v and -15v the same way. LABEL your wires at this point. Saves 
time in future.

Confirm this section before doing anything else.

Kris
P.s I lost my copy of the original book so having to retrieve it again, 
should be able to help more next time.

>From: "markfrancombe" <mark@...>
>Reply-To: ElektorFormant@yahoogroups.com
>To: ElektorFormant@yahoogroups.com
>Subject: [ElektorFormant] HELP with hot problm...
>Date: Mon, 08 Aug 2005 21:48:05 -0000
>
>OK I have tidied up my Old Formant PSU, Hurrah.. looks nice, stuck my
>(misunderstood) voltmeter on the wires and I get +15 where it should
>be +5 where THAT should be.. 0 on well um.. zero.. but.. how do I
>know it the -15 is working? (tried reversing the red and black
>probes.. no effect).. Anyway seems to be working... so
>
>I connect up an ADSR. Now thos of you that remember, I blew one, I
>think, connecting to my Blacet PSU... Now I know I blew it.. dead..
>so I chnge the IC's (yes I had cleverly bought a bunch of spares..)
>now when I connect (and please bare in mind that THIS ADSR used to
>work on THIS PSU) I feel the IC's and sure enough.. one is heating
>up ... I pull the plug.
>
>What do I know? My ADSR is blowing (maybe on ALL PSU's) particularly
>on one IC? Maybe the old ones are OK? (apart from this one)
>
>Questions?
>
>Well, How can I find out why this is happening.. believe me Ive
>stared at the circuit long enough looking for breaks and blobs etc...
>
>maybe its time to try a different module? a VCO perhaps?
>
>Next time I plug it in Im going to use a resistor to cushion the
>voltage
>
>Kris, you said you may have some way of telling if modules worked?
>you said...
>I think I have some test sequences in my report if you want
>I'll send you it ..
>er.. yes please!!
>
>
>
>

Thanks Kris.. I need all the help I can get (maybe we should take 
this off list? Dont wanna annoy the old pros's???)

> Is it a new module MSS2000 or the old one.
I think it must be one of the old ones? (how new is new? It wwas 
originally a school project for a Spanish friend, in the early 80's)

> On the schematic the solder pads are labelled, If you're lucky 
your board 
> will also be labelled.

It is...

> if not match it up with the one in the book and find all your 
power lines.
> 
> By the sounds of things your supply has went wrong or is being 
connected 
> wrong.
> 
> Test the wires, connect your black probe to the ground of the 
power supply 
> to wall socket. 

What do you mean here? touch black probe on gound of the circuit.. 
then.. what with the wall socket?


then the red to the Ov line out. This should read 0v,

Aha.. NOW I get it.. sorry...

OK TRIED THIS: COnnected BLACK to earth part of my wall socket
(actually power strip earth) and touched RED on all parts of the 
PSU..
I get OV everywhere (actually I get minus 0, but I gues that 
nothing?)

 
> Then test +15v and -15v the same way. LABEL your wires at this 
point.
> Confirm this section before doing anything else.

if I touch BLACK to the Ov out of PSU and red to +15 I get +15


if I touch BLACK to the Ov out of PSU and red to +5 I get +5


if I touch BLACK to the Ov out of PSU and red to -15 I get 0.

So I think the -15 is gone somewhere?

BTW. I notice that there is NO connection from the earth cable in 
the mains lead, blue and brown go to their places on the 
transformer, but the earth is cut off, it this a thing? SHould,nt it 
be connected to earth somewhere????????

Mark...



>

(DOH! no edit in Yahoo... and DANG no warning when you leave webpage 
and come back and your half writing message is gone... 2nd time im 
writing this... no wonder Yahoo is losing the battles...)

ANYWAY... gone a little further on my PSU problems and sussed out...

1. Definately its the PSU thats dead/wrong, hooked up a LFO 
(tentetively, hand on power switch)amd sure enough NO flashing LED's!

2. On schematics the volts IN from transformer (on one side of each 
of the three fuses) are quoted as 18, 18 and 10 volts "alternating" 
(if thats what the sideways S squiggle means?) SO I thought Id check 
there.. with voltmeter on the alternating position (its a cheapish 
digital BTW Kris)Black on ground and red to each of the places, I 
get GOOD readings!! HURRAH! about 19, 17 and 9.5 ish on each..

So problem lies AFTER that, in the depths of the circuit...

So what do I try next?

Kris, Harry?

Buhler?

cheers Mark

FIXED IT!!
Well PSU is fixed! What I did.. advice to idiots like me.. I had 
decided that I would NOT be using the COM module in my refurbish (so 
anyone wants it???) and the PSU had connection to this module both 
for power AND LED's.. I wondered if that completed a circuit and 
removed the LED's from the COM and put back (its marked on the 
schematic)on the PSU. BUt no.. it DIDNT WORK.. but now I had a 
visual indication of which bit worked and which bit didnt cos I had 
+15 Led ON and +5 LED ON, but no -15. SO I tried the old and tested 
method of... go over the circuit and heat up EVERY solder joint and 
let go when wet. SURE ENOUGH!!! I found a joint that looked a little 
cracked (must've cracked when I dismantled this.../) and BING! on 
comes LED!

I plugged in the LFO and BING BING BING THree happy flashing LEDS!

HURRAH for me... Back on track finally!

cheers for all that helped/// wish I could delete this whole 
thread... I feel I am now imortalised as a synthewanker...


cheers

MArk

markfrancombe wrote:

>  cheers for all that helped/// wish I could delete this whole
> thread... I feel I am now imortalised as a synthewanker...
>

No, you're a hero. Others will see your iron resolve to fix the problem
and
take courage from your example.

wanker would have said "screw synthesizers.  See you all at
counted-cross-stitch.com"

H^) harry

>
>
> cheers
>
> MArk
>
>
>
>
> SPONSORED LINKS
>
    Music sampler   Music synthesizers     Synthesizer music

    Synthesizer     Sampler                Electronic

> -----------------------------------------------------------------------
> YAHOO! GROUPS LINKS
>
>    +  Visit your group "ElektorFormant" on the web.
>
>    +  To unsubscribe from this group, send an email to:
>       ElektorFormant-unsubscribe@yahoogroups.com
>
>    +  Your use of Yahoo! Groups is subject to the Yahoo! Terms of
>      Service.
>
> -----------------------------------------------------------------------
>