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Robotrontechnik-Forum » Technische Diskussionen » Replacing PC1715 power supply with ATX one » Themenansicht

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000
02.12.2013, 19:46 Uhr
dreadbit

Hello,
I'm about replacing original power supply of PC1715 with an ATX one because the original fails to raise from the power-on values (+3?+5?) to +12.

I made an scheme of RC delay to the base of transistor from which I am going to feed +12 to the PC1715.

What should I be aware of? Can I damage 1715 this way? Is there a well-known way to run 1715 from AT/ATX power supply?

What causes 1715 not to run from direct +12V? Why it requires delay for +12?

Is there some well-known capacitor inside original power supply which always breakes leading to this behavior?

I'm sorry if this question was discussed somewhere in forum, but I cannot google it out since I do not speak german.

Dieser Beitrag wurde am 02.12.2013 um 20:13 Uhr von dreadbit editiert.

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001
02.12.2013, 20:46 Uhr
holm

Avatar von holm

First of all: don't do that. Better try to repair the original Supply, it has an "higher Quality" than usual PC supplies.

The order of apperance of the Supply Voltages is neccessary for the used Memory Chips (2708 and 4116). Both of them require that the 5N are present before 5P and before 12P.

Regards,

Holm
--
float R,y=1.5,x,r,A,P,B;int u,h=80,n=80,s;main(c,v)int c;char **v;
{s=(c>1?(h=atoi(v[1])):h)*h/2;for(R=6./h;s%h||(y-=R,x=-2),s;4<(P=B*B)+
(r=A*A)|++u==n&&putchar(*(((--s%h)?(u<n?--u%6:6):7)+"World! \n"))&&
(A=B=P=u=r=0,x+=R/2))A=B*2*A+y,B=P+x-r;}

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002
02.12.2013, 21:16 Uhr
Rüdiger
Administrator

Zitat:

holm schrieb
First of all: don't do that. Better try to repair the original Supply,

I completely agree.
--
Kernel panic: Out of swap space.

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003
03.12.2013, 18:36 Uhr
dreadbit

Zitat:

holm schrieb
First of all: don't do that. Better try to repair the original Supply, it has an "higher Quality" than usual PC supplies.

Sure, that's better! But it may take a looot of time. More, I'm afraid of power supplies.
Is there any guide, BTW?

Zitat:

holm schrieb

The order of apperance of the Supply Voltages is neccessary for the used Memory Chips (2708 and 4116). Both of them require that the 5N are present before 5P and before 12P.

At least not in my case! I have 3 x К573РФ2 as 2716 on main board and К565РУ6 as main memory. On the floppy controller there are two chips marked as U505D which I belive to be OTP ROMs (do they need -5 +12? I bet no).

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004
03.12.2013, 21:45 Uhr
holm

Avatar von holm

Yes, in later 1715's where no K565RU3 anymore. U505 are mask programmed 2708-like ROMs, but they are failing more often than the pincompatible 2708's.

What is your actual powersupply doing? Nothing at all? There is no cause to be afraid of PSU's.
We will help you.

Regards,
Holm
--
float R,y=1.5,x,r,A,P,B;int u,h=80,n=80,s;main(c,v)int c;char **v;
{s=(c>1?(h=atoi(v[1])):h)*h/2;for(R=6./h;s%h||(y-=R,x=-2),s;4<(P=B*B)+
(r=A*A)|++u==n&&putchar(*(((--s%h)?(u<n?--u%6:6):7)+"World! \n"))&&
(A=B=P=u=r=0,x+=R/2))A=B*2*A+y,B=P+x-r;}

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005
03.12.2013, 22:05 Uhr
dreadbit

Zitat:

holm schrieb
Yes, in later 1715's where no K565RU3 anymore. U505 are mask programmed 2708-like ROMs, but they are failing more often than the pincompatible 2708's.

That's a bad news.
But I have several motherboards and floppy controllers, one of them has РФ's in panels [and one is missing!] and I think I'll try to plug AT29C256 as an experiment. The other two working boards has U505 soldered in.

Zitat:

What is your actual powersupply doing? Nothing at all? There is no cause to be afraid of PSU's.

Currently it is working! Normally, I'm frighten by power supplies, but in my country I managed to frighten IT! ;-)
I've opened it and just blew dust off it.
I do not think I fixed the problem, but.
The problem will return, I'm sure. I'm not sure will it turn on tomorrow or not.

First, [looking to the leds of motherboard], normally, it turns on all the voltages except +12, which is less then +12 , then raise it up in a few seconds. But in broken condition it does not raise it. And whistles (or that's not a whistle?)

My monitor is not plugged into it (well, I have a native monitor, but the last time I switched it on, it began to smell, that's a another thing to fix in some future [but I'm afraid of monitors much more then power supplies even]) - I use composite MC6105 via converter, powered externally, so I power only motherboard+contoller + 2 disk drives [TEAC 80 head and MC5309].

From the other side, I have 1715M without power supply [so I have the only power supply for two PCs], so I'm still interested in using AT/ATX power supply.

Zitat:

We will help you.

Thanks!

Dieser Beitrag wurde am 04.12.2013 um 00:34 Uhr von dreadbit editiert.

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006
04.12.2013, 08:40 Uhr
holm

Avatar von holm

Hmmm... that "whisteling" is a sign of an possible overload. Do you already have the schematics from that PSU?

Try to change all the small electrolytics around the B260 and the MAA723s. (just in case..).
The +12V rail is switched on trough a pair for Transistors on the secondary side of the 12V PSU, There is a KT818A (V18) and a SD336B (V19) doing this. You should be able to measure 12V on the Emitter of V18 after the PSU startup and before the 12V rail is switched on.
Don't forget to clean up the fuse holder and the fuse fir the 12V rail, often they are heavily
oxidated.. This is F3 located on the base plate.

Where do you come from so you are able to frighten an PSU? :-)

The smelling Monitor is more bad News than a bad PSU. Has the Picture tube a copper-colored metal tape around it that is visible from the front?
As for the U505, if your 1715 is reading and writing disks fine, you don't have a problem with them.

Regards,

Holm
--
float R,y=1.5,x,r,A,P,B;int u,h=80,n=80,s;main(c,v)int c;char **v;
{s=(c>1?(h=atoi(v[1])):h)*h/2;for(R=6./h;s%h||(y-=R,x=-2),s;4<(P=B*B)+
(r=A*A)|++u==n&&putchar(*(((--s%h)?(u<n?--u%6:6):7)+"World! \n"))&&
(A=B=P=u=r=0,x+=R/2))A=B*2*A+y,B=P+x-r;}

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007
04.12.2013, 21:44 Uhr
dreadbit

Zitat:

holm schrieb
Hmmm... that "whisteling" is a sign of an possible overload. Do you already have the schematics from that PSU?

It should not be overload. As I said, I power monitor externally, and it eats +12 much more then floppies/motherboard/FDC (at least I think so).
A parasite shortage via dust? I do not believe.

I'll do what you advice (changing electrolytes etc). But they look unsuspicious.

Zitat:

holm schrieb
Where do you come from so you are able to frighten an PSU? :-)

Possibly I can understand the PSU ;-)

Zitat:

holm schrieb
The smelling Monitor is more bad News than a bad PSU. Has the Picture tube a copper-colored metal tape around it that is visible from the front?

I have not look inside yet (but I will do it after I consider my PC1715 to be mostly working and stable). First thing I've tried is to replace it by something common - and via sync mixer (one 7400, two transistors) I'm able to use it with composite monitor/TVset even, and then to VGA via that magic chinese video converter box I'm waiting to arrive soon.
Only then I'll look inside the monitor. (Last time I've turned it on was ~7-10 years ago; it worked)

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008
04.12.2013, 21:56 Uhr
holm

Avatar von holm

I don't meant a "real" overload, but more a partially short somewhere, you got it already right, look for such things and really check the Fuse F3 with its holder.

Nothing wrong with Russia, I have some friends there but unfortunately I forgot almost all of my school-Russian, and now try to write English, which I never had in the school..

You shouldn't look inside the monitor, just at the front of it. I'm trying to determine which Kind of Monitor you have, a MON2 or a MON3. The later one has a Philips Picture Tube which has a copper colored Metal tape around the screen which is visible from the outside. This one has western germany electronics inside and the philips tube. The MON 2 has electronics from the former GDR aka Robotron and when that one is smelling like vinegar, it is gone, almost forever since then the HV coil from the flyback transformer is gone.
This is a big problem we have here with that sort of stuff.

Regards,

Holm
--
float R,y=1.5,x,r,A,P,B;int u,h=80,n=80,s;main(c,v)int c;char **v;
{s=(c>1?(h=atoi(v[1])):h)*h/2;for(R=6./h;s%h||(y-=R,x=-2),s;4<(P=B*B)+
(r=A*A)|++u==n&&putchar(*(((--s%h)?(u<n?--u%6:6):7)+"World! \n"))&&
(A=B=P=u=r=0,x+=R/2))A=B*2*A+y,B=P+x-r;}

Dieser Beitrag wurde am 04.12.2013 um 21:58 Uhr von holm editiert.

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009
09.12.2013, 23:55 Uhr
dreadbit

Looks like my one has no any copper tape.
The only visible problem is that plastic cover of vertical freq transformer is cracked as you've expected.

I bet that's not possible to get the transformer replacement nowadays, right?

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010
10.12.2013, 20:33 Uhr
holm

Avatar von holm

...Right. It is almost hopeless.

You can do some experiments if you want, eg. try to place the HV Coil from a Junost TV in Place of the broken HV Coil, but look carefully, below the HV windings is a coil with thicker wire that's connected parallel to one of the primary side. This coil is neccessary for the Monitor Deflection to work.

Sorry, I don't have a useful recipe for the repair, we've tried to hit some coil winders to make new coils, but without any luck so far..

Regards,

Holm
--
float R,y=1.5,x,r,A,P,B;int u,h=80,n=80,s;main(c,v)int c;char **v;
{s=(c>1?(h=atoi(v[1])):h)*h/2;for(R=6./h;s%h||(y-=R,x=-2),s;4<(P=B*B)+
(r=A*A)|++u==n&&putchar(*(((--s%h)?(u<n?--u%6:6):7)+"World! \n"))&&
(A=B=P=u=r=0,x+=R/2))A=B*2*A+y,B=P+x-r;}

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