f



IBM Type 4 Complex, L2 128kB for 486 - voltage regulator

Hello friends,=20
I would like to ask you about type of Voltage regulator transistor (in uppe=
r right place of board with cooler) on this Type 4 complex ? I have today f=
ine haul of this board for empty CPU socket of model 90, but some sucker cu=
t this transistor out of this board.

I checked it here, but there is no info about this part :
http://www.walshcomptech.com/ohlandl/complexes/Type4-N.html
so I will be glad about any info what I should find.

There is also missing cache controller, but fortunatelly I have it in my co=
llection - so after adding voltage regulator there is a chance to make this=
 complex working again :)

George, Czech republic
0
Jiri
8/26/2016 10:25:09 PM
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http://ps-2.kev009.com/ohlandl/complexes/Type4-N.html

U85 LT1085CT VRM

This part has no suffix, just a date code.

3A Low Dropout Positive Adjustable Regulators
LT1085  3.0A output current

http://www.datasheetarchive.com/dlmain/766d414165fce80707b367e5bc469da470f109/M/LT1085CT




On 8/26/2016 17:25, Jiri Zlamal wrote:
> Hello friends,
> I would like to ask you about type of Voltage regulator transistor (in upper right place of board with cooler) on this Type 4 complex ? I have today fine haul of this board for empty CPU socket of model 90, but some sucker cut this transistor out of this board.
>
> I checked it here, but there is no info about this part :
> http://www.walshcomptech.com/ohlandl/complexes/Type4-N.html
> so I will be glad about any info what I should find.
>
> There is also missing cache controller, but fortunatelly I have it in my collection - so after adding voltage regulator there is a chance to make this complex working again :)
>
> George, Czech republic
>

0
Louis
8/27/2016 12:59:47 PM
George, was the heatsink still attached?

On 8/27/2016 07:59, Louis Ohland wrote:
> http://ps-2.kev009.com/ohlandl/complexes/Type4-N.html
>
> U85 LT1085CT VRM
>
> This part has no suffix, just a date code.
>
> 3A Low Dropout Positive Adjustable Regulators
> LT1085  3.0A output current
>
> http://www.datasheetarchive.com/dlmain/766d414165fce80707b367e5bc469da470f109/M/LT1085CT
>
>
>
>
>
> On 8/26/2016 17:25, Jiri Zlamal wrote:
>> Hello friends,
>> I would like to ask you about type of Voltage regulator transistor (in
>> upper right place of board with cooler) on this Type 4 complex ? I
>> have today fine haul of this board for empty CPU socket of model 90,
>> but some sucker cut this transistor out of this board.
>>
>> I checked it here, but there is no info about this part :
>> http://www.walshcomptech.com/ohlandl/complexes/Type4-N.html
>> so I will be glad about any info what I should find.
>>
>> There is also missing cache controller, but fortunatelly I have it in
>> my collection - so after adding voltage regulator there is a chance to
>> make this complex working again :)
>>
>> George, Czech republic
>>
>

0
Louis
8/27/2016 4:34:20 PM
Louis, unfortunatelly heatsink has been taken away also - only rest of 3 cut wires of transistor and one cut on oposite side (probably of cooler) are present on complex card . 
Thanks for link and tip - it seems the LT1085CT can be easily bought from China on ebay. And I believe I will find some fine cooler for it too.

On Saturday, August 27, 2016 at 6:34:21 PM UTC+2, Louis Ohland wrote:
> George, was the heatsink still attached?
> 
> On 8/27/2016 07:59, Louis Ohland wrote:
> > http://ps-2.kev009.com/ohlandl/complexes/Type4-N.html
> >
> > U85 LT1085CT VRM
> >
> > This part has no suffix, just a date code.
> >
> > 3A Low Dropout Positive Adjustable Regulators
> > LT1085  3.0A output current
> >
> > http://www.datasheetarchive.com/dlmain/766d414165fce80707b367e5bc469da470f109/M/LT1085CT
> >
> >
> >
> >
> >
> > On 8/26/2016 17:25, Jiri Zlamal wrote:
> >> Hello friends,
> >> I would like to ask you about type of Voltage regulator transistor (in
> >> upper right place of board with cooler) on this Type 4 complex ? I
> >> have today fine haul of this board for empty CPU socket of model 90,
> >> but some sucker cut this transistor out of this board.
> >>
> >> I checked it here, but there is no info about this part :
> >> http://www.walshcomptech.com/ohlandl/complexes/Type4-N.html
> >> so I will be glad about any info what I should find.
> >>
> >> There is also missing cache controller, but fortunatelly I have it in
> >> my collection - so after adding voltage regulator there is a chance to
> >> make this complex working again :)
> >>
> >> George, Czech republic
> >>
> >

0
Jiri
8/27/2016 8:47:25 PM
On Saturday, August 27, 2016 at 4:47:26 PM UTC-4, Jiri Zlamal wrote:
> Thanks for link and tip - it seems the LT1085CT can be easily bought from China on ebay. And I believe I will find some fine cooler for it too.

As I am of the suspicious type, it may be that the VRM was cut off because it blew up -- that's not something that happens often, but when it does it's rather loud and smelly.  Still, it's probably worth the modest investment to try to replace it.
0
ekblaw
8/29/2016 4:41:47 PM
Odd, since the N is not very upgrade friendly. Perchance the previous 
owner tried an upgrade 486... missing cache controller? Put er in wrong? 
Though having the LT1085 go pop sorta suggests something was drawing a 
bit more power... Or... maybe they were trying an upgrade 486 that used 
a VRM with an external power tap... Fan?

On 8/29/2016 11:41, ekblaw@vnet.ibm.com wrote:
> On Saturday, August 27, 2016 at 4:47:26 PM UTC-4, Jiri Zlamal wrote:
>> Thanks for link and tip - it seems the LT1085CT can be easily bought from China on ebay. And I believe I will find some fine cooler for it too.
>
> As I am of the suspicious type, it may be that the VRM was cut off because it blew up -- that's not something that happens often, but when it does it's rather loud and smelly.  Still, it's probably worth the modest investment to try to replace it.
>

0
Louis
8/29/2016 5:07:55 PM
Louis, its are interesting thinks and inspired me to detail inspect of board - and I have found that VIn and Vout (upper and centre) are shorted by rest of one cutted input wire of transistor ! 

http://cds.linear.com/image/10407.png

So function of missing VR transistor is directly "bridged" for input voltage from motherboard to complex card. 

I don't have clue (due to fact of of missing cache unit) if this complex should be safe to equip by new VR and cache controller circuit, and try to power-up in model 90. 
All installed on complex card (all chips, cache RAM modules and rest of passive circuits) seems as clean and untouched, and are not burned or fired... so I guess it would be worth to make it running again.

But on other side I really REALLY don't want to damage motherboard and other components of 90 by this "home-made refurbished" board...

What do you think about this situation ? 

On Monday, August 29, 2016 at 7:07:57 PM UTC+2, Louis Ohland wrote:
> Odd, since the N is not very upgrade friendly. Perchance the previous 
> owner tried an upgrade 486... missing cache controller? Put er in wrong? 
> Though having the LT1085 go pop sorta suggests something was drawing a 
> bit more power... Or... maybe they were trying an upgrade 486 that used 
> a VRM with an external power tap... Fan?
> 
> On 8/29/2016 11:41, ekblaw@vnet.ibm.com wrote:
> > On Saturday, August 27, 2016 at 4:47:26 PM UTC-4, Jiri Zlamal wrote:
> >> Thanks for link and tip - it seems the LT1085CT can be easily bought from China on ebay. And I believe I will find some fine cooler for it too.
> >
> > As I am of the suspicious type, it may be that the VRM was cut off because it blew up -- that's not something that happens often, but when it does it's rather loud and smelly.  Still, it's probably worth the modest investment to try to replace it.
> >

0
Jiri
8/29/2016 8:19:29 PM
On Friday, 26 August 2016 23:25:11 UTC+1, Jiri Zlamal  wrote:
> Hello friends,=20
> I would like to ask you about type of Voltage regulator transistor (in up=
per right place of board with cooler) on this Type 4 complex ? I have today=
 fine haul of this board for empty CPU socket of model 90, but some sucker =
cut this transistor out of this board.
>=20
> I checked it here, but there is no info about this part :
> http://www.walshcomptech.com/ohlandl/complexes/Type4-N.html
> so I will be glad about any info what I should find.
>=20
> There is also missing cache controller, but fortunatelly I have it in my =
collection - so after adding voltage regulator there is a chance to make th=
is complex working again :)
>=20
> George, Czech republic

George,

if you have any Intel 80497 66MHz parts spare, we could do an exchange, as =
I have P90 60 or 66 complexes with PODP 120/133 upgrade processors, that ha=
ve worked in the past, when the 80496 cache controllers were substituted wi=
th 80497s.

P.S. did you get my e-mail, I haven't checked my inbox lately?

Cheers,
WBST
0
WBSTClarke
9/12/2016 5:29:44 AM
Reply: