C128 power up

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C128 power up

traymond
Hi Mike,

Reguarding my C128 power up issue.

CAP-C106. Only getting 7V.  I changed it but no difference.

74LS. All of these are almost 5V on the pins you mention.

U59 REGULATOR-. The spec sheet I found on this describes it  this way:
LEFT PIN=OUTPUT
MIDDLE PIN=GND
RIGHT PIN=INPUT

I took a measurement using the center ground and you said right pin is 12V
Reading right pin=ZERO VOLTS
LEFT PIN=16V

Terry Raymond


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Re: C128 power up

Mike Stein

I guess left & right are relative; looking at U59 from the top with the mounting tab facing away from you the writing should be right side up and input and output are left and right respectively.
 
Sounds like the 5V side of the supply/switch/etc. are OK but something's wrong with the 12V side all right if your measurements are correct; 16V sounds about right for the input but the output should be 12V. Either U59 is fried or you have a short on the 12V line causing U59 to shut down (or both); often the culprit is a shorted tantalum capacitor but I can't look at a C128 board at the moment to look for a likely candidate.
 
m
 
 
----- Original Message -----
Sent: Thursday, June 29, 2017 8:05 PM
Subject: C128 power up

Hi Mike,

Reguarding my C128 power up issue.

CAP-C106. Only getting 7V.  I changed it but no difference.

74LS. All of these are almost 5V on the pins you mention.

U59 REGULATOR-. The spec sheet I found on this describes it  this way:
LEFT PIN=OUTPUT
MIDDLE PIN=GND
RIGHT PIN=INPUT

I took a measurement using the center ground and you said right pin is 12V
Reading right pin=ZERO VOLTS
LEFT PIN=16V

Terry Raymond


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Re: C128 power up

traymond
Are the Tantalum capacitors also called ceramic capacitors
are they a kind of tan color fairly flat 2pins?

The regulator is new.

The axial capacitor you mentioned read 7V wasn't 9V I tried a different one, same 7V

Terry Raymond

On Jun 29, 2017 7:02 PM, "Mike Stein" <[hidden email]> wrote:
I guess left & right are relative; looking at U59 from the top with the mounting tab facing away from you the writing should be right side up and input and output are left and right respectively.
 
Sounds like the 5V side of the supply/switch/etc. are OK but something's wrong with the 12V side all right if your measurements are correct; 16V sounds about right for the input but the output should be 12V. Either U59 is fried or you have a short on the 12V line causing U59 to shut down (or both); often the culprit is a shorted tantalum capacitor but I can't look at a C128 board at the moment to look for a likely candidate.
 
m
 
 
----- Original Message -----
Sent: Thursday, June 29, 2017 8:05 PM
Subject: C128 power up

Hi Mike,

Reguarding my C128 power up issue.

CAP-C106. Only getting 7V.  I changed it but no difference.

74LS. All of these are almost 5V on the pins you mention.

U59 REGULATOR-. The spec sheet I found on this describes it  this way:
LEFT PIN=OUTPUT
MIDDLE PIN=GND
RIGHT PIN=INPUT

I took a measurement using the center ground and you said right pin is 12V
Reading right pin=ZERO VOLTS
LEFT PIN=16V

Terry Raymond



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Re: C128 power up

traymond
Hi Mike,

If I could please get your email address I can send you a pic of 
The regulator, and at your convenience.

Terry Raymond

On Jun 29, 2017 6:47 PM, wrote:
Are the Tantalum capacitors also called ceramic capacitors
are they a kind of tan color fairly flat 2pins?

The regulator is new.

The axial capacitor you mentioned read 7V wasn't 9V I tried a different one, same 7V

Terry Raymond

On Jun 29, 2017 7:02 PM, "Mike Stein" <[hidden email]> wrote:
I guess left & right are relative; looking at U59 from the top with the mounting tab facing away from you the writing should be right side up and input and output are left and right respectively.
 
Sounds like the 5V side of the supply/switch/etc. are OK but something's wrong with the 12V side all right if your measurements are correct; 16V sounds about right for the input but the output should be 12V. Either U59 is fried or you have a short on the 12V line causing U59 to shut down (or both); often the culprit is a shorted tantalum capacitor but I can't look at a C128 board at the moment to look for a likely candidate.
 
m
 
 
----- Original Message -----
Sent: Thursday, June 29, 2017 8:05 PM
Subject: C128 power up

Hi Mike,

Reguarding my C128 power up issue.

CAP-C106. Only getting 7V.  I changed it but no difference.

74LS. All of these are almost 5V on the pins you mention.

U59 REGULATOR-. The spec sheet I found on this describes it  this way:
LEFT PIN=OUTPUT
MIDDLE PIN=GND
RIGHT PIN=INPUT

I took a measurement using the center ground and you said right pin is 12V
Reading right pin=ZERO VOLTS
LEFT PIN=16V

Terry Raymond



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Re: C128 power up

Clockmeister
The 78xx regulator is has a standard pinout, see the datasheet:
Pin 1 is input, pin 2 ground and pin 3 output.

If you have soldered it in the wrong way around there will be no
regulated 12V output.

http://pdf1.alldatasheet.com/datasheet-pdf/view/9044/NSC/7812.html



On 30/06/2017 10:01 AM, Terry Raymond wrote:

> Hi Mike,
>
> If I could please get your email address I can send you a pic of
> The regulator, and at your convenience.
>
> Terry Raymond
>
> On Jun 29, 2017 6:47 PM, wrote:
>
>> Are the Tantalum capacitors also called ceramic capacitors
>> are they a kind of tan color fairly flat 2pins?
>>
>> The regulator is new.
>>
>> The axial capacitor you mentioned read 7V wasn't 9V I tried a different
>> one, same 7V
>>
>> Terry Raymond
>>
>> On Jun 29, 2017 7:02 PM, "Mike Stein" <[hidden email]> wrote:
>>
>> I guess left & right are relative; looking at U59 from the top with the
>> mounting tab facing away from you the writing should be right side up and
>> input and output are left and right respectively.
>>
>> Sounds like the 5V side of the supply/switch/etc. are OK but something's
>> wrong with the 12V side all right if your measurements are correct; 16V
>> sounds about right for the input but the output should be 12V. Either U59
>> is fried or you have a short on the 12V line causing U59 to shut down (or
>> both); often the culprit is a shorted tantalum capacitor but I can't look
>> at a C128 board at the moment to look for a likely candidate.
>>
>> m
>>
>>
>> ----- Original Message -----
>>
>> *From:* Terry Raymond <[hidden email]>
>> *To:* [hidden email]
>> *Sent:* Thursday, June 29, 2017 8:05 PM
>> *Subject:* C128 power up
>>
>> Hi Mike,
>>
>> Reguarding my C128 power up issue.
>>
>> CAP-C106. Only getting 7V.  I changed it but no difference.
>>
>> 74LS. All of these are almost 5V on the pins you mention.
>>
>> U59 REGULATOR-. The spec sheet I found on this describes it  this way:
>> LEFT PIN=OUTPUT
>> MIDDLE PIN=GND
>> RIGHT PIN=INPUT
>>
>> I took a measurement using the center ground and you said right pin is 12V
>> Reading right pin=ZERO VOLTS
>> LEFT PIN=16V
>>
>> Terry Raymond
>>
>>
>>
>>


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