Spectravideo svi-808 pc

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Re: Spectravideo svi-808 pc

Postby LS120 on Thu Jan 13, 2022 6:18 pm

has a fan option but no fan..
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LS120
 
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Re: Spectravideo svi-808 pc

Postby LS120 on Thu Jan 13, 2022 6:19 pm

one of the power units out to check over at a later date..
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LS120
 
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Re: Spectravideo svi-808 pc

Postby LS120 on Thu Jan 13, 2022 6:20 pm

the case without the psu in.. time to close it up and put to one side to check the voltages later..
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LS120
 
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Re: Spectravideo svi-808 pc

Postby LS120 on Fri Jan 14, 2022 11:39 am

ok so did a bit of voltage checking and I'm a little perplexed..

The Spectra PSU; the main black AC box is fine both outputs have 16V ac on them,
The DC board has ....... 12v+ = +11.96v
5v+ = 0v prob the L4964 DC-DC.
-12v = -14.41v
-5v = -13.54v ? why so high

all are unloaded voltages

the Franken PSU; the main black AC box is fine both outputs have 16V ac on them,
The DC board has ....... 12v+ = +12.11v
5v+ = +5.12v
-12v = -14.52v
-5v = -13.73v ? why so high

all are unloaded voltages

any help ?? would it be ok at -13.73v on the -5v rail or is that a fault.. i'm picking it is an issue

thanks and keep watching
LS120
 
Posts: 432
Joined: Fri Jul 22, 2016 9:19 pm
Location: Wellington

Re: Spectravideo svi-808 pc

Postby LS120 on Sat Jan 15, 2022 2:37 pm

Well decided to have another look at the svi-808 power board (with the dead 5v+ rail) on checking i lost the other voltages and now it has 25v on the 12v rail.... so i decided to remove all the components from the board for a few reasons.

1: there was a problem with some parts and i will have to disorder them anyway to replace..
2: the caps are prob from when it was made..
3: some of the diodes look like they have been in and out a bit..
4: the most important of all is the circuit diagrams i have are of so low quality thay when i blow them up every thig is a blur and you cant read bugger all so what way to get the right values and numbers.. right... lol

one thing i noticed was the boards were not made very well at all and holes are all over the place not centered etc.. and some pads have come off all together will need to see if i need them or not.. but maybe a few cheap remakes coming soon..

enjoy the pics
Attachments
pb-4.jpg
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pb-2.jpg
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pb-1.jpg
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LS120
 
Posts: 432
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Re: Spectravideo svi-808 pc

Postby LS120 on Sat Jan 15, 2022 2:39 pm

even took sizes of board etc..
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pb-8.jpg
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pb-7.jpg
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pb-6.jpg
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LS120
 
Posts: 432
Joined: Fri Jul 22, 2016 9:19 pm
Location: Wellington

Re: Spectravideo svi-808 pc

Postby LS120 on Sat Jan 15, 2022 2:53 pm

the parts list:

U1 - L4964HT
U2 - L7812Cv
U3 - L7905CV
U4 - L7912CV

F1 - 1A
F2 - 3A

D1-D4 - 1N5402
D5-D8 - 1N4001
SD1 - IR30DF - 4 - 8J

R1 - 4.3K 5% 1/4w
R2 - 15K 5% 1/4w
R3 - 510 Ohm 1/4w

C1,C2,C8,C10,C12,C13,15,C16,C18 - 104K POLY (100V)
C3,C4,C9 - 2200UF @ 35V
C5,C6,C7,C11,C14,C17 - 100UF @ 25V
C19 - 222K POLY
C20 - 333K POLY
C21 - 2.2UF @ 63V

L1 - NOT SURE (dont know how to mesure)
Attachments
svi-808-A-26.jpg
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LS120
 
Posts: 432
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