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
 
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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
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LS120
 
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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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LS120
 
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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)
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LS120
 
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Re: Spectravideo svi-808 pc

Postby LS120 on Tue Jan 25, 2022 4:20 pm

ok so after the long weekend i had some time today to check out the 808 keyboard.. realy needs a clean.. also have a funny feeling that its a rubber membrane type.. also need to see how i can fix the missing and broken keys.. so here we go.......
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LS120
 
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Re: Spectravideo svi-808 pc

Postby LS120 on Tue Jan 25, 2022 4:22 pm

on first looks it looks like a normal type of key tops.. if so an easy to replace part..
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LS120
 
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Re: Spectravideo svi-808 pc

Postby LS120 on Tue Jan 25, 2022 4:26 pm

man look at the amount of crap under the keys... did anyone lose a cat..... lol :D
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LS120
 
Posts: 445
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Re: Spectravideo svi-808 pc

Postby LS120 on Tue Jan 25, 2022 4:28 pm

a good clean out and it looks better.. time to open it up..
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LS120
 
Posts: 445
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Re: Spectravideo svi-808 pc

Postby LS120 on Tue Jan 25, 2022 4:30 pm

hmmm looks like someone has been inside before.....
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LS120
 
Posts: 445
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Re: Spectravideo svi-808 pc

Postby LS120 on Tue Jan 25, 2022 4:32 pm

yep and they have rounded some of the screw heads as well... ohhh well time for the mulit tool to fix the problem... and now they are flat heads... tada....
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IMG_20220125_150816_464.jpg
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LS120
 
Posts: 445
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Re: Spectravideo svi-808 pc

Postby LS120 on Tue Jan 25, 2022 4:34 pm

so looking at the keyboard there were screws around the out side that should alow the main unit to come out.... but NO lets hide 2 screws under everything so you have to take the keyboard circuit off to undo the last 2 that attach the front to the frame.... ahhhhhhhhhhhhhhhhhhhh :shock:
LS120
 
Posts: 445
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Location: Wellington

Re: Spectravideo svi-808 pc

Postby LS120 on Tue Jan 25, 2022 4:36 pm

now we must be careful thaing the board off as the key pressers will fall out when we turn the frame over.. so take note.............. People................. :mrgreen:
Attachments
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IMG_20220125_150816_464.jpg
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LS120
 
Posts: 445
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