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Toshiba M-9485C VCR
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Re: Toshiba M-9485C VCR
I'm back, today I'm working on a board called "video ccd". It was on the video controller board in a can, and almost all the caps on it were bad. I've attached some pics of the board below.
One problem I'm having is with the surface mount stuff, I measured C421 as a short in circuit. I took it out and it measured infinite resistance, and 40 pF. I can't read the color code on it, but it looks like either brown black gold, or red black gold.
Are they supposed to measure as open with an ohm meter?
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Re: Toshiba M-9485C VCR
The cap may be connected in parallel with other component that may have low resistance. So what is the resistance reading do you get that shown as shorts, < 1 Ohm?Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809
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Re: Toshiba M-9485C VCR
Originally posted by budm View PostThe cap may be connected in parallel with other component that may have low resistance. So what is the resistance reading do you get that shown as shorts, < 1 Ohm?
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Re: Toshiba M-9485C VCR
Originally posted by HorenceAfter reading the whole post, I have learned more about this topic. Thank you so much.
I'm glad there is still some knowledgeable techs out there when it comes to VCR's. I'll post some more pics for anybody who wants to follow along. I've already spent 75 bucks on this machine. I know you all think I'm crazy, but it has sentimental value. It's also a great learning experience, both with mechanical and electronics skills.
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Re: Toshiba M-9485C VCR
Originally posted by R_J View PostThe style are called melf or mini melf (NO not milf) I believe its the same color code as the resistors. I have never seen a bad one. looks like L404 could be accross C421
I've got the head off, and am going to look at the motor drive. I already took apart and greased the capstan bearings and idler motors.
The head has a lost of oxidization around it because a tape was left in there for years. I want to make sure nothing got in there.
All in all the pictures been getting a lot better with all the re capping. It's still a little lite and gets washed out with very white scenes.
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Re: Toshiba M-9485C VCR
Originally posted by R_J View PostThe drum motor uses sealed bearings, nothing to lube. careful with the upper drum the heads are very fragile
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Re: Toshiba M-9485C VCR
I got the head apart today. There was a bunch of the tap rust stuff everywhere. I cleaned it out from around the heads with a wooden toothpick, and super fine tiny painters brush.
RJ I need your advice on this one, the magnet wire that's coiled around the drum has come loose in spots, and comes out. I'm pretty sure it should be glued down. Is it okay to use a bit of thin CA, or is epoxy better? I don't want to make it too heavy and throw off the balance.
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Re: Toshiba M-9485C VCR
Originally posted by R_J View PostI don't know why you took the drum motor apart but I wish you luck getting it assembled and timed properly. I don't think a bit of glue will affect the balance much.
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Re: Toshiba M-9485C VCR
RJ, yep you called it. I put it back together on the marks the grub screws left on the shaft. Must still be a bit off though, I guess I create more fun times.
It plays but it crinkles the tape and cuts out, it also sounds like the motor is changing speeds sometimes. Is the only way to fix it trail and error changing the set screws?Last edited by mike_drz; 05-25-2017, 07:08 PM.
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Re: Toshiba M-9485C VCR
The drum itself should not cause the tape to crinkle, it would cause the head switching point to be out or to have a very poor picture. try and see where the tape is being crinkled in the tape path. What else did you remove or adjust?
On the lower part of the drum there is a machined groove, the tape should be riding just above it. make sure the drum is mounted properly to the chassisLast edited by R_J; 05-25-2017, 07:33 PM.
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Re: Toshiba M-9485C VCR
Originally posted by R_J View PostThe drum itself should not cause the tape to crinkle, it would cause the head switching point to be out or to have a very poor picture. try and see where the tape is being crinkled in the tape path. What else did you remove or adjust?
Would the switching point show up on the scope as being off?Last edited by mike_drz; 05-25-2017, 07:32 PM.
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Re: Toshiba M-9485C VCR
The head switching will show up at the bottom of the screen, We usually used a tv or monitor with the vertical size reduced so we could see where the switching was taking place It should be around 6 lines up from the vertical pulse. If the sw pulse is too low it will switch in the vertical pulse causing the picture to jump, if its too high it would show up in the picture, that all
You should have found what was causing the problem before adjusting the tape path.
What all did you remove besides the drum assembly? It should have just droped back in and maybe only minor adjustments would have been needed. If the drum was not assembled properly it would have shown up as a very poor or no picture but the tape itself would still run smooth.Last edited by R_J; 05-25-2017, 08:40 PM.
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Re: Toshiba M-9485C VCR
Originally posted by R_J View PostThe head switching will show up at the bottom of the screen, We usually used a tv or monitor with the vertical size reduced so we could see where the switching was taking place It should be around 6 lines up from the vertical pulse. If the sw pulse is too low it will switch in the vertical pulse causing the picture to jump, if its too high it would show up in the picture, that all
You should have found what was causing the problem before adjusting the tape path.
What all did you remove besides the drum assembly? It should have just droped back in and maybe only minor adjustments would have been needed. If the drum was not assembled properly it would have shown up as a very poor or no picture but the tape itself would still run smooth.
The tape sounds like it's almost making a grinding noise against the drum, and the drum slows down. A few seconds later, it'll run smoother, with just the crunchy tape sound. Not very good at all, I swear I didn't touch the tape path until I heard that grinding noise and saw the tape starting to fold. I looked all around first, and couldn't see it getting folding on any of the posts or guides.
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