diagnosing portable VCR in a bag no video issues - Page 1
Forum section: electronics / repair

author: gooseEL34
author_rank: Regular Contributor
timestamp: July 27, 2014, 10:33:12 pm
content: Hey all.Unit is an Eddie Bauer VCR in a bag (actually it is an Audiovox ME10). Item powers up when attached to 12v and VHS tape plays and audio comes nicely out of speaker.Problem is no video.I do not know what to look for first when diagnosing a no video state.I cannot find schematic online.Thanks for advice

author: JohnWard
author_rank: Contributor
timestamp: July 28, 2014, 12:02:26 am
content: First thing is to clean the video heads - the amount of dirt required to go from good picture to nothing at all is very small.If someone has used a duff or mouldy tape in there, the heads could be totally clogged in just a few minutes of playback.

author: gooseEL34
author_rank: Regular Contributor
timestamp: July 28, 2014, 01:42:56 am
content: Wow...I guess I would expect to see SOMETHING on the screen even if the tape was crap. Will check that.

author: AndyC_772
author_rank: Super Contributor
timestamp: July 28, 2014, 06:34:01 am
content: I wouldn't be so sure. I'm reminded of the time I rented a movie which, halfway through, dissolved into video snow over the course of just a few seconds. There was a patch of crud on the tape - I don't even want to know what it was - which completely clogged the heads, and meant I had to spend the rest of the evening taking the VCR apart to clean them.

author: wagon
author_rank: Frequent Contributor
timestamp: July 28, 2014, 01:29:37 pm
content: Some machines mute the video when the signal is bad.

author: gooseEL34
author_rank: Regular Contributor
timestamp: July 28, 2014, 02:30:48 pm
content: well I have nothing. Essentially a blank screen, with no snow or any movement that is can be seen on the screen. I guess what I am asking is the following, when a monitor is internally connected to a video source what connections am I looking for to test? I am handy with a voltmeter know how to trace a schematic and feel comfortable soldering and checking for broken burnt or bad connections, but i dont no what input a video monitor is normally going to see. .

author: rstoer
author_rank: Regular Contributor
timestamp: July 28, 2014, 06:28:29 pm
content: Indeed, the first thing to try is cleaning the heads. If memory serves the head gap is <14 microns so they clog very easily and will often cause a no picture condition.HOWEVER - you must be very careful or you will snap a head off. If you do that (or it's already been done), throw the unit in the trash.First locate the video heads which are in small openings at the bottom edge of the head drum (the silver rotating drum with etched groves). There can be two (180 degrees apart) or four (90 degrees apart).The correct way to clean them is with a small piece of chamois dipped in alcohol (methanol is best but isopropyl is Ok). You must only wipe in the same path the tape would travel - NEVER up and down. Use the etched groves as your guide, gently wiping parallel to them. The chamois is used because cloth will snag and/or leave lint.If you've never done this before it might be best to view the heads through a loupe first. That way you'll know what the head looks like before you start wiping. Also, if it's already broken you'll see that too - instead of blaming yourself. The actual heads are usually about 3/16" long and about as thick as a sliver of mica. The gap is in the middle of the head - that's what clogs.Like wagon mentioned, some units will mute the signal below a certain threshold (like some TV's show a blue screen when there is no signal). Therefore you may not see snow with a clogged head.Be sure to clean the audio/control/erase heads while you're in there. They're in the housing that resembles a normal audio tape recorder head. No worries there - just wipe away.Good luck.

author: wagon
author_rank: Frequent Contributor
timestamp: July 29, 2014, 01:58:40 am
content: Also, if you don't have the special chamois cleaning stick, a piece of paper from your printer will work OK too, soaked in alcohol. (that's what I use!)

author: urbis
author_rank: Unknown
timestamp: July 29, 2014, 12:19:06 pm
content: Does this not have an OSD?Also, if it has video outputs, do they work on another screen?Wouldn't mind seeing a few internal pics of this.

author: Rasz
author_rank: Super Contributor
timestamp: July 29, 2014, 04:50:59 pm
content: does the lcd turn on at all?does the unit have tv_out?*lol at cleaning heads