Where to repair AG1980, or do it myself?

[RS456]

I replaced almost all of the SMD capacitors except two due to very narrow access and took a chance because in the other AG-1980 the smd capacitors going bad only involved the ones that were rated 10uF and lower. Do you think some of the regular capacitors have gone bad or the fuse in the Y/C board has gone bad? In the other one there were none. I have a doubt there would be an aligngment issue that bad because this was a previously used VCR until this problem stated.

[dpalomaki]

Once you have a viewable image you can better judge the tracking/alignment.

Fuses can be tested.

The other caps can be examined (visuals may not be conclusive) and the ESR tested.

Anything said here is speculation.

[RS456]

Is there any way to test the capacitors on the board without desodering them?

[RS456]

I changed all the SMD capacitors in the Y/C board but still no change in the image. It still looks the same. Should I just go ahead and change the regular capacitors also (100uF ones etc) even though they still look good? Regarding this VCR I was told no one attempted to repair it. It just one day started playing like this.

Also how do align the video heads? Service manual was not clear on what to adjust to align the heads.

Sample video :https://streamable.com/5rxma

[hodgey]

Quote:

Originally Posted by RS456

Is there any way to test the capacitors on the board without desodering them?

Not sure which tester you are using, but I know some ESR testers like the Peak Atlas ESR70 can test the ESR of capacitors in-circuit.

The last video showed doesn't look like an alignment issue, but rather some electronics fault. If you have a scope, the manual has some images of expected waveforms on various points on the pcb, which may be helpful to track down where the issue is.

Alignment adjustment can be found in the k-mechanism manual here, section 2-4 (1) specifically, guide posts p2 and 3. Ideally one would use an alignment tape, but since those are pretty much impossible to get, a commercially recorded tape will usually be fine (as it should have the right alignment). If you don't have a scope, you can eyeball it to a degree, though only mess with it if there is a clear alignment issue.

Bad alignment will typically cause noise at the top and/or bottom of the image, a bit like tracking being off but not creating a good image no matter where the tracking adjustment is set. Alignment being off means the the angle of the video heads and tracks on the tape don't line up properly. Hi-fi audio is especially noticeably affected. Typically this will be due to the guide posts loosening or tightening.

[RS456]

If it was an alignment issue it will look kind of like a tracking issue. So it my case it is most likely there is still another capacitor that is bad? I still have a few regular capacitors to replace. I would of done that a few days ago but the regular capacitors I got were faulty. Nearly all the 100uF capacitors were reading 85 uF.

FYI this is the 2nd AG-1980 I am trying to fix. The other looks like it is completely fixed. That one had an issue similar to this but not to this extent. You could still see the picture on that. It was fixed with new caps and a little bit a cleaning.

Quote:

Originally Posted by hodgey

Not sure which tester you are using, but I know some ESR testers like the Peak Atlas ESR70 can test the ESR of capacitors in-circuit.

The last video showed doesn't look like an alignment issue, but rather some electronics fault. If you have a scope, the manual has some images of expected waveforms on various points on the pcb, which may be helpful to track down where the issue is.

Alignment adjustment can be found in the k-mechanism manual here, section 2-4 (1) specifically, guide posts p2 and 3. Ideally one would use an alignment tape, but since those are pretty much impossible to get, a commercially recorded tape will usually be fine (as it should have the right alignment). If you don't have a scope, you can eyeball it to a degree, though only mess with it if there is a clear alignment issue.

Bad alignment will typically cause noise at the top and/or bottom of the image, a bit like tracking being off but not creating a good image no matter where the tracking adjustment is set. Alignment being off means the the angle of the video heads and tracks on the tape don't line up properly. Hi-fi audio is especially noticeably affected. Typically this will be due to the guide posts loosening or tightening.

[RS456]

I think I am confident enough to recap the VCR I am keeping. Is this list good enough to recap the Y/C board and the timer board? If not please revise it.

https://www.mouser.com/ProjectManage...sID=84d0f049a9

[RS456]

Almost mission accomplished on the 2nd AG-1980.

Before : https://streamable.com/5rxma
After: https://streamable.com/us5fi

[lordsmurf]

Please attach sample video and images to forum threads.

[RS456]

Luckily I was able to upload just by changing the extension of the video file. First is after recapping all SMD capacitors and 2nd is after recapping some of the regular capacitors. It seems like the big capacitors in that board went bad that is reason for the scrambled cable like video.

[RS456]

Can someone post the the parts list by boards in the AG-1980 with a brief description like 47uF 6.3V and if you could suggest for a matching part since most of them changed? I am mainly looking at the timer board and the Y/C (Video) board where most of the video playback problems are. I would like to order all of them at once from mouser.com and mainly looking at Panasonic.

[dpalomaki]

Pages PARTS-1 through PARTS-22 of the Service Manual lists the information you seek, grouped by board and component type. For example: C10 on the Timer board is listed as C6510 in the parts list page PARTS-21 and schematic diagram, "C" for capacitor, "65" for the timer board and "10" for the sequence number on the board. Y/C board parts start on page PARTS-9. An electrolytic capacitor list is also in a spreadsheet posted in another thread, the link was provided to you in a previous PM.

Many of the Panasonic part numbers are still valid, but you may need to cross reference to a new equivalent part for discontinued part numbers such as the bad SMD items. You will spend more time waiting for someone else to do this for you than it takes to DIY. If you cannot DIY it would be prudent to avoid working on the boards - the chance of serious error may be high. That is why folks like Grant charge what they do for repairing machines.

[RS456]

Actually I figured it out after looking at one of the boards I had out and the hint in your pm. All you had to tell me to correctly identify the parts in the manual was the number written on the board was the first part of the part number in the manual and the part number on the board was the 2nd part. I already fixed one AG1980. The 2nd was almost fixed but had that small accident and I had difficulty identifying the part then with the service manual. These two are the learning VCRs. The 3rd one which is the very first VCR samples will be the one I will be keeping replacing with almost exact parts. One issue I am facing with the 2nd VCR now is what can I replace that L1 inductor with on the timer board ELESQ221KA. It is rated 220uH, Q min is 50, Time frequency is 796kHz, SRF min is 4.0, DCR max is 6.5 ohms, and DC current mA is 112mA according to the pdf I found on ELESQ221KA.

[dpalomaki]

Inductors tend to be among the more durable of electronic components. If yours is beyond salvage and you can't find a equivalent replacement it may be time to cannibalize one from a parts machine.

[RS456]

It is beyond salvaging. One of the pins snapped off. I was told by mouser.com agent I can use this to replace that.

https://www.mouser.com/ProductDetail...78148S1224J000

What is your opinion.

[dpalomaki]

Certainly worth a try if it fits on the board.

[RS456]

It undoubtedly fits with a slight difference in mA from the original. Original is 112mA while this replacement is 250mA. I am being told I don't have to worry about that it has more current flexibility than the original.

[dpalomaki]

The lower resistance, higher current rating, and higher "Q" should be OK in the application.
Again the main issue is whether or not it physically fits on the board. Since it is an inductor it is desireable to have the coil in the same orientation as the one being replaced.

[RS456]

This won't have that problem. It looks more like a resistor diode than like the typical inductor with a visible coil. What do you mean by same orientation? The original inductor itself doesn't look like an inductor. It looks more like one of those nonpolar capacitors. What makes matters worse is there is a number on it which matches up and looks almost identical to the capacitor that is 220uF while this is 220uH.

[dpalomaki]

Quote:

What do you mean by same orientation?

The long axis is in the same direction.