Charles Lucas ezt írta (2022. július 17., vasárnap, 1:15:21 UTC+2):
> On Saturday, July 16, 2022 at 11:49:16 AM UTC-5, ohg...@gmail.com wrote:
> > On Monday, July 11, 2022 at 8:08:02 PM UTC-4, charles...@gmail.com wrote:
> > > On Sunday, July 10, 2022 at 8:30:31 PM UTC-5, Another idiot on google groups wrote:
> > > > Charles Lucas <charles...@gmail.com> wrote:
> > > > > On Saturday, April 15, 2000 at 2:00:00 AM UTC-5, wire wrote:
> > > > >> I am working on my aunts vcr and it just started to play color tapes
> > > > >> in black and white. I assumed it was just dirty and needed
> > > > >> cleaning. Took it apart and for the most part it is very clean.
> > > > >> cleaned up what little dirt there was and reassembled it. Still
> > > > >> plays tapes in black and white. What are some common things that
> > > > >> would cause this?
> > > > >> Thanks
> > > > >> Peter
> > > > > Check the luminance/chrominance [luma/chroma] circuitry that controls
> > > > > the picture output in black and white and color. I would check the
> > > > > 3.58 MHz crystal oscillator also on the video output as well. This
> > > > > things help with the color processing. Usually, it is an IC or
> > > > > integrated circuit (could even be a flatpack) that controls this or
> > > > > some discreet component like a transistor, resistor, or cap. that
> > > > > activates the IC).
> > > > Do you really think that after over 22 years, the poster of the article
> > > > to which you just replied is still waiting around for your answer?
> > > >
> > > > The article to which you repled was posted April 15, 2000.
> > > I saw the date (I can read) and I am truly sorry if my outrageously late reply deeply offends you somehow. I never expected either of us to wait and I am sure the original poster never expect me nor my specific answer to be available at any time. I posted a reply this late for archival purposes, as VCR's are outmoded now, for the most part. Besides, everyone else has had 22 years to provide some sort of answer (however simple or complex to solve the problem). Some of us when we service peoples' tech. needs are extremely busy and do not get around to writing on a forum like this. At any rate, archiving the answer is good for posterity, should anyone at any future time utilize the technology or the information and find it useful. You can perceive me as an "idiot" for the outdated response. The fact is I wanted to respond to this and thought I would offer my two cents worth (whether you value the actual input or not). The point is even though the original poster didn't wait for me or answer, somehow you did respond with a reply.
> > >
> > > Have a great day. God Bless.
> > >
> > > Charles Lucas
> > You didn't provide any specific help at all, unless you want to consider 'check the color circuitry' and 'it could be an IC, transistor, crystal, resistor, or capacitor' as helpful.
> Need a model number to do that. everything is specific to the model. Also,check any and all of those things- if not sure. A good
> service manual for the model would help to track down the critical components that activate the circuit. There are also many different
> integrated circuits and circuits out there and different ways to actuate them (a resistor,a diode, a transistor, or cap, etc...), so it depends on
> the design of the circuit. If I have a model number, I can tell you what pins to check to verify correct operation. I have been a tech. for 32
> years and not all circuits are designed the same. The initial information is generalized as a guide. If you want something more specific, please provide a model number or an FCC ID number. God Bless you.

Hello! I have read all your posts and you are absolutely right. Unfortunately, there are always such people who qualify the helpers. Well, I also learned a lot from what was written here, at the hobby level I repair a VHS VCR, which also has no color. The type is AKAI VS-3. I repaired the servo part and the power part did not work. Now it starts, plays, spins. The head drum was also bad, so I put in a new original one. Now there is a picture, but it is black and white and jumps a little. I can't adjust the tape path any better. I would really appreciate it if you could advise me. I checked the video pcb, all12, pb12 are fine. Unfortunately, I don't have a test cassette, although I tried to make a color bar cassette and check it at the test points, but I didn't have much success.
Thank you in advance for your help.

> Hello! I have read all your posts and you are absolutely right. Unfortunately, there are always such people who qualify the helpers. Well, I also learned a lot from what was written here, at the hobby level I repair a VHS VCR, which also has no color. The type is AKAI VS-3. I repaired the servo part and the power part did not work. Now it starts, plays, spins. The head drum was also bad, so I put in a new original one. Now there is a picture, but it is black and white and jumps a little. I can't adjust the tape path any better. I would really appreciate it if you could advise me. I checked the video pcb, all12, pb12 are fine. Unfortunately, I don't have a test cassette, although I tried to make a color bar cassette and check it at the test points, but I didn't have much success.
> Thank you in advance for your help.

Those old Akais had lots of electrolytic caps that get weak with age. Try heating the signal boards with a heat gun to see if the color returns. If it does, you're going to have to recap that unit if you intend to keep it.

ohg...@gmail.com ezt írta (2024. január 9., kedd, 18:24:36 UTC+1):
> > Hello! I have read all your posts and you are absolutely right. Unfortunately, there are always such people who qualify the helpers. Well, I also learned a lot from what was written here, at the hobby level I repair a VHS VCR, which also has no color. The type is AKAI VS-3. I repaired the servo part and the power part did not work. Now it starts, plays, spins. The head drum was also bad, so I put in a new original one. Now there is a picture, but it is black and white and jumps a little. I can't adjust the tape path any better. I would really appreciate it if you could advise me. I checked the video pcb, all12, pb12 are fine. Unfortunately, I don't have a test cassette, although I tried to make a color bar cassette and check it at the test points, but I didn't have much success.
> > Thank you in advance for your help.
> Those old Akais had lots of electrolytic caps that get weak with age. Try heating the signal boards with a heat gun to see if the color returns. If it does, you're going to have to recap that unit if you intend to keep it.

Thanks! I will try this way as well.

On 1/9/24 12:24, ohg...@gmail.com wrote:
>
>> Hello! I have read all your posts and you are absolutely right. Unfortunately, there are always such people who qualify the helpers. Well, I also learned a lot from what was written here, at the hobby level I repair a VHS VCR, which also has no color. The type is AKAI VS-3. I repaired the servo part and the power part did not work. Now it starts, plays, spins. The head drum was also bad, so I put in a new original one. Now there is a picture, but it is black and white and jumps a little. I can't adjust the tape path any better. I would really appreciate it if you could advise me. I checked the video pcb, all12, pb12 are fine. Unfortunately, I don't have a test cassette, although I tried to make a color bar cassette and check it at the test points, but I didn't have much success.
>> Thank you in advance for your help.
>
> Those old Akais had lots of electrolytic caps that get weak with age. Try heating the signal boards with a heat gun to see if the color returns. If it does, you're going to have to recap that unit if you intend to keep it.
>

Can you explain the heat gun technique for bad caps... how does it work?

On Tue, 16 Jan 2024 22:28:09 -0500, Usenetist <carg121@usenet.com>
wrote:

>On 1/9/24 12:24, ohg...@gmail.com wrote:
>>
>>> Hello! I have read all your posts and you are absolutely right. Unfortunately, there are always such people who qualify the helpers. Well, I also learned a lot from what was written here, at the hobby level I repair a VHS VCR, which also has no color. The type is AKAI VS-3. I repaired the servo part and the power part did not work. Now it starts, plays, spins. The head drum was also bad, so I put in a new original one. Now there is a picture, but it is black and white and jumps a little. I can't adjust the tape path any better. I would really appreciate it if you could advise me. I checked the video pcb, all12, pb12 are fine. Unfortunately, I don't have a test cassette, although I tried to make a color bar cassette and check it at the test points, but I didn't have much success.
>>> Thank you in advance for your help.
>>
>> Those old Akais had lots of electrolytic caps that get weak with age. Try heating the signal boards with a heat gun to see if the color returns. If it does, you're going to have to recap that unit if you intend to keep it.
>>
>
>
>Can you explain the heat gun technique for bad caps... how does it work?
When you heat up a bad cap, the ESR goes down and the capacitance goes
up and sometimes the problem goes away. You then replace the cap you
were heating when the symptom went away. I would suggest buying a
cheap esr meter on EBay. It is a quicker and more certain way of
finding bad capacitors.

On Tuesday, January 16, 2024 at 10:28:13 PM UTC-5, Usenetist wrote:
> On 1/9/24 12:24, ohg...@gmail.com wrote:
> >

> >
> > Those old Akais had lots of electrolytic caps that get weak with age. Try heating the signal boards with a heat gun to see if the color returns. If it does, you're going to have to recap that unit if you intend to keep it..
> >
> Can you explain the heat gun technique for bad caps... how does it work?

When I suspect a lazy/weak/ electrolytic capacitor as the cause of a failure, I take my heat gun and warm up the board in question. I get the board pretty hot but not hot enough to melt connectors, ribbons, or indeed the shrink wrap on the capacitors. If the device now performs correctly or even if the symptom changes, an electrolytic becomes a strong suspect. MOST weak capacitors improve with heat, but you'll find the occasional one that actually responds better to cold, but that's as about as rare or more so as finding an open silicon diode (most short). The heat may also affect defective semiconductors so if heat fixes it, it could still be anything on the board that's become heat sensitive, but most circuits that come back to life with applied heat will have a bad capacitor(s).

Once I identify weak dried out capacitors with heat, I'll either shotgun the device if it's old and I want it to be long term reliable, or I'll take out my ESR meter and go over the board when the board cools down if it's a board with a crapload of caps where shotgunning is time consuming. One way to get all the weak ones identified is to put the board in question in the refrigerator (or outside if it's cold), as even capacitors that work well at room temperature and not causing any immediate issues may fail at very cold temps. Capacitors that are in good condition won't be bothered by the cold, so it's a good way to ferret out the ones that will fail next. Caps that work at room temp but not in cold temps are on borrowed time.