Sanyo betacord model vcr 4900

[B Shanks]

Long story short, I need the service manual for a sanyo betacord model vcr 4900. The transformer in mine is dead, and I no longer have voltages to measure to find another.


Edit: I now have the service manual and the voltages. Can someone give me a link to a transformer that will work. Primary voltage is 120v, secondary voltages are 28v, 28v, 9.6v, 33v, 3.1v, 3.1v. It need not be exact, I will make it fit. I will do ebay if that is where one is located.

[B Shanks]

bump.

[Tony Wells]

I have 4 file boxes full of Beta manuals. I'll look thru them and see if something helpful is there.

Edit:
Sorry. Re-read your post. I do have the service manual as well as a circuit diagram and PCB layout diagrams.

No help on the transformer though. I might dig around and see, but don't get your hopes up.

[B Shanks]

Would it be feasible to install a 36 volt xfmr to a separate board, then drop the voltages with high watt pots? I have an idea how to expell the heat without melting the plastic chassis.

[radiotechnician]

Does it have a green fluorescent display? If so make sure your retro transformer
has the correct filament voltage.

Edit. I just looked and I have two Sanyo 3900 beta top loaders in plain view, there may be
other models but I have access an old computer file to find out. These used the flourescent
display. Any one have a manual to see if the tranny is the same ?

Overall, I seem to remember there should be about ten Beta machines here and about
100 VHS machines elsewhere. All may not be working, but should be more or less complete.

Wasn't the VCR era a good thing *not* to remember.

[B Shanks]

I was born toward the end of the vcr era. I don't have much to forget.

Does 3.1 volts sound correct for the VFD filaments?

My idea was to wire in some pots to the board, adjust them to the voltages listed, then install the unit and make final adjustments per the schematic. I am not worried so much about the voltages as I am about the heat produced. If I can't fix this unit, then I will be posting a wanted to buy ad for a unit with good heads and power supply.

By the way, the part # for the origonal xfmr is 4-251V-34800, and is rated at 33 watts. Part # for pw-1 circut board is 143-0-230V-13972, and pw-2 is 143-0-230V-14072. Pw-1 is the power board that contains the xfmr and other componets; Pw-2 is the board that contains the regulator and chokes. I doubt your unit's power supply is compatible though.

[radiotechnician]

I don't the manual for yours but I dug up a manual for a JVC HR DX 20 U and
the VFD filament was 3.5 VAC.


You truly will enjoy going through the pages of the schematic and interconnect
wiring of a 40 year VCR.

[B Shanks]

It's going to be even more "fun" putting it all back together now that I have it apart board by board. However, this is not the first vcr I have taken completely apart, and completely put back together. I have a knack for that sort of thing, ( and a pictorial diagram to bail me out if I forget how it goes back together).

By the way, The only circuit I need to repair is the power supply, and that circuit's schematic is not hard to read.

[SteveT]

Have you tried taking the transformer apart? Possibly just an open thermal fuse?

[WPPCProductions]

I had that VCR which I picked up at the fleamarket back in the late 1980's.I was still home at the time.My mother accidentally dump the power supply circuit board out in the garbage along with some other stuff.Which I think the STK chip was shot as I recall.

I have the original Sanyo service manual still here.

Heres a schematic of the power supply of the unit.

I see you have yours.

I'll post for others can see.

[B Shanks]

Thanks for posting that. that schematic is hard to scan. As for the power transformer, It is long gone. The last one in the unit was not made for it, and burned up within a year of it being installed. The only two reasons I am repairing is is that I am tired of paying $30.00 a tape to have them transfered to dvd, and it was my family's first VCR. It's Ironic that the first thing I ever repaired was a VCR, ( when I was 6 years old).

[WPPCProductions]

Thanks for posting that. that schematic is hard to scan. As for the power transformer, It is long gone. The last one in the unit was not made for it, and burned up within a year of it being installed. The only two reasons I am repairing is is that I am tired of paying $30.00 a tape to have them transfered to dvd, and it was my family's first VCR. It's Ironic that the first thing I ever repaired was a VCR, ( when I was 6 years old).

No problem.Yes I had to use my camera to get the whole schematic .

Yes I agree about the paying somebody to transfer your tapes .It will get costly if you have a truck load of tapes like me.Also they will refused to copy copyrighted videos like TV shows and wedding tapes.

I know Walmart and Ritetaid and Walgreen's reject photos that are takin by pro photographers if printed on back.. Like wedding,graduation or family portrait.

I still see pieces and parts from the 4900 floating around here.Much was stripped for other repairs.

I remember about 2 years after getting the Sanyo 4900 VCR I end up breaking the bank and getting a new Sony superbeta HiFi which I still have now.

[B Shanks]

What is funny is that the guy who did some transfers for us has 1,000's of nos vacuum tubes he wanted to sell me. Too bad they were tv tubes, I might have made him an offer if they were radio tubes. He is also the last guy in our area who transfers beta.

[B Shanks]

I am going ahead with the resistor idea. I have built a wire wound pot setup to lower the voltages from my variac, which I have set to 33 volts. This vcr has had wrong voltages to it and survived, so I am going to set the voltages low, then adjust the voltages under full load. Then I am going to measure the resistances, and mount a 33 volt Xfmr, and power resisters, and call it a day. If it blows up, I will post a Wanted to buy for a fixable unit here, and on other forums. Either way will be cheaper than $30 a tape for over 30 tapes.

[Beta_lover]

Hello !!!
Great idea to have a forum to restore those old school type machines.
I got a Betacord 3900 II from the internet and haven´t tried yet (mi fingers tremble)
Seller told me the mechanism works, but I have to replace belts.

By the way, do you have the service manual / schematics?

What's the difference between 3900 and 3900II?

Some PAL models have only 8 channel tuner... Why????

Thanks...