I have a 1981 Magnavox tv. Model number RA5054. It has a t815-09 chassis. It has not worked for a while but somehow i have convinced my mother not to throw it away. I was there when she bought it in january 1981. It has stereo speakers and separate 10watt amps to simulate stereo. It gave a little trouble when it was new, the crt module was replaced and an ic was replaced on the power module. When you turn it on the channel number displays, no picture, no sound, The picture tube gun lights but after 20 or so seconds the reset button kicks out. After reading some of your post i ordered a horizontal output transistor, installed and resoldered pins on the retrace module. It still does the same thing. I have had some repair training but would like the advice of an expert.

Check the 4-lead safety cap on the retrace module. They were known to short. If it's bad, you'll probably have to replace it with a current production "orange drop" cap because I don't think anyone makes the original 4-lead cap. Those 4-lead capacitors were not reliable, anyway. They would either short or blow open. If they open and the internal interlocking feature of the cap does not open, the HV will skyrocket and blow the neck off the CRT.

I am a little new to this, What is a orange drop cap?

I checked the safety cap and it is leaking so it is bad. The part number is 250663-18, also it says 648 at the top of the label. What rating cap do i replace it with. Also what is the best way to connect since there are four wires and only two on the cap?

Hi Firebird, welcome to VK.

I moved your posts to it own thread here in the Rectangular & SS Forum, it'll have a better chance of being seen and getting help than if it's attached to another unrelated thread.

I agree on that safety cap.. Replace first, and then if the set still kicks the circuit breaker out, you may have a bad HV tripler (the gray box with the anode lead from it, up to the top of the CRT). Those leaked a lot, and caused a heavy load on the power supply. Easy to verify; carefully unsolder and secure AWAY from any metal, the black wire from the tripler going to the flyback. Turn the set on, and see if it still shuts off. If not, the tripler is bad. But again, watch out for that black wire while you have it off the terminal. The RF can arc an inch or more, and will cause damage to other parts, or of course cauterize a hole in your finger ;-). Also, when you resolder that wire, use black silicone RTV sealant to cover it with a blob, so as to protect it from arcing later.

Charles

I also have the same question as Firebird with my 1977 T-995 chassis regarding replacing the 4 lead safety cap with a 2 lead orange drop cap on the retrace module. Do I just bridge the solder pads, or re-route the 2 leads a certain way? Schematic shows each lead goes to separate pins on one module socket. Pins 8,9,11,12 with a silicon diode across pins 8, and 12. I'm wanting to replace the 4 lead cap on my set for increased reliability after reading how they can fail, and destroy the crt. As far as I know it is the original one, and being 35 years old it could go bad any minute. Mine shows part 250563-11 which cross references to a .0086 mfd @1600 volts. The 250563-18 cross references to a .0135 mfd @1600 volts.

Yes, bridge the end terminals together. I had a T809 19" with a shorted 4-lead safety cap and I had to connect two HV orange drop caps in parallel to get the correct value. I removed the old cap from the chassis, bridged both sets of end terminals together on the chassis, installed the orange drop cap, and the set worked great.

When checking these caps, you will read a short circuit between each set of end terminals. There should be no short when measured from end to end. If it reads shorted or shows any resistance from end to end, it's bad and should be replaced.

Put in the capacitor. Set came on and stayed on. Still no picture. Where do i find a tripler? I have not been able to find one so far.

Are you looking for the tripler in the set...or are you looking to buy one? :) One of us might have a spare; I have a box of assorted triplers.

I am looking to buy one.

Do you have one for the T815-09 chassis?

Does anybody know where i can get one?

Do you know for sure that the tripler is bad? If you feel static on the screen when you turn on the set; then, you are getting HV and the tripler is likely OK. If no HV is at the CRT; then, unsolder the input lead to the tripler and if there is HV coming out of the flyback, the tripler is bad. If you have no HV coming out of the flyback, you have a problem in either the horizontal output, horizontal driver, or horizontal oscillator stages.

I have HV. Put in new horizontal output transistor. What do i look at next?

I would appreciate any help i could get.

What is the set currently doing when you try and run it?

Tuner lights no picture no sound

I recall an issue with solder joints on these sets. If you have HV, but no sound, that points to a "power supply" voltage common to both audio and video.

The key thing to remember is that not all power supply voltages come from a resistor (or voltage ladder) off the main power supply from the power transformer.

Many of these lower voltages are derived from a winding tap on the flyback, that feed a rectifier diode and finally a smaller value electrolytic cap. See if you have DC on the cathodes of any rectifier diodes fed from the flyback. Often, there is a low value or "fuse" resistor in series there.

I do not have the schematic on a set this new, but I could point it right out if someone could post it.

Have you resoldered the pins on the modules yet? That used to be the first thing I did to these sets years ago. I sure hope I'm thinking of the right chassis about now...

Soldered all the connections on the chassis till i got to the left under the picture tube. Did not have time to get to the video or audio boards on the left or the tuner. The picture came on in black and white, still no sound. Picture stretches a little to the right. Color sometimes appears when scene changes. Do i need to solder the rest or does it have a defective video or audio board?

Finished resolder, now when it comes on picture is red, no sound and the suction cup wire is arcing off bad at top of tube. If it is not the tripler then what would cause this?

Have you cleaned the bell of the CRT? Have you cleaned the suction cup?

You've probably bridged a solder connection. Check your work.

Did you solder the modules themselves, too?

Have you got a good magnafying (?) glass and a bright light source?

I am a little confused. Last week i resoldered the half of the chassis that has the flyback and it came on. Displayed a black and white picture with no sound. This week i resoldered all the modules on the sound and color half of the chassis and the flyback starts arcing. Still no color except for red and no sound. Why the arcing when i did not work on the flyback. I did solder the connection pins on the color and sound side of the main board. I double checked my work, no cross solder. Could the flyback or tripler be getting too much voltage?

How about the ground stakes that hold the circuit board to the chassis frame?

I wish I could see an image of what you are doing.

Whats the flyback arcing to?

I resoldered the ground stakes. The arcing is coming out from under the suction cup. I will try to post pictures.

Definitely clean the bell of the CRT around the HV connection. Be sure to discharge the CRT before you do anything having to do with this connection. Also, If you can find some silicone grease, clean the suction cup and put just a dab of the grease around the edge that touches the tube.

Is the ground connection from the CRT still connected to the chassis properly? This can cause wild problems, too.

Like Holmesuser01 said, clean the bell and cup first. Check your HV. If it's too high, it can arc even if it's clean.

Pictures of my Magnavox. Blue arc can be seen at top on right in picture three. Picture is faded.

Pictures

Better Picture.

All pictures are mirrored, taken with an apple macbook pro, so ask them why.

Grease fixed flyback. Still no color no sound.

Did you physically remove each module when you soldered the mother board? And, you did resolder the connections on the modules?

You shouldn't have to redo everything on the boards. It's just the high-current connections that flex and break

Sometimes, you can take some fine sandpaper and clean up the stakes on the mother board to get a better connection to the module.

When you turn on the set, do you get a thump sound in the speaker? That would tell you if the amplifier module is at least working. Examined the module for discolored parts?

You dont have a schematic, do you? The FBT also supplies power to some of the modules. Your no sound problem could be something as easy as a fusable resistor that is open.

Best of luck. I never really had alot of issues with these Maggie chassis, other than the module and mother board soldering problems, and the occasional tripler, and/or horizontal output transistor.

Does not make any sound. Does anyone have a sound or chroma module for the t815-09? I also need the remote receiver module. I soldered every pin on the main board and all the modules. Picture also pulls a little to the right, with cut off graphics.

Which resistors and transistors near the flyback should i replace?

Does anyone have parts for the T815 chassis? Help would be most appreciated.

I need the verticle oscillator module. I believe the part number is 704200-3.

Replaced all the capacitors on the verticle oscillator module now only have two thirds of a picture and its snowy.

Removed and reconnected some parts. Picture is back like it was, no color, no sound. I believe the tripler is weak. Could this be the problem?

Triplers dont get weak.

Why still no color no sound?

Look for a common voltage source between the sound module and the color module. Most voltages on that set (I think) come from the running flyback windings, thru a diode, and a low ohms resistor before being fed to the circuits.

If you found bad capacitors on the VERTICAL module, Don't you think other modules need capacitors, too?

You're having problems that I rarely saw when I was working on these sets, unless something odd had happened, like a lightning strike....

Those 4 lead caps are available from a seller on eBay. Do a search with "safety capacitor" and it'll come up. I've bought many from him over the last few years.

Radiotvnut says they can damage your picture tube. That is not the problem, i replaced it with a two lead capacitor. I can not find the reason for no color no sound.

If the 4-lead safety cap opens and the internal interlock does not break, the HV will skyrocket and literally blow the neck off the CRT.

I lost a beautiful Zenith console this way once. I turned it on to see what was up, and heard this SNAP and a rush of air. The neck snapped at the bell, and the yoke and convergence parts all let go and fell.

Your no color and no sound issues could be what I said before. Have you got a meter? Schematic? Schematic will help you.

I have a meter. No schematic. I have not been able to find any bad resistors. Have replaced most capacitors. I have not replaced the ones on the main board.

Any ideas will be appreciated.

Get a schematic and use that meter that you have.

I think it is a .68 resistor on the retrace board or a .69. Hard to find. It is one watt, brown, bands are blue, white, silver and silver.

Was not resistor and since i have no sound i think it could be the flyback. Does anyone have a flyback for the T815?

I've never replaced a flyback on the T815.

How do you fix no sound? Also has no color but sometimes flashes in for a second.

GET THE SCHEMATIC if you cant figure out whats what. The color is something else.

Didnt you have a picture at some point? Then you soldered up the grounds? Then no picture? Recheck your work!!!

I still have a picture, once i got it never lost it. It is just black and white. Pulls a little to the right.

Anyone have a flyback for the T815 chassis?

You should really get a schematic and measure the voltages around the sound and color sections before replacing the flyback. Have you tried SAMS 1860-1? It is available on samswebsite.com for $22, instant download (I have no affiliation with them).

https://www.samswebsite.com/en/photofact/search/index/samsid/1860_1

Does anyone have experience working on these sets?

I did authorized service on Magnavox TV's and worked on plenty of 815 chassis. It was a good design. Once I soldered most of them up, they rarely came back for service again. Get the schematic and take readings.

There have been multiple suggestions that you obtain a schematic, i suggest you heed that advice before taking any more stabs in the dark. You're only likely to cause self-induced faults by shotgunning parts into it, and I doubt there's anything wrong with the flyback if you still have high voltage.

No its the sound and color.

Go to Sams website, order the schematic if they have it.

See post #58.

My final reply on this.

Can anyone tell me what component would cause this set to have a near perfect black and white picture. No color, no sound. Picture does streach about a half an inch to the right. Tuner seems to work perfect on basic cable and of course there is no analog broadcast tv anymore. If you can help you will be a hero. TV has not played regularly since 1986 when it died right in the middle of a Joan Rivers joke. Of course i knew nothing about tv repair back then.

No we can not GUESS at what component may have failed. You need a schematic to troubleshoot. I know you have been told that many times but for some reason you do not want to listen. Heck if you don't want to BUY a Sam's for the set some good public libraries have collections, find it and make a Xerox!

Where i live in rural NC?

I live in rural NC, and have no problems getting schematics for things I want. Dont blame NC for your problems.:nono:

the techs here in this board will point you in the right direction but you have to perform the actual work.get a schematic and get busy.we will help you along the way but start with a schematic.ask for one here and you will get one.i wish you the best of luck on this set.pretty decent models with a fine picture when right.

Does anyone have a T815 schematic?

the techs here in this board will point you in the right direction but you have to perform the actual work.get a schematic and get busy.we will help you along the way but start with a schematic.ask for one here and you will get one.i wish you the best of luck on this set.pretty decent models with a fine picture when right.

I don't remember if that set is a modular set. The set came out around the time I quit repairing, on a regular basis.

I agree with Sampson159 as to finding a schematic for anything you attempt to service or repair, be it a TV, radio or anything else electronic, before troubleshooting; "blind" attempts at finding trouble in a set often cause more problems than are solved.

My only other advice, however, is to be cautious around the CRT, as it has a very high voltage (in the double digit kilovolt range) -- the second anode voltage -- on it that can be lethal or can cause serious injury if you don't take the appropriate precautions. In color sets like your Maggie, the normal HV will be around 25kV or so; in a b&w set, it is a bit lower, around 18kV or thereabouts, but still, nothing to take lightly. And whatever you do, do not work on a TV or radio while the unit is still under power (plugged in to the AC line). Pull the plug and discharge the CRT in a TV before doing anything inside the cabinet. To discharge the tube, simply slide a metal screwdriver under the cap covering the high-voltage lead coming from the flyback. Remember that the HV charge on a CRT can remain on the tube for quite a while after the set is turned off, even if it has been unplugged and unused for years.

To discharge the tube, simply slide a metal screwdriver under the cap covering the high-voltage lead coming from the flyback. Remember that the HV charge on a CRT can remain on the tube for quite a while after the set is turned off, even if it has been unplugged and unused for years.

Hopefully that is a GROUNDED screwdriver! :eek:

jr

I don't remember if that set is a modular set. The set came out around the time I quit repairing, on a regular basis.

Its got several modules. Other than the mentioned parts earlier, I rarely had one on my bench that had other problems. I worked on them from 1981-on.

I threw out a good T-815 chassis that had been sitting in my old shop for 10 years. Kept it because it worked, and the CRT went to air. Intended to use it, but never had another one to work on.

I will look and see if I have a t815 manual.

I looked and didn't find it. It may still be packed with some other stuff in th office. There is a folder of manuals missing.

Hopefully that is a GROUNDED screwdriver! :eek:

jr

I stand corrected. Yes, a grounded screwdriver should be used to discharge the residual HV charge on a CRT; I've been in electronics (as a hobby) and in ham radio 40 years, and should know that.

This is a good warning for newcomers to tube TV repair, however, as folks who have only known solid-state and, particularly (since the mid-'80s) flat-screen TVs may not be aware of the dangers of the redsidual charge on the CRT bell on old analog NTSC TVs -- even after the set has been unused for some time. The aquadag coating on the CRT bell acts as a huge capacitor and can hold a charge for a very long time, so discharging the tube by using a grounded screwdriver slid under the second anode cap until it contacts the terminal which connects to the 2nd anode well on the side of the tube is a must, before any work is begun on the chassis. (I would discharge the CRT even before changing tubes, as some older TVs had some tubes located near or directly under the CRT bell; I've owned a few -- my Philco Microgrid 390 23" console, now long gone, of course, comes to mind.)

Again, the voltage coming from the flyback in all CRT televisions is extremely high (20kV+ in color sets) and can cause serious injury or even death, so be careful. The voltage on LCD or plasma panels in today's flat TVs is nowhere near that high (several hundred volts at most), but, nevertheless, caution should be used around them as the potential for serious injury still exists.

Been away for a while, let me know if you find it.

Anyone here ever work for Magnavox?

I said before that I was finished with this topic. I cant help myself. It's like driving by an auto accident. I dont want to look, but I cant help it.

First, how old are you, Firebird?

Second, you've been given the SAMS PHOTOFACT number for your TV chassis. GET IT.

Third, BUY THE SCHEMATIC. You live in a rural area? So do I, and I dont have this problem. Didn't you get and replace a load of capacitors from somewhere? Those arent made in rural NC, either.

Fourth, Go back to posting #60, and comprehend it.

Fifth, I'm not being mean. You won't follow the suggestions that you have been given. Nobody here can fix your set for you if you just throw parts at it.

This said, I hope that you have a very Merry Christmas, and hope that Santa brings you a T815 chassis.

Anyone here ever work for Magnavox?

The ones that are still around, probably ended up in a rubber room. :D
I never kept it a secret, that I was never thrilled with Magnavox TV's.
Too many PITA call-backs. :thumbsdn:

The ones that are still around, probably ended up in a rubber room. :D
I never kept it a secret, that I was never thrilled with Magnavox TV's.
Too many PITA call-backs. :thumbsdn:

There were several Maggie models that gave me fits. Several of the tube models come to mind, and the first all solid state console with the board connectors that would literally BURN.

I got alot of repair business out of Magnavox sets after the factory warranty ended. Same with RCA, and a very few Zenith sets.

I needed the Magnavox name so I could buy parts from them, as they didn't like doing business with just anybody.

I'd consider a rubber room if the time ever comes. At least if I hit the floor, I wouldn't be hurt, much.

I can not find a repair manual. Does anyone know of a part that may cause these problems. Can a bad flyback prevent color or sound?

I thought the non-stop posts about that stupid Samsung annoyed me until I saw the threads on this set.
NOOOOOOOOOOOO DUDE. It is NOT YOUR FLYBACK (for like the millionth time) DUH!

I thought the non-stop posts about that stupid Samsung annoyed me until I saw the threads on this set.
NOOOOOOOOOOOO DUDE. It is NOT YOUR FLYBACK (for like the millionth time) DUH!

Wow dude, did you forget your morning Coffee? :scratch2:

Sorry Eric,
But geez...... have you read this thread from the beginning?
I do believe the 5 hour energy I took has made me cranky tho. (haha)

I dont drink coffee

I have a 1981 Magnavox tv. Model number RA5054. It has a t815-09 chassis. It has not worked for a while but somehow i have convinced my mother not to throw it away. Very nice......... I wanna wish ya luck getting her going :):)

I love a good Magnavox. Specially the old classic 25 inch consoles.

I like that scene in the movie "Carrie" where the mother tells her: "They're all gonna laugh at you!" It's especially good when watching it on a Magnavox of that vintage that actually works........

What is wrong with wanting advice from experts?

I like that scene in the movie "Carrie" where the mother tells her: "They're all gonna laugh at you!" It's especially good when watching it on a Magnavox of that vintage that actually works........
Is that the movie with the teen-age girl and the weird mother. She started to bleed in the girl's shower room and didn't know about it. :D

I like the movie Psycho. He was his mother.

Firebird, you're liable to never get this set fixed until you get a diagram that will enable you to properly troubleshoot and diagnose the problem. Someone gave you the Sams Photofact file number, so you can go to Sams website and order a copy. Or, you can check ebay for one.

Either way, you might spend $20 for the service manual but that's a heck of a lot cheaper than buying parts to throw at it in the hopes that you might just hit the right one. Often times, certain chassis are known to have certain problems and certain parts that everybody knows cause problems...those are the easy ones, but your issue doesn't sound like one of those.

You came to the right place to get answers, so I suggest you take that advice and buy the service manual.

What is wrong with wanting advice from experts?

I am curious if you have verified if all wires are in fact OK (good/acceptable) You must remember you are working on a TV that is now 32(+) years old! Wires of this age can break down over time, causing an increase in resistance in the copper conductor (or aluminum in some special cases due to corrosion due to the presense of moisture) which can lower the operating voltage(s) needed for CRITICAL circuits! However YOU MUST and I stress the word MUST be VERY and I stress the word VERY careful when working in and around a powered (or unpowered) TV (television) set of this age (1981 as you mentioned earlier in this thread, on April 16, 2012 at 5:32 PM). There are DANGEROUS, I repeat DANGEROUS voltages in and around the printed circuit board (the thin composite sheet like "board" that contains the (majority) of TV (television) components). The CRT (Cathode Ray Tube) contains the highest of dangerous voltage(s). If one is not aware of these dangerous voltages (a schematic diagram is of the utmost importance) the service technician may be at risk of potential electrocution not to mention damage to electrical (or electronic) testing/analyzing equipment. I STRONGLY ADVISE that YOU be fully familiar with the operation characteristics and voltages of this TV (television) before performing ANY, I repeat ANY electronic repair/service work. You may want to seek (find/locate) a schematic diagram for your particular TV (television) and CAREFULLY study (comprehend) it so that YOU may be FULLY AWARE of these voltages. :yes:

I would concur with Norbert. The voltages are VERY dangerous.
Also, I'm not sure if you're aware, (as your TV became inoperable before the transition) but there are no analog signals OTA (over the air), and you will need to get a set-top box and use that remote, because if indeed your Magnavox ( not the company in existance today) has a remote option, you will be better off with a set top because if it is ultrasonic, it will damage your hearing. Also.. and most don't realize this, is that early 80's sets usually had an LED read-out, and you must NOT look at it for very long, as it could burn your retinas out......

A quick look at the schematic I think you have two seperate problems. You may need to change the chroma module, and the audio module. The only module that affects both is the secondary control module. You need to verify the power to each of these modules first. Volume, tone, color, and tint controls are on the secondary control module. Check the connections to this module. Power from these is not from the flyback. It comes from the 30 volt power supply, but this also provides power for a lot of the modules so I doubt there is a problem there.

Also.. and most don't realize this, is that early 80's sets usually had an LED read-out, and you must NOT look at it for very long, as it could burn your retinas out......


I never heard of a light emitting diode (LED) causing issues with viewing. With laser devices, yes, but not LED's. I sure saw a lot of my red LED clock radio in the late 70's, early 80's that was sitting right on my nightstand. Were the tv manufacturers using something odd or different for channel displays? Last time I checked, LED's were just a fast pulsing, non focused light, especially in segment displays as the light was super diffused.

I have only come across 7 segment modules for each number or a fluorescent, plasma like tube display if there were other colors beyond red in the display.


Would love to know more about this.

Does anyone have a chroma module and sound module?

Check those supply voltages, and the secondary control panel connections before you start changing modules.

Does anyone have a chroma module and sound module?

I have (own) them both (2 modules), in used (but working) condition. However, they (the modules and TV set) were last working some number of years ago. It is imperative to note that there is no guarantee on the functional status (working condition) of these particular referenced modules. I would like to get $100 for each (individual) module (chroma and sound as initially requested) plus the cost of S+H (shipping and handling). If you are interested, please PM (private message) me via the Video Karma messaging system. However, if you are not interested, you do not need to PM (private message) me. Only PM (private message) me if you are interested. However, if you are NOT interested you may also reply back on this public discussion board (the forum).

:lmao:

:banana:If only it were true.

This is all I have on this anymore.

:lmao:
HAHAHAHAHA! Norbert... As I was reading the post, I thought it was another member that posts in a similar style. I still can't quit laughing!

Thanks holmesuser01

I don't understand the humor, as frankly, I am somewhat disappointed but also confused as to what was/is so humorous? :dunno:. But regardless, if you (Firebird) are interested (in the modules) then they are available for the aforementioned (previously stated) price. Regards to all (everyone).

I don't understand the humor, as frankly, I am somewhat disappointed but also confused as to what was/is so humorous? :dunno:. But regardless, if you (Firebird) are interested (in the modules) then they are available for the aforementioned (previously stated) price. Regards to all (everyone).

Sorry Norbert! I didn't mean to offend or cause confusion. I was confusing you with another VK (Video Karma) member, who also is extremly detailed in (his) replies.

Sorry Norbert! I didn't mean to offend or cause confusion. I was confusing you with another VK (Video Karma) member, who also is extremly detailed in (his) replies.

I understand. Thank you for the explanation. Regards.

They cost more than the tv when it was new.

When i adjusted the horizontal board color came back. still no sound. Did not change size of picture.

They cost more than the tv when it was new.

No they don't.

But regardless, if you (Firebird) are interested (in the modules) then they are available for the aforementioned (previously stated) price. Regards to all (everyone).

Seriously? $100 each for modules for a TV he'd be lucky to get $25 if it was working perfectly?

This thread has deteriorated badly, perhaps I should just close it?

Let me look and see what I have. At one time, I had a few Magnavox modules from this era. If I still have them and if you can use them, I'd be more than happy to give them to you.

I probably shouldn't say this in public; but, I'm going to. Those $100 modules are a rip-off and it's just a case where, "he needs them; so, they are now valuable".

Over the years, people have been very generous in giving me needed repair parts to fix various things and if I have something here that I have no use for that someone else can use to fix something; then, why not give it to them? Besides, I'm doing this as a hobby and not to get rich.

I've also had people attempt to stick it to me on parts that would have otherwise likely ended up in the dump; but, I don't have a problem with saying "no" to such people.

Thanks

Disconnected the speaker wires that go from the mother board to the ten watt amp. Reconnected to the speaker. Got very faint sound with the volume all the way up.

In that case, the problem is most likely on the external amp chassis. First, you need to check and see if you're getting B+ voltage to the amp.

Where should i check, the power supply?

In that case, the problem is most likely on the external amp chassis. First, you need to check and see if you're getting B+ voltage to the amp.

Hmm. I dont recall a 10 watt amplifier on these sets. I'm not doubting anyone, but I dont remember ever seeing one. I started seeing power amps when MTS stereo came along around 1984.

I don't recall a 10 Watt amplifier on these sets either. Maybe added by earlier repair shop to solve a sound problem. Schematic shows speaker connected to pin 5 of P1 on the sound module through a coil. Was this set a combo?

It was a simulated stereo set. Has a speaker on both sides of the picture tube and a 10 watt amp mounted near the tuner.

Set came brand new out of box December 1980 from Harveys Warehouse in Gastonia NC. Picture of chassis.

Amp is in the left behind antenna terminal.

Well Noow. I have not seen that. Check voltages going to the amp chassis, look for wiring going back to the power supply. I don't have a schematic for the amp, well I might have it's just not with this chassis. Amp may have bad output transistors or IC, and may need recapping. I wonder if it has the standard sound module that could be used to drive one set of speakers. It wouldn't be stereo, but I would then have sound. Wish you were close to me, I would like to see this set.

I tried one speaker without amp. Got very faint sound at full volume.

Where does the amp connect to the sound module? Is that where you connected the speaker? What is connected to pin 5 of P! on the sound module?

A set of speaker wires come from the motherboard near the sound module to the amp. The pins are on the motherboard and i will have to check. I plugged these wires to the main speaker and got weak sound.

I think his sound problems are with this amplifier if he has a very weak sound with the volume turned wide open.

Yes, I think the external amp is the problem, or the B+ to the external amp.

I would get a ESR meter and ESR all the caps in the amplifier. That model had serious cap failure problem from the caps drying out. The description of the problem points that way!

Dont have an ESR meter so i am trying to find all the caps. Will let you know results.

You should check the power supplies first. That costs you nothing. Get the schematic.

I have the schematic. Thanks to Bill R. I checked power supply and have voltage.

I have the schematic. Thanks to Bill R. I checked power supply and have voltage.

:banana: :thmbsp: :boring:

I think your trouble is on the amplifier board. You might want to post a picture of the amplifier schematic and we can help you. There can easily be a blown pico fuse on that critter.

I don't think the amplifier schematic is in that folder. I was not that common. If it is not I would need to find another set that uses that amp.

Oh... Maybe Firebird can find some ID on the amplifier module for us?

I removed amplifier module to take pictures. When i reinstalled picture came back on folded in the middle with black bars on the sides. Then it changed to horizontal lines with black bars on the side. Then back to the folded picture.

Ext Sound Amp 704182-1

I will probably get in trouble for this but could a bad flyback cause such symptoms? No i did not replace parts with the power on. I did turn the adjustments on the sound amp and returned them as close as i could to original with no effect. The only thing that seems to effect anything is the adjustment on the horizontal oscillator board, with no change except it went from lines to picture. It was still folded in the middle. I have had electronics training but no experience repairing tvs so i have never seen this before.

Well....
Can you post a screen shot of what the picture looks like?
The flyback would have nothing to do with sound. I'm pretty sure your set has a flyback AND a high-voltage tripler. Now either of those could cause a folded picture if there was not enough high-voltage, but a screen shot of your set would help.
Your audio issue tho, would have nothing to do with that, so I'm wondering if you have 2 seperate problems going on?
Is there anyone in your area you could take it to for repair? You might be in over your head on this one. No offense, as I am NOT good on solid state stuff myself, especially a Magnavox.
So, I was trying to go thru your posts from the beginning. What was the original issue? I think you said no picture? IIRC you replaced the horiz output transistor?

I have been told several times that the flyback powers the sound. This has led me to believe it is either the flyback or tripler or both. I have tested the resistors and diodes. I found no defects. There are very few repair people left in this area and even fewer with knowledge of this type of television.

Well... whoever told you that gave you some major MISinformation, and if it was someone from this forum (which I doubt) I would like them to post and explain why they think that is. Audio has NOTHING do do with your high-voltage circuit. NOTHING.
To make it simple... a flyback and tripler act as a step-up device to deliver the 25KV needed to light up your screen. In your set (1981 Vintage) a flyback rarely fails, It's usually the tripler, and if that were bad, your symptoms would be either : NO picture, or poor focus, or.. if you have a high-voltage probe, you may find that the set is not putting out the 25KV needed.
In the years I worked in a repair shop, never once, was a no audio problem caused by anything in the high-voltage side.

I have been told several times that the flyback powers the sound. This has led me to believe it is either the flyback or tripler or both. I have tested the resistors and diodes. I found no defects. There are very few repair people left in this area and even fewer with knowledge of this type of television.


Until we got pictures, nobody here even KNEW that your set had the power amplifier. The flyback supplies voltages allover the chassis, but NOT that power amplifier. Notice the power transformer... black thing... beside the power amplifier? That would be a power transformer for the amplifier.

Why did the picture fold when i turned the drivers on the amp? Why did it come back when i turned the driver on the horizontal oscillator? These are the things i find confusing.

Not sure yet what you turned on the amp. Were there any labels? I doubt turning anything on the amp caused the picture problem. A bad connection on the horizontal board would be more likely cause the problem, and touching the adjustment on the board made the picture come back. If anyone knows the sams number for a set with that amp I will look up the amp schematic. Shame you can't get the entire chassis here to West Tn. I would look at it for you. It would be to fragile to ship, but if you happen this way let me know. I have a test jig and really don't need the CRT or cabinet.

Module number is 704182-1. Chassis number is T815-009.

Module number is 704182-1. Chassis number is T815-009.

Young man, I suggest you take your TV to a qualified service technician. You apparently have no idea what you are doing and will only cause more damage to the TV or yourself. I am not trying to be offensive, but this thread has been going non stop with nothing but "shot in the dark" attempts at a repair, which is the most foolish way of troubleshooting. The members here have apparently made an "attempt" to help, but nobody can diagnose a TV on line for which they cannot see. There has been no attempt at gaining a schematic either which only contributes to more guessing games. A qualified technician with the appropriate diagnostic instruments needs the set in THEIR hands so that THEY can do the troubleshooting and get it fixed correctly and SAFELY.

I have a schematic, for some reason the audio amp is not on it and since there are no repair techs around anymore with experience in crt tv i am afraid that would be impossible.

Do not turn any adjustments unless you know what they are for. Guys the problem is that the amplifier schematic is not part of the sams set. I can not find any reference to an external power amplifier, yet there it is. I have been unable to find a schematic for that amplifier. i could possibly fix it if I had it here, but he is 7 or 8 hours away from me. if the set still has the on board sound module, it may be possible to connect one set of speakers to the speaker level output of that module. This is not where the external amp connects to the chassis, unless that set does not use the sound module called for on the Sams schematic. Firebird, you have more than one problem. As long as you have a picture concentrate on getting the sound working. Then, using the schematic you can troubleshoot the color problem. You still may have solder problems around the horiz. osc. board. The flyback and tripler are not your problem. They are fine. On newer sets most if not all of the B+ voltages came from the flyback windings. This is not the case on your set. Your flyback is fine, and would not cause any sound issues. Not having the schematic I would first check the output transistors or IC on the external amplifier. Then the driver transistors. Replace any that are bad and check any emitter resistors. Be sure the solder connections are good. I would then check every electrolytic capacitor with an ESR meter or just replace them all. Do not turn any adjustments. Right now we do not know what they are for, and if they were bias adjustments could cause you to blow new transistors. If there are no output transistors, there should be an output IC. Check it for shorts. Replace it if necessery. How may connections go to the external amplifier? If it only has power, signal and speaker out. I may be able to fix it without the rest of the chassis. Let me know. After you get sound fixed, you can move on to the Horiz Osc board, and its connections. This will get you a stable black and white picture. Then move on to the color issue. The color is processed through about 3 differnt modules, none of which will cause sound or unstable picture issues. So get the other problems solved first, the move to the color problem. Solder connections were a huge issue with these sets, I know you resoldered some of the connections, did you pull the chassis out and look at the bottom of the motherboard for bad solder connections?

Buy the way, is the fuse good on the power amplifier?

I put a new one on even though it wasn't blown. I resoldered the whole chassis. That was how i got it to come back, that and replacing the HOT transistor as well as replacing the safety capacitor with a regular capacitor. I resoldered the motherboard, connectors and modules.

Replaced the safety capacitor with a regular one? I'm not too keen on that. They are specific capacitors for the circuit.

May not have been much choice but to use a regular capacitor. The original may very well be NLA. Usually not a problem if proper size and voltage caps are used. Since it is a safety componant, and I always try to avoid litigation, I would never do that on a customer set, but on my set I might if it was all I could get.

I was told that if the original version failed it could destroy the picture tube.

I was told that if the original version failed it could destroy the picture tube.

I've seen it snap the neck off of a 23" CRT.

Other than the updated versions of the safety capacitors, I've never had to replace one with anything else.

T815-09

I plugged it in today, took off the back to observe. I use a digital box now as we no longer use cable and the satellite does not have an rf connector. When i changed channel to one with a cartoon the picture started trying to unfold and became full width on the left. Still a quarter inch black band on the right.

From looking around the net i have concluded that the problem is the Horizontal Oscillator module. Since no one seems to have one and i can not pin down the exact component, i will have to rebuild the module.

Good luck with that.

An odd film capacitor is near the horizontal hold driver. Numbers are M4/00 TRW 4700H. Does anyone know how to read this?

I need more than luck. Some advice would be nice.

Check the power supply voltages going to the module first. Low B+ may also be a problem. I would check the electolytics with an esr meter, but I dont recall problems with the other caps.

Power supply is fine, electrolytics are all new. I am having trouble finding the film capacitors and transistors on the board.

Horizontal oscillator module number is 703881-3 if anyone has one.

You can get an ESR meter for $50 from everybody's favorite made-in-China electronics supplier, matelectronics.com. http://matelectronics.com/test-equipment-products/9281-mul-3333.html

Or if you have a scope and signal generator, you can use them as an ESR meter. Instructions here: http://fullnet.com/~tomg/esrscope.htm

As far as the black bands go, my guess would be that you bumped something around the horizontal module when you were troubleshooting the amplifier, but if you reseated the module and that did not fix anything, that's not the case. Maybe there's a width or horizontal hold control somewhere that is dirty and got disturbed?

Anyway, keep at it and troubleshoot one thing at a time. I am almost completely certain you are dealing with multiple failures that each need to be corrected, not a single failure that is causing all the faults you are observing.

I will let you know when i get all the parts for the horizontal board and the capacitors for the sound amp. Thanks.

Replaced the horizontal output transistor again. Picture came back in color. Still have a small line in the middle where it tries to fold. Flickers a little. Waiting on capacitors and other parts to rebuild the horizontal oscillator board.

Check the components on the retrace board. Some of these parts are safety components, so be sure to use the correct replacement, including that multi lead safety cap. Check the other caps and diodes on that board.

The foldover is usually a problem with a solder connection in the horizontal driver stage or on the flyback itself. These tend to burn off connectors on the flyback to PC board.
Also, these sets were very prone to safety cap (the four lead cap near the horizontal output transistor) failure. Hopefully the end will pop off when it fails, disconnecting the horizontal output transistor and killing high voltage. Also, if the horizontal output transistor is running hot (check the temperature when the set is off or it may be quite a surprise) don't run it too long or it will kill the new transistor.
If the four lead cap is bad, be careful replacing it with a two lead of the same value. Some caps can't handle the load placed on this capacitor and open with catastrophic results. If the new cap gets warm, try another type, not just a different brand but a different composition.

High output transistor gets too hot. The capacitor that replaced the safety capacitor is rated at .158uf@1600v. It should be .0068uf@1600v. Hard to find. Does anyone have such a capacitor?

Hey i found it. Let you know if it works soon.

For some reason seems to be too much voltage. Shouldn't .0068uf 1600v be the same as 6800pf 1600v. Picture is folding severely, when i tried to adjust height flyback arced at back of case.

Can't seem to find a capacitor to replace the safety capacitor.

Those can be replaced with those "orange drop" units that are often spoken of here. I'm not sure of the specs needed though; check the Avanti resto thread for pointers.

Found a capacitor, turns out it was .0086uf@1600v. Picture still folds in middle. A while back i found a new tripler and replaced it. Occasionally i hear a sizzling but do not see any sparks. Could the new tripler be bad.

Been away for a while. Will try to put the old tripler back soon.

Hey guys i finally made page 2.

I wish someone knew how to fix this thing.

I have a t815-02 complete chassis.

I have a t815-02 complete chassis.
There ya go. May as well just swap 'em and keep the other for parts.
TV has not played regularly since 1986 when it died right in the middle of a Joan Rivers joke.
Yup, that would do it. :D

foldover in the middle and a hot running horizontal output transistor are an indication of insufficient drive to the transistor. Look for the wire going to the base of the horizontal output transistor and trace it back to the driver transformer. Connnected to the other end of the transformer winding should be a capacitor and resistor. The cap is probably dried out (open) and this overheats the resistor. As these parts fail, the horizontal output overheats and shorts.
Can you post the horizontal portion of the schematic?

I would but for some reason i can't post it here.

I have a t815-02 complete chassis.
Thought you might have missed this as the page rolled over.

Replaced capacitor closest to the horizontal board transformer. Picture shows red and still folds in the middle. Capacitor was a film capacitor.

I think i got schematic to send.

I can't help but wonder why when i answer peoples questions no one replies.

Damn this 81 Magnavox STILL has a problem??

Picture folds, no sound and HOT transistor gets too hot.

Is it true a bad flyback can cause vertical fold over?

If you replace your flyback, and the foldover continues, I would say no. Replace capacitors first.

Already posted five posts down.

One would think that in the 2 1/2 years this post has floated around, the set would be fixed...

Damn this 81 Magnavox STILL has a problem??
More than it did at first I'm sure.

More than it did at first I'm sure.

I totally agree.

This is a really old television from the early solid state age. Parts are hard to come by because they only sold a few because at the time there were so many new brands on the market. If any one is such an expert i welcome your help. Any time you want to show up at my door i welcome the help. I still have it after 34 years because it meant something special. It was a Christmas present from my mother and father. 1981 Thanks for all your help.

I am curious if you have verified if all wires are in fact OK (good/acceptable) You must remember you are working on a TV that is now 32(+) years old! Wires of this age can break down over time, causing an increase in resistance in the copper conductor (or aluminum in some special cases due to corrosion due to the presense of moisture) which can lower the operating voltage(s) needed for CRITICAL circuits! However YOU MUST and I stress the word MUST be VERY and I stress the word VERY careful when working in and around a powered (or unpowered) TV (television) set of this age (1981 as you mentioned earlier in this thread, on April 16, 2012 at 5:32 PM). There are DANGEROUS, I repeat DANGEROUS voltages in and around the printed circuit board (the thin composite sheet like "board" that contains the (majority) of TV (television) components). The CRT (Cathode Ray Tube) contains the highest of dangerous voltage(s). If one is not aware of these dangerous voltages (a schematic diagram is of the utmost importance) the service technician may be at risk of potential electrocution not to mention damage to electrical (or electronic) testing/analyzing equipment. I STRONGLY ADVISE that YOU be fully familiar with the operation characteristics and voltages of this TV (television) before performing ANY, I repeat ANY electronic repair/service work. You may want to seek (find/locate) a schematic diagram for your particular TV (television) and CAREFULLY study (comprehend) it so that YOU may be FULLY AWARE of these voltages. :yes:

I found this earlier post from Norbert, that is quite helpful...

I repaired over 100 of these T-815 Magnavox sets when they were younger. Trust me, it's not considered an early solid state set.

The only thing your set has that I didn't see often is the stand-alone audio amplifier.

We've all suggest things to check on it for you, but you only come back and announce that something else is wrong. Replacing a single capacitor won't fix but one thing, friend.

Did you actually go through the chassis and re-flow solder on the chassis ground connections, and check the stakes that the plug-in boards connect to? Bad factory soldering was most of the problems I ever saw on the T-815.

Also, check the plug-in boards for bad soldering especially the board plug connectors.

Use a magnifying glass and a bright light to examine the soldering. You will see crack marks around connections. Use a small soldering iron and some decent thin solder to add a tiny amount of new solder to whats already there.

Be slow and thorough with your work.

THE END.

I agree with you here. The T-815, and 809, were part of the THIRD or so generation of SS sets from Magnavox--the first being the T979 and 989. The T-995, and 991, was probably the 2nd gen.

I ALSO saw a number of bad safety caps on these, vertical problems and triplers too. Along with PLENTY of bad connections !!

Yes, safety caps and triplers. I replaced a capacitor or two on some vertical modules. Our shop was kind of surprised when they stopped coming back for repairs. I know I've seen plenty of them in peoples homes still running and looking good.

Sage advice.
Also be damn sure you got the right hoz output ( HOT) in there.
Check PC at hoz drive transformer on the hoz osc board IIRC.
Check for a low ohm resistor going from B-E on HOT out of circuit.
If you changed the 4 lead cap put back the origional unless you KNOW its bad. Orange ones usually OK but white ones suspect.
Some Maggys had plug in flybacks, check the pins, they would burn.
Only think of the fold over, dont be distracted by other problems.
SOLDER SOLDER SOLDER. All Maggy uprights from 13" - 25" had
tons of bad connections. Dont forget the ground tabs from the steel
frame on mother board, they complete some connections.

73 Zeno:smoke:



I repaired over 100 of these T-815 Magnavox sets when they were younger. Trust me, it's not considered an early solid state set.

The only thing your set has that I didn't see often is the stand-alone audio amplifier.

We've all suggest things to check on it for you, but you only come back and announce that something else is wrong. Replacing a single capacitor won't fix but one thing, friend.

Did you actually go through the chassis and re-flow solder on the chassis ground connections, and check the stakes that the plug-in boards connect to? Bad factory soldering was most of the problems I ever saw on the T-815.

Also, check the plug-in boards for bad soldering especially the board plug connectors.

Use a magnifying glass and a bright light to examine the soldering. You will see crack marks around connections. Use a small soldering iron and some decent thin solder to add a tiny amount of new solder to whats already there.

Be slow and thorough with your work.

THE END.

Never did get it absolutely correct.

what it is

I have a t815-02 complete chassis.

If I were you I'd take him up on the offer. :banana:

I tried to send you a private message. For some reason it echoed. I am still interested. Just need details.Please just let me know. thank you.

I would love to have fixed the tv. It is the only thing i could not fix. i can not find Eberts. I would love to have had the parts. I have the schematic. Wish i could have fixed it before my mother passed as it was her tv. Maybe i can find a repairman. It was a brand new tv when she bougth it. A guy came and cut it out of the box in our living room. Thanks for all your help. Model RA-5054

Hello