View Full Version : Long time no see! And new tv: Stromberg-Carlson "Broadview"
BandDirector 06-10-2020, 08:33 AM https://imgur.com/gallery/BloNXk0i have NOT removed anything!
What next?
Picked up Sam's sheet
Replaced Hi V rect
Misc video tubes cleared
Has raster, no sound.
BandDirector 06-10-2020, 02:13 PM https://imgur.com/gallery/BloNXk0
BandDirector 06-11-2020, 07:24 PM Finally figured out how to get the chassis out.
Why is the HV rec not glowing inside the flyback housing?
Electronic M 06-11-2020, 07:41 PM The filament of the HV rect can only be seen from underneath and is not bright...the filament for it is powered off the flyback so no horizontal deflection = no glow.
BandDirector 06-11-2020, 09:46 PM The raster now flickers and it needs to be dark to see it, when you turn the contrast to an extreme you see a faint raster. If you turn the brightness knob the raster glows very bright some but then disappears.
Can I pick the brightness problem and work backwards, checking components, and the actual knob/switch? I forget what it is called, that raises/drops brightness.
How do you track whether enough voltage is getting to the crt?
Fun fact- this Stromberg has a replacement RCA Silverama 21" tube, same as the RCA console that I have. And the flyback has been replaced in the Stromberg.
Notimetolooz 06-12-2020, 08:55 AM You will need to replace the electrolytic capacitors as well as the paper capacitors. Some other components as needed. You also need a multimeter at a minimum.
The set really doesn't "work" yet.
BandDirector 06-12-2020, 10:24 AM I do have a multimeter, and some other good test equipment; vactube vm, oscope, vhf signal gen etc.
I think the smart thing to do is to trace each circuit using the pjotofact, test for capacitance and resistance, and move down the circuit. Is that a best practice?
DavGoodlin 06-12-2020, 10:46 AM I have a Hallicrafters of the same age as this SC that did this, after a complete recap. I thought I goofed in the video and DC restoration circuits.
Yet, I still did not try connecting RF and all it needed was a signal. The video was fine for a weak 12LP4, but under no signal, was almost black.
Try an analog signal before going any further.
Electronic M 06-12-2020, 11:20 AM The brightness drop sounds like HV sag. If it passes video you can confirm HV sag by watching the image expand as it goes dark.
If it is HV sag the horizontal should be recapped and the HV rectifier substituted.
All paper and Electrolytic capacitors should be changed, but do them 1-3 at a time and check performance between each group. It is easier to catch any mistakes you might make that way.
Notimetolooz 06-13-2020, 10:23 AM I do have a multimeter, and some other good test equipment; vactube vm, oscope, vhf signal gen etc.
I think the smart thing to do is to trace each circuit using the pjotofact, test for capacitance and resistance, and move down the circuit. Is that a best practice?
That would be a way to do it. You also would become more acquainted with the circuits. Sort of an aid in learning.
However, capacitors as old as in this TV have a very high probability of being bad, not every one but most. Some bad parts cause big problems, some just cause lack of best performance. Some might be OK for the moment but soon fail. You can't tell unless you completely test each one, that takes a lot of time and effort. You really need to unsolder at least one lead to test a capacitor. You should test for capacitance and leakage at near rated voltage. The other approach is to replace all the electrolytic and "paper" internal construction (some types of paper caps have plastic cases) capacitors. Resistors are a bit more reliable and easier to test.
Electronic M 06-13-2020, 03:51 PM That would be a way to do it. You also would become more acquainted with the circuits. Sort of an aid in learning.
However, capacitors as old as in this TV have a very high probability of being bad, not every one but most. Some bad parts cause big problems, some just cause lack of best performance. Some might be OK for the moment but soon fail. You can't tell unless you completely test each one, that takes a lot of time and effort. You really need to unsolder at least one lead to test a capacitor. You should test for capacitance and leakage at near rated voltage. The other approach is to replace all the electrolytic and "paper" internal construction (some types of paper caps have plastic cases) capacitors. Resistors are a bit more reliable and easier to test.
Really any cap that old should be considered shot even if it tests good. Case in point (on newer sets known for having better capacitors) I checked every lytic in my 1962 Zenith 29JC20 color set and over 2 months of regular service it blew a an original section I left in every week or two....till I eventually got pissed and changed all the lytics. Back when I was a poor college student and didn't get believe in online parts vendors I bought a NOS 3KV .001 tubular ceramic cap that the seller claimed was a film dielectric to replace the original 2KV .001 paper dielectric tubular ceramic in my CTC15 clone....it shorted in a few months and took out other stuff too.
Original caps in 50s sets like that should never be trusted and even the better 60s stuff can still crap out.
BandDirector 06-14-2020, 09:49 PM I am pretty sure a cracked flyback wheel won't make a crt jump up and shine, I think I made that happen trying to resolder the hv lead to the tube cap.
Oh well. Need to replace it. Now I can get over trying to just see it glow a bit and start the real work.
Electronic M 06-15-2020, 10:49 AM I am pretty sure a cracked flyback wheel won't make a crt jump up and shine, I think I made that happen trying to resolder the hv lead to the tube cap.
Oh well. Need to replace it. Now I can get over trying to just see it glow a bit and start the real work.
Most flybacks windings of that era were covered in wax or tar as insulation. NOS flybacks can have that insulation cracked too.
It is no big deal that the insulation cracked the flybacks will work with it cracked perfectly fine (assuming no other problems in the flyback or horizontal system)...the worst that that might happen as a result of the crack is Corona or arcing between that point and ground....you can fix the crack by GENTLY removing any loose wax/tar around it (if there is any) and then smearing a bit of sensor safe automotive RTV silicone over the crack/bald spot.
Some flybacks that have gotten hot in opperation have melted that wax/tar coating clean off and work without it.
The key thing with flybacks is that they aren't open (check winding resistance against that listed in the sams for your model to confirm it isn't open), and don't have shorted turns (that can be checked with a ring test, but most people don't bother unless there are troubles post recap).
TLDR: your flyback is probably just fine, silicone the crack and start recapping the chassis.
Notimetolooz 06-15-2020, 06:37 PM He might mean that the HV lead broke off when he tried to resolder the rectifier tube cap.
Electronic M 06-16-2020, 09:31 AM He might mean that the HV lead broke off when he tried to resolder the rectifier tube cap.
Possible. That also potentially can be fixed if he can find the winding end stub or get a solder joint on one of the wires a few turns away from it.
BandDirector 06-16-2020, 09:39 AM That is a good idea. Last night I was tracing circuitry and found a disconnect between a cap and the flyback, still working. The crack in the hub/wheel around the transformer occurred when I tried to lengthen the HV wire, pulled too hard stripping insulation.
The on/off switch is failed now, click but no power flow. *Now seems to be okay*
*I still cannot get the flow of voltage between horizontal output to return through rectifier.
How can I store the crt?
BandDirector 06-16-2020, 10:29 PM Tonight I soldered in a better wire for the HV rec, the vac tube had a low green glow. The crt produced a wider blurred line than just a thin line, probably 2" horizontal size, dim. The shape didn't quite make to the right edge of the screen.
The analog input is supplied by a vcr from 1987, when you hit tv/vcr to take if off the tape, the screen goes dark. So, the tuner apears to be reacting to an input signal.
I guess these signs are as good as any to start recapping. Tomorrow I will test audio output, then make a starting point to replace caps and make an short order sheet.
It is sure trying to work.
BandDirector 06-17-2020, 10:24 AM No sound output...moving on.
BandDirector 06-26-2020, 11:26 PM Today I have replaced 8 caps, and 3 tubes- horiz output, sound, damper.
Before doing this today, the set stopped powering on as of last week. When I plug in the tv I have live voltage through to the switch on the front of the chassis, turn past the click- nothing. Still 118/120 v and yet no tubes warming up, nothing.
I desoldered the switch, it is a combo on/off/volume and an outer contrast knob. Before this I checked current to the switch, it was just waiting, turn the switch and nothing.
I took it to my supplier and wrote the part number for him to research next week.
??
Kevin Kuehn 06-27-2020, 11:07 PM You could solder a jumper wire across the power switch and continue on with your troubleshooting/recapping? You could then turn it off/on with an external switch on a outlet strip, or simply unplug it from the AC line.
BandDirector 06-28-2020, 08:02 AM Brilliant. Did it this morning. Worked perfectly
vortalexfan 07-14-2020, 02:36 PM Brilliant. Did it this morning. Worked perfectly
Try taking the power switch section of the switch off the combo switch and shoot some WD-40 into the power switch and work the power switch lever back and forth a few times and then flush the switch out with contact cleaner and measure the switch with a continuity tester on your digital multimeter in the "on" and "off" position, in the on position it should beep at you, in the off position it should measure open.
More than likely your power switch's contacts had arced and welded themselves in the off position, spraying the WD-40 into the switch and working it back and forth will work the contacts free, I've done that before on a 1936 Philco Model 116B radio I'm working on restoring which had the same issue, except in my case I couldn't get the radio to turn off with the power switch rather than like yours where you couldn't get it to turn on.
Hope this helps.
Electronic M 07-14-2020, 03:59 PM Try taking the power switch section of the switch off the combo switch and shoot some WD-40 into the power switch and work the power switch lever back and forth a few times and then flush the switch out with contact cleaner and measure the switch with a continuity tester on your digital multimeter in the "on" and "off" position, in the on position it should beep at you, in the off position it should measure open.
More than likely your power switch's contacts had arced and welded themselves in the off position, spraying the WD-40 into the switch and working it back and forth will work the contacts free, I've done that before on a 1936 Philco Model 116B radio I'm working on restoring which had the same issue, except in my case I couldn't get the radio to turn off with the power switch rather than like yours where you couldn't get it to turn on.
Hope this helps.
If the contacts are badly worn from arcing it is a wise move to get a relay with a 120VAC coil and make the switch only power the relay coil then wire the relay switch contacts to control power to the radio/TV. Some power switches were underrated for their application and those need the relay treatment.
vortalexfan 07-14-2020, 04:44 PM If the contacts are badly worn from arcing it is a wise move to get a relay with a 120VAC coil and make the switch only power the relay coil then wire the relay switch contacts to control power to the radio/TV. Some power switches were underrated for their application and those need the relay treatment.
And it also happens due to wear and tear, especially if the item in question was used heavily over the years.
Switches arc just during general operation (look at a snap switch on an old fan when powering the fan on, and you'll see an electrical arc from the switch going between the different speed settings).
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