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 Post subject: Re: Crosley 9-408 [RCA 630TS clone]
PostPosted: Mar Thu 08, 2018 6:04 pm 
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Joined: May Thu 14, 2015 4:15 pm
Posts: 958
Location: Dallas, TX
If you send the meter to a calibration company it will cost more that buying a new meter.
It may not be necessary you might get close enough by measuring a fresh battery cell.
The way I run my railroad is to have one new name brand factory calibrated meter that I use
as a standard. Maybe someone near to you can help you out.

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Tim
It's not the Destination, It's the Journey.


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 Post subject: Re: Crosley 9-408 [RCA 630TS clone]
PostPosted: Mar Thu 08, 2018 8:19 pm 
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Joined: Mar Sun 01, 2009 10:27 pm
Posts: 4546
Location: Ann Arbor, MI
stuben wrote:
I will have to ship this to someone to have it calibrated and am wondering if anyone here might be able to recommend someone in the northeast who might be able to help me out.

The Heathkit VTVM that I have has a small dot on the meter face just above the highest mark. The manual says to buy a new carbon-zinc battery and adjust the meter so that the needle points to that dot. I just measured a new alkaline battery with my DVM and it measures 1.601 volts. So you could use an alkaline battery as a voltage standard to adjust your meter.

I have a high precision voltage standard that I got from the place where I worked. It is good to 6 decimal places. But you don't need anything like that to adjust a VTVM.

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 Post subject: Re: Crosley 9-408 [RCA 630TS clone]
PostPosted: Mar Fri 09, 2018 5:28 pm 
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Joined: Jun Thu 25, 2015 3:21 am
Posts: 1256
if you have a tube tester i would check the tubes in your vtvm. not only for emitions but if it is a dual tube you want both halves balanced. balanced means you get the same reading for both halves of the tube. to work on vacuum tube electronics you will really need a good tube tester.

you have the ac/ohms dc and ground lead for your vtvm. a high voltage probe is something used to measure voltages higher than the maximum voltage allowed by your meter. a rf probe would be used to take measurements in rf and if circuits. if you can i would try to get both these probes for your vtvm.

to check calibration on your vtvm you can get away with using the ac plug for the ac range a battery for the dc range and several persision resistors for the ohm meter range. if you have a dvm which you said earlier i think compare the readings to that. also a vom of not less than 20000 ohms per volt can be used to compare readings. try to find the manual for your vtvm and it should have a calabration proceedure listed. for proper calabration the most important thing is the tube in the bridge circuit is balanced.

you use a vtvm the same way you would use a vom or dvm to make measurements.

if you dont have a tube tester you really should get one. hickok is the best in my opinion. they also cost an arm and a leg. mutual conductance tester is the best but a emitions tester will due and is less expensive. no one tube tester will cover all tubes. make sure the tester you buy has the necessary sockets to test the tubes you will need to test. mine has sockets for the old 4pin 5pin 6pin 7 pin tubes found in early radios an octal socket loctal socket 7 pin minature and 9 pin minature which will cover most if not all the tubes i need to test. if you work on newer equiptment you will need a tester that also will test magnoval novar and decal tubes as well as nuvistors. so what vintage tester you buy depends on what you want to use it for.

to work on tvs a good crt tester is indispensible in my opinion. also a b@k television analyst is very helpfull. i own the 1075 television analyst.

for soldering to the chassis a 150 watt soldering gun and for soldering to a tube socket a 75 watt gun. anything less just wont cut it. a good desoldering bulb is also good to have but you can get away with solder wick.

a good condenser tester is also necessary.

for color tv work you will need a good dot bar generator.

an inductance meter will come in handy.

for doing alignment on televisions an oscilascope is necessary for some steps.

a sweap generator and marker generator also is necessary.

im sure im forgeting something but this will get you started.


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 Post subject: Re: Crosley 9-408 [RCA 630TS clone]
PostPosted: Mar Wed 14, 2018 4:39 pm 
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Joined: Oct Thu 23, 2014 5:15 pm
Posts: 95
Thanks thomas13202! Wow! That is a lot of gear to have to own and way beyond my budget. After re capping my RCA 8T241, which was very clean and all there I was rewarded with a set that works very well and I enjoy watching it. I guess I just got lucky. I do have a friend who went to electronics school that has an oscilloscope and lots of other gear and he knows someone local that collects old televisions so he may be able to help me out.

I'm still working on this Crosley 9-408 and decided to remove the transformer as the flux band needed to be re soldered and the light rust painted so that has been done. I am painting the chassis where it was rusted and removed the tuner, as I did not want any of that stuff getting inside the tuner then sandblasted with 220 aluminum oxide before painting to ensure a good bond to areas that were galvanized. While removing the tuner, there were two shielded wires one of which is green that not only had the shield soldered to the chassis but the green wire too. This did not seem right so I checked the wiring diagram in the Riders manual and it shows this wire should be soldered to pins 5&6 of valve #108, a 6AT6 the first audio amp, so maybe this was my problem. I also went ahead and ordered several new resistors from just radios to replace ones that had drifted out of spec. It will be a while before I get everything back together, but I will be making an update in a week or so.

Thanks again all!


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 Post subject: Re: Crosley 9-408 [RCA 630TS clone]
PostPosted: Mar Thu 22, 2018 6:31 pm 
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Joined: Oct Thu 23, 2014 5:15 pm
Posts: 95
Still having lots of trouble. My B+ is way too high. Measuring voltage at pins 4&6 on the 5U4G's I get 384VAC measuring to the transformer center tap. The chart says 390, so this seems okay. At pins 2+8 I get 400VDC and the chart says it should be 300VDC. I have no clue as to why. Any ideas where to look? At least the chassis looks nice now! No rust, but also no raster now.

Thanks!


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 Post subject: Re: Crosley 9-408 [RCA 630TS clone]
PostPosted: Mar Sat 24, 2018 1:56 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 13752
Location: Fernandina Beach, FL
stuben wrote:
Still having lots of trouble. My B+ is way too high. Measuring voltage at pins 4&6 on the 5U4G's I get 384VAC measuring to the transformer center tap. The chart says 390, so this seems okay. At pins 2+8 I get 400VDC and the chart says it should be 300VDC. I have no clue as to why. Any ideas where to look? At least the chassis looks nice now! No rust, but also no raster now.

Thanks!

Could it be possible that you have no load on the B+? Since you have the proper AC input, the unloaded output on the 5U4 would be higher. A load should drag it down. Not having a raster sounds as though there is something wired incorrectly or open.

Just a thought.

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 Post subject: Re: Crosley 9-408 [RCA 630TS clone]
PostPosted: Mar Sat 24, 2018 9:27 pm 
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Joined: Aug Thu 12, 2010 6:25 pm
Posts: 182
Location: Durham, NC
It sorta sounds like there's an open filter choke in the power supply circuit. (Some TVs used the speaker field coil as a choke, but I don't think this is one of them.) Without a load the voltage will rise at the rectifier. See if the too-high voltage appears elsewhere in the chassis (where the 300V should be) to hunt down where the open circuit is.

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A collector of TV signal boosters and UHF converters -- God help me!
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 Post subject: Re: Crosley 9-408 [RCA 630TS clone]
PostPosted: Mar Sun 25, 2018 11:29 am 
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Joined: Oct Thu 23, 2014 5:15 pm
Posts: 95
Thanks for the responses.

I got this set from someone who used to collect and repair televisions. I am not sure if he worked on this set in the past, but someone obviously did. Everything inside looked to be all original and complete when I started replacing the electrolytics and paper capacitors. The center tap of the power transformer was soldered to one of the ground lugs on C220. I downloaded the Rider manual that has a wiring diagram and see that it is soldered to the chassis, so I have moved it there and now have a B+ of 306VDC, much closer to 275 as specified. I also discovered one of the shielded wires from the tuner not only had the shield soldered to the chassis but the wire also, this is the green wire coming off the tuner. Looking at the wiring diagram it shows it should be connected to pins 5&6 of V108, a 6AT6 the first audio amp, so I have moved it there. Still no raster. Odd that I at least had one before I made these corrections. Perhaps one or more tubes have gone south. I will try to post some pictures later today after checking any critical lead dress.


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 Post subject: Re: Crosley 9-408 [RCA 630TS clone]
PostPosted: Mar Sun 25, 2018 6:27 pm 
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Joined: Mar Sun 01, 2009 10:27 pm
Posts: 4546
Location: Ann Arbor, MI
stuben wrote:
The center tap of the power transformer was soldered to one of the ground lugs on C220. I downloaded the Rider manual that has a wiring diagram and see that it is soldered to the chassis, so I have moved it there and now have a B+ of 306VDC, much closer to 275 as specified.

I wonder if one of the ground lugs of C220 should be connected to the chassis. If one should be then the center tap connection you found would make sense and would have worked if C220 was connected correctly.

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 Post subject: Re: Crosley 9-408 [RCA 630TS clone]
PostPosted: Mar Sun 25, 2018 11:16 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1720
Location: Lafayette, CO
The power resistors in your cage can cause this if one is open. Craig


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 Post subject: Re: Crosley 9-408 [RCA 630TS clone]
PostPosted: Mar Mon 26, 2018 3:26 pm 
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Joined: Oct Thu 23, 2014 5:15 pm
Posts: 95
Thanks everyone for the suggestions!

Tom, I don't think so because this capacitor has an insulator between the chassis and can. One of the multi section cans does not have an insulator and has one of the ground lugs soldered to the chassis.

Checked the power resistor in the high voltage cage, checks out fine!

Looks like it was an error on my part with the wiring. I have been taking pictures as I go along, and when replacing the power transformer the picture I was looking at was taken at an angle that looked like that center tap went to a ground lug on the capacitor can. I looked back much further and found a good shot of the connection that clearly showed this wire was soldered to section C of C#220 in the riders manual which is the 80mfd 150 volt section. Another wire then connects this section to ground. Now that I have things wired correctly all my voltages look good, negative voltages in the bleeder resistor compartment are spot on. However while working on the set something started to smoke again making a horrible smell. I quickly shut it off and looked underneath the chassis but found nothing melted or charred. I had the chassis right side up when I noticed the smoke and it looked like it was coming from the power transformer or C#220. Perhaps there was a problem with the power transformer initially as it had the flux bands unsoldered when I got it. This morning I got out the dim bulb tester and the set passes the test! Looks like I have an intermittent short somewhere.

At this point I am afraid to turn the thing on again. I'm putting this aside for a while.


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