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  #1  
Old 10-26-2011, 12:44 PM
47'Plymouth 47'Plymouth is offline
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Recapped a CTC 7AH..still have a problem

got a '58 RCA CTC7AH color console"Grenoble"
completely replaced all of the E-caps;including a old Bumblebee on the A/C
safety interlock...047@600volts..on the variac on the first power up it shows a huge current drawon the Amp gauge..I then use my 3way Dim-bulb tester with all of the tubes pulled and the CRT unplugged also..bulb does'nt light...while on the variac brush starts to arc..i shut her down instantly.i tested the set on the Dim-bulb alone to test for a short in the Primary...no problem there...double checked all connections with the schematic to make sure i didn't mess up on that end...what gives
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Old 10-26-2011, 12:46 PM
DaveWM DaveWM is offline
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Quote:
Originally Posted by 47'Plymouth View Post
got a '58 RCA CTC7AH color console"Grenoble"
completely replaced all of the E-caps;including a old Bumblebee on the A/C
safety interlock...047@600volts..on the variac on the first power up it shows a huge current drawon the Amp gauge..I then use my 3way Dim-bulb tester with all of the tubes pulled and the CRT unplugged also..bulb does'nt light...while on the variac brush starts to arc..i shut her down instantly.i tested the set on the Dim-bulb alone to test for a short in the Primary...no problem there...double checked all connections with the schematic to make sure i didn't mess up on that end...what gives
check resistance at the plug
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Old 10-26-2011, 12:47 PM
DaveWM DaveWM is offline
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I am assuming you are starting at zero with the variac, should be zero volts and zero amps.
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  #4  
Old 10-26-2011, 12:52 PM
DaveWM DaveWM is offline
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should be about 3-4 ohms on the plug. with the power switch on.

if that checks then check resistance at B+ (right after the choke), should be around 10k AFTER the filter caps charge up from the voltage of the VOM, do this with the set unpluged of course. If the B+ resistance is a lot lower then you have a short somewhere or a filter cap installed backwards. If it uses a doubler cap in the power supply make sure you have it wired up with the correct polarity, check it to the schematic, doublers can be tricky.

Last edited by DaveWM; 10-26-2011 at 12:56 PM.
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  #5  
Old 10-26-2011, 12:56 PM
47'Plymouth 47'Plymouth is offline
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ok with power sw on with no power of course..you stated that to test for 3 to 4 ohms @ the safety interlock..trace over to the filter choke.correct?@10K ohms
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Old 10-26-2011, 12:58 PM
DaveWM DaveWM is offline
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I trust nothing so I would check the actual plug for the 3-4 ohms.

so if that clears yes look for the filter choke I think there is a thermal breaker there.

again triple check those 160uf caps C1 should be a single section or a single cap the neg does NOT go to the chassis ground.
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Old 10-26-2011, 01:12 PM
47'Plymouth 47'Plymouth is offline
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that's correct..on the set having a thermal switch; one side goes to the single section 160uf@250 is on the positive side of the caps center leg; going too the thermal switch,and on to the filter choke..the negative is to the safety fuse holder,and one leg on thermal sw is going to the power switchthe single cap is not grounded...this must be a simple fix..i hope i've not damaged this 53 year old set..it has a beautiful cabinet

Last edited by 47'Plymouth; 10-26-2011 at 01:16 PM.
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Old 10-26-2011, 01:16 PM
DaveWM DaveWM is offline
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you lost me on the power switch. it goes plug, saftey cap, on off switch, thermal switch (the heater part), primary of transformer.
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  #9  
Old 10-26-2011, 01:18 PM
DaveWM DaveWM is offline
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was it working before the recap?
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  #10  
Old 10-26-2011, 01:27 PM
47'Plymouth 47'Plymouth is offline
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Dave
I installed a new 160uF@250 that's on a fiber wafer....the other 2 E-cans,2 and 3
were junk; i used 2 new terminal strips that were long in length mounted them
on the empty space rear of the tuner soldered all of my new radial E-caps
to the new strips making sure to only ground the one side that was required
too...place the leeds to each correct value one at a time..double checking as went according to the schematic no the set
hasn't been on for over 35 years
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  #11  
Old 10-26-2011, 01:29 PM
DaveWM DaveWM is offline
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pm sent
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  #12  
Old 10-26-2011, 01:31 PM
47'Plymouth 47'Plymouth is offline
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the color picture tube is mint; tested with my Sencore CR-161 tube tester
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  #13  
Old 10-26-2011, 02:34 PM
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Electronic M Electronic M is offline
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If you haven't replaced the papers/or paper-milars those can some times cause troubles in early roundys.
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  #14  
Old 10-26-2011, 03:35 PM
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Phil Nelson Phil Nelson is offline
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Quote:
Originally Posted by Electronic M View Post
If you haven't replaced the papers/or paper-milars those can some times cause troubles in early roundys.
Here is my CTC-7 after I had replaced only electrolytics. Bad horizontal, lousy vertical, colors all hosed:



Here it is after I replaced the old "maroon drop" mylar caps:



Still need to do the usual setup (convergence, etc.), but you get the basic idea.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html
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  #15  
Old 10-26-2011, 03:51 PM
DaveWM DaveWM is offline
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Phil, can you pls confirm the resistance of the primary of the power transformer.

my 3-4 ohms is on a CTC-16
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