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ITT CK500 problems.

 
neil1974
(@neil1974)
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Posts: 601

Hello all, Could someone give me any pointers on the fault with this set (CVC5 chassis) basically I thought ill switch it on and see what happens, well not a lot actually as the line output section never woke up and the multi can cap C270/272/274/277 got very hot :ccf . so can anyone shed some light as to where to look as it has me puzzled.

Thanks,Neil.

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Topic starter Posted : 04/09/2013 11:20 pm
Alastair
(@alastair)
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Posts: 292

Hmm....

Sounds like there's two faults.....

The hot caps is probably due to leakage,--bringing them up on a variac to re-form them should help a lot....

As they were leaking--quite a lot by the sound of it--the supplies to the various stages--particularly the line osc wouldnt be right and probably too low to allow it to run.

Try re-forming and then give it another bash is my advice...

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Posted : 04/09/2013 11:32 pm
Focus Diode
(@focus)
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Line output stage not waking up? Several possibilities here: the valves of course, screen grid feed resistor to the PL509, the 400mA fuse to the LOP stage blowing assuming the valves remain cold.

I've also known a defective tripler blow the 400mA fuse. A blown fuse could also be due to the boost capacitor having gone s/c. Assuming the LOPT is ok disconnecting the tripler will bring the stage back to life with sound.

Hope that's some help,
Cheers,
Brian

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Posted : 05/09/2013 12:19 am
Anonymous
(@anonymous)
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Being a CVC5 dont forget the solder conections from the lopt to the main board.
ROB T

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Posted : 05/09/2013 1:48 am
neil1974
(@neil1974)
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Well the cap has reformed (quite quickly actually) but there is still no operation after checking the resistor and fuse etc. does this mean the lopt is dead or am I missing something obvious again.

Cheers,Neil.

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Topic starter Posted : 22/09/2013 2:54 pm
Anonymous
(@anonymous)
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If you have not already done so disconnect the trippler and try again.
rob t

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Posted : 22/09/2013 3:10 pm
danny
(@danny)
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Posts: 106

Hi neil sorry you are having problems with this set. check for negative volts on the grid of the line output valve and let us know what voltage is there. also is the pl509 showing stress or is it just glowing normal.
with the power off using an avo or similar meter check the resistance of the top cap on the pl509 and chassis . There should be no reading. Next you need to check that ht is actually reaching the line output stage ?. Many moons ago i had a good old decca bradford with overheating line output valve there was negative volts drive but this was only slightly low causing me to suspect the lopt this was replaced and the fault was still pressent after changing most components in and around the line output stage i noticed the main smoothing cap had a bad bulge this was tried in desparation . You guessed it was the culprit so dont get caught out check all voltages agains a manual.Another possibility is bad connetions on fuse holders . if in doupt you could try the cvc 8 lopt to see if there is any improvement. Danny

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Posted : 23/09/2013 12:55 am
Focus Diode
(@focus)
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Excellent advice above. I haven't heard any mention of blown fuses, especially the 400mA one in supply to the line output stage. If intact it's hopeful the stage is actually ok and the fault is in the supply to the stage. The multicaps could overheat if the supply to the stage is absent, say if it's s/c close to the reservoir. Also- do the PL & PY valves overheat or run cool?

Another possibility if the supply is intact and the PL509 and PY500A overheats: the top caps to the valves should cross over. It's not impossible someone before you connected them the wrong way round. Usually the 400mA fuse blows but not if it's been over-rated. Unlikely to be the case here but worth noting nevertheless.

Cheers,
Brian

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Posted : 25/09/2013 1:12 pm