#16
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The filter cap went south on my Zenith System 3.
It uses the 9-160-05 board Was wondering on the big 2 section cap, if that is what one tries to get when replacing caps on the board (if even still available) or if you just replace it with 2 caps? Also.. for those who have rebuilt this board, anything else to watch out for, or re-do? |
#17
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Use 2 caps & be sure any grounds tied by the old can are retied.
Go over the PCB real good for cold joints, there ARE some. Check the 200 V supply filter cap. Right rear near FBT. IIRC 10 mfd 415V. There was also a lytic in the H drive that could int kill the HOT but I dont remember the details. 73 Zeno |
#18
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From Zenith Factory service information.
9-160-03G, 05D, 05E, 08A Module CM 133 / 4-43C 26Kv Board 9-160-06D, 09A Module CM 133 / 4-43F 30Kv Board 11-1981 Manual CM-133 section 4-43. Unless key is broken off the yoke interlock will not attach without forcing it. rrrhre2s |
#19
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The capacitor that causes the board to keep blowing the HOT is located behind the HOT heat sink 47uf at 16v across two low value resistors (value varies with version of the board. This capacitor was a CX meaning it was related to safety.
Run the set 15 minutes remove power check the temperature of the HOT heat sink if more than just warm replace the capacitor. Later boards were reworked to eliminate the 2 resistors and capacitor in parallel. Note the driver circuit was also changed. 9-160-06 R3324 replaced with a jumper. R3334 0.18 ohm 3w 9-160-05 R3324 0.33 ohm 3w R3334 0.18 ohm 3w Have problems reading the copy I have may have the numbers wrong. The 0.18 ohm resistor is on the emitter of the HOT. The 0.33 ohm resistor is between the base and the horizontal driver transformer. rrrhre2s |
#20
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well.. the set didn't blow the hot. (Perhaps I caught it quick enough?)
It's pulling in from the sides a bit, and I have a hum-bar in the picture. |
Audiokarma |
#21
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Your thread hijack is reminding me I need to finish that board swap...
__________________
Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
#22
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Well I tried the swap about a week ago and the results seem to be no/inconclusive.
A couple of the 2-pin connectors ton the topside do not seem to be the same place or letter. I did hook it up and nothing was damaged, but only got ~5-7KV of HV and no sound. I then put the working 030 variant back into the working 13" set it came from and that continued to work (so no harm done). I then examined the non-working 05 variant, and found a major coil had badly cracked solder lugs, and decided to re-touch all bad looking solder joints as a final try/courtesy before junking it. That fixed the audio hum, but got me no HV so before throwing up my hands in disgust with the set on I wiggled some of the connectors on the back of the 9-190-05 and it suddenly came to life. There may not be interchange in the way I wanted, but I did get both sets working.
__________________
Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
#23
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Well...you SURELY have a pair of good tubes !!
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