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Post by jukeboxmarty on Jul 9, 2023 19:47:25 GMT
Good news! Hopefully it stays issue free.
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Post by prime on Jul 9, 2023 22:30:09 GMT
I was hoping i could ask you one last question. I notice that an orange wire goes from the left and right tap for 16 watts to the 7199 tubes, can i clip on to either 16watt tap and to ground to confirm output transformers, i so what do i expect to read on my meter. pete  |
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Post by jukeboxmarty on Jul 9, 2023 23:52:07 GMT
Yes, you can measure ohms between each orange wire and ground... but don't expect to see much resistance!
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Post by prime on Jul 9, 2023 23:58:10 GMT
I will but i just realized that one of the voltage tests that were done at the filter caps was the 370 coming from each output transformers ,that probably confirmed they were ok.
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Post by jukeboxmarty on Jul 10, 2023 0:05:10 GMT
That +370vdc is going INTO the transformer on the primary side. Getting that voltage at the filter cap does not confirm the transformer's primary is good.
The resistance measurement (with the power off) between the orange wire and ground, is across the transformer's secondary.
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Post by prime on Jul 10, 2023 0:30:59 GMT
Measured across orange to ground both sides 1.7 ohms
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Post by jukeboxmarty on Jul 10, 2023 1:24:42 GMT
That's about right!
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Post by prime on Jul 10, 2023 14:45:23 GMT
Sorry Marty i lied, i have one more question. I was testing the volume pot on the defective amp and on the working amp. connecting to the center and left post on the lower three posts of the 6, i get 350ohm to 420ohm using the volume knob, using the same terminals on the working amp i get 270ohm to 2 million using the volume knob, i looked at parts list for HFSA-3 and HFSA-5 and they same to be the same switch or pot. Ive attached photos of front and back. where would i test to confirm this is ok or have i found my issue? pete postimg.cc/gallery/sQbN2qN |
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Post by jukeboxmarty on Jul 10, 2023 16:47:16 GMT
As you can see by the parts list, the pot specified should have a value of 1 meg. Ideally the measurement should be around 0 ohms to 1,000,000 ohms.
350 - 420 ohms is not correct.
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Post by prime on Jul 10, 2023 16:52:11 GMT
I cleaned the pot using Deoxit-5, and after working the knob back and forth about 60 times i now get 47ohm all the way to the left and 473kohm all the way to the right. I think that is still very low. On the working SHFA-3 it looks like the same pot i get 70ohm far left and 1,9m ohm far right
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Post by jukeboxmarty on Jul 10, 2023 17:45:29 GMT
Although your latest result may not be to spec... it shouldn't prevent sound from coming through.
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Post by prime on Jul 10, 2023 17:53:34 GMT
After extensive testing left wire to center, 40ohm far left 360k ohm far right right to center 8ohm far left 1.8 m ohm far right. So either way whatever is pulling down left side ,it cannot affect right?? Ive decided to give up on the amp not sure where else to look, I reinstalled the amp i just capped and not sure if trying to use the other amp has damaged a tube or maybe bad ground somewhere in the new amp but i get a low hum when the record starts at no volume, the volume and the sound is clear and undistorted with good bass and treble but in the back ground is this hum, it was not there last time i installed the recapped amp to try it ,but it was there before recapping. after record rejects hum is gone , I tried removing the power to the fluorescent lights, also the three prong feed from the tone arm and cart, no change, tried three tubes 6973 and 7199 on left ,then right no change but not as loud if left or right tubes out. Cant really hear it when volume at 50% only low volume. Could be dirty power from receiver just don't know how to test that.
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Post by jukeboxmarty on Jul 10, 2023 20:09:06 GMT
Many things can cause a hum. It's probably not the selection receiver. You seem to be gaining a history of things not working properly after you fix them! 
(Just a joke!)
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Post by prime on Jul 10, 2023 21:23:06 GMT
I took a couple of people out to hear the jukebox playing and changing records, they didnt notice the hum, I may be a little too critical. I think i will leave it be. And yes it seems lately i have been running into issues. This was the first box i ever owned and worked on, when i got it it didnt select and when it finally did the sound was unbearable. This box introduced me to Ron Rich and through repairing this i got to know him and his abilities. I have a soft spot for it, its why im trying hard to get the amp back to playing. pete
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Post by jukeboxmarty on Jul 11, 2023 4:08:09 GMT
Working on these machines can be a rewarding experience. I certainly remember the first two machines I purchased and repaired, a Wurlitzer 2150 and a Seeburg M100B. I get to work on loads of family heirlooms; Machines that have been passed down from one generation to another. To these owners, their machines are just like members of their families!
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