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Post by jukeboxmarty on Jul 3, 2023 16:04:21 GMT
Just keep in mind that the volume control is actually two pots in one. Both segments would need to be bad to cause both channels to be out.
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Post by prime on Jul 3, 2023 17:28:18 GMT
Thanks, ive spoken to a few people that live quite far from me, or i would meet up with them, I get the feeling using the oscilloscope cannot damage anything on the amp unless i cross connections. I notice most people use a signal generator and a dummy load for speaker. Can you think of any reason i couldn't just test the amp in the box playing.
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Post by jukeboxmarty on Jul 3, 2023 17:56:34 GMT
If you are using a scope, you can certainly test while the amp in the box with a record playing.
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Post by prime on Jul 3, 2023 22:59:06 GMT
Im not sure if the receiver can affect the sound but i see a ground wire hanging loose and i think it may go to the cap near the small red circle. ( I figured it out, that use to go to the positive side of the original cap, the tv repair guy that replaced it, grounded the positive lead on the replacement cap on the other side, making that wire redundant)  |
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Post by jukeboxmarty on Jul 4, 2023 16:59:16 GMT
Since you are getting some sort of static/white noise through the amplifier, I would still bet money on the signal input.
You could always try a different input source.
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Post by prime on Jul 4, 2023 18:05:53 GMT
Now that's something i should have done in the first place great idea. it rules out everything before the amp. Not sure what i have that has a rca out, but believe me i will be looking Thanks pete I jumped the gun, that model doesn't use rca, please correct me if i am wrong, Im going to use a turntable and alligator clips, finishing nails that fit perfectly in the three prong holes without damaging them, I will run one alligator clip to the nail in the single hole (ground) then the other end to the outer edge of the rca cable ,then another clip to the nail in the left or right hole , then to the center of the rca. I will get only left or right but that will confirm its either the amp or wiring to the amp. your thoughts
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Post by prime on Jul 4, 2023 19:16:37 GMT
OK i pulled out the 3 prong audio in plug, inserted the nail as mentioned , loaded a record on the box to light up the 5U4 tube,used my external record player, could hear the record playing faintly , moved the balance to see if it would increase, no luck. Before i checked the amp for bad solder or wiring i had a bit of a hum and static, after working on the amp i get very low volume still but clear sound. Cant find any loose or broken wires, tested the three diodes and bass and treble all tested good. I think im correct in saying the issue cant be at the 6973 or 7199 tubes or sockets because both sides when out at the same time. pete
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Post by jukeboxmarty on Jul 4, 2023 19:17:00 GMT
EDIT: crossed posts again!
Yes, or you can use the alligator clips directly on the component side. |
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Post by jukeboxmarty on Jul 4, 2023 19:18:21 GMT
Speaker connections?
EDIT: Are you sure both channels were working before?
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Post by prime on Jul 4, 2023 19:31:08 GMT
I definitely had both sides working before, i still have both sides now, i only tested one just now, i will test them both at the same time . I can move balance from left to right to get sound in each speaker, just low sound.
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Post by prime on Jul 4, 2023 20:35:22 GMT
I connected a radio directly to the speaker wires on the box, very clear ,very loud. No issues with the speakers, I connected the same radio to the ground and left channel connectors in the box, while lighting up the 5u4 tube the sound came through distorted and louder, im sure it is not designed for that i was just curious.
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Post by jukeboxmarty on Jul 4, 2023 20:43:26 GMT
We are starting to run dry.  |
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Post by prime on Jul 6, 2023 20:58:21 GMT
Hi Marty just want your thoughts on this, I picked up another amp, it has not been serviced yet but i made sure no components were touching and all wires sound. Texted the amp with a dim wat to confirm no shorts. Put it in the box and have full volume, unfortunately with the volume i get a loud hum, i figure just issues because its never been recapped, just making sure the hum cant come from the receiver side ,or do you agree it probably just failing components in the amp pete
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Post by jukeboxmarty on Jul 6, 2023 22:20:22 GMT
Agreed, you probably have a bad filter cap (or two... or three...) in the amp.
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Post by prime on Jul 9, 2023 17:24:05 GMT
Recapped the SHFA-3 and now the unit works perfectly, one strange side note ,i was having an issue with the box only playing A sides but selecting and rejecting B sides when the tone arm landed, now A and B are working perfect. I will still keep working on my SHFA-5 . thanks for all of you assistance with trying to figure out the issue, pete
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