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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment.

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Old 22nd May 2019, 7:12 pm   #1
kirstyd
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Default HMV 2338 stereogram rustling on right channel

I cant resist a bit of teak especially when its from the late 60s or 70s .The unit was left in a bungalow that i have just moved into .I just had to plug it in just to see what would happen i was rewarded with a big fat nothing time to investigate a bit further .As i moved the wires going from the main unit to the transformer [bolted to the bottom of the cabinet]it burst into life on closer inspection i found one of the thin wires coming out of the transformer had come adrift soldering it back on cured this problem .The controls were very noisy [a good squirt of Servisol cured that ] but the amplifier is working [no radio]after some more testing i found two of the AF 115 transistors were not working .I removed them and zapped them using the charged up cap method .After putting them back in the tuner works on all bands the only fault now is a kind of rustling /hiss sound from the right hand channel .Not sure what could be causing this any suggestions would be much appreciated.Forgot to mention earlier that the tuner knob was completely seized and would not move .I got it tuning by warming it with the soldering iron . I spotted another oddity when cleaning the volume control [its also the on off switch ] The main switch is a double pole .At some point in its life the live side of the switch must have broken so whoever repaired the thing simply joined the two live wires together leaving the switched neutral as the only switch [hope all of this makes sense?.The last photo has nothing to do with the thread i just thought that those of you that are old enough may find it amusing .It was under the old carpet in the lounge
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Old 22nd May 2019, 7:58 pm   #2
ronbryan
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Default Re: HMV 2338 stereogram rustling on right channel

The TV ads of the time had the jingle “This is luxury you can afford - from Cyril Lord”

Ron
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Old 22nd May 2019, 8:46 pm   #3
kirstyd
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Default Re: HMV 2338 stereogram rustling on right channel

Yes I remember it well. Carpets made with Enkalon whatever that was.
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Old 22nd May 2019, 9:57 pm   #4
ekjdm14
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Default Re: HMV 2338 stereogram rustling on right channel

The rustling/hiss is quite likely the fault of a Germanium transistor, I notice the output pairs are AC176/AC128 and have experienced this symptom with the 176 before.

Other suspects would be carbon resistors or perhaps dirt still resident in one of the pots. Is the hiss/rustle more or less constant or does it vary depending on volume level or input setting?
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Old 22nd May 2019, 10:33 pm   #5
Ted Kendall
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Default Re: HMV 2338 stereogram rustling on right channel

Have you checked/cleaned the pickup balance preset on the PCB? I had one here where this led me a merry dance...
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Old 23rd May 2019, 7:14 pm   #6
kirstyd
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Default Re: HMV 2338 stereogram rustling on right channel

Quote:
Originally Posted by ekjdm14 View Post
The rustling/hiss is quite likely the fault of a Germanium transistor, I notice the output pairs are AC176/AC128 and have experienced this symptom with the 176 before.

Other suspects would be carbon resistors or perhaps dirt still resident in one of the pots. Is the hiss/rustle more or less constant or does it vary depending on volume level or input setting?
The hiss/rustle is constant all the time. It gets ever so slightly louder when the vol is up full and the tone and bass controls also alter the sound of the hiss. After a good clean and working back and forth all the pots are now working smoothly with no noise at all.
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Old 23rd May 2019, 7:15 pm   #7
kirstyd
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Default Re: HMV 2338 stereogram rustling on right channel

Quote:
Originally Posted by Ted Kendall View Post
Have you checked/cleand the pickup balance preset on the PCB? I had one here where this led me a merry dance...
I have not touched the balance control. Will have a look at it tomorrow.
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