I am looking for a schematic or service information for this tuner. Sams does have a, schematic only, listed in folder 978-sed.
I replaced bad caps and it works good but i don't seem to be getting stereo separation. The stereo light does come on on any reasonably strong station. Also there is a knob marked separation _ + on front panel. When in stereo mode and turned fully ccw it kills volume.(has no effect in mono mode). Is this normal operation? Thanks for any help.
Paul
If you think this circuitry description might equally tie in with your unit, considering that your unit is not being TUBED in the MPX section, I will electronically prep its schema up for you. |
:Hello,
: I am looking for a schematic or service information for this tuner. Sams does have a, schematic only, listed in folder 978-sed.
: I replaced bad caps and it works good but i don't seem to be getting stereo separation. The stereo light does come on on any reasonably strong station. Also there is a knob marked separation _ + on front panel. When in stereo mode and turned fully ccw it kills volume.(has no effect in mono mode). Is this normal operation? Thanks for any help.
:Paul
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::Hello,
:: I am looking for a schematic or service information for this tuner. Sams does have a, schematic only, listed in folder 978-sed.
:: I replaced bad caps and it works good but i don't seem to be getting stereo separation. The stereo light does come on on any reasonably strong station. Also there is a knob marked separation _ + on front panel. When in stereo mode and turned fully ccw it kills volume.(has no effect in mono mode). Is this normal operation? Thanks for any help.
::Paul
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Sir Edd,
Thank you for the help.
The tubes in this tuner are 12at7, 12at7, 6cb6,6au6,6al5,12at7, 6au8, 6me8. I may have found the problem. The first five tubes in the tuner are not marked on the chassis and I am assuming they are correct. The last three tubes are marked on the chassis and i think they make up the mpx section (correct me if i'm wrong). Here's the problem I didn't notice on the bench and should have, the 6me8 is supposed to be a 6ar8.
Would this cause no stereo separation?
I did use a set of stereo "can" headphones and could not hear any separation. The tuner is hooked to a fisher x101c amp.
Gee, oh gosh, oh golly Batman . . . . is being more in line for color demodulator service in a '60's vintage color TV receiver. Proper Preliminary Preparation Prevents Piss Poor Performance. |
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::Sir Paul. . . .
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::I thought that I remembered someone needing info on a Knight FM tuner with its multiplex decoder.
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::Well . . . . . it seems that my info at hand is for a Samuels 1350 which would be newer than your 978 folders vintage.
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::Lets sample their commonality . . . . the front end of this unit is using a VERY-VERY-VERY RF quiet 6CW4 nuvistor toobie for its RF stage along with one ALSO in the mixer and local osc stage and even another . . . . . fourth . . . . one as Miller effect incorporated AFC for the mentioned local osc..
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::THEN . . . circuitry all goes to transistors for the 4 FM IF stages . . .with the use of 2N1180 first generation PNP "geranium " units for its 4 stages.
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::TWO solid state diodes handle the FM detection and THEN, AND THEN, your point of interest, the FM de-muxer, which is using six TR604 /or / 2N408 first gen PNP transistors also.
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::Also there is a knob marked separation _ + on front panel. When in stereo mode and turned fully ccw it kills volume.(has no effect in mono mode). Is this normal operation?
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::Very-very-VERY rarely do I see that stereo separation pot adjustment accessible, as it is usually only a tech accessible trimmer pot hidden down in the circuitry proper .
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::Also, it never did lock in my mind about its possibly killing of the FM proper or just one channel if it was set at one extreme end.
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::If you think this circuitry description might equally tie in with your unit, considering that your unit is not being TUBED in the MPX section, I will electronically prep its schema up for you.
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::Now, by all means, don't use aural comparison of the units acquired stereo effect with SPEAKERS, use a big ole set of "CAN" headphones for evaluation and check out MANY stations as well as the proper program materiel / songs at that very particular instant in time.
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::THEN try out your separation control, initially rather rapidly, then zero in and differentiate and evaluate for optimum separation of L&R.
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::Update me on the acquired results . . . .
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::73's de Edd
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::The first 90 percent of a task takes 90 percent of the time, the last 10 percent takes the other 90 percent.
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:::Hello,
::: I am looking for a schematic or service information for this tuner. Sams does have a, schematic only, listed in folder 978-sed.
::: I replaced bad caps and it works good but i don't seem to be getting stereo separation. The stereo light does come on on any reasonably strong station. Also there is a knob marked separation _ + on front panel. When in stereo mode and turned fully ccw it kills volume.(has no effect in mono mode). Is this normal operation? Thanks for any help.
:::Paul
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:Sir Edd,
: Thank you for the help.
:The tubes in this tuner are 12at7, 12at7, 6cb6,6au6,6al5,12at7, 6au8, 6me8. I may have found the problem. The first five tubes in the tuner are not marked on the chassis and I am assuming they are correct. The last three tubes are marked on the chassis and i think they make up the mpx section (correct me if i'm wrong). Here's the problem I didn't notice on the bench and should have, the 6me8 is supposed to be a 6ar8.
:Would this cause no stereo separation?
:I did use a set of stereo "can" headphones and could not hear any separation. The tuner is hooked to a fisher x101c amp.
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Thanks, Edd
6ar8 tube on order.
Paul