Seeburg tsa1/tsa3 amplifier

Hallo

I have a Problem with a seeburg tsa3 amplifier. I was recapping it and worked for 1 Hour Good . The Sound was okay .

After i turned the Jukebox Off and later on i have no Sound.
I was checking the voltages. I have nearly the voltages as in the Manual.
-47 Volt i have 45 ,-30 Volt i have 33 Volt but on q101 other side q109 and q102 other side q110 the voltages are nearly 0 .
The voltages on q103 other side q111 are correct .
Prehaps sombody can help me .

Greetings Eric

Eric, it would help if you quote voltages by naming the terminals on the transistors.

For instance; Q101's collector should have approx 4.8 volts DC on it (undriven) There should be 0.2 on the base and 0.3 on the emitter. --All these require that the pickup be connected for accurate readings. if the pickup is not connected the first stage has no voltage divider (DC is present in the pickup in this goofy design). Without a pickup the first stage is 'swamped" and biased to cutoff.

With pickup connected and normal voltages in the first two stages, and still no sound, look for a problem in the mute relay circuit. Start a record playing and thump the side of the amp (don't bludgeon it -just a few hard taps). If sound comes back it probably means residual magnetism in the mute relay.

If still no sound, try removing the green mute/trip plug from the map. If sound returns it indicates the mute contacts in the mech are not opening during play.


Rob/NYC

Hallo


Thanks for Feedback.

I checked now the voltages with the amp. in the Jukebox . The Green Plug Not installed,the tonarm plugs installed. There are no voltages on q101 and q102 ( Same on the other side ) .
The Muterelay is okay
Thanks Eric

Rob,
Starting with the TSA 1, and all TSA's, and SHP's, except the 2A, there were no "mute contacts" on the mechanism-
If the mute relay is energized, or residual, the phono will trip off the selection prior to playing. Ron Rich

Ok, I miss-identified the contacts ...but let's not further confuse things here. There are contacts on the mech that pull-in and hold the relay in the mech that trips the mech at record end, mutes the sound and squelches the AGC.

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To the original poster; this is an odd situation. Obviously if the two first stages on each channel are not powered there would be no output. That would immediately signal a look at the minus 30 power supply. However you stated that voltages around Q103 and Q111 which also are on that same -30v source are normal.

The only ( I can thinks of) that would kill voltage to the first two stages would be a failure of R108 and R142 but having them both fail simultaneously seems very unlikely.

I am really stumped here.

Rob

Hallo

Thanks for answer!

I have -34 Volts ; on q103 the Voltages are correct .
Q101 and q102 are totally dead . I was changing the whole Equalizer Board , taken from a tsa1, the Same mistake .

So now i m a little perplexed.

Eric