Deepstar 1

[Octopulse]

Hello gurus
I have in my possession a very lightly used original Deepstar. The problem I have is the detector will power on okay with a strong audio but after several seconds the detector threshold dies away to nothing and nothing can be heard….I have to power cycle to get the detector working again but then the problem starts again. I have ruled out a battery problem. All connections look clean and solid. Is the Threshold potentiometer a likely suspect or further downstream to maybe a bad capacitor ? Thanks for any ideas.

[Octopulse]

These two diodes are “dead”…..no voltage at all.

[Altra]

Those diodes are connected to one of the MC14538's and control all of the sampling times. The diodes may be good, but test bad in circuit. Unsolder one side and lift the leg off the pcb then retest. Can you take photos of the whole circuit board? On the Aqua pulse there is a PTC fuse it looks like a capacitor and is mustered color. If your deep star has one of these ptc's it could be the problem? A defective ptc will cut the power as it heats up.

[GeoMax]

Hello Altra,

The Deepstar 1 does not have a PTC fuse; instead, it uses a conventional fuse. The problem might lie within the auto-tune circuit, where the target signal is suppressed after a few seconds. Please refer to the CS6PI schematic for details; it shows how the auto-tune circuit operates.

[Carl-NC]

I wonder if there is an auto-retune circuit in there that's gone open-loop.

[Altra]

Hello Altra,

The Deepstar 1 does not have a PTC fuse; instead, it uses a conventional fuse. The problem might lie within the auto-tune circuit, where the target signal is suppressed after a few seconds. Please refer to the CS6PI schematic for details; it shows how the auto-tune circuit operates.

Thanks GeoMax,
I have not seen a Deepstar or a schematic up close. I hope Octopulse post some more photos.

[Octopulse]

I will post some photos and upload later. The Auto-tune as a problem might be possible as the threshold starts strong and then fades away after a couple of seconds. The fuse looks conventional to me. Every other diode on the board gives me a voltage but with my limited knowledge then I wouldn’t know if that is helpful. I just started simple and inspected all components in detail. All the pots test as per their values and the wipers change value when rotated. Pictures soon and thanks for the advice.

[Octopulse]

Having problems uploading images....."Security Token" was missing ??

[Octopulse]

These two diodes are “dead”…..no voltage at all.

Okay, managed to get a brief voltage reading on those two diodes (before detector cuts out altogether).....they are good after all.
I will look at the CS6PI for further detective work......

Is there an easy way to test the caps without removing the whole board....they are flush with the board and no legs to get at....grrrrr.

Detector just dies completely....new 14.4V battery is being used and +- connection to the board is fine. The little battery gauge on the front is all over the place but I can't see how that is part of the battery as it's on its own little circuit.

All resistors are clean and bright and test in situ but I have no idea of their original values (well I can decode the colours if I have to) without the schematic ?

Still can't upload photo's......"Security Token" error ??

[GeoMax]

Hello

Could you perhaps post some pictures of all the ports and controls? I'd like to see if you have an early, original Deepstar 1 or a later version of the Deepstar 1 that was personally upgraded by Eric Foster. Thanks.

[Octopulse]

Hello

Could you perhaps post some pictures of all the ports and controls? I'd like to see if you have an early, original Deepstar 1 or a later version of the Deepstar 1 that was personally upgraded by Eric Foster. Thanks.

I have sent some photo's to you....feel free to upload on my behalf. This Deepstar belongs to a friend of mine but it must be an original from 1999 (from the serial number).

[Altra]

Octopulse can you clarify if you are losing power to the circuit or just losing the audio? After it goes silent see if there is 10v between pin 4 and 8 on the TLO62/72 op-amp. If you have 10v its probably the SAT circuit as Carl suggested above. First place to check is the 500k SAT pot. If this has become open it could cause drift in the audio threshold to silent. An easy test to see if the pot is bad, short the two wires together connected to the pot. This will bypass the pot and restore the threshold audio. If you are losing power that would be a whole set of other possibilities.

[Octopulse]

By SAT pot, do you mean the Threshold pot?
No SAT on the original Deepstar 1

[Octopulse]

I will do those tests tomorrow
Thank you

[Octopulse]