• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Counterpoint SA-5000 phono stage problem

Hi first time posting. I recently picked up a lightly used Counterpoint sa-5000 tube pre-amp. The line stage sounds great and kinda throws shade at my restored Threshold Sl-10
. BUT I can't seem to get anything from the phono inputs. I tried changing the phono and rectifier tubes but still nothing- just inky black nothing. All the leds on the board are green except red led 210 on the contorl board which isn't described in either the owners manual or service manual. Any ideas?
 
The main PSU is shared between all audio sections, so if you both channels of line out functioning then that is a good start. Do the yellow LEDs light up as you change the input selection form CD to Tuner to Video etc?
If yes, then LED209/210 are working fine.
Then check that you are selecting the MM/MC option correctly (whichever you are using) - this is an easy mistake to make, so reads the owners manual carefully for this.
After that, remember to have ALL valves inserted BEFORE turning the preamp on and don't EVER run the preamp with empty valve sockets - there are exceptions to this but you have indicated limited skills so please adhere to this simple rule.
Now turn it on, and using the silkscreen legends, hunt down the following LEDs in the phono section
LED1 'BALANCE'
LED2 'BALANCE'
LED3 'BALANCE'
LED4 'BALANCE'
A photo would likely help
 
Yes the leds light up when I change the input selection. on my unit they are red. The tubes all are seated and the LED 1-4 are green.
IMG_8876.JPG
 
Yep, I did assume that I was doing something wrong. So I tried a different pre-amp, different inputs into sa-5000, different phono settings, different tubes and trying all the switch options with these various setups trying to be as systematic as I could. Still no dice on the phone input! My regular local repair guy doesn't want to deal with Counterpoint gear so I'm reaching out.
 
Cool. Based on visible date codes (1975) this guy shouldn't be too weird or esoteric. Even Audio Research's didn't stray far from classical forms in the 1970s. Any chance you could find a schematic? It'll be tough for folks trying to advise troubleshooting without one. Perhaps strangely, a pix of the whole back panel, showing jacks and their labels, might be useful.

All good fortune,
Chris
 
Text copied from a French forum and coming from a guy who knows what he's doing.
I also knew that this preamp is adored in Japan, maybe more likely to find the service manual there.

This Sunday, the children went skating, I had planned the shots, in the alignment program of a Counterpoint SA5000 preamp.

Icon of the 90s, the SA5000 remains the flagship model of a brand that has now disappeared. A quarter of a century after its launch, it remains a sought-after preamp, particularly in Japan, where it has received reviews and prizes rarely awarded to an export product.

Technically, on-board solutions are no longer very fashionable today, because it is a hybrid preamp. In addition it is of rare complexity with 2em are floating chassis, are separate power supply and these buffers. It is a preamplifier that requires a bit of familiarization and above all reading the user manual.

Technically there are 12 power supplies, including a regulated tube and a single unregulated one, 3 stages with an MC with 58dB of gain, an MM with 26dB and passive RIAA and a line stage with 22dB to that we must not forget a buffer for tape them out.

In short, it's a gas plant, with the presence of about twenty LEDs which inform the poor technician of the states of the power supplies and the different stages involved in the amplification chain. We are miles away from a passive meadow.

Here is in case of change of tubes, it is my case, the machine must be aligned, count a small half-day and equipment not necessarily available at the audiophile.

The machine pushes hard, at bottom the 83dB of gain is easily reached with a noise lower than 80uV and a distortion of the orde of the %. I had to look several times because I often thought I was measuring the distortion of my Audio Precision generator because the stages have wide bandwidths and no distortions.
 
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The 1975 date codes on the WonderCaps fooled me. This actually is from the era of super complicated American preamp designs. Even more complicated than a contemporary Audio Research. The back panel shows no required external looping or other common Gotchas. VivaVee's advice about MM/MC switching in post #4 seems especially appropriate.

All good fortune,
Chris
 
VivaVee was the Counterpoint service tech for NZ (and probably Aus) back in the day, and knows what he is talking about. He helped me find a design/implementation error on the PSU board for an SA5.1 I used to own, that I had chased my tail on for a number of years. He made me do the thinking and troubleshooting to find it, which annoyed me a bit at first, but helped me greatly in understanding things about circuits. Moderator Anatech was the same for Canada, and has done a lot of work with this preamp, including updating and improving it.
 
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Next step WITH POWER OFF and the MUTE/OPERATE switch in the MUTE position: (no apologies for going slow and steady...;))
Plug the tonearm leads into the MM input sockets
Toggle the MM/MC selector switches that are inside the unit and then leave them in the MM position.
Turn it on and see if you get anything now
 
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