Bottlehead Kits > Eros Tape

Test frequency?

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PS2500:
If I want to quickly establish whether a connection problem between a tape deck and the Eros is more likely to be in the Eros or the tape deck, can I input a frequency from a signal generator to the Eros and read it from the output?

For my first connection attempt, all I was able to get is hum. So something is either wrong in the way I connected to the heads, or there's a problem in the Eros. As I did the voltage check of the Eros at the end of the build, and all seemed well at the time, and there is nothing that shows up from a visual reinspection of the solder joints (so far), I think my problem is more likely to be in my tape deck connection.   

Would a frequency check help to show if the problem is actually in the Eros, and if so, what should I feed in?

Paul Birkeland:
Grab an old phone with a headphone jack, use a 1/8" TRS to RCA adapter cable, then feed music into the Eros with the volume on the phone down one step up from the lowest setting, then have a listen. 

There will be too much bass and not enough treble, but otherwise everything will pass through.

PS2500:
Thanks Paul. As luck would have it, I have such a cable. I performed surgery on one of those to make my headblock to Eros cable, replacing the 1/8" TRS end with a six-pin male connector, for plugging into the female board connector of the cable that goes to the playback amp board.

I can use the spare cable and an iPad with a jack to feed out the music.

Doc B.:
What tape deck and how is the head output wired?

PS2500:
It's a Technics RS1500. Theres's one cable from the headblock switch to the playback amp. It's terminated with a four pin plug (female) at the head switch end and six pin plug (female) at the playback amp board end. The six-pin plug and the connection point on the board are labelled "V".

I thought I could just make an RCA cable with a male six-pin plug at the other end, and plug that into the female V connector on the cable coming from the head switch.  Then I could have a cable that can be unplugged easily: in particular, I wanted to test the setup first and be able to return to the original wiring if it didn't work out.

I have a photo of the plug I made, which I can post, but it'll be a day or two before I transfer it off my camera. I may have mis-soldered this plug, but as I understood it, I would need to connect a twisted length of the shield braid of the cable to the outer two pins on left and right (four pins total) to match the grounding shown in the schematic. Therefore I soldered the braid so that it crossed the outer pin to terminate on the next inward pin, and was soldered onto both. In other words, pins 5 and 6 are shorted together, and pins 1 and 2 are shorted together. 3 and 4 are the + pins for the left and right channel.

But it may be that I've read the pinout wrong, and shorted + to - ?

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