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Jul 11

Some notes on Sanpera 1 repair

Green Bass Strings

Green Bass Strings

jdmorriso, on the Peavy Vypyr forum posted the following information.  I’m making a copy of his post here so that I can find this information:

Hi, I’ve just solved a problem with similar symptoms where my Sampera 1 would not light up consistently. I’d turn on the amp and most of the time the Sampera would not show any activity. Disconnecting the MIDI cable and reconnecting several times would occasionally light up the Aux LED and nothing else. Sometimes it would light up the Main LED and work correctly but this was very rarely. My Vypyr 30 worked fine by itself but I really wanted to get the Sampera working with it. I also wanted reliability, having to turn the amp on/off several times to get the Sampera up was not an option for me.

Sorry for the long post, but I’ve tried to consolidate all my findings from other posts and the steps I went thru to solve the problem.

1. Confirm cabling ok

1.a Check MIDI cable. Needs to be 8 core (not your standard MIDI cable). Tested connectivity end to end with a multi-meter. Cable ok.

1.b Check MIDI cable direction. Some forum posts mentioned that changing the direction of the cable made a difference. I’m not sure about this but I tried swapping which end went into the Vypyr. No difference.

1.c Check MIDI cable inserted fully. I found that the Vypyr MIDI socket had a somewhat loose feeling. I opened up the Vypyr and looked closely at the MIDI connector board and socket. Looks like someone had forced the connector into the socket the wrong way as the socket had split in half and the board was pushed back from the chassis. The Vypyr MIDI socket wasnt the greatest, only mounted by two small screws and held together with thin plastic pins. I could push it back together but I wanted a more secure connection so decided to replace the socket. Using a soldering iron and solder wick, I removed the existing MIDI socket pins and black plastic socket case from the Vypyr MIDI board. I bought a new 8 PIN DIN socket, mounted it to the chassis and wired it up to the MIDI board. This fixed the suspect socket on the Vypyr and I knew I had wired it up correctly as on occasion the Sampera would work correctly but it hadn’t fixed the intermittent failure to startup correctly.

2. Confirm Vypyr ok

2.a Check Vypyr Firmware. Turn the Vypyr off. Press and hold preset button 1 and 4 during power up. The unit will display LED around the first three encoders. The position of the LED relates to a number, with the “top left” led being zero. The numbers proceed clockwise around the encoder. For example, on the stompbox encoder “TubeScrm” is 0 and “Bypass” is 1 and so forth. Likewise on the amp encoder “DZL” is 0 and “TWN” is 1 and so forth around the encoder. On the effects encoder, “Tremolo” is 0 and “Bypass” is 1. I had version 1.5.8 and wasnt game to upgrade as there was no indication as to what 1.5.9 fixes.

2.b Check Vypyr Reset. Turn the Vypyr off. Press and hold preset button 1 and 2 during power up. All presets are reset back to factory defaults. This didn’t solve my problem.

2.c Check MIDI board ribbon cables. Some posts mentioned that the glued ribbon cables can come loose. Mine were glued so I “unglued them” pulled them out, cleaned them and re-seated them back in. No problem there.

2.d Check MIDI board resistor R2. One person said that some MIDI boards had an incorrect R2 resistor which was rated 2.2k rather than 1.1k. This is used for the MIDI IN circuit on the board. To fix this they put another 2.2k resistor in parallel with the existing one (which makes 1.1k). Unfortunately, my MIDI board had the right R2 resistor.

2.e Check power from Vypyr. As the LED wasn’t coming on with the Sampera, I suspected a power issue. I checked pin 6 of the MIDI cable as it should be supplying an unregulated DC voltage for the Sampera. Using a multimeter between pins 6 and 8 I read 7.0 volts. This was ok. Everything else on the Vypyr was working fine so I thought I’d focus attention to the Sampera.

3. Confirm Sampera ok

3.a Check 5V on Sampera. The sampera has a LM2594 chip labeled U100 which regulates the 5V power for the board. Using a multi-meter I checked the voltage between pins 8 and (6 or 5) of U100. It read +5V. So power to the Sampera wasn’t a problem.

3.b Check Sampera startup. The sampera is based on a CY8C27443 chip, labeled U200 which is a Programmable System-on-Chip. Unfortunately the Sampera doesn’t have an on/off switch or a reset button, but relies on some circuitry to hold this chips reset pin high on power-up. I suspected this circuitry to be my problem. Luckily Peavy exposed the reset pin of U200 on an external header P301 pin 4. Connecting this pin to +5V will reset the U200 chip back to a known state. Another header P306 pin 1 has +5V DC. So I connected two wires to the Sampera main board, one to P301 pin 4 (middle pin), one to P306 pin 1 (bottom right pin). When I connected these two wires together it would reset the Sampera and up it would come 100% of the time. I drilled a hole in the main sampera chassis, mounted a push-button switch and connected these two wires up to it. The Sampera now had a reset switch. Yeh!

3.c Check Sampera Calibration. Now I had the Sampera working reliably I was celebrating until suddenly the amp stopping puting out any output whenever the Sampera powered up. The amp worked fine until I connected the Sampera, pressed the reset button, and its LED’s lit up. This was a finger problem, or should I say foot problem. I didn’t realize that the Sampera main pedal was in the off position and resetting volume down to 0. To calibrate the pedal, press and hold preset 4 on the sampera. Press preset 1 while holding 4. Aux will blink. Move pedal to bottom position then press preset 1. Main will blink. Move pedal to top position then press preset 1. Now sampera pedal is calibrated. Now I always check that the pedal is off the low position whenever the Main LED is on. Duh!

So problem solved. Whenever I turn my amp on and the Sampera doesn’t light up – I simply press the new reset button on the Sampera and up it comes. Since I’ve made this small change to the Sampera 1, it has worked 100% reliably. In summary the two key changes I made to get my Vypyr and Sampera going were 1.c and 3.b.

Hope this helps other people get the most out of the great amp and pedal.

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