Peavey Vypyr

[Techknowman]

I have a little Peavey Vyper that is having boot up problems.
The unit came in and one of the diodes for the bridge rectifiers was shorted and the 7805 was bad. replaced that.
Now 5V and 3.3V regulator are putting out good but FX processor will sometimes not start.
The clock won't run. I can warm up the crystal and it will kick off and run.
I replaced the crystal with same frequency. same issue.
replaced the small capacitors that imbalance the crystal and should kick start it. no luck.
I think the FX chip may be damaged. Replace the whole FX board?
1231.pdf

[Brian Swatton]

I had a very similar issue with a Fender G-Dec, intermittent starting after replacing a rectifier diode. I would really recommend replacing the rest of the rectifier diodes before thinking of changing an expensive PCB. After much head scratching, I found that the others were intermittently breaking down on switch on, though they measured fine at meter test voltages. Once I'd replaced them all the problem went away completely.

Good luck.

[km6xz]

Replacing the xtal with the same frequency only is a valid replacement if the cut of the crystal is of the same angle and plane, the cuts have different modes of operation. For example some are cut as overtone crystals which are intended to operator on a multiple of the cut dimension frequency. Was it exactly the same part number? Put all the original parts back in since you know your mod did not solve a problem but probably introduced another.
If the 5volt supply is clean and it does fire up with heat, check the caps you put in, the value might be the same but if type is different the change in reactance can prevent oscillation at the original value of capacitance. Mica or ceramic caps are usually used in oscillator circuits because of their low inductance and stability at high frequencies. Ceramic caps have poor aging characteristics so when they are used in an oscillator circuit and oscillation become balky, they are suspect. Crystals can because hard to start, sometimes by surface contamination, or cracks or impurities in the substrate. A measurement of the frequency will usually spot these problems.
Start by figuring out the current state of the circuit and factors that would result in the observed symptoms instead of randomly throwing parts at a problem. If you introduce more ambiguity in the circuit with not-known-to-be-good parts or incompatible parts the harder trouble shooting will be, particularly from a distance.

[Enzo]

You had power supply problems. The crystal is way down the list of things that might have been damaged, and the LSI chips way more likely.

Is it still under warranty? Most of them are.


And don't be afraid to pick up the phone and call the factory. Ask for Gene Ford, he's a very helpful support tech.

[Techknowman]

You had power supply problems. The crystal is way down the list of things that might have been damaged, and the LSI chips way more likely.
Is it still under warranty? Most of them are.
And don't be afraid to pick up the phone and call the factory. Ask for Gene Ford, he's a very helpful support tech.

Thanks.
The only reason I was suspicious of the crystal was because I could squirt it, and only it, with freeze spray and it would stop oscillating once it was running.
Then I could take my soldering iron and warm it up and it would kick off and run.
Letting it stabilize at room temp 60-70F it was intermittent starting.if I warmed it up slightly it would start 100% of the time.
It may have been under warranty before I got hold of it. probably not now. Not a authorized service center.

[Enzo]

Oddly enough, I have a Vypyr here also that won't start reliably under about 60 degrees F. Warmer is fine. CHill the thing and no start. I plan a boad swap, rather than an easter egg hunt on mine.


SO you could do that and then the unit would operate? Then I'd be thinking the Xtal worked, but the system around it was not. You froze the thing to stop whatever was going on, then reheating it allowed a system reset, and then it worked. I might be looking at the power-on reset circuit of the main processor. Then again, the crystal drive may be marginal.

And I might also be pricing replacement boards - if a board costs $30 - and I made that price up - why spend two hours labor on it?

[bkahuna]

The Vypyr's are pretty famous for not working in the cold. I've had numerous Vypyrs in for repair here with the same problem. The fix is to replace 3 of the electrolytic caps on the DSP pcb. I don't have the info in front of me right now, but I'll look it up and add it later...

[HDSarge]

Cold start issue

Enzo, There are three smt caps (C73,83,and 85) on the digital board that have an ECR problem, that causes unreliable cold starting on the Vypyr. Peavey is aware of this and
the parts they provide as replacements have proven to correct the problem.

Also, check R2 on the little switch pcb if it is 2.2K change to 1.1K. This will cure switching problems (like not switching) when using the Peavey pedal.

The KIA brand voltage regulators have also proven to be poor. If there replace them.

[bkahuna]

edit: looks like Sarge beat me to the punch!

OK. Looks like it's C73, C83, and C85 on the DSP board.
I'll attach a pdf of some notes I made awhile back while conversing with one of the PV techs about these amps. He seemed to know of ALL the problems with these amps. Keep in mind, I've spoken with someone else more recently who seemed shocked and surprised that there were ANY problems with these amps! Go figure...

[Enzo]

Cool, I was going to call them, but you beat me to it.

[Techknowman]

The 5V regulator went bad in the one I have.
I replaced it with a TS7805. (Taiwan Semicondutor) it works but regulates at about 4.96 and get fairly warm. When the Vyper is "working"
Thanks All!
I'll look at getting the parts and going from there.

[Brian Swatton]

Do I take it from the "working" that you still have the original problem?

[Techknowman]

Do I take it from the "working" that you still have the original problem?

I haven't changed the caps yet. When the system boots up and runs, it pulls power making the regulator hot.
when it doesn't boot up, the regulator stays cool. I was, and still am, concerned about the running current and how hot the the TS7805 gets

[Techknowman]

Cool, I was going to call them, but you beat me to it.

Did you find anything out about your Vypyr? I shelved mine to work on other things. ready to get back to it.

[Enzo]

NAh, customer has it. Works fine as long as he doesn;t leave it out in his garage to get cold. I put the small caps on my parts order, I don't stock those yet, and once they come in, I'll change it out when it is convenient for the guy to return with the amp.