PV-7 Muting too long!

[Noelstan]

Hello and thanks to you all. I recently acquired my first CJ product- a PV-7. The owner’s manual states a 45 (approx) delay before the relay is switched on. I timed my unit and it takes about 90 seconds to come on. The sound is excellent though. Is this because the cap in the relay circuit needs to be replaced or is it possibly the uni-junction transistor out of spec? I plan on replacing the Electroharmonic tubes it came with as I’s sure they are old. Possibly will this help? I believe a 47uf electrolytic is involved in the muting circuit. Thanks in advance for the help.

[goonybird]

My pv10 is similar, seems to take an age to un-mute. I am about to swap out the electrolytics. Be interesting to see if it afffects mute timing.

[admin]

If there is no sound degradation then I don't think it's a problem. Components can fail over time and the PV-7 is no "spring chicken". You can test the components although it may be easier and not really that expensive to just replace them.

[AnotherJohnson]

This is one of the issues about which I have posted elsewhere.

I went through it with my PV5, which I dearly loved.

The relay ages out and the time to kick the output on changes.

Replacement parts of the same age were available, but they were the same age as the parts that were no longer performing as earlier in their lives.

It was explained to me by the technician at CJ who had done the other repairs (recap and other necessary items) that he could install an NOS relay, but it would also probably not match the original time delay. This was many years ago now. I used my PV5 for 25 years as my primary preamp, and I continued to use it for another 5 years in my secondary or tertiary systems.

My take on it is that it’s fine to just wait for the relay to kick over. 45 seconds, 70 seconds, 90 seconds, whatever. You want the whole system to warm up for 15 minutes. Turn it all on and walk away. You won’t even know how long it took to kick over the output on the preamp.

If the unit sounds good, leave it alone. It will sound better after the warm up anyway, so forgetting about it until it fails completely isn’t even a compromise.

[Noelstan]

Thank to all who replied. I will not attempt any repair myself. I will try to remember to turn it on 15 minutes before serious listening. If this issue gets stuck in my “craw” I will send it in to CJ in Virginia!

[roberto]

Hola Chicos...

The circuit that drives the relays on each channel takes sometimes about 3 minutes. It is a simple capacitor-resistor timer clock. Change the capacitor for less value, and the time will change. Less capacitance, less time. C10 on the PV-10 is the capacitor. At the diagram value is 47uF @ 35V.

My advise is, wait that time. You don't want to have an odd heavy transient while the small tubes are warming up. When you have the click, no odd transient noise is present.

Happy listening!

[AnotherJohnson]

I won’t argue that you can’t fiddle with this to change what it does.

In my case CJ recommended that I not waste the money due to the uncertain performance of a NOS relay.

FWIW, it was good advice. I bought the ET3SE and a TEA2MAX, and was blown away.

[goonybird]

Just to add replaced the 3x Electrolytics in my PV10a Including the timer one, c10. and made no difference to a lengthy turn on.

[roberto]

That tells me that the timer is OK, and that is its design. About 3 minutes, right? Or is it taking longer?

[Joe Appierto]

According to CJ's manual for the PV-7 the muting should be for about 45 seconds:

"Turn on: Because of the delayed warm up characteristics of vacuum tube equipment,
a time delay muting circuit is incorporated in this preamplifier. Output 1 and Output
2 are grounded via a relay for approximately 45 seconds after the unit is turned on in
order to suppress warm up transient noises. The relay grounds the outputs again
immediately at turn off or in the event of any power line interruption."

[goonybird]

Ok just timed my pV10a at 50 seconds, so to spec, Still seems like an age.....

[roberto]

Waiting that time, less than a minute, and hear a possible transient that could cause a speaker damage if you are using a very efficient speaker or just an odd noise, is a benefit to have that mute circuit. My ET-7 takes 1:22 sec to go on.


Happy listening.

[roberto]

Just to add replaced the 3x Electrolytics in my PV10a Including the timer one, c10. and made no difference to a lengthy turn on.

Did you change the capacitance? Use less capacitance value. Use the half and check. Same working voltage os course.

Happy listening!

[goonybird]

same values as schematic/parts list

[roberto]

Less capacitance will shorten the time. That’s what you want to do, right? Use same voltage value.

[AnotherJohnson]

Or just forget about it until the relay totally fails.
Turn it on. Walk away for 15 minutes of warm up.

You won’t even know how long it took to clear the relay.

I have to wait through both preamp and phono preamp relays. I have no idea how long they take to click. I’ve never put a stop watch on them.

Works for me.

[admin]

In all honesty, if the delay is a few minutes I would just leave it. There is no harm with that time period and I personally like to give a 15 minute warm up period on all my tube gear. If you do decide to repair it, make sure you don't error on going too short with the delay. There is no harm in going to long but going to short may present issues.

[Musictek]

Just to add replaced the 3x Electrolytics in my PV10a Including the timer one, c10. and made no difference to a lengthy turn on.

Did you change the capacitance? Use less capacitance value. Use the half and check. Same working voltage os course.

Happy listening!

Reduce the value of the 47uF cap in the mute timer. That is the primary thing that controls mute timing. Experiment. You can't hurt anything as long as you use caps rated the same voltage as original or higher

[roberto]

That is super correct!...great advise. That's what I meant. Again, there is a reason why you should wait the CJ mute time. This is necessary for the tubes to warm up and sometimes the tubes while turning on, produce odd noises and heavy transients.