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91
Amplifier Discussion / Re: Peavy Rage 158 no sound after 1-5 mins
« Last post by substatica on June 15, 2019, 02:24:33 PM »
It seems the power transistor is grounding through the heat sink to the chassis and that causes the signal to cut out. So by taking the board off everything worked, putting it back the transistor grounds and the signal cuts out.

I guess previously there was enough heat sink compound to prevent the short, and when it got hot enough it conducted, when I replaced the board the first time I must have put it on more secure and therefore made the short permanent (until I took the board off again).

It seems, by the layout that it's suppose to ground here anyway. Could they really have been depending on the heat sink compound to prevent this?

Unless the TDA2040 has an internal short.
92
Amplifier Discussion / Re: Peavy Rage 158 no sound after 1-5 mins
« Last post by substatica on June 15, 2019, 01:32:35 PM »
Took the board off, pulled the solder off R49 again, cleans the area (some brown residue), soldered it back again, took off C31 and it read fine. Re-flowed some questionable looking pads and it's working again. Have to try it for an extended period once my  8-month-old is up from his nap ;)
93
Amplifier Discussion / Re: Fender Acoustasonic Jr. Squeal
« Last post by g1 on June 15, 2019, 01:20:58 PM »
Try again how you did it with the electric guitar plugged in, but set all the guitar controls (and reverb) to zero.  Still squeal?
94
Amplifier Discussion / Re: Peavy Rage 158 no sound after 1-5 mins
« Last post by substatica on June 15, 2019, 11:25:51 AM »
I can't get any signal out of it now, seems like I left it on long enough for something to fry for good. All of the voltages checked against the schematic seem within reason 3.2 VDC where it says 3, 26.8 VDC where it says 25, 30.7 VDC where it says 27. Nothing too out of whack.

One odd thing is when I touch D7 it reads 13.8 VDC, but I get a big pop and radio starts coming through.
95
Amplifier Discussion / Re: Fender Acoustasonic Jr. Squeal
« Last post by phatt on June 15, 2019, 09:07:04 AM »
OK Obviously a Electrical problem and not acoustic FBack.

Ok the reverb was faulty and you fixed it but if you are not familiar with reverb circuits there are a few thing that can catch you out.
1/ check the tank leads for correct in/out. The owner may have tried to fix it and messed up the plug connections. So don't assume it was correct when you got it.
(some rev circuit will squeal if plugs are reversed)
2/ check your work and make sure you did not inadvertently ground the wiring on the drive end of the tank.

Note that the driver circuit (U9A) output is not grounded,, while (U9B) the Pickup circuit IS Grounded.  If the leads have been reversed it will likely squeal like a pig.

The Ground lifted output of U9A has to be reflected in the tank connections as well.
If you follow the ground connections in the tank you will (should) find that the tank Case is only grounded on the Pickup end.

If unsure how to establish correct in/out then rule of thumb is the drive transducer will be the lower resistance. Ball park readings would be ~30-Ohms for drive Tx and ~200-Ohms for PU Tx.
Only the Pu Tx is grounded to reverb tank if both Tx's are grounded to case then you may have  wired it incorrectly when you fixed it.
Phil.
96
Amplifier Discussion / Re: Peavy Rage 158 no sound after 1-5 mins
« Last post by substatica on June 15, 2019, 09:03:54 AM »
Q: What exactly does the amp call itself on the serial number plate?  Rage 158 TT?  Are there any other numbers there like '92.
A: TRANSTUBE RAGE

Q: Does this drawing set match your board better?
A: Yes, I think that's it. Thanks.

97
Amplifier Discussion / Re: Peavy Rage 158 no sound after 1-5 mins
« Last post by Enzo on June 15, 2019, 04:25:47 AM »
The PV Rage and Blazer are the same amp.  The Blazer just includes a reverb, the Rage does not.  The "missing" parts on your board are the reverb circuits not installed.

What exactly does the amp call itself on the serial number plate?  Rage 158 TT?  Are there any other numbers there like '92.


Does this drawing set match your board better?

98
Amplifier Discussion / Re: Fender Acoustasonic Jr. Squeal
« Last post by magicD16 on June 14, 2019, 11:21:57 PM »
Thank you for your reply, Phil!

I was testing this amp with an electric guitar. It belongs to a friend and I am working on it for him. It came to me for non functioning reverb, which ended up a bad connection on the connector inside of the reverb tank that connects to the output coil.

I thought that it was a feedback problem created by my guitar, but it still squeals without anything plugged in to the input jack. That is, if you depress the "master phase" switch and turn the master reverb past 4. I might drive myself crazy with this issue.  :loco

I've attached the service manual/schematic. Any suggestions would be greatly appreciated!
99
Amplifier Discussion / Re: Peavy Rage 158 no sound after 1-5 mins
« Last post by substatica on June 14, 2019, 08:25:49 PM »
Here's the amp. The initial problem I fixed was the top, left-most solder joint on R49 had cracked out. Probably due to the board mounted jacks and minimal board support.
100
Amplifier Discussion / Re: Peavy Rage 158 no sound after 1-5 mins
« Last post by substatica on June 14, 2019, 07:20:54 PM »
Q: Next time it kills the sound, leave it running, ball up your fist, and whack the top of the amp.  Does the amp come back on, even for a moment?
A: No.

Q: Does the amp react to your whack in ANY way, like a noise?
A: No.

Q: When it dies, listen CLOSELY to the speaker, is there any background hum or hiss? 
A: Yes.

Q: Turn up the controls to hear that better potentially.   If there is any such background, to the volume and tone controls affect it at all?
A: Low hum, not affected by volume or tone, buzzes louder if I short the signal cable with my thumb.

Q: Get the schematic from customer service at Peavey, and then see if your power supplies are remaining up or if they are going out.
A: 120VA into the transformer, 25VA out  in the no-signal state.

Q: With it running and signal applied, poke each part on the board with a wooden chopstick or similar.
A: No effect.

I tested the diodes, they all read good except for the two 1N4003's by the power transistor, they short both ways -- maybe that's expected? It also seems if I leave it on in the no-signal state for 5 minutes or so the power cycle no longer fixes the issue, I'll have to wait and see if it works again after being off for a while. That brings me back to heat, but nothing on the board seems overly hot (hit it with infrared thermometer).

Also, still trying to determine if that's the correct schematic. It's a Peavy Rage 158 w/ Transtube, but the component markings aren't all matching up. The initial sold solder I fixed was on an R49 which I can't seem to locate.

The amp is the same as the one pictured on this thread,

https://www.diystompboxes.com/smfforum/index.php?topic=97068.0
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