Search found 20 matches
- Mon Mar 08, 2021 1:10 pm
- Forum: Guitar Amplifiers
- Topic: Peavey VTX Classic troubleshooting help
- Replies: 31
- Views: 10569
Re: Peavey VTX Classic troubleshooting help
So I checked continuity between points from Q6/7 working my way back to Q4/5. It was either a bad solder joint and or broken trace between the emitter of Q6/7 and R126/130. I ran some jumpers and hooked everything back up then checked all voltages on the tube pins, Vi and Vk, and the power board. Al...
- Sun Mar 07, 2021 2:08 pm
- Forum: Guitar Amplifiers
- Topic: Peavey VTX Classic troubleshooting help
- Replies: 31
- Views: 10569
Re: Peavey VTX Classic troubleshooting help
So I went ahead and pulled Q4/5 out and checked them and they tested fine. Then I pulled r123/124/128/129 and the all tested fine. So, at this point I'm at a loss for where to go next. Anybody have any ideas?
- Sat Mar 06, 2021 7:27 pm
- Forum: Guitar Amplifiers
- Topic: Peavey VTX Classic troubleshooting help
- Replies: 31
- Views: 10569
Re: Peavey VTX Classic troubleshooting help
I found some info on using diode function of DMM to test parts out of circuit.
- Fri Mar 05, 2021 6:01 pm
- Forum: Guitar Amplifiers
- Topic: Peavey VTX Classic troubleshooting help
- Replies: 31
- Views: 10569
Re: Peavey VTX Classic troubleshooting help
I've took a different DMM and rechecked the transformer readings and wah la they're where they should be. So I changed out Q4 and Q5 and turned it on. I could hear that there was noise coming from the speakers so I grabbed a guitar and low and behold I've got sound, albeit a little fizzy sounding. S...
- Tue Feb 16, 2021 7:28 pm
- Forum: Guitar Amplifiers
- Topic: Peavey VTX Classic troubleshooting help
- Replies: 31
- Views: 10569
Re: Peavey VTX Classic troubleshooting help
So planning for a PT replacement I start searching for Peavey P/N# 705-18718 and 705-18348 and turned up zilch. What would you recommend if an OEM PT is not available Enzo?
- Tue Feb 16, 2021 12:02 pm
- Forum: Guitar Amplifiers
- Topic: Peavey VTX Classic troubleshooting help
- Replies: 31
- Views: 10569
Re: Peavey VTX Classic troubleshooting help
No place but online to get parts so.... in the interim .. Enzo, I found these tests from GEOFEX to meggar the PT. I am a little confused on how perform these steps and want to do them correctly.
- Mon Feb 15, 2021 7:54 pm
- Forum: Guitar Amplifiers
- Topic: Peavey VTX Classic troubleshooting help
- Replies: 31
- Views: 10569
Re: Peavey VTX Classic troubleshooting help
I had switched scales on the DMM. When I'm on the 200V range the readings are 183, I switched to read both taps to the higher range (500V) I got 303 but forgot to go back to the individual taps and retake. The individual taps are 151 on the higher range. Why the difference? I have no idea.
- Mon Feb 15, 2021 6:22 pm
- Forum: Guitar Amplifiers
- Topic: Peavey VTX Classic troubleshooting help
- Replies: 31
- Views: 10569
Re: Peavey VTX Classic troubleshooting help
Readings were still 100V low with F1 removed and standby switch OFF. I'll check the website thanks Enzo, or taking it to the curb.
- Mon Feb 15, 2021 3:25 pm
- Forum: Guitar Amplifiers
- Topic: Peavey VTX Classic troubleshooting help
- Replies: 31
- Views: 10569
Re: Peavey VTX Classic troubleshooting help
It looks worse and worse for this amp as I wait for parts. F1 blew yesterday, I replaced it and so far it has not blown again. My heater readings are down to 5.7VAC, where they were a consistent 6.3VAC. My DMM had a low battery so I posted some erroneous readings yesterday, I've re-posted today. To ...
- Sun Feb 14, 2021 8:34 am
- Forum: Guitar Amplifiers
- Topic: Peavey VTX Classic troubleshooting help
- Replies: 31
- Views: 10569
Re: Peavey VTX Classic troubleshooting help
I took some more readings on the AC side of things on the power board. Seems I'm short of voltage there too.
- Sat Feb 13, 2021 7:16 pm
- Forum: Guitar Amplifiers
- Topic: Peavey VTX Classic troubleshooting help
- Replies: 31
- Views: 10569
Re: Peavey VTX Classic troubleshooting help
So looking for replacement parts for Q4/5 I can find MPS6530 and 2N3904 both from Mouser. The 2N3904 was suggested from another forum. I don't have a clue what the difference is between the two of them. Enzo the readings I took from Q6/7 left legs were indeed in DC as you speculated. I did run the p...
- Sat Feb 13, 2021 3:44 pm
- Forum: Guitar Amplifiers
- Topic: Peavey VTX Classic troubleshooting help
- Replies: 31
- Views: 10569
Re: Peavey VTX Classic troubleshooting help
I have a new set of tubes but I'm hesitant putting them in until I get a functioning preamp section.
- Sat Feb 13, 2021 8:22 am
- Forum: Guitar Amplifiers
- Topic: Peavey VTX Classic troubleshooting help
- Replies: 31
- Views: 10569
Re: Peavey VTX Classic troubleshooting help
The Q6/Q7 measurements were taken as referred to in the attachment. If you were facing the front panel they were taken on the left left leg. At the time I ordered parts I hadn't considered replacing Q4/Q5. Not a good move. Thanks for the reply Enzo.
- Fri Feb 12, 2021 9:07 pm
- Forum: Guitar Amplifiers
- Topic: Peavey VTX Classic troubleshooting help
- Replies: 31
- Views: 10569
Re: Peavey VTX Classic troubleshooting help
I've done some more research on other forums and found out some more readings to take. Q6 leg = 0.02 Q7 leg = 0.48 Junction of R119/C39 junction = 1.92 (R119 15v leg = 16.8V), R116/CR28 junction = 0.64, R127 = 1.27, R121/CR32 junction= 1.3, R136/CR37 junction = 1.05. The Q6 leg and R116/CR28 junctio...
- Thu Feb 11, 2021 10:43 am
- Forum: Guitar Amplifiers
- Topic: Peavey VTX Classic troubleshooting help
- Replies: 31
- Views: 10569
Re: Peavey VTX Classic troubleshooting help
I replaced Q6 and Q7 with MJE15030G transistors, powered up the amp and F2 immediately blew. Replaced the fuse, powered up, F2 did not blow, and then took some readings: Vi - V1 = 3mV V2 = 28mV Vk - V1 = 88.4 V2 = 89.8 Plugged a guitar in no loud hum but no sound. I took some more readings and came ...