Is anyone intrested in helping me get an old peavey running?

[fenderstrat]

Have a 74 Peavey hybrid. have schematics. if anyone is interested I will upload some pics. The chassis is out of the cabinet. I have very limited knowledge so Hopefully whoever helps me will have patience

[Enzo]

Well which hybrid, PV made a number of them? And use the search function on this forum for your model name. He have ongoing discussions about the Heritage VTX, the Classics, even the VIntage if I recall.

[oc disorder]

This is the one with the table cloth possibilities Enzo.
Fenderstrat you could have kept it in the original thread anyway did you check the 1k 5watt ? It the one mounted at the back of the amp between the two capacitor terminals.
If you have had the amp on you may need to discharge the capacitors before measuring
the resistor as you alluded to in the other post.
A 1k resistor should do it to ground from both terminals.
Does the amp make any noise when on like hum or hiss ?
Need to suss out if its the pre or power amp.
But first base is the power supply .

[fenderstrat]

I checked the big cap with a volt meter and have a zero reading. I only see 1k 5watt between the 60/500 and 40/500 on the schematic but Having a problem locating it in the chassis. I read blueprints all day long and things are exactly how they are drawn but not scematics. anyway in the back of the chassis all I see is the on/off switch which has two black caps then the hole next to it which does have a resister on it getting no resistance reading on it and then theres the tube sockets to the left of that. I can do this its just hard to figure stuff out when the resistors have no numbers only the rings on them

[JHow]

I'd go for the big brown rectangular one on the right side of the board? Does it have the value written on it?

Oh no, wait, i spotted another large res on the tube socket.

[fenderstrat]

yeah 1k 5%

[fenderstrat]

I try an ohm test get no resistance

[fenderstrat]

[fenderstrat]

I think what I should probably do is to by a book to get a better understanding to the amp process maybe even a small amp build to further my knowledge. Its worth the time to me due to the amount of amps I have. I thank all who have tried to help.

[JHow]

Sorry if I steered you wrong. I just took a glance at your picture and saw only two likely candidates for a 5W resistor, but its hard to tell from a picture what is where. To be honest, you probably don't need to measure any resistors yet.

Anyway. Don't be discouraged. Everybody starts somewhere. Here is a good place to start if you haven't checked this out already. Go to geofex, look for the "Tubeamp debug page" and have a read through. New Page 1

THere are really good people on the board who can do this in their sleep, but bear in mind they aren't there with you, so it's all secondhand.

[fenderstrat]

Im not discouraged but I read a post here about one time posts and really was dissappointed that someone would write that. I am dissappointed because prior to them learning how to work on there stuff they were doing exactly what i am doing to learn. I bought this broken amp just so I could work on it and learn. I have 4 complete setups did I really need to buy a broken one. I have been to many tube amp sites and the first thing that pops out is WARNING this may kill you. I want to learn becuse I want to know what goes in my amps not what someone can save .20 cents on and put cheaper parts into my expensive equipment. I say to buy a marshall 410 for $2100 and bring it to a tek and hope for the best. Im a little bit more leary to that senerio. Im not giving up. If anybody wants to learn to be a cabinet maker ask away I have 30+ years experience WARNING you could cut off your hand with a table saw and bleed to death.

[fenderstrat]

I checked the power transformer that leads to the pc board with these findings meter set to 2k black-black .001 again set to 2k red-red/yellow .060 and heating winding green-green .000 what I think there calling the rectifier heating winding blue-blue yellow 22.5 set on 200 according to what I had read on the page listed above it should be under 10 ohms being over would indicate a bad transformer. my only question I have is do I have the settings on the meter set write for the last test or should it also Be set to 2k. one more thing is that when I did turn it on, the light on front did come on and the tubes did glow

[oc disorder]

Fenderstrat On the diagram between the two positive terminals of the dual capacitor is that 1k resistor the 5 watt one. I meant at the back not on the back. The one Jhow thought
was mounted on a tube socket.That is the one to the right of the tubes.
As I said in my previous post there is not a HT fuse thus if there is a problem with a short in the tubes (very common) its likely that resistor will burn out and will give no reading.
This will stop the amp working. Regarding the disclaimers and warnings from this end
looking at the screen I have no idea if you're a 13 year old or an 83 year old !
If I give advice thats leads to your demise particuarly if you were a 13 year old there is a possibility that the 13year olds parents may wish to commence litagation against the forum . The USA leads the way in this sorta stuff although its catching on here in Aust too.
Anyway if I understand you correctly "I try an ohm test get no resistance" that resistor is open circuit.I might add if there is any charge in the capacitors, that would upset your meter and give incorrect readings. I wasn't suggesting you discharge the capacitor to save your life , I was aware that it would affect the resistance readings.
By the way I did a Radio + TV course in the early 70's if that means anything.

[Enzo]

Oh sorry, I didn't put 2 and 2 together and recognize the amp from the other thread.


Let me say something here. When someone new comes along, and we don't know who they are or their skill level, we tell them this stuff is lethal because we don't want them getting hurt. Many times while working in a music store, one of hte salesmen would wander into the shop, reach over my shoulder and tap on some part in a chassis and ask, "What's this?" Well it could have been his death. A part with 600v on it looks no different from one with nothing on it. In no way is the safety warning intended as a slight, nor to scare anyone off. It is there to make people aweare there is danger that may not be obvious.

And I bet if a new apprentice came into your wood shop you wouldn't ignore safety glasses and the blade guards on the table saws. I would be telling a new woodworker to always use a push stick with the table saw to avoid losing fingers, you bet I would.


There is more than one kind of diagram in electronics. Schematics show the electrical relationship between parts. Wiring digrams (also called layouts) show the physical relationship between parts. The layout is the equivalent of a blueprint, it shows where things are located. Many times we only have the schematic. To a power supply, it doesn;t much matter where they put the resistor, as long as the two ends of it are wired to the other things that need it.


In this amp, the main filter caps are in that can cap upper right in the photo, and I'd wager the rectangular resistor sodlered betwen two legs of it is the 1k from the schematic.

However, I am getting a funny feeling. This amp is a Classic A series from the front, but the imnnards are looking like the B series, at least as far as the power suply goes. You have no standby switch, do you? Or is that power switch ON one way and STANDBY the other, center off? ANd looking at that resisto soldered between two terminals on the can cap upper right in the photo, does it have 1k or 1000 printed on it, or does it have either 390 or 400 printed on it? Also, there is a color banded smaller resistor to the third terminal. Does it happen to be colored blue-gray-orange, or gray-red-orange? I suspect this is a transitional form, and may be a little bit of A and a little bit of B. SO even if that is a 1k resistor, ther still is the other resistor which wouldn;t be in the A series.


If neither end of that 1k resistor has high DC voltage on it, then something basic is missing.


Maybe i am just getting old, but can you state exactly what we are trying to solve at this point?

As far as I can tell we have no high voltage. Is there any other sign of life in the amp? DO the tube heaters glow orange? Is ther any voltage in the preamp at all?

If there is no DC and no standby switch, then is there several hundred volts of AC between the red and red/yellow wire from the transformer?

[fenderstrat]

I understand the disclaimer not trying to sound harsh I Am beng very careful and even though I get a zero reading on any charge readings I still havent reached in and physically touched anything. First thing is enzo your right there is no standby It is either on or off for the power switch it actually is a three way switch off being in the center so in order it would be on/off/on. Next the 1k ceramic looking block has no reading across its legs. the resistor next to it which is orange grey orange also has no reading across it, but I would like to add that I was starting to go through every resistor and just see if I would get a reading across it and most I did but some I didnt Is there a film possibly on the legs of the resistors? , do I need to sand the legs lighty. and last I am trying to figure out whats bad there has to be a simple formula of tests that teks do to find out where to go when someone brings in there gear for repair. I havent done any tests with it plugged in only because I am not sure how to start the testing process

I know theres a positive side and a negative reading side. I can tell you I have been to 50 sites and they all have bits and pieces of the process but none of them have a step by step process such as of ( ok do this and your reading should be that then do this.....etc). So I guess what Im trying to say is I am trying to stay safe and also I dont want to make a mistake and possbly short out another part in the process. also I am not sure about switching it on with no speaker load on it