Search found 428 matches

by dak
Sat Feb 10, 2024 5:42 pm
Forum: Bass Amplifiers
Topic: POP when switching on / off
Replies: 5
Views: 1484

Re: POP when switching on / off

That's more against switchoff bangs than pops and doesn't help with switch-on noises (unless we are talking about switching on immediately after switching off). Would need to look at the circuit diagram to see whether there is a good remedy.
by dak
Sun Feb 04, 2024 7:31 am
Forum: Bass Amplifiers
Topic: Max 112 bass combo hums
Replies: 19
Views: 5910

Re: Max 112 bass combo hums

Well I finally got ahold of Peavey, and Chris sent me the schematics, and is sending the diodes... he also told me to check a couple other things to check... all of which seemed to check out fine. I'm hoping replacing the diodes will get this amp off and running again. I hate stuff that doesn't wor...
by dak
Thu Feb 01, 2024 3:39 pm
Forum: Bass Amplifiers
Topic: Max 112 bass combo hums
Replies: 19
Views: 5910

Re: Max 112 bass combo hums

Rotorranch wrote:
Thu Feb 01, 2024 3:21 pm
Any idea what could have caused this diode to die in the first place?

Rotor
The way it looks to me, optimistic design may be partially responsible. Particularly so if some opamps were upgraded to ones with less quiescent current.
by dak
Thu Feb 01, 2024 3:38 pm
Forum: Bass Amplifiers
Topic: Max 112 bass combo hums
Replies: 19
Views: 5910

Re: Max 112 bass combo hums

D9/D10 probably don't have "values", they are diodes (and don't look like Zeners). Look like a standard 1N4148 to me. Now we might be getting somewhere. 1N4148... OK. What voltage and milliamp rating would be suitable? I have tried to contact Peavey multiple times with no results. Rotor Ok, a 5-min...
by dak
Wed Jan 31, 2024 3:56 pm
Forum: Guitar Amplifiers
Topic: Duel 212 intermittent output
Replies: 18
Views: 7633

Re: Duel 212 intermittent output

I guess I'm not going to get any help here... 🤔. So now I'm the proud owner of 2 Peavey amps I can't use... Oh well. Rotor This is a forum, not a repair shop. You already got help from several people, but any actual technical work will require a technician. You should try getting the schematics for...
by dak
Wed Jan 31, 2024 3:42 pm
Forum: Bass Amplifiers
Topic: Max 112 bass combo hums
Replies: 19
Views: 5910

Re: Max 112 bass combo hums

I tried checking resistance between the cable and the AC input ground, and got nothing... infinity. In other words, open. I pulled the head and looked for bad or broken solder joints, leaking caps, etc. and found a hot spot on board #2. Not sure if this is an issue or not. Any thoughts? Rotor I've ...
by dak
Wed Jan 31, 2024 3:31 pm
Forum: Bass Amplifiers
Topic: Max 112 bass combo hums
Replies: 19
Views: 5910

Re: Max 112 bass combo hums

D9/D10 probably don't have "values", they are diodes (and don't look like Zeners). Look like a standard 1N4148 to me.
by dak
Fri Dec 29, 2023 11:21 am
Forum: Keyboard Amplifiers
Topic: Opening a KB/100A
Replies: 2
Views: 2157

Re: Opening a KB/100A

Not seen a KB/100A in particular, but the usual procedure is to remove the 4 screws on top and 3 to 4 screws (however many there are) at the bottom edge of the backside amp panel. Then you carefully pull it out to the back (halfway out you'll need to unplug speaker connectors, possibly a reverb tank...
by dak
Wed Nov 29, 2023 8:11 pm
Forum: Keyboard Amplifiers
Topic: Replace KB60 ICs for reliability?
Replies: 1
Views: 895

Re: Replace KB60 ICs for reliability?

I wouldn't worry too much here. We are talking about a maximum of about 10mA per dual opamp idle current. How many are there?

But there may be better choices than the NE5532. In particular it does not seem a good match to high impedance signals with regard to noise current and input impedance.
by dak
Fri Oct 27, 2023 8:30 pm
Forum: Guitar Amplifiers
Topic: Soldered In IC vs socket
Replies: 8
Views: 2742

Re: Soldered In IC vs socket

Done. Let's hope that we can clean this distraction from this thread soonish...
by dak
Fri Oct 27, 2023 5:15 am
Forum: Guitar Amplifiers
Topic: Soldered In IC vs socket
Replies: 8
Views: 2742

Re: Soldered In IC vs socket

Let me check. OK, same here. Anybody an idea who to contact about this?
by dak
Wed Oct 25, 2023 4:48 pm
Forum: Guitar Amplifiers
Topic: Op-amp orientation
Replies: 21
Views: 4960

Re: Op-amp orientation

If you are worried about Q1 and/or the reverb switch logic, just short Q1's source and drain (the two pins without an arrow in the schematic) and the reverb will be always-on. I don't think that's where the trouble is likely to be.
by dak
Wed Oct 25, 2023 3:01 pm
Forum: Guitar Amplifiers
Topic: Soldered In IC vs socket
Replies: 8
Views: 2742

Re: Soldered In IC vs socket

dadroadie wrote:
Wed Oct 25, 2023 2:15 pm
I would post the schematic but for some reason I keep getting a warning any time I have tried to upload one lately.
Is anyone else having this problem?
I think you just cannot attach PDF files, so you need to print the respective page to a PNG file first (for example). Maybe it's that?
by dak
Wed Oct 25, 2023 11:31 am
Forum: Guitar Amplifiers
Topic: Soldered In IC vs socket
Replies: 8
Views: 2742

Re: Soldered In IC vs socket

Hi to all, I recently finished up my Peavey Backstage Chorus 208 ,( new Reverb chip,power supply caps, cleaning pots and jacks and everything sounds good so far. In doing the repairs I'm wondering if I might have made a mistake. All of the IC,s where installed with sockets with the exception of U2 ...
by dak
Wed Oct 25, 2023 6:43 am
Forum: Guitar Amplifiers
Topic: Op-amp orientation
Replies: 21
Views: 4960

Re: Op-amp orientation

Q1 (transistor?) according to the schematics is the black object below the IC in this picture I took a few days ago. it looks to be cocked to the left, maybe touching r25. I wonder if that could be it, stuck in the off state? I'll inspect it. https://ibb.co/x6Lf1Cj https://ibb.co/x6Lf1Cj JFET (junc...