Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - Enzo

Pages: [1] 2 3 ... 136
1
Amplifier Discussion / Re: Hum increases with 3-prong cord
« on: Today at 02:28:00 AM »
The nature of the power amp output stages is not likely the issue.  When you added the third wire ground, exactly WHERE did you attach it to chassis?

And for that matter, is the hum 60Hz or 120Hz?  (Assuming you are in the USA or Canada.  50Hz or 100Hz in 240v land)

2
SIlvertone was simply Sears brand name for audio gear.  Sears and Silvertone are the same thing.  It doesn't matter who MADE the amps for Sears, likely DanElectro.  In any case, you apparently have the part numbers for them, so whoever owned that part number, look it up in NTE or similar to see what they would use.  It is a valuable clue.

Earlier amps may have used the driver transformer, but certainly the later ones did not.

DO you know the chassis number of that model?  Or post the schematic.

3
Amplifier Discussion / Re: Sears Transistor Part Numbers equivalents
« on: December 03, 2021, 05:22:11 PM »
Probably something common like 2N3055.

Use the Silvertone part number and go to the NTE web site and look up their cross.  It may not be exact, but it will tell you what NTE thinks the part needs to be.

If the amp is working, I'd leave them alone.  Transistors don't wear out like tubes do.

4
Amplifier Discussion / Re: Peavey Bandit as speaker cab
« on: November 21, 2021, 01:16:22 AM »
The speaker wires are less than a foot long, so size doesn't much mater.  18ga, 20ga, sure either is fine.

Positive and negative do not apply to AC, no, but the speaker wires are a hot and a return.  You do want to maintain that.  Usually in PV amps th yellow is hot and the blue is return.  WHen you switch, you want the yellow connected onto the + terminal of the speaker, and likewise the yellow connects to the tip of the jack in the other setting.

I;d use a big old toggle, not so much for current but for sturdiness.   ^a switches are common, so are 15A or 20A.  All those are 125v ratings (or higher).  Your speaker won't come anywhere near that.  PLus those ratings are what it can SWITCH, not what it can carry.  I sure hop you do not plan to flip that switch while cranking the amp.

Yes, I forget the size, but I had a drawer full of the speaker terminal size crimp on connectors.   You can also just solder the wires to the speaker.

5
Amplifier Discussion / Re: Peavey Bandit as speaker cab
« on: November 18, 2021, 05:04:29 PM »
Or mount a switch and a jack on a small panel.  Wire the speaker wires to the center posts of a DPDT switch.  Wire one end of the switch to the amp chassis, and the other end of the switch to the jack .   Now the switch selects th speaker to connect to either the amp or the jack.  NO possible way for the jack to connect to the amp.

6
Amplifier Discussion / Re: Peavey Bandit as speaker cab
« on: November 18, 2021, 12:26:16 AM »
Just my opinions here...

I don't like the output of the bandit on a male plug.  If it is not plugged into a jack, then it is just flopping around, and that tip could touch something grounded while the amp was unintentionally powered up.

The simplest thing is to put a cutout jack on the rear as others have suggested.  Use the Bandit as its own enclosure.

ALWAYS turn power off when connecting or disconnecting speakers.

Mounting bracket?  A piece of aluminum bent 90 degrees.  One flat surface gets a couple screw holes and is screwed to the wall of the cabinet.  The other flat surface gets a hole to fit the jack.

I recommend CLiff jacks.  They are all plastic so there is never an issue with the jack grounding itself.  Be aware that the cold side terminal of the speaker is NOT at ground in many SS amps, Bandits included.

Jack wiring?  On the Cliff jack, wires from amp chassis to the tip and sleeve cutout contacts, and the wires to the speaker from the tip and sleeve contacts.  That leaves normal operation.  PLug a remote amp into the jack and the amp chassis is disconnected and the outside amp connects to the speaker.

7
Amplifier Discussion / Re: 80's Era Roland JC50 blows internal fuses
« on: November 07, 2021, 03:59:03 PM »
Glad you got it.

Corroded?  Not likely.  Bent, way more likely.

8
Amplifier Discussion / Re: 80's Era Roland JC50 blows internal fuses
« on: November 06, 2021, 05:31:56 PM »
SO the amp works seemingly fine on speaker, I don't recall you mentioning the adaptor. 

Adaptors come in two styles:  stereo to stereo, and stereo to mono.  Any chance the 1/4" male end is just tip and sleeve, and has no ring?   In other words if you plugged your little adaptor ONLY into the phones jack - no ear phones - does that cause fuses to blow too?

If so, then plugging it into a stereo phone jack will short one side to ground.

Can you come up with a pair of headphones with a real 1/4" TRS plug, jst to try?

9
The bulb is intended for testing.  It lets you apply power to the system while protecting it in case of excess current draw, which lights the bulb instead of burning up the amp.   This process does limit the mains voltage some and that is a problem for operation.   But the bulb unit is not intended for operating the amp.  Once we know the unit will work without blowing fuses, we ditch the bulb.

Then there is the variac,  if you dial it up slowly, the amp passes through unstable periods at the reduced voltage.   and with a speaker load, it won't always settle down.

You worked on the amp, fired it up, and it worked.   Then oddly you decided to fix it some more and put it back under test conditions.   The amp works, now is the time to go over it and make sure no adjustments remain to be made under real operating conditions.

10
Amplifier Discussion / Re: 80's Era Roland JC50 blows internal fuses
« on: October 26, 2021, 07:46:45 PM »
OK, so don't plug in the phones any more.  Open it up.  Is there DC voltage on the phones jack?  Is anything loose inside that an inserted phones plug could make touch something else?

Do yoi have different phones to try?

11
Amplifier Discussion / Re: Remote channel/FX switch
« on: October 24, 2021, 01:02:47 AM »
Sure, there are other ways to get home.  I was addressing the OP question.  He apparently wants to design his own with these features.  I mean, how can I add a gain channel to my amp is a separate question from what pedal should I put in front of my amp.

12
Link worked for me, four pages.

13
Amplifier Discussion / Re: Remote channel/FX switch
« on: October 22, 2021, 10:52:14 AM »
Switching is simple, it was his desire to have a remote reverb level control that was a challenge.

14
Amplifier Discussion / Re: Remote channel/FX switch
« on: October 20, 2021, 10:05:11 PM »
RElays are clean, and can switch signal at 40mv or 40 volts  Relays let you control completely isolated from the signal path.  I have found them darn reliable over my decades.  I have replaced a few, but that is in thousands of amps. 

But I expect relays to be here a long long time.  DG419?   And when they stop making them?  Remember the useful TL604 that were used in large numbers in the 1980s?  GOne now.

Don't get me wrong, if you have a useful design based on them, go ahead.   I just didn't buy the backup argument

A common approach to using a FS and panel switch is to run them in series.  The FS jack between panel switch and ground, with its normal shunt completing the circuit when no FS is used.

A remote level control?  I'd hate to run the signal path outside the amp and back.  If you want to run a control voltage, you'd have to have a supply out to the FS, and make up a control circuit there.  VCA?  Would work, I don't know what is current in VCA chips.  On th other hand a simple digital pot would likely work too.

15
Amplifier Discussion / Re: First attempt to do upgrade
« on: October 07, 2021, 09:28:26 PM »
https://www.icollector.com/L-M-Sound-Reader_i9447359

A picture doesn't tell us much.   I am not even sure what the thing is.   WHat do you want to do with it?

Pages: [1] 2 3 ... 136