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Messages - Enzo

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1
Amplifier Discussion / Re: Hartke HA5000 tripping relay
« on: December 06, 2021, 06:02:58 PM »
You said it has to run 30 seconds before it trips.  Does that offset voltage slowly grow?  or is it just 0.2v high from the start?

The TA7317 circuit could be acting up.  The chip itself is usually reliable,  but I often find the little electrolytics are not.  The amp is what, 15-20 years old?  Those age.  Let us explore that.

There is a tiny negative supply to pin 1, with a little 1uf/50v cap.  That supply is a reference for the chip.  Off pin 7 is a teensy 0.47uf/50v e-cap.  and to the right is another 1uf/50v.  Those are always suspect whenever I chase shut off issues in these amps.  And when I replace those, I go ahead and replace the 470uf/10v and the 100uf/25v too.  All those are clustered around the 73317 IC on the schematic.

2
Amplifier Discussion / Re: Sears Transistor Part Numbers equivalents
« on: December 06, 2021, 03:30:44 AM »
As suspected, the outputs are 2N3055 under the skin.  NTE130 is the cross for 2N3055.

In all my years I have not seen a Sears to anyone cross ref guide.  The NTE book has been pretty much it.

Look on your schematic, someone noted TIP31 and TIP32 as the drivers.  I would believe that.  The 8534 part I believe is just a date code on the part.

The amp should be, well, "solid as Sears".  The power amp is a basic design taken right from the RCA books.

If you need preamp transistors, any general audio transistors NPN and 50v or better would work fine.  Low noise types even better.  The differential pair same thing but since the power rails are 75v apart, even though they idle at about 37v, more is likely, so higher voltage please.   Q5 can generally be the same as Q9.

3
Amplifier Discussion / Re: Hartke HA5000 tripping relay
« on: December 05, 2021, 07:04:28 PM »
Sure.  Power up with no load.  Allow the few seconds so the speaker relay clicks on.  Now, is there any DC voltage sitting on the output?   Something is off on the low side power module.

Bias?  Maybe, is the heat sink getting hot in that 30 seconds?   I'd just turn the bias to the coldest setting and see if it stays awake.  If so, fine tune it later.

4
Amplifier Discussion / Re: Hum increases with 3-prong cord
« on: December 05, 2021, 06:44:47 PM »
Usually is fine in general, but how about on the GSS100?

5
Amplifier Discussion / Re: Hum increases with 3-prong cord
« on: December 04, 2021, 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)

6
Amplifier Discussion / Re: Sears Transistor Part Numbers equivalents
« on: December 04, 2021, 02:24:34 AM »
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.

7
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.

8
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.

9
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.

10
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.

11
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.

12
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?

13
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.

14
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?

15
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.

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