Hartke HA5500

[Smokerx]

Hi, I have a Hartke Ha5500 that was blowing fuses. I traded the fuse out for a proper fuse from the schematic and it blew that fuse. I then replaced Q310 and Q314, as they tested bad and plugged it in with no limiting bulb or variac. The amp driver board then shot sparks and blew the fuse. I will attach a pic. Everything in Orange shot smoke out. Everything in Green Ive tested as good. Im thinking Im ready to plug it back in and see if it shoots more smoke.

[Smokerx]

I also am including the other side of the amp board Ive tested on.

[Smokerx]

Ok, I built a suicide cord. I guess Im going to try to find a 100watt filament bulb.

[DrGonz78]

Yup that’s the point of the light bulb limiter. It literally limits the number of times you have to replace fuses. If that lil light shines bright you have a problem. It will save you from yourself.

[Smokerx]

I think I rushed it hoping it was easy and just a wrong fuse type, then hoped it was just a few bad MJL21193 or 4 in those rows. When smoke and sparks started shooting out it was easier to diagnose. Now Im going to go real slow, realizing there might be a major problem Im not seeing and use a light bulb limiter. I think im running Tool schism at 12 watts? and I need bigger hammer ons.

- tested it and it did not throw the fuse with the amp driver board out. and only dimly lit a 60 watt test bulb. I think thats conclusive that the problem is on this amp driver board.

Really wish I had a variac and scope but it makes the cost of getting all the watts as uneconomic.

- I probed CN 103, that feeds the case fan, to get a DC voltage reading. As it looks like it passes across the power supply, portion and got a reading of 20 volts. Schematic says 24 volts DC. That doesnt appear to be wildly unacceptable that would cause alot of voltage to blow up the Amp driver board, In my opinion.

OK..EDIT:

I got the Amp driver board back in and mounted paying attention to what screws on that board might help ground the amp driver board to the case. I was hesitant, as I thought I might be making a mistake not just ripping and replacing all SC3200's But I powered it up with the amp power board installed, all switches and settings off and no speaker load and my current limiter light glowed medium on a 60 watt bulb. Then it did not let out smoke or sparks and the fuse did not blow. So I got it powering up to the point I can start measuring voltages and Bias or whatever.

PROGRESS!

is it possible that, on the first round, when I changed out the driver transistors it caused the weak components up stream to try to power it up so I caught whatever was causing them to blow watching those up stream components let out smoke? As Q310 and Q314 both bit the dust on the 2 previous power up attempts. First time it just blew the fuse and I replaced Q310 and Q314, hoping it would power up and work. But instead it blew Q310 and Q314 back out and verified bad components upstream by spitting smoke and sparking out.

Im super hesitant about pushing the power button right now. Right now I just have this ominous feeling if I plug a speaker load into it everything goes up in smoke again.

[Smokerx]

Ok I got too excited. With the amp driver board plugged in I get no voltage at the fan. So the current limiter light clicks on but neither fans nor power led receive enough volts to power on. Im not sure how to move forward from here. Find a bigger bulb for the current limiter light?

Ok I realized where I messed up. Its a 450 watt amp. So 60 watts glowing and the amp not powering up at all indicates nothing. I need a bigger bulb and said bruh, where you supposed to find a bulb that big? but I found a 300 watt incandescent, so will be picking that up.

[g1]

Bigger bulb will just allow more stuff to burn as it offers less limiting.
You are not running any power yet and should be running unloaded until everything checks out. Unloaded you should be able to work with the 60W bulb.
Measuring the AC volts across the 60W bulb will give you an idea of the current being drawn by the amp.

[DrGonz78]

I have 40, 60 & 100 watt incandescent bulbs. Those are all I have ever used and is all I need for a light bulb limiter. You never want a speaker plugged in on testing of solid state amps and no load until 0v on the output. Think about it this way. If you plug a 40 watt bulb between a perfectly working amp it will have a faint dim glow. As you change it to a 60 or 100 watt bulb it will glow dimmer as you increase wattage. Most of the time 100 watt bulbs will be so dimly lit that you barely see it. What this tells you is you are better protected with lower wattage bulbs. A 300 watt bulb might be just the same as plugging in straight to power.

[Smokerx]

I plugged in the 300 watt bulb and same situation happened. No voltage arrived to the case fan. The 300 watt bulb glowed bright. So I pulled the amp driver board back out and will start from scratch on verifying that boards components. With the 300 watt bulb on a 450 watt amp (500 watts according to the case) I read some things about current limiter bulbs, specifically that that would be what you'd expect to see from a 60 watt bulb and suggested I find a bulb closer to 75% to 100% the rating of the appliance I was testing. So went with it.

"Measuring the AC volts across the 60W bulb will give you an idea of the current being drawn by the amp." my guess is without a limiter the amp demands ALL OF IT...until it shoots smoke and sparks out and blows the fuse.

Heres my source on using the 300 Watt bulb before reading here that it should be able to power up with 60 watts.

"The 40-watt bulb glows very brightly and the radio doesn't play. This is not a sign of trouble—the bulb is simply too small, only a little over half the wattage drawn by the radio." ....This is normal behavior for a good radio when the wattage of the bulb is roughly the same as the radio's wattage.

If this 75-watt bulb shone brightly, rather than dimly, that would indicate a problem

https://antiqueradio.org/dimbulb.htm

[x-pro]

There are devices in which the power supply is switching. The topology of some switching power supplies is such that they do not start when the lamp is turned on as a current limiter.

[x-pro]

You are offered a 60W lamp to test the amplifier in static mode. That is, without a load and without a signal at its input.
And it is right.
Disconnect the power supply to the terminal amplifier. This is the CN105A connector. Either pull it out or unsolder pins 2 and 3.
You can then check to see if the rest of the unit turns on.

[g1]

Some guys want to test the amp into load running signal, that is when you need a higher power bulb. (or to use the radio, as in your quote)
That is for when the amp is already fixed, and is really kind of pointless.

For static tests on an unloaded 'broken' amp, you want a low power bulb like x-pro mentioned. It is used for protection and prevents blowing fuses or parts. The higher the wattage of the bulb, the lower the amount of protection.

[Smokerx]

It powered on with a 60w bulb shining dim with the CN105A unplugged I dont know what that means besides maybe I should start testing around where it enters the amp driver board from CON501, like test around Q319 and R351 and start looking into C401 and C402? That seems to be some completely separate power supply that whats driving the 24volt case fans. I kind of thought the problem was coming in from AN101 and maybe forming around Q301. Maybe thats because I dont know what Im talking about.Maybe the Filter caps at C401 and C401 blew short?

Yeah..I think its bad filter caps. I guess im back to square 1 with testing all over the Amp driver board but Tell me to disconnect at CN105A. Im thinking it might be those filter caps.

I got a B+ and B- Voltage of 139 volts entering the connection 501 at the Amp driver board (with the 60 watt bulb). Its not like they spec that out anywhere but this other guy said he got 95 volt. So that seems high and might let sparks and smoke out.

[Smokerx]

Maybe that isnt too hot since this guy is saying hes seeing 137volts at R317 and then the 90volts after it goes across the Amp board.
https://drive.google.com/file/d/0B6K..._-E3RFPWQ1NJuA

[g1]

The main filter caps C401 and C402 are shown as 100V caps. If that is true and you are measuring 139V on them they will explode quick and make a real mess.
There are several versions of the HA5500, so what someone has at R317 may be completely different. In this version you have, R317 would not be getting anywhere near the full B+ or B- on it.
This is a very difficult amp to service for a non-professional.