Hartke Schematics; any solid state guys out there?

[wizard333]

Anyone out there have a schematic for a Hartke 5000 bass amp?

Have one thats blowing fuses; current draw is enough to smoke my 10 watt current draw test resistor immediately if I plug the output (what passes for an OT and power amp) section into the B+; I've isolated it to that but not the component. Its a pc board with transistors screwed to a heat sink; hardly what i'm used to.

Solid state and transistors arent my thing but I agreed to take a look since I service the guy's tube amp. Any solid state guys out there have any ideas?

thanks!

[tim]

Near the back of the power module is a large 6 pin (I think) molex type connector. Disconnect that and then power amp up. If your 10 ohm resistor still "smokes" then it's probably the power tranny or the bridge rectifier. If it doesn't then its gotta be on the power module. It usually ends up being one or several of the power transistors. If you need a schematic, someone around here might have a pdf of one. I have a schematic but it's on a paper drawing and large so I can't scan it (even if I had a scanner). A call or email to Samson (they own Hartke now) might net you a schematic.
Good Luck,
tim

[wizard333]

Its a 1 ohm 10 watt resistor I use in series with an ac input to the amp so I can read current draw under different conditions not a 10 ohm.

I already did what you are saying but since that end is also connected to the speaker outputs and I didnt want to run the amp with no load, I disconnected it at the other end where it hits the main board by the filter caps. Provides the same effect since disconnected at one end is the same as the other, but it leaves the speaker load connected. I also separately checked the connect to the speaker load and the speaker output board; all that checked fine so there is no short there. Thats how I isolated it to the power section.

My next question would be, how do I check the power transistors in this thing? Assuming they are bad, whats a good source for replacements?

Thanks for the help, like I said I'm a tube amp guy this transistor stuff is foreign to me.

[Enzo]

Troubleshooting is troubleshooting. For example a shorted rectifier is still a shorted rectifier whether it is a tube or solid state. Either one will load down your power tranny. And so on.

First, solid state amps do NOT require a load. You can run a SS amp to ful output clip without a speaker and leave it running. In fact, in some cases, the amp can be putting high DC on the output, but only draws excess current when a load is strapped on.

As to unplugging the power amp module, even if a load was needed, if the power is removed from the amp module, it would no longer need the load since it was not powered up. But it doesn't need a load anyway, so just unplug it. If the amp draws excess with the module disconected than the power supply has problems. If the amp only draws excess with the module plugged in, then the module is bad.

If you isolated the problem that way to the module, then we search that.

Send me an email with Hartke 5000 schematic as the subject line and ask for it:

tmenzo at msn dot com

The power transistors are pinned out thus looking at their front, legs down: base, collector, emitter - B, C, E. No two legs should be shorted together. Most likely are E to C shorts, but anything is possible. All the same numbered ones on a side are in parallel, so they need to be removed to test completely. MCM has been a good source for me over the years, I have not been getting fake parts from them. DO NOT UNDER ANY CIRCUMSTANCES use the NTE or similar replacement parts.

The smaller driver transistors and other stuff are suspect here. And check for burnt resistors.

[wizard333]

Thanks enzo will shoot you an email for that schematic.

Definitely isolated to that section.

I realize that the functional areas are the same, but WHERE ARE THE POWER TUBES AND OT? LOL

If the transistors arent shorted can I assume they are good?

[Enzo]

Open transistors are rare. If they are not shorted, MOST of the time they are OK.

A shorted 6L6 will ground off the B+ and blow a fuse.

A shorted output transistor will ground off the supply rail and blow a fuse.

And there are a few SS amp they slapped output transformers into for one reason or another.

[wizard333]

Email Sent Enzo; should be there unless spam filter whacks it.

Thanks!

[Amp Kat]

And there are a few SS amp they slapped output transformers into for one reason or another.

We have them in our amps using class 2A wiring to convert 25 and 70 ohm outputs for long runs and transformer speakers for paging but I can't see an advantage otherwise unless for line outs 600 ohm matchers like on the MACE.
I can't stress more of what ENZO says about when any thing on that positive or negative drive and output circuit goes the rail voltage will be almost zero and when you find it and lift it out of the circuit the voltage will come back up saying there isn't an open resistor or another open component.

[Enzo]

Of course for CV lines, but I meant just dumb guitar amps. PV made a couple with output transformers. You could remove it and run straight easily enough, so I don';t know what advantage it provided.

No email yet, not in spam land either

[wizard333]

XXX right?

Will send again. Thanks again for the replies and the offer of the schematic!

[Enzo]

Yes, it got here today. will respond.

(I took the link from your post. It was correct, I just prefer not to leave it out there for robots to find and add to their lists. I hope you don't mind.)

[wizard333]

Finally got a schematic from Hartke. Here's what I'm seeing:

All the big power transistors look fine, no shorts

There are two smaller transistors on either side of the heatsink that seem to serve basically as drivers; if you look at the schematic Q310 (A1659A transistor) shows the following:

B-C: 398 ohms
B-E: 473 ohms
C-E: 76 ohms.

Q309 (C4370 transistor) shows the following:
B-C: 67 ohms
B-E: 41 ohms
C-E: 25 ohms.

Not exactly complete dead shorts but the readings are awfully low; very close to a dead short. I can't find the data sheets for those transistors online but looks to me like they both may be toast; what do you think? Unsoldered all the above to test them.

There are also some very small transistors on the board. Q305 reads as a short C-E, Q308 reads as a short B-C, C-E; Q312 reads as a short C-E. Didnt desolder those to test them but I dont see anywhere in the schematic that would have them show as shorted unless they were. The rest of the smaller ones looked ok.

Seems to me like a number of the smaller transistors on this power section went tits up, would you concur?

[Enzo]

I just Googled 2SA1659 and the first thing there was a data sheet. Same for 2SC4370. if those resistances wwere with the legs in the air, they're screwed.

There are two identical amp channels, so you can always compare readings. DOn't let a handful of screws deter you.

Replace any xstr seeming shorted. ANy xstrs exposed to the fault current path replace. And above all, look for open resistors. Like the one between the drivers - it goes from the bases of the outputs on one side to the other.

[wizard333]

Thanks for the reply!

A few questions:

When I googled them, a lot of things *saying* they were data sheets came up, but when you actually click on them and try to find a data sheet, you keep getting re-routed in circles around some korean electronic's company's site and can never actually get to a data sheet. If you were actually able to pull one up, could you post a url? I looked through about 10 google search pages of that sort of spam before I finally gave up. Sort of like when you search on some music products and all you get are sites that keep taking you to Musician's Friend, who dont carry that product.......

The big power resistors after those tested good but are you saying I should replace them as well?

I searched for those parts on the MCM site your recommended but they dont carry them. The only place I was able to find them listed are as "cross referrenced NTE parts" on Mouser's site, and on some Korean parts sites with no enlish translation. I'll see if Hartke can supply them (probably NTE from them to unfortunately).

[Rick Erickson]

Go to [www.datasheetarchive.com/]

When dealing with Japanese transistors, add "2S" in front of the part number. Axxxx becomes 2SAxxxx, same for Bxxxx, Cxxxx etc. Some European (British) parts are labled Cxxxx, and the prefix for these is usually "B". So for example a C149A would be a BC149A if it is European, or 2SC149A if it is from Japan. The codes can be confusing to someone not familiar with SS troubleshooting. Did anyone mention the importance of using both a Variac and/or a Series Lamp when powering up a freshly repaired SS amp? In order of importance, my vote is for the series lamp. It can save you a lot of time and money if something tries to smoke your output devices. Keep it connected until you are SURE there's no intermittent connections, bad components etc.. I use mine every day.

RE