collapse

Recent Posts

Pages: 1 [2] 3 4 ... 10
11
Schematics and Layouts / signal tracing
« Last post by Crich on December 06, 2019, 10:34:07 PM »
Trying to repair a fender FM15 DSP that blows the F2 fuse. Trying to use an audio probe but can't read schematics. very well. Need to trace signal from input to out put. Can anyone help me? I also think the problem could be in the DSP board but not sure the schematic even shows it. Would like to know how to bypass it if possible.  This is a learning project for me so don't need to buy another amp Thanks.I
12
The Newcomer's Forum / Re: Eight Audio Kit TDA7294 and TDA2050 from India
« Last post by Enzo on December 05, 2019, 08:10:57 PM »
That is what he means, but really, why not just insulate it like most installations, and then it doesn't matter if the heatsink gets grounded.   You can bolt the sink right to the chassis, which ads to the sinking.
13
The Newcomer's Forum / Re: Eight Audio Kit TDA7294 and TDA2050 from India
« Last post by laikairawk on December 05, 2019, 12:27:39 PM »
Thank for the reply.

By floating, do you mean the heatsink is not connected to any ground and just as it is. Attached only to the ics.
14
Amplifier Discussion / Re: The Dangers of Speaker Impedance Mismatching
« Last post by Enzo on December 05, 2019, 11:44:14 AM »
We are technicians, we need to know what the problem is.  "Goes bad" doesn't help.

A.  I have been an authorized Peavey repair center for over 30 years, and I have never seen one of their products so defective they fail en masse.  For that matter I cannot think of any brand like that.  Besides even if there were some systemic failure, it wouldn't happen to all of them at the same time.

D.  No.  Any solid state amp will run cooler on 8 ohms instead of 4 ohms, it puts out only half the power that way.  So no issues there.  I suspect the difference in sound is not the ohms, but the brand and model speaker.

C.  Cables and carpet?  No.

B.  Not likely.

I choose E.


One of these amps if fully repaired, should run about forever.
15
Amplifier Discussion / Re: The Dangers of Speaker Impedance Mismatching
« Last post by phatt on December 05, 2019, 03:28:27 AM »
"Amp going bad" is a very vague term.
Maybe explain the symptoms and folks here might be able to help you out.
I doubt the damping is an issue.
Phil
16
Amplifier Discussion / The Dangers of Speaker Impedance Mismatching
« Last post by looselectron on December 05, 2019, 12:33:12 AM »
Hello. New forum member here, and a proud owner of two of three Peavey Blazers. Why two of three? Well, I was so impressed by this little amp that I wanted another to use with for stereo delays. Unfortunately the second one I got for $12 didn’t work right. So recently I found a third for less than $50 which works fine...so far.

Unfortunately, the first one and the second one seemed to go bad at the same time which could be caused by:

A. Manufacturing defects... :duh
B. Using them together in stereo without proper grounding.  xP
C. Unplugged cables lying on a static-charged carpet.   :o
D. Swapping the stock 4Ω speakers in both each with an 8Ω Jensen C8R. :loco
E. None of the above.  ::)

Can we rule out D?

The data sheet for the TDA2040 suggests it will work fine with an  8Ω speaker, and indeed I found the amp sounded better that way.

OR could the speaker dampening circuitry in Transtube amps make it susceptible to damage?
17
Amplifier Discussion / Re: Gallien Kruger GT200
« Last post by gbono on December 04, 2019, 02:54:12 PM »
I substituted 2N6284 for the PMD1603. The trim pots have very little effect over the crossover distortion. I will look at this adjustment again. Also will look at voltages at base of Q7/8 and cathode end of D1/2.
18
Amplifier Discussion / Re: Gallien Kruger GT200
« Last post by g1 on December 04, 2019, 02:11:52 PM »
.05V across .33 ohms would be 150mA current through those output devices.
That sounds pretty hot.  I would not expect to see crossover distortion with that kind of idle current.
19
The Newcomer's Forum / Re: Eight Audio Kit TDA7294 and TDA2050 from India
« Last post by Jazz P Bass on December 04, 2019, 09:45:34 AM »
The rear tab on both ic's, both boards, is connected to the B- power supply.

If the heat sink is 'floating' and not at ground potential then there is no need to isolate the tabs.

As to bridge mode, I am not sure.
They appear to be stereo amplifiers.
20
The Newcomer's Forum / Eight Audio Kit TDA7294 and TDA2050 from India
« Last post by laikairawk on December 04, 2019, 08:34:43 AM »
Hullo,

I'm from India and have bought the two module from Eight Audio, a company here in India. Since i've purchased the pre-assembled board their website conked out and there is no support from their side. It didn't come with any schematic or paper. Just plain board. I have the following questions. Both of them cost approximately 12 us dollars.

1. Since both boards utilised two ICs, When fitting a heatsink, do i need to used washers/insulation?

2. Since both can be used in bridge mode. How to activate this?

Thanks
Pages: 1 [2] 3 4 ... 10

* User Controls

 
 
Welcome, Guest. Please login or register.
Did you miss your activation email?

* Recent Posts

signal tracing by joecool85
[Today at 01:57:35 PM]


Fender Mustang II v.2 by Enzo
[December 08, 2019, 04:46:37 PM]


Eight Audio Kit TDA7294 and TDA2050 from India by g1
[December 08, 2019, 03:11:47 PM]


The Dangers of Speaker Impedance Mismatching by Enzo
[December 05, 2019, 11:44:14 AM]


Gallien Kruger GT200 by gbono
[December 04, 2019, 02:54:12 PM]

* Sponsors