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Power Amp module pic.
Hello great people,I have this new version of the Marshall AVT100 that need repair.
Can anybody that has repair this model tell me the value of R23(burned).
or better anyone with schematic that would help me..
Thanks
Had to look it up---- "Marshall AVT100 100W 1x12 3-Channel Combo with DFX. 100 Watts of Power plus 16 effects!!" Well looks like there are getting 100 watts out of two devices but it needs forced air cooling so typical Marshal fashion they are runnng the "sooooot" out of it. Looks like you have it apart, so now is the time to check the output devices because Ill bet they go by by. Post the numbers on the power devices. The problem with new equipment is that the manufacturer dosen't let the schematic loose on the public for some period of time. Is this your amp? or are you in the repair biz?
While we are here, what is Marshal's policy on shcematics? can you buy them? I'll bet you have to be an authorized repair shop to get schematics for the new stuff.
While we are here, what is Marshal's policy on shcematics? can you buy them? I'll bet you have to be an authorized repair shop to get schematics for the new stuff.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I am the repair busines,I am not keen to the let my client be slaughtered by the authorized service centers.I am qualified to repair and don't any manufacturer dispute this.
My moto is I don't support greedy manufacturer.haha
Help anyone??please.
Well Google is a wonderful thing. Sanken Electric SAP16 Transistor And here is a thread on repairing a HI FI that uses the same outputs.
http://www.diyaudio.com/forums/solid-state/135913-help-troubleshooting-blown-amp-sap16.html
I suggest you check check those transistors for shorts, and pull the burned resistors loose,. try to measure the value with a meter. Even though they are badly burned, you might be able to figure out what they were.
http://www.diyaudio.com/forums/solid-state/135913-help-troubleshooting-blown-amp-sap16.html
I suggest you check check those transistors for shorts, and pull the burned resistors loose,. try to measure the value with a meter. Even though they are badly burned, you might be able to figure out what they were.
So mabe this amp design is not so new.
Like 1999 2000 vintage. In this thread they post some schematics, but I think Marshal made a version with a diferent output section.
Marshall AVT100 Schematic
The schematics shown here are for the right model, but it calls out a TDA7293chip amp for the power section -- Id be tempted to look for just the power amp assembly for sale.
Like 1999 2000 vintage. In this thread they post some schematics, but I think Marshal made a version with a diferent output section. Marshall AVT100 Schematic
The schematics shown here are for the right model, but it calls out a TDA7293chip amp for the power section -- Id be tempted to look for just the power amp assembly for sale.
Id be tempted to look for just the power amp assembly for sale.
I know what youre thinkin,..wanting to make guitar amp ei?
I am thinkin the same too...haha
The TDA7293 module burnt up too often, they designed that small discrete power amp in its place. Look for the schematic for AVT100X or AVT150X. The X version has the later power amp.
R23 is 33 ohms.
Resistors do not burn up by themselves. I would wager my lunch money that TR9 is bad, and possibly TR10 as well. And it would not surprise me if other parts were bad.
R23 is 33 ohms.
Resistors do not burn up by themselves. I would wager my lunch money that TR9 is bad, and possibly TR10 as well. And it would not surprise me if other parts were bad.
I have measured the burned resistor,and it read 180ohm,feeling unsure then I have email Marshal through their site referring to technical dept.Still waiting for their reply and would see at this case to judge their corporation and support to 3rd party guitar tech like myself.
I know from experience that Marshall will tell you absolutely nothing. They'll just tell you to take the amp to an authorised repairman. UK manufacturers are very paranoid about giving tech advice to non-qualified people and Marshall wouldn't even advise me if JJ EL34 tubes were too tall to fit into a Marshall 50/50 power amp.
Thank you gilgy for sharing your experience,
Well a few days ago our local authorized Marshall Dist.in Malaysia emailed me the info and I am thankful,but they could not email me the schematic.
sometimes I think manufacturers think that they are the only ones who are so smart and every one else are stupid in electronics,
I have communicated with ENGL,RocktronUSA,and H&K they replied with full technical assistance,visit website like fender,carvin,vox etc.With downloadable schematics,They are not afraid to disclose those tech sheet(amps technology are not rocket science). Even they could see the possible added support,marketing promo and good words from us guitar tech worldwide.
I have been servicing amps(most times without support of a schematics) for 15+ years but when the need for help is required Marshall,Roland etc is not there,
So ungrateful of them,They forget unlike them(profit minded) we the tech are doing it because we love doing it,its favor to friends,to the community and for an extra income for daily survival.
I have come to a conclusion that these company are just here to acquire profit in sales and services to the highest level.
By the way Marshall,Roland
Where were you in the the 90's when my client needed you!If it wasn't for me a lot of your amp would just be paper weight here.
From now on I will support and give good promo to other companies that are not afraid and want to be ahead in market penetration.Those kind companies will even get free sales push from me.
Marshall,Roland and others,You have chosen to neglect us,keep it up and you'll be left behind.haha
Well a few days ago our local authorized Marshall Dist.in Malaysia emailed me the info and I am thankful,but they could not email me the schematic.
sometimes I think manufacturers think that they are the only ones who are so smart and every one else are stupid in electronics,
I have communicated with ENGL,RocktronUSA,and H&K they replied with full technical assistance,visit website like fender,carvin,vox etc.With downloadable schematics,They are not afraid to disclose those tech sheet(amps technology are not rocket science). Even they could see the possible added support,marketing promo and good words from us guitar tech worldwide.
I have been servicing amps(most times without support of a schematics) for 15+ years but when the need for help is required Marshall,Roland etc is not there,
So ungrateful of them,They forget unlike them(profit minded) we the tech are doing it because we love doing it,its favor to friends,to the community and for an extra income for daily survival.
I have come to a conclusion that these company are just here to acquire profit in sales and services to the highest level.
By the way Marshall,Roland
Where were you in the the 90's when my client needed you!If it wasn't for me a lot of your amp would just be paper weight here.
From now on I will support and give good promo to other companies that are not afraid and want to be ahead in market penetration.Those kind companies will even get free sales push from me.
Marshall,Roland and others,You have chosen to neglect us,keep it up and you'll be left behind.haha
The manufacturer doesn't know what your technical capability is and that is why the don't send schematics out they can then ensure their products are repaired to a good standard by there authorised repair departments. If you are confident in your ability apply to be an authorised service engineer that way you will get all the help you need.
And as you have already been told R23 is a 33R, R20 is an 18k, and R28 is an 8k2
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That's rather a hopeful statement
Lack of service information is more to do with restricting access to the data that any alledged 'quality of repair issues'.
As for 'applying to be authorised', that's EXTREMELY unlikely, assuming Marshall even do such a scheme?. Most manufacturers tend to have a small number of authorised agents (many of which are absolutely useless!) and it's all but impossible to get on their authorised list - with many manufacturers actually dropping existing ones.
Thank you,My apology if I offended someone that works for Marshall.I guess I am the only ones in this world that require a schematics for repairs every now and then.Haha
Honestly I guess I am not at that level of experience yet.Well there's always forum for help.
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We all need schematics now and then. It is not fair to a company to call them names and accuse them of thinking you are stupid just because you don;t agree with their documentation policies.
My shop is authorized for most major brands, and the factories supply me with the support I need. WHen I became a Marshall - or Peavey or Fender or whatever - repair center, they are not just taking my name and sending me schematics. Their name is on the product, so they have an interest in having it serviced properly. Their name is on MY work, by extension. If a local shop doesn't fix an amp right, the customer is going to think that his darned Marshall amp is bad, not that his amp is good but the shop is bad. The customer will think of his product as unreliable, not thinking that a different repair shop might have done it better. A company like Marshall then has determined that my shop will be qualified to do the work. I had a recommendation from a dealer that I be awarded the service center status to support their product sales. Marshall would want to see photos of my store and work ares to see what customers would see - they are not interested in sending a customer to some kid's basement workshop. And most companies want to see that you have been in business for some minimal period, for Fender it was at least a year as I recall. They want to know that your repair shop is a viable business, not someone they set up this week, and a month later has gone under. Fender has a tech exam you have to pass. They also don;t want to have too many service centers in one area. If there is already a MArshall repair center in an area, they don;t need to set up another to compete.
My shop is authorized for most major brands, and the factories supply me with the support I need. WHen I became a Marshall - or Peavey or Fender or whatever - repair center, they are not just taking my name and sending me schematics. Their name is on the product, so they have an interest in having it serviced properly. Their name is on MY work, by extension. If a local shop doesn't fix an amp right, the customer is going to think that his darned Marshall amp is bad, not that his amp is good but the shop is bad. The customer will think of his product as unreliable, not thinking that a different repair shop might have done it better. A company like Marshall then has determined that my shop will be qualified to do the work. I had a recommendation from a dealer that I be awarded the service center status to support their product sales. Marshall would want to see photos of my store and work ares to see what customers would see - they are not interested in sending a customer to some kid's basement workshop. And most companies want to see that you have been in business for some minimal period, for Fender it was at least a year as I recall. They want to know that your repair shop is a viable business, not someone they set up this week, and a month later has gone under. Fender has a tech exam you have to pass. They also don;t want to have too many service centers in one area. If there is already a MArshall repair center in an area, they don;t need to set up another to compete.
I have the same situation as above: R23 is burnt, I replaced it, and still hums like hell at the output, like a shorted output transistor. It seems they're ok, but I'm not pretty sure, I measured them and there was no problem. I'm thinking on trying a TIP142-147 pair with some mods (like the 0.22 resistor SAP16's have inside) and see what happens. I'm not able to find those SAP16's, only STD03's and they are a bit different, and quite expensive
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