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Technical information
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Memories Of The TV Trade
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1971 Beovision 3200
1971 Bush CTV1120
Granada Television Brochure, 1970s
Long Gone UK TV Shops
Memories of a Derwent Field Service Engineer
PYE Australia Circa 1971
Radios-TV VRAT
Fabulous Fablon
Thorn TX10 Chassis
Crusty-TV Museum, Analogue TV Network
Philips N1500 Warning!
Rumbelows
Thorn EMI Advertising
Thorn’s Guide to Servicing a VCR
Ferguson 3V24 De-Robed
Want to tell us a story?
Video Circuits V15 – Tripler Tester
Thorn Chassis Guide
Remove Teletext Lines & VCR Problems
Ceefax (Teletext)
Suggestions
Website Refresh
Colour TV Brochures
1970s Lounge Recreation
CrustyTV Vintage Television Museum
Linda Lovelace Experience
Humbars on a Sony KV2702
1972 Ultra 6713
D|E|R Service “The Best”
The one that got away
Technical information
The Line Output Stage
The map
Tales of a newly qualified young engineer.
Tales of a Radio Rentals Van Boy
Sanyo SMD
Disastrous Company Rebranding
1969 Philips G22K511
Memories Of The TV Trade
Crazy house
Dirty TV screens
Dual Standard and Single Standard CTV’s
Radios-TV on YouTube
The Winter of 62/63
A domestic audio installation
1979 Ferguson Videostar Deluxe 3V16
Music centre modifications
Unusual record player modification
B&K 467 Adapters
Mishaps In The Trade
1971 Beovision 3200
1971 Bush CTV1120
Dynatron 1275A series - schematic or help!
Hi All,
I've got a Dynatron 1275A on the bench, with an amplifier module blowing fuses. It's a simple amp with a pair of BD103's as output.
There's a driver transistor, Q207 which is dead short. What is it (was it)? It's only markings are 1113 and a date code 7503
Any info greatly received...
Hi Andy,
I've got the data, I'll get scanned for you ?
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This web page claims to have a circuit but you need to join, I am not a member so cannot confirm if it’s correct.
http://www.diyaudio.com/forums/parts/218868-amps-1975-dynatron-1275a-quad-405s.html
The other thought is it a 2SC1113
https://www.el-component.com/bipolar-transistors/2sc1113
Frank
There you are a Chris to the rescue ? .
Frank
Data is now in the library
CrustyTV Television Shop: Take a virtual tour
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According to my data the driver is a 2sc1115 140/80V, 10A, 100W, 10MHz
eqiuvs are BD245D, 2N3442, 2SD551, 2SD1047, KT864A
Note: your fitted 2sc1113 120/100V, 6A, 40W, 10MHz
equivs BD243C, BD543D, MJE 15028, 2SD866, 2N6372, KT808A
CrustyTV Television Shop: Take a virtual tour
Crusty's TV/VCR Collection: View my collection
Crustys Youtube Channel: My stuff
Crusty's 70s Lounge: Take a peek
Dynatron started to use a peculiar mix of transistors in the 1970’s, being a Dynatron dealer we used to get exact replacements from them. I would have thought they would have stayed with Mullard seeing that they were all under the same umbrella company.
Frank
It certainly isn't a 2SC1113, as it's a TO-5 can (I should have mentioned that earlier!) The circuit diagram (thanks Chris and Frank!) shows a C1131 , which isn't a 2SC1131 either, as that's also a TO-66
So, the diagram show as an MA8003 as the complimentary TR206, which is :
Type Designator: MA8003
Material of Transistor: Si
Polarity: NPN
Maximum Collector Power Dissipation (Pc): 0.8 W
Maximum Collector-Base Voltage |Vcb|: 80 V
Maximum Collector-Emitter Voltage |Vce|: 60 V
Maximum Emitter-Base Voltage |Veb|: 7 V
Maximum Collector Current |Ic max|: 0.8 A
Transition Frequency (ft): 50 MHz
Forward Current Transfer Ratio (hFE), MIN: 100
Package: TO5
So all I need to find is the PNP equivalent 🙂 BC557 or similar...
Do the other transistor types in the circuit match the ones in the amp?
Edit, what transistors are in the other amplifier?
Frank
Like a dumbo, for years I used to wonder what "Ether Stereo" was on some Dynatron radiograms ....I used to think it meant "either" stereo or mono !!
Now the penny finally has dropped, it is of course stereo FM radio.....unless I'm mistaken. ?
To understand the black art of electronics is to understand witchcraft. Andrew.
I don’t remember seeing that label, still I was fixing the things. The more expensive amplifiers were decent but the less expensive ones ( notice I didn’t say cheap) were not that great in build quality but they sounded good.
Dynatrons in the 1970’s were sold for their cabinet, Queen Anne style etc. If one half the partnership wanted a Hi-Fi in the house, the cabinet had to suite the other partner.
I will leave it as which half was which.
Frank
Posted by: PYE625Like a dumbo, for years I used to wonder what "Ether Stereo" was on some Dynatron radiograms ....I used to think it meant "either" stereo or mono !!
Now the penny finally has dropped, it is of course stereo FM radio.....unless I'm mistaken. ?
Dynatron were very fond of the "Ether" prefix - it goes right back to the early 30s. Pity they became little more than Ekco/Pye/Philips in a posh frock in the end - enough to make the Hacker brothers start production under their own name shortly afterwards!
Posted by: NuvistorDo the other transistor types in the circuit match the ones in the amp?
Edit, what transistors are in the other amplifier?
Both amps are identical. It matches the circuit, except for that one number.
Any resistor burn up?
I am using my phone so not really able to look at the circuit. My iPad has been commandeered by the granddaughters and all have gone to birthday party.
If I get it back today I will check the circuit again.
Frank
Posted by: NuvistorAny resistor burn up?
I am using my phone so not really able to look at the circuit. My iPad has been commandeered by the granddaughters and all have gone to birthday party.
If I get it back today I will check the circuit again.
Nope. I'll dig out sensible PNP later if the workshop cools down and see what happens.
Excellent, presume just old age with the transistor going short then. Luckily nothing else got damaged, get one go and it’s very often a chain reaction.
They sounded very good, not classed as true HiFi but certainly a nice sound.
Frank
Turned out nice again
http://andydoz.blogspot.com/2018/07/sam-and-queen-anne-dynatron-1275a-series.html
I don’t remember there being a general problem with hum with these sets, not enough for customers to complain about, I do remember the slider controls gave problems though.
They were sold on cabinet design we had just as good or better products for less money but not with the same styling. Customers came into the shop specifically for the cabinets.
So has it pride of place in the house?
Frank
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