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Dead 128K heatsinkUnfortunately my 128K heatsink died suddenly and with no apparent reason. I had the Kempston Pro interface connected and when i powered it on the ztx…
... current flowing through Tr4, thats why it gets hot. This (collector) flow ... current in the base of Tr4. Through R60/R61, these ... self-generated pulses that block Tr4, and more specificly the very ... rise of the current through Tr4 during powerup,
a ... -
Dead 128K heatsinkUnfortunately my 128K heatsink died suddenly and with no apparent reason. I had the Kempston Pro interface connected and when i powered it on the ztx…
... current flowing through Tr4, thats why it gets hot. This (collector) ... self-generated pulses that block Tr4, and more specificly the ...
Symptom: Short persists with tr4 removed
Action: Check tr5 ... .
Symptom: TR4 blows again
Action:
Issue 2 voltage troubleDear all, I got my hands on an old issue 2 from a friend. Price was close to zero so I did not hesitate to take it. After powering it up I was sur…
Just thinking: when so much power is leaking away that the voltage swing is too low (say a defect winding), then the oscillator will work to the max to restore the correct output. This then must result in a very hot Tr4.Issue 2 voltage troubleDear all, I got my hands on an old issue 2 from a friend. Price was close to zero so I did not hesitate to take it. After powering it up I was sur…
... to you. But TR4 is not getting hot or warm at all ...BeginnerIm having a go at fixing a spectrum which has been in the loft for 20 years and would like some advice please.... I have downloaded the 'spectrum se…
... the switch mode circuit, that Tr4 cannot be broken. The hissing ... culprit(s) might be getting hot. Or not.
In ...Colour blocks on displayHi all, I have just acquired another Sinclair product, my first one being a C5, it's a 48K ZX Spectrum. It shows colour blocks on the display when p…
... if I order a replacement TR4, TR5 & C46 I should ... /> Note: If you use the hot air method to remove the ...TR4 is goneMy TR4 transistor is burned. Can I replace this transistor with a TIP31B or C ? My 4116 RAM ic?s are showing +0.05V, +5V and +8.49V... :) My Spectru…
Yeah... replaced TR4 by a TIP31 again and... ... or 5), it got too hot.
I think the problem ...Help changing TR4 and TR5Hi all! Please, help me! :) I think I'm not understanding the correct pins of TR4/TR5 and the transistors. So, if anyone know the correct pins, help …
... TIPP31 and TIPP31 gets too hot! And I didn't have ... ]
Simplified workings: whenever TR4 gets conducting, a pulse via ... TR5 pull the brake. When TR4 stops conducting, the brake is ... is how TR5 helps TR4 oscillating. A hot TR4 could (could...) a.o ...Flashing coloured blocks - diagnosisHiya, hope this is the right place for this... Was given an Issue 2 48K by a someone yesterday that hasn't been powered on in 20 years, which works …
... that only show problems when hot, but I don't think ... your problem.
Transistors TR4 and TR5 are part of ...48k + Spectrum Issue 4S Display IssueHi all! Brand new user here. Growing up I had a zx spectrum for a little bit, and recently I have bought a working 48k + Spectrum (Issue 4). I was…
... on where I am.. took TR4 out and tested it. It ... .
Took the new TR4 out and it had blown ... have to replace both, the TR4 with another ZTX651, but will ... ? or was the fact that TR4 blowing a sign its something ... ? None of them are getting hot.48k + Spectrum Issue 4S Display IssueHi all! Brand new user here. Growing up I had a zx spectrum for a little bit, and recently I have bought a working 48k + Spectrum (Issue 4). I was…
... ? or was the fact that TR4 blowing a sign its something ... them are getting hot.[/QUOTE]
The next TR4 would be gone ...Repairing a torn trace on an Issue 2 PCBI've found what I think could be the reason for my Issue 2 board not working properly... There is a torn PCB trace beneath one end of where a new ULA…
... on TR4 ZTX650.
Faulty RAM chips rarely get hot - they ... to function. They CAN get hot sure, but they don't ...Some problems with 2 ZX Specturm board'sHi, last week i got some ZX Spectrum stuff. Also 2 ZX Spectrum 48K's, one in the orginal case the anoter one in a DK'tronixs case. Both have problem'…
... 9).
Usually replacing TR4 (ZTX650) with a ZTX651/2 ... ) that is usually measured when TR4 is blown.
3 ... spot-on, which means that TR4-TR5 circuitry is working somehow ... ZX, then look for very hot chips.Fixing my old ZX Spectrum 48K issue 4AHi Guys, I trying to fix my old Spectrum 48K. Looks like my dad used a wrong power supply as the ULA had a bit missing and so did the 7805. So I rep…
... /> I have noticed that TR4 runs very hot so I suspect I ...Fixing my old ZX Spectrum 48K issue 4AHi Guys, I trying to fix my old Spectrum 48K. Looks like my dad used a wrong power supply as the ULA had a bit missing and so did the 7805. So I rep…
Hmm, TR4 shouldn't be running that hot if lower RAM is (currently ... circuit formed by the coil/TR4/TR5.
BFixing my old ZX Spectrum 48K issue 4AHi Guys, I trying to fix my old Spectrum 48K. Looks like my dad used a wrong power supply as the ULA had a bit missing and so did the 7805. So I rep…
... ;776165]Hmm, TR4 shouldn't be running that hot if lower RAM ... circuit formed by the coil/TR4/TR5.
B[/QUOTE ...AAAARRRRR DIV-MMC ENJOY againIve recently been posting trying to get to the bottom of problems with my +48 not working with this rechid addon.Now ive finaly worked out theres not…
... bottom left has got so hot its actually burned my finger ... I don't know how hot it runs on this board ... like this do often get hot when working hard. (On ... that I referred to are TR4 (a ZTX650, but replace ... br />
The circuit that TR4 and TR5 are in, is ...ZX Spectrum 48K AV IssueOK so I dugout my old 48K Speccy today and decided to AV mod it. I did the mod (pretty easy) but the picture I am getting is this. [url=http://posti…
... a finger on TR4 to see if it gets hot) while monitoring ... is any sign of trouble: TR4 getting hot or the +12V supply ...Faulty 48+ Help NeededHi, This is what I get when I plug in the spectrum, this is tuned in. Vid shows a reset. Any ideas, or pointers on the first thing to check. Keyboa…
... next step is to replace TR4. Use a ZTX651.
It ... they are fitted near the hot heat sink.
A ...Hot plugable edge connector?Could the spectrum's edge connector have been made hot plugable without adding much to the manifacturing costs? I was thinking along the lines of a…
... /> - Power circuit stops oscillating, blowing TR4
- Without -5v and +12v ... would fail any definition of "hot pluggable" that I'm aware ...'Interesting' Issue 2 modSo I've been lurking on this forum for a while and I've got to the point where I want to see if I can repair a speccy.. so I bought me a 'broken' one…
... hot, that failed, short circuited their supply rails and took out TR4 ... in case).
Replace TR4 (again), test voltages to ensure ...'Interesting' Issue 2 modSo I've been lurking on this forum for a while and I've got to the point where I want to see if I can repair a speccy.. so I bought me a 'broken' one…
... the internal on-board inverter (TR4) which then caused the -5V ... /> Start by cutting out the hot DRAM chips...
Test ... or suspect DRAM chips. Replace TR4, and try again....
'Interesting' Issue 2 modSo I've been lurking on this forum for a while and I've got to the point where I want to see if I can repair a speccy.. so I bought me a 'broken' one…
... .
I also checked TR4 and TR5 as per the ... line with expecations:
TR4 - .633 & .695
TR5 ... 'upper ram' chips is getting hot too, if I just remove ...'Interesting' Issue 2 modSo I've been lurking on this forum for a while and I've got to the point where I want to see if I can repair a speccy.. so I bought me a 'broken' one…
... then needed is to replace TR4 to restore colour (the LM1889N ... (chuck the ones that get hot), get your supply rails back ...Issue 1 schematics?I'm fault-finding an issue 1 board. So far I've found a hot memory chip and snipped it's supply legs, then swapped the burnt-out 7805 for a switched…
For TR4 use a ZTX651 or a ... they are fitted near the hot heat sink.
You ...12V ripple with lower ram installedI repaired a speccy this week. Before doing anything I replaced all caps and measured the transistors in the power section. When doing this I found t…
C50 should not be warm. Are you sure about the direction of it? Could it be heated by any other hot part via the cupper layer of the PCB.
Are you sure that C7 is soldered right - minus at the collector of TR4, plus at the catode of D17?Toastrack - faint monochrome displayHi all, I've got a Toastrack with a video issue on both RGB and RF. I get a faint monochrome screen: on one LCD display it is predominately white,…
Sometimes the coil has been hot, and windings got interconnected due ... for testing, after a new TR4 gets hot within(!) a second, is ...Disabling the ROM without removing the whole thingHi! I've got my hands on a non-working issue 6a. I suspect the ROM may be bad, but other things may be faulty as well. I've read that in an otherwis…
... the voltages). Except TR5 and TR4: on diode mode, the multimeter ... . When the probes are inverted, TR4 showed OL, but TR5 gave ... don't know just how hot they run in normal situation ...Trying to repair a Speccy 48k - No PulsingI've had this machine for ages. I'd I've been putting off fixing it for some time now. So a couple of days ago I pulled it apart and started prob…
... blowed the TR4 and possibly also TR5. Remove the hot chip from ... the board, check the TR4 using a ...Trying to repair a Speccy 48k - No PulsingI've had this machine for ages. I'd I've been putting off fixing it for some time now. So a couple of days ago I pulled it apart and started prob…
... 4114 RAM that was very hot, but then I found another ... hot one and removed that also. ... I was also probing around TR4 and TR5 as you suggested ...
